PPT-1 L1-3 PPT-2 L4-6 PPT-3 L7-9 PPT-4 L10-12 PPT-5 L13-15
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# Master Ppt Uis

Nov 04, 2015

## Documents

NishitGarg

underwater
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• PPT-1 L1-3

PPT-2 L4-6

PPT-3 L7-9

PPT-4 L10-12

PPT-5 L13-15

• What is Underwater Intervention?

G T Reader Winter 2015 2

Underwater Intervention could be defined as the utilization of any form of vehicle, device or diving equipment that enables underwater missions to be accomplished.*

* Design Aspects of Underwater Intervention Systems, J G Hawley, M L Nuckols, G T Reader, I J Potter, Kendall-Hunt Publishers, ISBN 0-7872-1510-4, 1996 (Modified).

• Archimedes Principle and The Law of Buoyancy - 1

G T Reader Winter 2015 3

1. The above underpins the design and construction of all underwater intervention systems, especially underwater vehicles.

2. You will have already encountered these concepts in school physics and in undergraduate fluid mechanics/dynamics courses.

3. One way of stating the principle is: If an object is wholly or partially immersed in a fluid its weight appears to be reduced by an amount equal to the weight of the fluid it displaces.

• Archimedes Principle and The Law of Buoyancy - 2

G T Reader Winter 2015 4

4. If the weight of the fluid displaced is greater than the weight of the object, the object will have positive buoyancy (float); if the weight of the object is greater than the weight of the fluid the object will have negative buoyancy (sink), and if the two weights are equal the condition will be known as neutral buoyancy (hover).

5. These three conditions have important implications for the design and operation of any Underwater Intervention System.

6. You may also recall from your previous studies that the total weight of an object can be considered to act at an imaginary point called the Centre of Gravity* (G) whereas the weight of the fluid displaced acts an imaginary point called the Centre of Buoyancy (B). The relative location of G and B are also important factors in the design of underwater vehicles.

7. The fundamental concepts are well illustrated for a submarine in the following short video clip taken from a US Navy training film of many years ago.

* Physicists usually prefer the term Centre of Mass

• G T Reader Winter 2015 5

http://www.maritime.org/fleetsub/

Buoyancy and Ballast

• Further Fundamental Concepts - 1

G T Reader Winter 2015 6

1. Obviously we will not be able to design, construct, and manufacture a UIS if we cannot get the device to submerge under the sea surface. A UIS does not necessarily have to have the ability to float or hover but it is usually a distinct advantage (!) especially if the device is manned*.

2. The ability of a UIS to change its buoyancy is usually paramount. By changing its buoyancy the UIS can achieve vertical motion through the water column. This property is by itself put to good use in a class of UISs known as Profiling Floats 0r sometimes Argo floats. These ocean data collection devices of which there are over 3,000 deployed ocean-wide are used extensively in oceanographic research.

* A generic term covering both genders.

• Profiling Floats & Vertical Motion

G T Reader Winter 2015 7

http://www.noc.soton.ac.uk/JRD/HYDRO/argo/gallery/operation_park_profile.jpg

• Horizontal Motion - 1

G T Reader Winter 2015 8

1. The profiling float does also move horizontally but in drift mode i.e., as a result of theunderwater currents. In most cases we also require the UIS to be able to move horizontally in adesired direction and at a desired speed (velocity).

2. The desire for regulated and specified underwater* horizontal movement generally means we willneed some form of propulsion system for the UIS and if the underwater device is not reliant** ona power feed from the surface, an onboard power system and energy convertor.

3. In recent years a novel solution to the horizontal-vertical motion needs has been developed basedon the buoyancy engines of the profiling float and Archimedess Law of Levers. These UISs arecalled Underwater Gliders.

* Depending on the UIS we may also require horizontal movement on the water surface. ** Usually referred to as untethered.

• Underwater Gliders

G T Reader Winter 2015 9

Bing images

• Horizontal Motion - 2

G T Reader Winter 2015 10

1. If we wish to move the vehicle then we will have to overcome the resistance (drag) of the fluid to the movement. Simply stated the power required to move the vehicle will then be;

Power = Drag Force x Velocity (speed)

2. The drag force will depend mainly on the form and shape of the underwater body and the viscosity effects (skin-friction) of the fluid at the desired speed.

3. The drag force is proportional to the square of the velocity and hence:

Power Velocity3

4. These are two important relationships as they indicate that even a small increase in velocity will require a significant increase in power and a large increase in drag. Thus, to reduce the power requirement for a given speed the reduction of drag is a prime need.

5. The determination of drag forces is a complex subject.

6. Obviously a combination of vertical and horizontal motions will give us a wide-range of 3-D motions.

• Manned UIS Developments - 1

G T Reader Winter 2015 11

1. According to a number of ancient texts (Aristotles era) and more recent books from the middle ages, Alexander the Great of Macedon was one of the first to venture underwater in a vehicle. Although this cannot be proven, and it would be another century before Archimedes principle was formulated, it would appear that there is some evidence of submarine operations in these early times.

http://www.mlahanas.de/Greeks/UnderWater.htm

http://www.photolib.noaa.gov/bigs/nur09514.jpg

• Manned UIS Developments - 2

G T Reader Winter 2015 12

2. Whatever the voracity of the Alexander story it would be another twenty centuries before man ventured under the sea again, and the late 18th century before the construction of combat versions were developed Bushnells Turtle.

3. However, in just over two more centuries the largest and, at the time, most sophisticated was launched the Soviet Typhoon Class - a.k.a The Red October.

4. For almost the whole of the 20th century UIS development was in the hands of the military following the initial success of the German U-Boats in the 1914-1918 World War.

5. By the 1960s manned submersibles began to appear, as the military in particular sought to chart and characterize the deeper oceans.

6. The increasing electronic transparency of the oceans was one of the prime movers of the needs for scientific investigations and engineering advancements

7. The fundamental design principles have remained the same.

• Two Centuries of Combat Submarine Development

G T Reader Winter 2015 13

Bushnells Turtle of the American Revolutionary War.U.S. Navy photo & text courtesy of chinfo.navy.mil.

Soviet Typhoon Class

US Navy Ohio Classhttp://en.wikipedia.org/wiki/File:OHIOSSG

NCONVERSION.JPG

Nuclear Powered

Muscle Powered

• Relative Sizes

G T Reader Winter 2015 14

178m

Changzhou Tianning Temple Pagoda

Great Pyramid at GazaTyphoon & Ohio Class

German Type XXI -1945

HMCS Windsor RCN c. 1990

Holland

Turtle c. 1776

• The 21st Century

G T Reader Winter 2015 15

1. Despite the almost monopoly of the undersea environment by the military (except for fishing*) for many decades there has been an increasing focus on the underwater environment for non-military purposes especially over the past 40 years and in particular in this new millennium.

2. In some instances underwater activities over-lap between military and non-military uses. For example, the acquisition of basic scientific data on the structure and composition of the oceans and lakes is required for both purposes.

3. The need for the development of UISs, supporting instrumentation, and sensors has in turn lead to the requirement for the knowledge base of engineers, scientists, and technologies to become more common throughout their global communities via education programs and research activities.

4. There is then a growing need for more underwater engineers which will likely lead to an almost exponential rise in career opportunities as the 21st Century progresses and the emphasis on sustainable development becomes a key to the future health of the planet.

* Although fishing, commercial and recreational, is an underwater activity the operational and control of the endeavor is from either the surface of the sea or from land except for a few exceptions.

• Underwater Engineers & Technology

G T Reader Winter 2015 16

1. As yet there is no engineering discipline called underwater engineering.

2. However, in addition to Civil, Chemical (Petroleum), Mechanical, Materials, Electrical and Electronic Engineers, there are Ocean Engineers (relatively new), Marine Engineers, Naval Engineers and Naval Architects who are involved in what we can term underwater or subsea engineering.

3. As we shall see the involvement of System and Software engineers is becoming increasing important in the underwater environment.

4. As we need to know the physical conditions of the environment or realm under which we, as engineers, need to design, operate, and maintain the intervention systems then closer relationships with specialized professions/scientists, in particular oceanographers, hydrographers, and military strategists is crucial.

5. We also need to bear in mind that we must not repeat our historical ignorance of the sustainability of land resources and the environmental impact of human activity as we move increasingly faster to make greater use of the oceans.

• The Underwater Realm - 1

G T Reader Winter 2015 17

Oceans, Seas, Lakes, and Rivers:

Our Studies will concentrate almost exclusively on the Ocean environment.

There is really only one ocean and all its parts are interconnected but generally the parts have universally agreed names The Pacific (50% of the whole ocean), The Atlantic, The Indian, The Arctic, and the Southern (Antarctic & Sub-Antarctic).

