1 SHIP PROPULSION SYTEMS Prof. Emin Korkut
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SHIP PROPULSION
SYTEMS
Prof. Emin Korkut
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SYLLABUS
1. Introduction to Ship Resistance and Propulsion
2. Introduction to Propulsion Systems
3. The Ship as a Federation of Systems, Review of
Main Machinery; Power Plant Concepts
According to Ship Types
4. Review of Main Machinery; Diesel power plant,
Gas turbine power plant, steam and nuclear power
plant, Combined power plants
5. Transmission system and its components
6. Propulsors
7. Machinery selection-The Designer’s choice:
Criteria’s how to choose prime mover
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SYLLABUS
8. Marine Diesel Engines
9. Marine Gas Turbines
10. Engine room layout; General arrangement of a
ship, machinery spaces, noise in machinery
spaces, simple torsional vibration calculations
11. Engine room layout; General arrangement of a
ship, machinery spaces, Lloyd Rules
12. Alternative marine propulsion systems. Sub-
systems of propulsion system (typical fuel,
electrical, air, lubrication oil, cooling system etc.).
Fuel types in marine field
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REFERENCES
• Ship Propulsion Systems by Mohamed Morsy El-
Gohary & Hossam Ahmed El-Sherif.,
• Modern Ship Design by Thomas C. Gillmer
• Marine Propellers and Propulsion, Carlton, J.S,
2007, 2nd Ed., Butterworth-Heinemann, ISBN:
978-07506-8150-6
• Ship Design and Construction Vol-I,II, SNAME
• Marine Gas Turbines, Woodward, John B., ISBN
0-47195962-6
• Course text Marine Gas Turbines, Woodward,
John B., ISBN 0-47195962-6
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Lecture notes can be found at:
http://pruonline.pirireis.edu.tr/
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Assessment
Criteria
Activities Quantity Effects on
Grading,
%
Midterm 1 30
Homework 2 10
Term Paper/Project 1 20
Final Exam 1 40
TOTAL 100%
Effects of Midterm
on Grading, % 60%
Effects of Final on
Grading, % 40%
TOTAL 100%
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Introduction to Ship Resistance and Propulsion
Resistance:
• The act of stopping, opposing or withstanding when
an object is in motion in a fluid.
• Ships, aircrafts, cars etc. experience resistance
when they are in motion. Frictional forces of the
water/air against the moving object cause this
resistance.
T
V
RT (RESISTANCE) Main engine
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T o t a l R e s i s t a n c e
R e s i d u a r y R e s i s t a n c e
W a v e R e s i s t a n c e
V i s c o u s P r e s s u r e R e s i s t a n c e
F r i c t i o n a l R e s i s t a n c e ( F l a t P l a t e )
V i s c o u s R e s i s t a n c e
Fr r
C
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• Types of Resistance
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• Resistance of a ship depends on speed, displacement
and type of a hull form.
• The total resistance RT, is composed of mainly three
components
– a) Frictional resistance, RF
– b) Residual resistance, RR
– c) Air resistance, RA
• Frictional resistance RF of the hull depends on the
size of the hull’s wetted area S, and on the specific
frictional resistance coefficient CF.
• When the ship is in motion through the water, the
frictional resistance increases at a rate proportional
to the square of the speed of the ship.
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• Frictional resistance represents a considerable part of
the ship’s resistance, often some 70-90% of the
ship’s total resistance for low-speed ships (bulk
carriers and tankers), and sometimes less than 40%
for high-speed ships (cruise liners and passenger
ships).
• Residual resistance RR comprises wave resistance
and eddy resistance. Wave resistance refers to the
energy loss caused by waves created by the vessel
during its propulsion through the water, while eddy
resistance refers to the loss caused by flow
separation which creates eddies, particularly at the
aft end of the ship.
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• Wave resistance at low speeds is proportional to the
square of the speed, but increases much faster at
higher speeds. In principle, this means that a speed
barrier is imposed, so that a further increase of the
ship’s propulsion power will not result in a higher
speed as all the power will be converted into wave
energy. The residual resistance normally represents
8-25% of the total resistance for low-speed ships,
and up to 40-60% for high-speed ship.
