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THE BIRTH OF JET PROPULSION

P M V Subbarao

Professor

Mechanical Engineering Department

Another Beak Through Idea by an Individual.

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Working Principle of Propeller

aircraft

Vm

jet

Vm

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Aerofoil Theory of Propeller

aircraftjetthrust VVmF

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Anatomy of Propeller

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Capacity of Propeller

aircraftjetthrust VVmF

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Engines to drive propeller

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Need for Alternative Propulsion Method

Dr. Hans von Ohain and Sir Frank Whittle are both

recognized as being the co-inventors of the jet engine. Each worked separately and knew nothing of the other's

work.

Hans von Ohain is considered the designer of the first

operational turbojet engine. Frank Whittle was the first to register a patent for the

turbojet engine in 1930.

Hans von Ohain was granted a patent for his turbojet

engine in 1936. However, Hans von Ohain's jet was the first to fly in

1939.

Frank Whittle's jet first flew in in 1941.

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Parallel Invention

Doctor Hans Von Ohainwas a German airplane designerwho invented an operational jet engine.

Hans Von Ohain, started the investigating a new type of

aircraft engine that did not require a propeller.

Only twenty-two years old when he first conceived theidea of a continuous cycle combustion engine in 1933.

Hans Von Ohain patented a jet propulsion engine design

similar in concept to that of Sir Frank Whittle but different

in internal arrangement in 1934.

Hans Von Ohain joined Ernst Heinkel in 1936 and

continued with the development of his concepts of jet

propulsion.

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A successful bench test of one of his engines wasaccomplished in September 1937.

A small aircraft was designed and constructed by Ernst

Heinkel to serve as a test bed for the new type of

propulsion system - the Heinkel He178.

The Heinkel He178 flew for the first time on August 27,

1939.

The pilot on this historic first flight of a jet-powered

airplane was Flight Captain Erich Warsitz.

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Think Different.

A Royal Air Force officer.

His first attempts to join the RAF failed as aresult of his lack of height, but on his thirdattempt he was accepted as an apprentice in1923.

He qualified as a pilot officer in 1928.

As a cadet Whittle had written a thesisarguing that planes would need to fly at highaltitudes, where air resistance is much lower,in order to achieve long ranges and highspeeds.

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Piston engines and propellers were unsuitable for this

purpose.

He concluded that rocket propulsion or gas turbinesdriving propellers would be required.

Jet propulsion was not in his thinking at this stage.

By October 1929, he had considered using a fan enclosed

in the fuselage to generate a fast flow of air to propel aplane at high altitude.

A piston engine would use too much fuel, so he thought of

using a gas turbine.

After the Air Ministry turned him down, he patented theidea himself.

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In 1935, Whittle secured financial backing and, with Royal

Air Force approval, Power Jets Ltd was formed.

They began constructing a test engine in July 1936, but itproved inconclusive.

Whittle concluded that a complete rebuild was required,

but lacked the necessary finances.

Protracted negotiations with the Air Ministry followed andthe project was secured in 1940.

By April 1941, the engine was ready for tests. The first

flight was made on 15 May 1941.

By October the United States had heard of the project andasked for the details and an engine.

A Power Jets team and the engine were flown to

Washington to enable General Electric to examine it and

begin construction.

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The Americans worked quickly and their XP-59A

Aircomet was airborne in October 1942, some time beforethe British Meteor, which became operational in 1944.

The jet engine proved to be a winner, particularly in

America where the technology was enthusiastically

embraced.

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The biggest aircraft

An-225 Cossack 1,322,750 lb L: 275'7";S: 290'

The An-225 Cossack is the largest airplane in the world.

Powerplant:6 ZMKB Progress

D-18 turbofans, 229.5 kN each

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The popular Biggest Aircrafts in the World

# Plane Max. Weight Dimensions

1. Hindenburg * 484,400 lb L: 804';D: 135'

2.An-225 Cossack 1,322,750 lb L: 275'7";S: 290'

The An-225 Cossack is the largest airplane in the world.

3.HK-1 Spruce Goose 400,000 lb L: 218'6";S: 320'The HK-1 Spruce Goose has the largest wingspan of all aircraft.

4.Airbus A380F 1,305,000 lb L: 239'3";S: 261'8"

The Airbus A380F is the largest passenger airliner in the world.

5. KM Caspian Sea Monster 1,080,000 lb L: 348';S: 131'

6. An-124 Condor 892,872 lb L: 226'8.5";S:240'5.75"

7. C-5 Galaxy 840,000 lb L: 247'10";S: 222'9"

8. Boeing 777-300ER 775,000 lb L: 242'4";S: 212'7"

9. Airbus A340-600 807,400 lb L: 246'11";S: 208'2"

10. Boeing 747 875,000 lb L: 231'10";S: 211'5"

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The world's largest aircraft engine, the GE90-115B

Max. Thrust: 569kN

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The fastest Aircraft

X-15 is having a 4,520 mph world speed record.