The underwater workplace is defined by:

(a) Pressure, Temperature (horizontal and vertical), Density(b) Light and Sound characteristics. (c) Chemistry, Geology, Biology (d) Tides, Waves, Currents(e) 3 Dimensional Space

• The Underwater Realm & Essential Oceanography

G T Reader Winter 2015 18

1. Oceanography is the name given to the study of the oceans.

2. There are four main oceanography sub-disciplines: Geological, Physical, Chemical, and Biological.

3. While all the sub-disciplines are of interest to underwater engineers it is Physical Oceanography the study of ocean currents, waves, tides, wave circulations, and the air-sea interface - that provides much of the realm data we will need in the design of the Underwater Intervention Systems.

4. An excellent website dealing with many aspects of physical oceanography can be found at the University of Texas A&M http://oceanworld.tamu.edu

5. The oceans are usually defined in zones and layers and the interchange of the some of the terminology can lead to confusion at times.

• Ocean Zone Terminology

G T Reader Winter 2015 19

http://www.srh.noaa.gov/jetstream//ocean/oceanprofile.htm

• The Underwater Realm - 2

G T Reader Winter 201520

1. We live on the planet Earth yet over 70% of its surface is covered by the Ocean(s) which contain almost 1.4 billion cubic kilometers of salt water.

2. Relative to sea-level the oceans are much deeper than the land is high.

3. Only 11% of the land is above 2,000m (6,561 ft*) whereas 84% of the sea bottom is below 2,000m**.

4. Forty times more CO2 is stored in the oceans than in our atmosphere*** .

5. Most of the O2 in the atmosphere comes from the Oceans***.

6. The oceans contain 97% of the planets available water.

* 6561 ft 85/32 in

**G L Pickard and William J Emery, Descriptive Physical Oceanography: An Introduction, Pergamon Press, 1993, 6th edition, 2011 with L D Talley & J H Swift.

*** http://oceanworld.tamu.edu/home/key-concepts.html

• The Underwater Realm - 3

G T Reader Winter 2015 21

7. Sea water is 832 times denser than air and sounds travels over 4 times faster.

8. The air (atmospheric) pressure decreases with increasing altitude such that at the top of Mount Everest (29,029* ft 8,484 m) the pressure is about 0.3 of that at sea level. In the deepest place in the oceans Challenger deep (35,755 36,201 ft** or 11,034m) the water pressure is almost 1100greater than at sea level.

9. A rule-of-thumb is that water pressure increases about 0.44 psi per foot or 1 atmosphere (101.325 kPa) per every 10 metres.

10. Thus, at the bottom of the Challenger*** Deep the pressure is equivalent to about 250 elephants per ft2 or 16,000 psi.

11. So if we wish to operate below the water surface, even at modest depths we will need to be aware of the engineering of pressure vessel design.

* Measured as high as 29,035 ft ** Various Sources *** Named after HMS Challenger British Royal Navy Ship

• G T Reader Winter 2015 22

The Underwater Realm 3a

This file is

the Creative

Commons

Share Alike 3.0

Unported

Kmusser

• The Underwater Realm - 4

G T Reader Winter 2015 23

• Underwater Realm - Density Variations

G T Reader Winter 2015 24

It has been stated previously that the density of water is many times that of air. Just how many times depends upon whether the water is fresh or salty and the depth of operation.

The most important dynamic property of sea water is its density (). Density is generally calculated from the equation of state of sea water*, which is expressed as a function of temperature (T), salinity (S), and pressure (p). Typical values of surface oceanic density vary from 1020 to 1030 kg/m3 (63.7 - 64.3lbm/ft3).

Differences in water density can significantly affect the operation of any underwater work system -such as a submersible - which uses water tanks for ballast and depth control purposes. For example, the buoyancy effect per cubic unit of an empty ballast tank varies with the density of water around it by as much as 2.57o between fresh and salt water. Thus, an underwater vehicle designed for salt water operation will be more negatively buoyant and operate shallower in fresh water, which is not as dense. As with temperature and salinity, density-depth profiles are given a 'cline' name, in this case pycnocline.

* A new equation was proposed in 2010 by an International Committee. The equation has to be solved by advanced numerical analysis.

• Underwater Realm Density Variations & Layering

G T Reader Winter 2015 25

As with temperature variations the ocean waters can be divided into three density layers: the less dense top layer the surface mixed zone; the pycnocline zone, just mentioned, is a transition zone between the surface mixed

zone, and the bottom layer where the water remains cold and dense.

The pycnocline is a major controlling element within the ocean system as we shall now seein a recent video from the Scripps Institute of Oceanography by Professor Peter Franks. Theinformation contained will also be useful background for our study of Tides, waves andcurrents.

• The Underwater Realm - Temperature

G T Reader Winter 2015 26

1. As engineers we know that the thermodynamic property we call temperature effects many phenomena we have to deal with including ; a. physical properties of materials including the physical properties of materials including the phase, density,

solubility, vapor pressure, thermal and electrical conductivity, and so on.b. chemical reactions and the extent to which they occur and the rate of such reactions.c. the amount and properties of thermal radiation emitted from the surface of an object (Stefan-Boltzman Law).d. speed of sound ( which as we will see plays a crucial role in underwater communications).e. The efficiency of energy conversion and so on.

2. Ocean surface temperature is effected by the amount of solar radiation it receives, as illustrated in the next slide. As can be implied from the diagram, the water surface temperature at the poles is lower than that at the equator.

3. The surface temperature also effects the ocean water circulations and global weather patterns (El Nio).

• Global Net Surface Radiation Annual Means*

G T Reader Winter 2015 27

Oceanworld.tamu.edu modified from Kallberg et al, 2005 * Averaged over a 40 year period

• The Underwater Realm - Vertical Temperatures

G T Reader Winter 2015 28

As can be seen the solar heating effect only extends to a relatively shallow depth even in the low latitudes either side of the equator.

A thermocline is a zone in the ocean where temperature changes dramatically with depth.

• The Underwater Realm -The Oceanic Temperatures Layers

G T Reader Winter 2015 29

Hawley et al, Op Cit,1996

Precise knowledge of the properties of layers is a major requirement for both stealth and detection

In the deepest parts of the ocean

the temperature is nearly uniform with an average

metre.

• The Ocean Realm - Salinity

G T Reader Winter 2015 30

1. Salinity is essentially the saltiness of the oceans and seas relative to what we term freshwater*.

2. How to precisely define salinity (S) has been a problem for oceanographers for over a century but for our purposes we can say it is the total amount of dissolved solutes or "salt" in the water. lt is the total weight of solid material (in grams) found in I kilogram of sea water. The salinity is commonly expressed in grams of solids per kilogram of sea water or parts per thousand (ppt), which can be abbreviated to o/oo.

3. The amount of dissolved salt present is largely controlled by (a) evaporation and precipitation in open ocean regions, (b) fresh water runoff in coastal zones,** and (c) ice formation, sublimation, and melting in polar regions. Salinities of between 0 to 30 are found in estuaries and polar regions, typically 30 - 34 in coastal regions, and in the open ocean salinities are in the range 33 37 .

4. Salinity-depth profiles shown on the next slide also have a cline name haloclines.

*Salinity is usually less than 0.5 ppt: ** The Black Sea is so diluted by river run-off that its salinity is only about 16 on average.

• The Ocean Realm Salinity Haloclines

G T Reader Winter 2015 31

Of all the oceans the North Pacific is the least saline and the North Atlantic the most saline. As with temperature, there is a surface mixed layer where salinity is sensibly constant but below this, at about 200 m, a strong halocline develops. There tends to be a salinity minimum of around 800 - 1000 m at mid-latitudes

• The Ocean Realm - Salinity

G T Reader Winter 2015 32

1. We often think of the salt in the sea is solely sodium chloride (NaCl) but that is not the case as the table on the left shows.

2. Salinity is very difficult to measure directly and so the usual procedure is to measure the conductivity of the water which can then be related to salinity through an International

agreed set of equations. 3. Sea salts decrease the freezing point of water*

and the speed of sound increases as salinity increases.

4. Ice formed from seawater is fresh and does not include salts. Most sea salts are composed of 11 particular ions and compounds

and their composition has remained nearly constant for millions of years the so called steady state or kinetic principle in Chemical

Oceanography*. *W Corso & P S Joyce, Oceanography, Applied Science Review, 1995, ISBN 0-87434-608-8

• But the Oceans contain more than Salt

G T Reader Winter 2015 33

A typical yet largely unknown example is Uranium*:

It takes 1200 tonnes of U to power a 5 GW power plant for 1 year

At the current consumption rate the global conventional reserves of uranium (7.1 million tonnes) could be depleted in 100 yrs

Uranium in the ocean (3-3.3g/L3) is estimated at 4.5 billion tonnes!