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Prediction of Effective Power (Resistance):
• For Model Testing: In order to achieve a flow
similarity between two geometrically similar bodies
(full-scale ship and model) Froude similarity should
be satisfed that the non-dimensional parameter,
Froude number (Fr) should be the same for the ship
and model.
𝐹𝑟 =𝑉
𝑔𝐿𝑊𝐿
= 𝐹𝑟𝑠 = 𝐹𝑟𝑚
where g is acceleration due to the gravity, LWL is the
ship length in waterline, indices ‘s’ and ‘m’ represent
ship and model, respectively.
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a) Froude’s Method: The resistance of a model or ship
can be split in two components: a frictional resistance
and residuary resistance as CT=CF+CR
i- Scale factor between ship and model is defined λ =𝐿𝑆
𝐿𝑀
and this yields 𝑉𝑀 =𝑉𝑆
λ
ii- Measure RTM corresponding to the model velocity, VM
iii- Calculate total resistance coefficient of the model as
𝐶𝑇𝑀 =𝑅𝑇𝑀
1
2𝜌𝑀𝑆𝑀𝑉𝑀
2
iv- Frictional resistance that is supposed equal to that of
an equivalent flat plate and usually given by ITTC1957
formula: 𝐶𝐹𝑀 =0.075
(𝐿𝑜𝑔 𝑅𝑒𝑀 −2)2 𝑅𝑒 =
𝑉𝐿
𝜈 where 𝜈 is the
kinematic viscosity of water
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v- CTM=CFM+CR then, CR=CTM- CFM Residual coefficient
CR will be the same for model and ship.
vi- Ship frictional resistance coefficient is calculated as
𝐶𝐹𝑆 =0.075
(𝐿𝑜𝑔 𝑅𝑒𝑆 −2)2
vii- Then, the total resistance coefficient of the ship is
obtained as CTS=CFS+CR
viii- Total resistance of the ship is calculated by using the
formula 𝑅𝑇𝑆 = 𝐶𝑇𝑆1
2𝜌𝑆𝑆𝑆𝑉𝑆
2
ix- Finally the effective power of the ship is calculated as
PE=RTSVS
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a) ITTC1978 Method: The resistance of a model or ship
can be split in two components: viscous resistance
and residuary resistance as CT=CV+CR=(1+k) CF+CR
where (1+k) is the form factor and determined by
Prohaska method.
Similar to Froude method;
v- CR=CTM- (1+k)CFM Residual coefficient CR will be the
same for model and ship.
vi- Ship frictional resistance coefficient is calculated as
𝐶𝐹𝑆 =0.075
(𝐿𝑜𝑔 𝑅𝑒𝑆 −2)2
vii- Then, the total resistance coefficient of the ship is
obtained as CTS=(1+k)CFS+CR
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viii- Total resistance of the ship is calculated by using the
formula 𝑅𝑇𝑆 = 𝐶𝑇𝑆1
2𝜌𝑆𝑆𝑆𝑉𝑆
2
ix- Finally the effective power of the ship is calculated as
PE=RTSVS
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Propulsion:
• Propulsion is the act or an instance of driving or
pushing forward of a body, i.e. ship, by a propeller
(in our case a screw propeller).
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Summary of efficiencies in powering
Reduction gear
B
PD T
PT
PB S
V
RT
PE
D
H
BEHIND HULL
R
0
PT
PD0
OPEN WATER
Main engine
B
DS
D
T
D
D
R
D
TB
T
E
H
D
E
D
P
P
P
P
P
P
P
P
P
P
P
P
0
0
0
RB 0
HRD 0
T Thrust
R Resistance
V Ship speed
PT Thrust power
PD Delivered power in behind hull condition
PD0 Delivered power in open water condition
PB Brake power
PE Effective power
0 Open water efficiency
R Relative-rotative efficiency
B Behind hull efficiency
S Shaft transmission efficiency
H Hull efficiency
D Propulsive efficiency