* Data Given by Alexander Slocum, Pappalardo Professor of Mechanical Engineering, MIT at OSES Conference, Windsor, Ontario July 11, 2014

• Underwater Realm Chemical and Biological (Oxygen Factors)

G T Reader Winter 2015 34

1. The chemistry of the oceans is very complex and continues to be a major focus of scientific research. Of the manychemicals, oxygen is one of the most, if not the most, important as some 45-85% of the oxygen in the atmospherecomes from the oceans.

2. Most of this oxygen comes from tiny ocean plants called phytoplankton that live near the waters surface anddrift with the currents. Like all plants, they use sunlight and carbon dioxide to make food a process we callphotosynthesis. A byproduct of the process is oxygen.

3. However the amount of oxygen dissolved in water is typically less than 0.001% whereas in air it is approximately21% (by volume).

4. Dissolved oxygen plays a pivotal role in UIS designs and operations, especially in manned operations. Humansuse their lungs to extract oxygen from the environment. Underwater the amount of water we would have toprocess to extract sufficient oxygen is beyond the surface area of our lungs and requires more power than thehuman body can generate. This is a major obstacle to human activity underwater, so UISs must carry their ownoxygen supplies. However, our bodies are every sensitive to oxygen levels and at certain levels we will face deathfrom oxygen poisoning*.

* If a human breathes 100% oxygen then at a depth of about 20ft, oxygen poisoning would occur.

• Underwater Realm Chemical and Biological the roles of Oxygen

G T Reader Winter 2015 35

1. Fish use gills to extract the oxygen but even they have to expend a great deal of energy and process large quantities of water in the extraction process. This may then be the reason that fish are cold-blooded.

2. So far, unsuccessful efforts have been made to develop artificial gills for humans but the use of different breathable oxygenated liquids has shown more promise*.

3. Apart from manned missions requiring an onboard, synthetic, breathable atmosphere containing oxygen a key design feature there are also other effects of dissolved oxygen which will impact UISs.

4. Oxygen also plays a pivotal role is ocean-sea health as we shall see.

* A fictional version was used in the James Cameron Film, The Abyss, to allow a diver go to extreme depth.

• Underwater Realm Chemical and Biological Corrosion and Oxygen

G T Reader Winter 2015 36

Work site chemical and biological conditions become important if the intervention systems remain on-site for extended periods or are not properly cleaned after each operation. Careful selection of materials, especially those which are contiguous, is crucial to prevent galvanic action and resultant corrosion. The US Navy, for instance, in the 1990s estimated its annual economic loss due to corrosion failures at over \$5 billion.*

Steels are still used extensively in underwater systems and their rate of corrosion in water is governed by the dissolved oxygen content. The amounts of dissolved oxygen and other elements vary with depth and location within the sea, and these must be known if the designer is to forecast the potential for material rust or decomposition. The amount of oxygen dissolved in sea water may vary from 1.0 to 8.0 mL per L as shown in the next slide*.

* Citied in Hawley et al, 1996, Op Cit.

• Underwater Realm Chemical and Biological -Biofouling

G T Reader Winter 2015 37

Corrosion may also be initiated by the attachment and growth of bacteria and other marine organisms. The biological processes associated with such organisms also affect the concentration and distribution of oxygen in the oceans. Metallic interfaces and surfaces provide sites for microbial activity and biofouling can occur at many different depths being depending on the physical characteristics of the individual site and the type of local organism. Biofouling can have very adverse affects on underwater work system operation by causing the impairment of optical and acoustic surfaces, the choking of intakes, and the obstruction of rotating surfaces. The problem of biofouling removal has been perennially expensive for the maritime communities, but in more recent times some technological advances have been made by trying to prevent rather than remove the bio-growths*.

* Citied in Hawley et al, 1996, Op Cit.

• Underwater Realm Chemical and Biological Negative Oxygen The Baltic Example

G T Reader Winter 2015 38

http://www.smhi.se/en/theme/oxygen-in-the-sea-1.11274

While surface water is usually saturated with oxygen in deeper waters the oxygen is consumed when breaking down the organic matter that sinks from the surface. The oxygen in deep water comes from the vertical mixing of the ocean layers or from the addition of new water brought to the area by ocean currents. In regions with poor water turnover such as the Baltic Sea, dissolved oxygen levels sink to 2 or less ml/l. As the oxygen is used up, the organic material continues to break down, as bacteria use the sulfates as an oxygen source, producing hydrogen sulfide which is poisonous to all higher organisms, and leads to dead zones on the sea floor. In these situations the term "negative oxygen" is used, corresponding to the amount of oxygen needed to oxidize the hydrogen sulfide.

• Underwater Realm Light Penetration.

G T Reader Winter 2015 39

Euphotic Sunlight ZoneDisphotic Twilight ZoneAphotic Midnight Zone

1. The Sunlight Zone extends from a few cm to a maximum of 200 metres depending on location and state of the water. Its thickness is defined by the depth beyond which less than 1% of sunlight penetrates. It is considered that about 90% of marine life lives in this zone which supports photosynthesis.

2. Almost no light penetrates to the Twilight Zone and photosynthesis is not possible although there is some marine life*.

3. The Midnight zone starts at depths of about 900-1000m and includes about 90% of all the oceans. It is in permanent darkness. We now know that there is marine life in this zone such as the vampire squid**.

* In 1854, the scientist Edward Forbes proposed that no life existed below 600m. (He was wrong)** A very small animal about 25 cm long, with large red eyes and a cloaklike appearance hence the name.

• Underwater Realm Light Penetration 2

G T Reader Winter 2015 40

1. As was shown on the previous slide the wavelength of particular constituent of the visible light determines its penetration into the oceans. The shorter wavelengths penetrate deeper with blue light* going the deepest. If the water contains solid particles for example in coastal areas and river estuaries these effect the light penetration and water appears brown or green in colour.

2. Most of the visible light spectrum is absorbed within 10 m of the surface and only a tiny percentage ~ 1% , reaches below 150 m at best.

3. This general lack of light penetration even in the clear open oceans means that we cannot see where we going.

4. The lack of optical visibility then presents a serious challenge to the use of oceans by humans. However it has produced a similar and perhaps more serious problem to the oceans and deep waters in general because of a invariable out-of-sight, out-of-mind societal attitude. Thus the dumping of waste materials of every conceivable type and cavalier fishing techniques have until recently continued without thought or indeed

knowledge of the consequences because we cant see the effects.

* This is why the deep ocean water and some tropical waters appear to be blue .

• Underwater Realm Light & Sound Communication, Navigation, Data Collection

G T Reader Winter 2015 41

1. The lack of light penetration in water has important ramifications for UIS design and operation for it means we cannot see to navigate or to avoid obstacles. It can then provide unwanted stealth. In shallower areas the spectrum of light penetration can however provide the basis for the colour(s) of submarine hull camouflage, e.g., a green painted hull rather than the more traditional black.

2. In recent years the technological advances made in opto-electronics has enabled consideration of using light e.g., lasers and high brightness Blue/Green LED sources for underwater communication and navigation, at least over short distances*.

3. The submarine and radio telegraphy were initially developed in the early 20th century. However there was no marriage of the two technologies because radio waves are severely attenuated in water. Although Extremely Low Frequency (ELF) 3 to 300 Hz radio waves can to some extent penetrate water, in essence radio communications and Radar are virtually useless underwater.

* See for example Study of Land-To-Underwater Communication by Yoshida et al, 2011 and The Role of Blue/Green Laser Systems in Strategic Submarine Communications by Wiener et al, 1980 full citations on CLEW site.

• Underwater Realm Sound & Acoustics Communication, Navigation, Data collection

G T Reader Winter 2015 42

1. Sound travels much faster* in water than in air and more efficiently than light; and it can penetrate the deepest parts of the oceans.

2. Like light, sound is absorbed (attenuated) by water, especially at the higher frequencies, but the speed of sound increases with increases in salinity, depth (hydrostatic pressure), and temperature, with the latter two being the primary controllers of sound transmission. The sound speed is also related to the frequency(n) and wavelength() of the sound by the usual wave equation, c = n.

3. The wave equation and the equation relating the speed of sound to the physical conditions give us the basis for the use of

underwater acoustics for navigation and data collection.

* 1500 m/s compared to 330 m/s under equivalent conditions

Sound speed as a function of depth ata position north of Hawaii in thePacific Ocean derived from the 2005World Ocean Atlas.

• Underwater Realm Sound & Acoustics Communication, Navigation, Data Collection

G T Reader Winter 2015 43

1. The British used the echo-sounding concept which they called ASDIC to locate German submarines in the 1914-1918 war. ASDIC is now more commonly known as SONAR.

2. SONAR then is the water equivalent of RADAR, although echo-location can also be used on land for navigation and location purposes.

3. Nevertheless early submarine communication was by wireless telegraphy using Morse code. These submarines which more accurately should be called submersibles would be at or close to the sea surface when receiving the signals through an antenna (aerial). Communication was essentially one-way because of the limitations of vessels transmitter-antenna systems. Even so by the 1920s* low frequency (16 kHz) signals could be sent to submerged submarines over a range of 3,000 miles (4,800 km) at a depth of just of 6m (21 ft.).

4. So why the need for acoustic communications?

* D F Rivera & R Bansal, Towed Antennas for US Submarine Communications: A Historical Perspective, IEEE Antennas and Propagation Magazine, Vol 46, No 1, p 23- 36, Feb 2004.

• Underwater Realm Sound & Acoustics Communication, Navigation, Data Collection

G T Reader Winter 2015 44

1. As Sonar (ASDIC) and Radar became more sophisticated in the 1940s it was dangerous for submarines to go to the surface to check communications and their location. However they had been designed for the majority of their operations to be on the surface.

2. Radar became increasingly effective and it was possible to detect a submarines snorkel mast which is used to allow it to stay below the surface for longer periods of time.

3. The advent of the nuclear powered submarines and passive (listening) sonar resulted in the need for two way communications and deeper operations to become crucial, if the vessel was to retain its stealth but also receive operational orders especially during the so called Cold War.

4. Although submerged radio wave communication was improved by the development of towed array antennas the depth at which communication was possible was still very limited. Accurate submerged navigation now became a problem, compounded by the lack of knowledge of underwater topologies.

5. All these factors lead to investigations and development in underwater acoustic systems.

• Underwater Realm Sound & Acoustics Communication, Navigation, Data Collection

G T Reader Winter 2015 45

After over 70 years of investigations and development on Underwater Acoustic Signal Processing the work continues. At the recent IEEE Workshop on the topic, held in October 2013 at the University of Rhode Island, the intent was to review theoretical and experimental research at an early stage of development*. The areas of particular interest were:

1. Adaptive processing in non-stationary interference 2. Detection, localization or tracking, and classification 3. Underwater acoustic communications 4. Marine mammal related acoustic signal processing 5. Multistatic sonar signal processing 6. Performance analysis for active and passive sonar 7. Physics-based signal processing algorithm design and analysis 8. Signal processing for AUVs or deployed autonomous systems 9. Synthetic aperture sonar

*IEEE Conference Announcement

So the work continues and will need to be supported by ocean measurements

• Underwater Realm Sound & Acoustics - Measurement

G T Reader Winter 2015 46

1. The basic equation for determining the speed of sound in sea water is:C = (1/)0.5 where is the adiabatic compressibility and is the density

2. Both and depend upon salinity, temperature and depth(pressure), it could be expected than an analytical equation can be derived. While this is the case the accuracy of such an equation is insufficient for accurate predictions and so a number of semi-empirical equations have been derived but these are far from simple, e.g., The Mackenzie equation*:

C(T, S, z) = a1 + a2T + a3T2 + a4T

3 + a5(S - 35) + a6z + a7z2 + a8T(S - 35) + a9Tz

3

where T, S, and z are temperature in degrees Celsius, salinity in parts per thousand and depth in meters, respectively. The constants a1, a2, ..., a9 are:

a1 = 1448.96, a2 = 4.591, a3 = -5.30410-2, a4 = 2.37410

-4, a5 = 1.340,a6 = 1.63010

-2, a7 = 1.67510-7, a8 = -1.02510

-2, a9 = -7.13910-13

3. The Mackenzie equation is accurate over a wide range of ocean conditions but there are other equations which are more accurate over wider ranges they are also even more complicated.*

*http://resource.npl.co.uk/acoustics/techguides/seaabsorption/

• Underwater Realm Sound & Acoustics - Measurement

G T Reader Winter 2015 47

4. For our studies the actual numerical details of the speed of sound equations are not important. The point is that even the expression for the speed of sound is complicated and is symptomatic of the area of underwater acoustics. The need for actual measurement is paramount for accurate design and operation of UISs.

5. In the same way as the operation of high altitude military aircraft provided our initial encounters with the phenomenon we now call the jet-stream, the need to measure sound speed and acoustic penetration at increasing depths lead not only to the development of deep diving scientific submersibles, but also our encounter with the Deep Scattering Layer (DSL).

6. The DSL was discovered when apparently false readings of depth were obtained using echo-sounders. These false readings were also variable in value depending upon the time of day and the geographical location of the measurement. This horizontal layer is caused by the vertical movements of certain marine animals which scatter the sound waves. As with the jet-stream we have found ways of overcoming the difficulties, but for some it provided a good hiding place for the submarines of the nations who knew of its existence.

• Underwater Realm Tides, waves, currents

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1. Tides are produced mainly by the solar and lunar gravitational forces acting on the oceans and other water masses. The actual rotation of the earth also gives rise to the Coriolis effect which also plays a role in the phenomenon we call tides.

2. Although there are different types of Tides the one we usually encounter is the "principal lunar semi-diurnal tide when two high water and two low levels occur in a time period of half a lunar day , ~ 12 hours 25.2 minutes. We can, because of the work of famous mathematicians and physicists, and direct observations dating back at least to the 2nd century BCE, forecast the timing of the tides with great accuracy and also the high and low water levels although it should be noted that consecutive levels of highs and lows will not be the same.

3. The tidal range (difference between high water level and low water level) can vary from a few inches (~6 cm) in the Great Lakes to as much as 53 feet (16m) in the Bay of Fundy in Nova Scotia, Canada.

4. For the Bay of Fundy this means that twice a day it is filled and emptied with a billion tonnes of water*.

• Underwater Realm Tides, waves, currents

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1. Tidal knowledge is therefore very important for both the design and operation of ships and UISs in coastal waters.

2. However, as we shall see, we can use tidal variations to drive water turbines to produce green power. In essence, the ocean equivalent of land-based wind power.

http://www.openhydro.com/company.html http://www.marineturbines.com/SeaGen-Products

3. In our studies we focus more on UISs that could produce power from tides, rather than the effect

of tides on more conventional UISs, e.g., submarines.

• Underwater Realm Tides, waves, currents

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1. Waves are formed by wind driven forces and are essentially surface phenomenon. As such they are not an area which we will focus on in our studies, except as they impact the stability of those UISs who have to operate, even for a short time, on the surface.

2. We can also produce energy from waves but it far less predicable or reliable as tidal power.

3. As we saw in the pycnocline slides/videos there are also internal waves in the oceans a controversial concept in the 1960s. In the design and operation of certain UISs these internal waves must be accounted for in the same way as air turbulence effects aircraft design and operation.

• Underwater Realm Tides, waves, currents

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1. Current is water flow. In the surface layers winds generates surface waves but also move the water. In the late 19th century the Norwegian zoologist, explorer and Nobel Peace Prize winner Fridtjof Nansen observed that the ocean (Arctic) current direction was to the right* of the wind direction and postulated that the wind driven current was also being effected by the earths rotation (Coriolis force) and hydrodynamic drag**. A theoretical model of this effect was postulated by the Swedish physicist Walfrid Ekman from which it was predicted that (a) the current direction would change in a spiral manner as the depth increased and (b) the strength (speed) of the current would exponentially decrease with depth.

*http://oceanmotion.org/html/background/ocean-in-motion.htm

2. Although the Ekman transport model is idealized it explains the water circulation (current) patterns down to the pycnocline layer which acts an effective block to any further vertical motion.

3. Below the pycnocline factors such as temperature and salinity variations are the major drivers of water circulation.

4. In the surface layers the current strengths may be in the region of the 2 m/s (Gulf Stream) but in the deeper waters below the pyncocline the current is usually in the region of 1-2 cm/day hardly a current at all!

* True in the Northern Hemisphere but in the Southern Hemisphere the direction is to the left. ** R H Stewart, Chapter 9, Op Cit

• Underwater Realm Tides, waves, currents.

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Bing Images - cmore.soest.hawaii.edu

1. While the surface layers of the oceans are in constant motion as a result of winds and tides, in deeper waters the ocean motion is due to thermohaline circulation, which acts like a conveyor belt as the oceans absorb, store, and redistribute vast amounts of solar energy around the globe. Without this circulation, places at the same latitude across the globe would generally have the same average temperatures. However, because of this circulation, Norway located at similar latitude to Manitoba, Canada has an average annual temperature that is nearly 20F warmer*.

2. One lap of the conveyor belt will take a millennium or more.3. In general, the very weak currents below the surface layers will not have

a significant impact on UISs design. However, the conveyor belt circulation is considered to have monumental effects on our global climate

4. Direct measurements of the properties of belt circulation can only be made by UISs.

The Great Ocean Conveyor Belt

*(http://www.enviroliteracy.org/article.php/545.html)

• The Underwater Realm - Summary

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1. Water and especially sea (salt)-water have chemical, biological and physical characteristics which are totally alien to air-breathing humans. If then we are to explore and ethically exploit the oceans, we or surrogate robots need to go underwater using UISs.

2. From an engineering viewpoint the colossal pressures and drag forces encountered underwater pose many technical challenges on UIS design and operation as do the difficulties we encounter in communications, navigation and the almost complete lack of visible light.

3. To date, other than for military purposes, surface transportation, fishing (more accurately over-fishing), and some oil and gas extraction, we have used the oceans more as a large waste disposal site rather than as a source of renewable energy and a means to counter climate change impacts caused by land-based human activities.

• But how much do we know?

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Maybe the underwater realm has been neglected because we are lacking in knowledgeand understanding? but the previous slides appear to indicate that human knowledge ofthe oceans and seas is extensive. So as land-based resources become exhausted or tooexpensive to extract or use we will turn, no doubt, to the ocean sources or alternatives.But do we really know enough about the underwater realm?

The following video clip is of a short speech given by Craig Mclean of NOAA at the Oceans2012 conference. (The URL is given on the CLEW site).

• Next Lectures

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In the next lecture on the (In)visible Ocean we will see how ocean engineers and scientists together with computer specialists have been able to combine most of our present knowledge about the underwater realm to produce a visible topography of the oceans. Then in the following lectures we will consider some of the attempts that have already been made to design, develop, and operate UISs in this hostile environment and in particular the efforts being made to use the oceans as a source of renewable clean energy.

• Underwater Intervention Systems

92-590-54 & 88-590-28 21 January

92-590-64 & 88-590-38 15 January

Lectures 4-6

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• Brief Recap of L1-L3

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1. We looked at the nature of the underwater work-site especially with regard to the oceans.

2. We found that the physical characteristics of the oceans, especially vertically, are hugely different from those we encounter on land.

3. Water* is at least 800 times more dense than air.

4. Pressure rapidly increases with depth at a rate of 1 atmosphere per every 10 metres.

5. For underwater operations, especially vehicular buoyancy effects are the prime controlling factor.

6. The oceans are virtually impenetrable to visible light** and radio waves, except near to the surface layers.

7. Acoustics play a major role in the operation of UISs

* In the case of standard sea-water the factor is 832.

** Which is a form of EM radiation

• The (In)visible Ocean

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1. While it can appear that we know a great deal about our oceans, as we have seen that is not the case.

2. However, we are adding to our knowledge on a daily basis and at an increasing pace. We need this knowledge so we can design better, cheaper, safer UISs but we need UISs to obtain the knowledge in the first place. So we have a chicken and egg problem or in engineering language a iterative approach.

3. As with space exploration ways have been found of taking raw data and using leading edge advanced software animation and modeling techniques, coupled with massive processing power, to produce images of a visible ocean system.

4. This has enabled an incredible video of the ocean system to be produced where we can see everything, or at least everything we think we know.

5. The URL will be given on the CLEW site but you may wish to take notes for future reference in your project work.

• G T Reader Winter 2015 59

LIGHT THE OCEAN VIDEO

The URL for this video can be found on the CLEW course site.

• L4 L6 Applications and Uses of UISs

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1. Basic Types of Underwater Vehicles.

2. Examples of Underwater Vehicle Types, Commercial, Recreational, Naval and Scientific.

3. Example of recreational web submersible, underwater scooters and future concepts.

4. The Arctic Challenge.

5. Energy from the Sea Tidal Power and OTEC.

• Applications and Uses of UISs

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1. Because of the close relationships between naval and scientific uses and applications of UISs, especially over the past 50 years, these will be dealt with in tandem after we first consider their commercial applications.

2. However, as we shall see, all three main areas of application (naval, commercial and Scientific) are inter-related in many ways. For example, the advent of acoustic echo-sounders (SONAR) enabled fishermen to locate at what depth and geographical location schools* (large groups) of fish could be found.

3. The ocean, lake, and river surfaces have been main platforms for recreational (pleasure) vehicles for over a century. The manufacture and supply of these vehicles represent a sizeable global industry. However, more recently, recreational marine vehicles have been developed which can operate underwater.

* Sometimes called Shoals or apparently the more correct modern term is Host.

• Basic Types of Underwater vehicle - 1

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1. Not all Underwater Intervention Systems are vehicles, although the majority can be classified asvehicles whether manned or unmanned.

2. Other than tourist submarines there have been few official attempts to standardize theterminology. Some claimed that only vehicles which would never need to come to the surfacecould be classified as submarines, all others should be called submersibles. Using this approachthe total number of submarines is zero since even nuclear submarines have to surface when theyrun out of food for the crew!

3. In 1996 an attempt was made by Hawley et al*, to define as precisely as possible - the differenttypes of vehicles. Since that time new types of vehicles have been developed such as DiverPropulsion Vehicles (DPV) and Underwater Gliders so the 1996 attempt needs to be updated.

4. However, for our studies we can use the Hawley list modified to take account of the new vehicletypes. A discussion on the terminology issue has been posted on the CLEW site.

* Hawley et al, 1996, Op Cit

• Basic Types of Underwater vehicle - 2

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5. In the main manned naval underwater vessels will be referred to as submarines although thedescription submersible may be more accurate in some cases. These naval vessels areusually known as conventional powered or nuclear powered submarines.

6. Conventional submarines almost without exception have diesel-electric power plants. If theyalso include a third type of power system such as a Stirling Engine or Fuel cell the vessel isreferred at as an AIP (Air independent Propulsion)* submarine. This can be confusing to thosenot in the underwater community since nuclear powered submarines are also air-independent in terms of power production.

7. It is common practice to call civilian submarines, submersibles but this traditional is by nomeans a formal definition.

8. Unmanned Underwater Vehicles (UUVs) are simply those which do not have people on board.There are several different types of UUV.

* Originally called hybrid submarines but as the term hybrid in engineering terminology means the use of 2 or more different power systems then all conventional naval submarines are hybrids.

• Basic Types of Underwater vehicle 3 (ROVs & AUVs)

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An ROV is an unmanned tethered vehicle connected by an umbilical cable to a surface ship. It is controlled by a surface operator and can receive its power from the surface, or from a power pack, or both.

Remotely Operated Vehicles (ROVs) Autonomous Underwater Vehicles (AUVs)

An AUV is an unmanned

untethered vehicle which carries its own power pack and can

operate independent of surface control

Bing Images

• Basic Types of Underwater vehicle 4 (Unmanned)

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The underwater industry continues to innovate in the design and construction of UUVs. While this isexciting from an engineering point-of-view it also mean that the classification (and hence theeventual formulation of globally acceptable codes and standards) of such vehicles is becoming morechallenging. Typical examples of these new UUVs are the vehicles shown below which are known asROV/AUV hybrids. In essence the ROV element is acting as a host platform for the AUV taking it toand from the desired work-site.

MAYBE A BETTER NAME WOULD BE UNDERWATER ROBOTS?

• Basic Types of Underwater vehicle 5Naval Submarines

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1. There are two basic types* of naval submarine conventional (diesel-electric) and nuclear. Thesedescriptions apply to the type of power plants onboard the vessel and NOT to the type of weaponsthey carry.

2. Although the public perception is that all naval submarines are nuclear in fact the majority of thesubmarines are conventionally powered. There are approximately 450 naval submarines in theWorlds navies and of these at least 400 are of the conventional type.

3. As most of the major navies are more concerned these days with shallower water (Littoral orbrown-water) rather than deep-ocean (blue-water) operations there has also been a trend towardsequipping conventional submarines with an additional AIP power system. The Littoral zone

extends out from the coast to a depth of about 60m.4. Conventional submarines are much smaller than nuclear submarines mainly because of the

different missions they perform or national policy regarding the use of nuclear power.

* See discussion on CLEW L4-L6 support materials.

• Basic Types of Underwater vehicle 6Naval Submarines

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1. The exact number of navalsubmarines is always difficult toquantify especially with regard tohow many are in service, or at sea,at any one time.

2. A naval rule-of-thumb is that out ofevery three submarines, 1 will be atsea, 1 will be in harbour, and 1 willbe undergoing an extendedmaintenance period or upgradingrenovation*

* Known as a Refit

• Examples of Naval Submarines

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Nuclear PoweredRoyal Navy

Conventional Powered

US Navy

Russian Navy Royal Australian Navy

German Navy

Japanese Defence Ship

• Basic Types of Underwater vehicle 7 Submersibles

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1. Although there are unmanned, as well as manned, submersibles we will concentrate on examples of the latter. The navies of the world also use submersibles as distinct to submarines but for exemplars we will use mainly scientific and commercial versions.

2. One type of submersible which was basically only used by navies until the late 1980s was the wet submersible. A wet submersible is a manned submersible designed to be free flooding such that the pilot, crew, and passengers require personal diving equipment.* These types of submersibles are used as delivery vehicles for special forces divers (frogmen) but a Canadian company, International Venturecraft Corp (IVC), started to develop them for security and recreational use in 1986, and a few years later developed an automatic buoyancy and depth control system together

with a system which did not require the user to wear scuba equipment.

3. We shall take a closer look at IVCs Sportsub wet submersibles when discussing recreational applications.

Hawley et al, 1996, Op.Cit.

• Examples of Submersibles - 1

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Deepworker 3,300 ft operated by NOAA built and designed by Nuytco Research Limited, North Vancouver, B.C., Canada

Pisces IV examines the wreck of an American landing craft from WWII. Image courtesy of Terry Kerby, Hawai'i Undersea Research Laboratory. Can operate to 6,500ft. Built by International Hydrodynamics of Vancouver, B.C., Canada .

Information gleaned from NOAA, Naval-Technology.com and constructors websites.

Slingsby LR5, submarine rescue submersible operated by the Royal Navy. Can operate at depths to 2,000 ft. Built by Slingsby of Yorkshire, UK.

• Examples of Submersibles 2

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Japan Agency for Marine-Earth Science and Technology (JAMSTEC) submersible, Shinkai 6500, depth of 21,280 ft in service since the 1991.

MIR 1 & 2, operated by the Soviet, now Russian, Academy of Sciences built by the Finnish Company Rauma-Repola has been

tested at depths of 20, 200 ft.

The famous Alvin submersible has been operated by Woods Hole Oceanographic

Institution (WHOI), since 1964. Now being refitted to extend its maximum depth from

14,800 ft to 21,325 ft. Built by the US companies General Mills & Litton Industries

(Now part of Northrop Grumman), owned by the US Navy .

• Comment on Naval Submarines and Commercial/Scientific Submersibles

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1. The manned submersibles we have just viewed all go to greater depths than naval submarines.

2. The design of these deeper diving submersibles, is, as we shall see, different from naval submarines especially with regard to the pressure hull shape and the construction materials.

3. Naval submarines are designed to go much faster than submersibles and therefore their shapes are more hydrodynamic.

4. The submersibles in slides 15 and 16 are used for specialist tasks such as deep sea rescue, data gathering, and object location. The lease on one of these vehicles will cost between \$30,000 and \$50,000 per day.

• Recreational Uses of UISs -1

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1. With the odd exception, recreational use of underwater vehicles are designed to operate just below the water surface in the top 10m* or so of the euphotic (sunlight) zone.

2. Recreational (sometimes called Scuba) diving is the most popular of human underwater activities we will return to this topic later when we discuss life-support systems.

3. In recent times the most popular underwater recreational UISs has become the Diver Propulsion Vehicle** (DPV) or underwater scooter, but manned, shallow depth submersibles have also been built, or are under investigation or development.

4. A detailed study of these recreational vehicles is out of the scope of this course but as they appear to be increasingly popular, and are part of a growing commercial enterprise, we shall

briefly review the application area.

* On average 80% of visible light is absorbed by the time this depth is reached.

** Also used by Naval Special Forces

• Recreational Uses of UISs -2

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1. Because these vehicle types will not be operating at great depths the pressure effects on structural integrity is not as a significant design concern unless transparent materials are used.

2. Moreover the tourist type vehicles will be designed to operate in the upper layers of the euphotic zone as 60% of visible light is absorbed within a metre of the water surface and 80% within the top 10 m. As we know the top layer of the photic zones may be as shallow as 10 m in coastal waters but could extend to 100 m or sometimes 200 m in open ocean waters.

3. The DPVs and underwater scooters are commercial versions of the special forces naval vehicles but are used for the same purposes (except stealth) to enable longer or faster transits to be made. They are invariably powered by a battery-electric system and the battery of choice is increasingly lithium ion.

• Examples of Submersibles -3 - Recreational

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Tourist (Recreational) Submersibles

Sportsub wet submersible

• Examples of Other Recreational UISs

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Aqua Star (of Florida USA) AS 2 Underwater Scooter

http://www.hydrodome.com/hydrobob.html

seabobamerica.com

The Sub Aviator designed to dive to 1000ft!

• Future Recreational/Personal UISs

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1. The idea of underwater habitats for humans is not new and indeed has been tried. These specialized UISs may become a reality as the 22nd century approaches and futuristic designs for underwater cities are already being conceptualized by leading international companies. We will also need personal underwater vehicles to move between the land and these habitats should we desire the same type of freedom of movement that the automobile provides on land.

2. However, we have also seen that the use of the underwater environment for personal and recreational use is on the increase. This growing market has also attracted the interest of commercial companies both large and small. Here too, concept vehicles (perhaps without too much thought to actual design and manufacture challenges) have been

showcased.

3. In the next video clip we take a look at these future vehicle concepts.

• Commercial Uses Resource Exploration and Exploitation

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1. The four main uses of the Oceans, Seas, Lakes, and Rivers have, and continue to be as: (a) a method of transporting people and goods; (b) a food supply (fishing); (c) a place to dump waste, and (d) a source of fossil fuels although only in more recent times.

2. The transportation of people, goods and services involves the surface shipping. This topic is beyond the scope of this course except that these so-called SLOCs (sea lanes of communication) can be threatened or protected by naval submarines and UISs.

3. Similarly as fishing in a surface ship activity albeit using underwater appliances (nets) we will only briefly consider this use of the oceans as it impacts the need for scientific UISs.

4. In terms of waste disposal and fossil fuel extraction we will only briefly consider them in this lecture but more information will be provided on certain aspects especially from a Canadian viewpoint during Lectures 15 and 16.

5. To these four uses we can now add a fifth renewable energy. Energy can be produced from the oceans using the thermal energy that can be extracted from the temperature differences in the vertical water column or by using the potential and kinetic energy of the ocean tides and waves.

6. In this lecture section we will focus mainly on the renewable ocean energy aspects but here again we will return to this topic when considering the technical design aspects of UISs.

• Fishing and the Need for Scientific UISs -1

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Data from UN: http://www.theglobaleducationproject.org/earth/fisheries-and-aquaculture.php

1. Ocean & Lake Fishing has always been a crucial source of food for humans.

2. As we can see from the United Nations Data for some countries and areas, fish products account for over 20% of the daily human protein intake.

3. In recent years because of overfishing and ignorant fishing at least 75% of the natural stocks of fish have been depleted and to compensate the Aquaculture (Fish farm) industries what we may term grow your own fish having been rapidly increasing in production and also seeking ways to

genetically modify fish to reduce the time-to-market.

4. Is this fishing problem just a result of global population increase?

• Fishing and the Need for Scientific UISs -2

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1. As the ocean fishing industry became more automated and ways of finding fish (e.g., echo-location) were significantly improved the rate of fish extraction increased more rapidly than the global human population.

2. By the early 1990s the fish stocks could not cope with the extraction rates and nations started increasing their aquaculture activities.

3. For some species the rate of extraction depleted the stocks to such an extent that recovery was almost impossible the Atlantic Cod situation is an example.

• Fishing and the Need for Scientific UISs -3

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Northwest Atlantic Cod Fishing

1. The disastrous cod situation lead to a Canadian moratorium cod fishing.

2. It is estimated that cod stocks are now 1% of what they were in 1977 and show

no signs of recovery.

3. The cod type situation has been replicated globally with about 75% of the other main fish species.

• Cod & The Northwest Atlantic are not the only problem

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Oceanworld.tamu.edu

There are many examples of overfishing and ignorant fishing as shown in the diagrams above butthere is a third factor ocean acidification which is also considered to impact the marine-life foodchains above the pycnocline. This acidification is thought to be due to the increases in atmosphericCO2 caused by fossil fuel usage although this is not universally accepted.

http://www.terpconnect.umd.edu/~mvanhove/climatemyth.html

• Fishing and the Need for Scientific UISs -4

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1. Scientific knowledge of fish migration, reproduction and theirplace in the oceanic food chain has not kept pace with thetechnology of fishing. So the impact of the rates of extractionand the timing and location of extraction were not known oracknowledged by the fishing industry.

2. For some countries notably the USA the impact of fishingon national GDP was and is only in the region of 4% - which isnot an attention grabber.

3. For many other nations, especially China and Japan, the ocean

fishing resources are crucial.4. Scientific Fish research has rapidly increased worldwide but

the collection of data is hampered by the need to deployunderwater instrumentation (UISs) from surface ships.

http://pmel.noaa.gov/co2/file/Puget+Sound+Cast

• Fishing and the Need for Scientific UISs -5

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1. Scientific advances in sampling techniques such as DNAidentification of fish species from water samples are openingup the opportunities for the design and construction ofautonomous underwater vehicles, especially gliders, as morecost effective and efficient platforms for fish research thansurface ships.

2. Most of the ocean resources exploited by nations arecontained in the coastal waters of their continentalshelves. Thus, many have announced EEZs (EconomicExclusion Zones) stretching out about 200 nautical milesfrom their coastlines. In these areas the nations claim thatall the resources are theirs and theirs alone.

3. However, the definition of coastline is problematic.

• EEZs and Resource Conflicts

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The United Nations Convention on the Law of the Sea (UNCLOS III*) defines the rights and responsibilities of nations in their use of the world's oceans, establishing guidelines for businesses, the environment, and the management of marine resources.It is not clear whether UNCLOS can be claimed to be International Law or is effective in resolving competing national claims.The Arctic Ocean is a particular hot area as the USA do not agree with Canadian claims, and the Canadian do not agree with Russian claims. All three countries are increasing their military presence in the area because the prize is oil.

* Established in 1982. By 1994, 60 countries have ratified theconvention and by 2012 this has increased 3-fold. The country

noticeable by its absence is the USA.

• Oil Resources in The Oceans The Arctic

G T Reader Winter 2015 86

http://www.parl.gc.ca/Content/LOP/researchpublications/prb0807-e.pdf

Green area high potential

About 30% of the globaloil production comesfrom the 8,000 or sooffshore drilling rigs. Atthe moment the worldsproven oil reservesappear to be mainly onland in the Middle Eastbut geological surveyshave indicated that largeoil and gas reserves are inthe Arctic region.

• Oil Resources

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1. There are 4 main types of offshore drilling ofwhich three are in common use, semi-submersibles, jackups (platform legs on sea floor)and drill-ships. In all cases ROVs are used tosupport rig maintenance and diver operations,pipeline laying and pipeline inspections. Thedrilling operations themselves can be consideredto be UISs but we generally see just the surfaceportions of the oil platforms themselves. Thedrilling depths are getting increasingly deeper andfurther from the coastline.

2. Offshore is particularly important for the USA butthe recent promising surveys from the Dakotasmay change the priority.

3. Offshore oil drilling, extraction and transportationis an expensive activity.

http://www.thecqiscotland.org/North/n_reports.htm

Although artists impressions the above diagrams arereasonably accurate with a number of differentunderwater robots being involved in offshore oil

operations.

• Ocean Pollution Oil in the Oceans 1

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1. In any use of the ocean on the surface or under the surface - we must take account of theenvironmental impact, but it is really only relatively recently that the focus on such matters in theinvisible oceans has been made.

2. Invariably the public and media perception of pollution and environmental impacts is flawed. Forexample, whenever air pollution is mentioned we are shown pictures and videos of steam (wetgaseous water) rising from power station cooling towers as an example of the effect of humanproduced CO2 on climate change even when the power plant is nuclear!

3. In the same way oil spills always make the headlines and can often result in Governments callinga halt or a moratorium on drilling, pipeline, and tanker shipping activities. Although their impactshould not ever be underestimated they are almost always exaggerated and measures to negatetheir effects usually achieve the reverse.

• Ocean Pollution Oil in the Oceans 2*

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* Mainly Modified from data and links on University of Texas A&M website http://oceanworld.tamu.edu

The largest accidental oil spill in history, The Lakeview Gusher occurred on land in Kern County,California 1910-1911, and released 1.2 million tons of US Crude. The recent, 2010, DeepwaterHorizon disaster in the Gulf of Mexico released 492,000 tons also in the Gulf of Mexico in 1979. TheIXTOC 1 spill released 454,000 tons.

• Oceans Oil Spills

G T Reader Winter 2015 90

* Modified from University of Texas A&M website http://oceanworld.tamu.edu

Oil spills from oil tankers operating at sea world-wide account for only 7.7% of oil in the ocean, yet

large spills attract far more attention than other much larger sources of oil pollution. The

International Tanker Owners Pollution Federation Historical Data has information on all spills, large

and small. They note that "The average number of large spills per year during the 1990s was about a

third of that witnessed during the 1970s."

Exxon Valdez

• Oceans Pollution Oil in the Oceans 3

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http://oceanworld.tamu.edu

Natural seepage accounts for 60% of oil in North American Marine waters.

http://dels.nas.edu/global/osb/Pollution-In-The-Ocean

• Ocean Pollution - Waste & Dumping

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1. While the impact of oil spills is not to be under estimated it is greatly exaggerated by those withparticular political and obdurate environmental agendas. Yet, even if we eliminated all oil spills therewould still be 92% of the oil contamination sources left of which one-half to two-thirds would befrom natural sources.

2. According to the data compiled by the National Oceanic and Atmospheric Administration (NOAA),approximately 1.4 billion lbs of trash is dumped in the oceans every year.* Over 80% of wastedumped into the sea is from land-based human activities.

3. What is more concerning is that munitions, chemical, and nuclear waste has been dumped into theoceans over the last 60 years. UISs are now giving a means of locating, identifying, and monitoringthe dump sites and the accidental waste sites. It is a very disturbing picture. We shall briefly returnto this area later in the course.

*http://www.buzzle.com/articles/ocean-pollution-facts.html

• Energy Extracting UISs

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1. As with all renewable and sustainable energy sources the main drivers for development are thedesire to reduce the use of, and reliance on, fossil fuel sources, and to reduce the production ofCarbon Dioxide. Nuclear power which could address these issues is still not popular among thepublic and some national governments.

2. The use of wind power and solar power has significantly increased in recent years although thefinancial costs remain higher than conventional power generation in terms of capital investmentsand operations.

3. The use of the physical characteristics of the oceans to produce energy by no means a new idea has attracted increasing attention over the past decade or so.

4. The main Ocean Energy developments have been the use of tidal power and thermal energy. Thelatter is known as OTEC (Ocean Thermal Energy Conversion) and uses the temperature differencebetween the cooler deep and warmer surface ocean waters to run a heat engine.

• Energy Extracting UISsThe Underwater Wind (Tidal Power) Farm

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• Energy Extracting UISs Tidal Power 1

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1. Tidal Power is the ocean version of wind power on land and many of the sametechnical and operating principles apply.

2. The four main differences between tidal and wind power is that (a) water is muchdenser than air, (b) maintenance can be more challenging,(c) installation is morechallenging and (d) the level of tidal power generation is predictable

3. However tidal power can produce a higher level of power and it is not as visible ornoisy to the land based humans.

4. The tidal power devices can be in the form of what are essentially the underwaterequivalent of 2/3 bladed wind turbines, or multi-bladed fluid turbines normallyencountered in turbo-machinery. They are usually all known as marine currentturbines.

• Energy Extracting UISs Tidal Power 2

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1. We will look at some of the design aspects including efficiency limitations in a later lecture.Underwater turbines also experience high axial forces* and the hydrodynamic phenomenoncavitation**.

2. A series of review papers will be uploaded to the CLEW site dealing with tidal power to give yousome insight into the technical design processes and information suitable for a course project. Forthis lecture section a paper by P L Fraenkel has been placed on the website.

3. Tidal power depends mainly upon the water flow rate*** which itself depends upon the tidalrange (differences between high water and low water levels). There are certain places in the worldthat are particularly attractive for tidal power because of the size of the range these are usuallyclose to shore or in river estuaries or deltas. However there are many other factors involved in thedesign, construction, and operation of these UISs

* These are caused in the direction of the flow because the turbine is extracting energy i.e., reducing the velocity and changing the momentum.

** We shall see a description of what is cavitation in a later video clip.

*** The fluid dynamics cube rule.

• Energy Extracting UISs Tidal Power 3

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1. There are a number of Tidal power plants in use or under investigation globally.Some have been in operation for many years. Two of particular interest are theSEAGEN project in Northern Ireland and the FORCE* project in Nova Scotia,Canada.

2. The Nova Scotia project is taking place in the Bay of Fundy which has the largesttidal range in the world. For the FORCE project a number of different marinecurrent turbines are being considered.

3. We will take a look at these two projects in the following video clips, whose URLswill be posted on the CLEW site.

* The Fundy Ocean Research Center for Energy

• THE FUNDY FORCE PROJECT 1

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FORCE Fundy Ocean Research Centre for Energy.This is a not-for-profit organization which works closely with the University of Arcadia, especially on environmental issues, and Nova Scotia Power, Inc on Tidal Power. There are projects with five major tidal power companies. Each of the companies, Alstom, OpenHydro, Lockhead-Martin, Marine Current Turbines-Siemens, and Atlantis Resources Corp will install different trial systems in the Fundy area.

Note that the following website is worth visiting as a portal of information on energy research http://fern.acadiau.ca/fundy-tidal-energy-demonstration-facility.html

• THE FUNDY FORCE PROJECT 2

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Tidal devices operating in the Bay of Fundy may endure tides moving atspeeds up to 5 metres per second, rising up to 16 metres vertically, andexpanding up to 5 kilometres horizontally. The Bay of Fundy has been calledthe Everest of tidal energy. If you can produce power under thoseconditions, and produce it safely and reliably, you have met the FundyStandard. If you can make it here, you can make it anywhere.

THEIR VISION

• THE FUNDY FORCE Project Hopes and Concerns Video

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1. Note the concerns expressed and the attempts being made by University scientific researchers to address these concerns.

2. The relationship between the power extracted and the impact on tidal ranges is also discussed.

3. Details on how to obtain this movie will be given on the CLEW site.

• The Fundy Force Project The practicalities video

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1. The video demonstrates what happens with most largeand innovative engineering projects and usually results inthe project team going back to the drawing-board andalso updating their simulations.

2. The URL is posted on the CLEW site.

• Tidal Power Progress towards Reality including new ideas

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1. We have seen that hopes, expectations, and simulations are not always realized in practice at leastinitially. This is the nature of Engineering and Design; we often have insufficient data but we dontalways know it until we try it!

2. One of the Fundy industrial collaborators ALSTOM has obviously learned some lessons andrevamped its approach but the next movie clip is still part reality, part simulation. One of the lessonsthey dont appear to have learned is that the Bay of Fundy is in Canada!

3. We shall see that, when we take a closer look at turbine design, the maximum efficiency of suchdevices appears to be governed by the so-called BETZ Law. Others have challenged this Law asgiving efficiencies that are unrealistically high, whilst others claim it is too low! Of the latter, theAustralian company Tidal Power claim their new Davidson Hill Venturi (DHV) Turbine is an example.

4. The DHV movie clip shows perhaps one of the future directions for Tidal Power research.

• The ALSTOM system video

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URL is on the CLEW Site.

1. Note that the system appears to have been optimized for one-way flow.

2. Important aspects of Tidal Power are stressed.

• The DHV Turbine video

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1. It has to be remembered that this short movie clip is a promotional and marketingvideo and not surprisingly some sweeping claims are made.

2. It is nevertheless an interesting video in that it also provides the context for tidalpower research and its potential impact.

3. The URL is available on the CLEW site.

4. Note that in June 2012 TE commenced a Joint Venture with Thailand companyPotential Energy Ltd (PE) and registered a new company "Tidal Energy Asia" (TEA) inSingapore as a vehicle to hold a regional license for 10 Far Eastern countries.

• Energy Extracting UISs OTEC - 1

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1. As we saw in slides 44-47 (lecture 1-3) the solar radiation especially around the latitudes close to the equator causes the surface water temperature to be in the region of 250 C but not far below the thermocline the temperature drops rapidly to 3-50C. The difference in temperature in the water column can then be used to drive a heat engine for the main purpose of producing electricity. Although even the highest possible thermal efficiency Carnot - will be low the colossal amount of available heat energy can result in very large amounts of (gigawatts) work transfer (Laws of Thermodynamics).

2. The concept of OTEC dates back to the latter part of the 19th

century and OTEC plants have been in operation for several decades but on a relatively small scale.

3. There are 3 main types of OTEC system, open-cycle, closed-

cycle, and hybrid cycle.

• Energy Extracting UISs OTEC - 2

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These diagrams have been taken from the paper On the ocean heat budget and ocean thermal energy conversion by Mohammed Faizal and M. Rafiuddin Ahmed, which has

been uploaded to the CLEW site.

The Closed Cycle version is considered to have the highest efficiency and is the one which is attracting more present

day attention.

• The Lockheed-Martin System

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1. This company is a global engineering company with over 120,000 employees and is one of the worlds largest defence contractors.

2. Its interest in OTEC is driven by the defence needs of the country it is working with, in the sense of ensuring the security of energy supplies.

3. Note that the video indicates it is working in a region where the 200C difference is not coming from particularly warm surface waters.

4. Although as with the Tidal Power video the following video is a promotional video it does contain some useful information. The URL is on the CLEW site.

• G T Reader Winter 2015 108

Any Questions?

• Underwater Intervention Systems

L7-9 : Naval and Narco Submarines; Submarine Developments & Technical Design Estimates (1)

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NAVAL UISs & NARCO Submarines

• NAVAL Submarine Developments -1

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There were many attempts in the second half of the 19th century to develop combat submarines but the ones that caught the attention of navies was the CSAs ( Confederate States of America) CSS Hunley as this 40 ton human-powered submarine during the American Civil War was the first submarine to sink an enemy ship, the USAs (then the Union of States of America) 1200 ton USS Housatonic.

• NAVAL Submarine Developments -2

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1. The CSS Hunley demonstrated that a small inexpensive submarine could sink a large costly surface ship even with a very crude weapon the spar torpedo which was basically a bomb on a stick.

2. There were many other 19th century attempts to develop combat submarines and better underwater weapons but the one that revolutionized this kind of UIS was the submarine type invented by J P Holland originally constructed for an Irish-American terrorist group later versions were bought or constructed by the Governments of the USA, the UK, and British Columbia (taken over by the Canadian Government a few weeks later). The original Holland used a two-stroke Brayton* IC Engine.

3. The Holland submarines in terms of design were way ahead of their time but were not particularly successful in operation because of a variety of factors.

* The Brayton engine was a reciprocating engine, it was only later that the Brayton thermodynamic cycle was considered to be the ideal cycle for the gas turbine.

• NAVAL Submarine Developments -3

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Scientific America 1898

The picture at the top left is of a model of the Royal Navys Holland submarine. A Wolseley 170 hp petrol engine was used together with an Electric motor; a torpedo tube was added and the shape was in the style of a porpoise, ideal for submerged operation.

Many of the submarines developed at this time were designed with submerged operation in mind, but the choice of power systems was variable most navies favoured steam engines while usually their inventors didnt! Eventually the diesel engine became the prime mover of choice for most Naval submarines and remains so even today.

• NAVAL Submarine Developments -4

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1. Many navies were not that enthusiastic about using submarines from either an operational, or an ethical, viewpoint. Consequently, leading up to the Great War of 1914-1919*, the submarine was seen more as a small coastal craft serving in support of a surface fleet.

2. As it was envisaged that the submarine would spend most of its time on the surface the advanced porpoise-type hull shape designs were radically changed as these were excellent for submerged operations but not ideal for surface operations. The main armament was to be the deck gun although some would have torpedoes.

3. Internal Combustion engines were to provide surface propulsion and the new electrochemical batteries were to power electrical motors when underwater. Prior to the start of the war the German Navy successfully developed closed cycle kerosene (Spark-Ignition (SI)) and Diesel (Compression-Ignition) engines which could be operated on the surface and when submerged. The work was stopped completely when a worker was killed in an explosion with the SI engine fuel system.

* An armistice was signed in 1918 but the peace treaty was not agreed until 1919 and indeed in Russia the war continued into the 1920s.

• Naval Submarine Developments - 5

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1. The use of submarines quickly spread to the oceans and the underwater campaigns by the British in the Gallipoli campaign, and the Germans in the 1st

Battle of Atlantic achieved some success. On the British side a significant number of the submariners were Canadians.

2. Submarine operational tactics were in their infancy and the escorted convoy system eventually negated the submarine threat.

3. Between the two major 20th century wars navies continued to develop submarines, especially with regard to power systems, and again tried to use steam engines, but the diesel-electrical system dominated. There were no game-changing advances in either design or concepts of operational use until the 1937 1945* war. Advanced submarines of the type developed by the Germans (shown in the next slide) were still very much state-of-the art in terms of design concept over 20 years later.

The 2nd World War started with the Japanese invasion of China in 1937, not the German invasion of Poland in 1939 or the attack on the Malay States (Malaysia) Hawaiian

Islands in 1941. It did not finally end until September 1945.

• The U140 (Project 46)*

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As the technology rapidly developed, the submarines, especially of the German Navy, became more sophisticated. The one shown in the photograph was 1,950 tons displacement:

Propulsion: 2 x 1750 hp (1300 kW) 4 stroke diesel engines (surface), Battery-Electric (submerged), ~ 500 hp (370 kW).

Speed: 15 knots on the surface, 8 knots when submerged.Range: 12,000 nautical miles @ 10 knots surface, 90 nautical miles @ 4.5 knots when submerged.

Crew: 55-70.Weapons: Torpedoes plus 2 6 (15cm) deckguns.

Diving depth ~ 75m with a pressurehull thickness of 25mm

* The U-Boat, Eberhard Rssler, Arms & Armour Press, 1989, ISBN 0-85368-115-5.

• Naval Submarine Developments - 6

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1. As the second world war approached improvements in naval UISs began to appear. The Italians and the Dutch had separately and independently* developed the snorkel** - a means of taking atmospheric air to run the diesel engines without the need to surface. The Japanese significantly improved torpedo design both for submarines and surface ship use.

2. The British together with Canadian physicists started to develop sound location systems (ASDIC) which they gave freely to the USA and which became SONAR (Sound Navigation and Ranging). At the same time scientist

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