Fastest manned aircraft.

Not only is the North American X-15 the fastest piloted

aircraft ever, it is the highest flying.

Thrust was obtained from one engine that produced 313kNat maximum altitude.

The North American X-15 was produced to explore the

limits of sub-orbital supersonic flight.

Three were produced. They flew a total of 199 times. The X-15 first took to the sky on June 8, 1959. The last

flight took place on Oct. 24, 1968. A 200th flight was

never made, even after several attempts.

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Course Overview

This undergraduate level course teaches theprinciples of jet propulsion.

The primary focus of the course is on the teachingof thermodynamics and Gas dynamics in aircraft

engines. The course provides information that will enable

the engineering analysis of

ramjets and turbine engines and

its separate components including inlets, nozzles,combustion chambers, compressors, and turbines.

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Course Objectives

Students successfully completing MEL 341 will get:

A basic understanding of thermodynamic cycles of jetengines.

A basic understanding of the rational behind several typesof jet engines.

A basic understanding of the compressible fluid flow ininlets and compressors and turbines.

A basic understanding of the combustion physics incombustion chambers.

The ability to analyze jet engines; determine propulsionefficiency and design inlets and nozzles.

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Course Contents

UNIT- I: PROPULSION

Aircraft Propulsionintroduction -- Early aircraft engines --

Types of aircraft engines -- Reciprocating internal combustion

engines -- Gas turbine engines -- Turbo jet engine -- Turbo fan

engine -- Turbo-prop engine

Aircraft propulsion theory: thrust, thrust power, propulsive and

overall efficiencies -- Problems.

UNIT- II: THERMODYNAMIC ANALYSIS OF IDEAL

PROPULSION CYCLES

Thermodynamic analysis of turbojet engineStudy of subsonic

and supersonic engine models -- Identification and Selection of

optimal operational parameters. Need for further development

Analysis of Turbojet with after burner.

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Thermodynamic analysis of turbofan engineStudy ofsubsonic and supersonic systems -- Identification and

selection of optimal operational parameters. Design of fuel

efficient enginesMixed flow turbo fan engineAnalysis

of Turbofan with after burner. Thermodynamic analysis of turbo-prop engine

Identification and selection of optimal operational

parameters.

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UNITIII: GAS DYNAMICS OF PASSIVE

COMPONENTS OF TURBO ENGINES

FUNDAMENTALS OF GAS DYNAMICS : Energy equation for a

non-flow process -- Energy equation for a flow process -- Theadiabatic energy equation -- Momentum Equation --Moment of

Momentum equation -- Stagnation Velocity of Sound --Stagnation

Pressure -- Stagnation Density -- Stagnation State -- Velocity of

sound -- Critical states -- Mach number -- Critical Mach number --Various regions of flow.

ANALYSIS OF DIFFUSERS AND NOZZLES: Introduction

study of intakes for subsonic and supersonic engines -- Comparison

of isentropic and adiabatic processes -- Mach number variation --

Area ratio as function of Mach numbers -- Impulse function -- Mass

flow rates -- Flow through nozzles -- Flow through diffusers

Effect of friction -- Analysis of intakes for supersonic engines

intakes with normal shockoblique shocks Study of special

supersonic nozzles and diffusers.

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UNITIV: STUDY OF COMPRESSORS

Design and Analysis of compressorsClassificationanalysis of centrifugal compressorsvelocity triangles

design of impellers and diffusersanalysis of axial flow

compressoranalysis of stagecharacterization of stage

design of multistage axial flow compressorPerformances

analysis of centrifugal and axial flow compressors.

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UNITV: GAS DYNAMICS OF COMBUSTORS

Stoichimetry of combustioncalculation air-fuel ratio

gas dynamics of combustorsthermal loading factors

design and selection of combustors.

UNITVI: STUDY OF TURBINES

Concept of gas turbineanalysis of turbine stage

velocity triangles and characterization of blades and stages

Design of multistage axial flow turbinePerformance

analysis of turbines.

UNITVI: ADDITIONAL TOPICS

Thermodynamic analysis real turbo engine cycles

performance analysis and thermodynamic optimization.

Introduction to ramjetsstudy of rocket enginesstudy

of missile engines.

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Books & References

Jet Propulsion:

Flack, R.D.., Fundamentals of Jet Propulsion,Cambridge University Press,2005.

Baskharone, E.A., Principles of Turbomachinery in Air-Breathing Engines,Cambridge University Press, 2006.

Kerrebrock J.L., Aircraft Engines and Gas Turbines,MIT Press, 1992.

Mattingly, J.D., Elements of Gas Turbine Propulsion,McGraw-Hill Inc.,

1996. Gas Dynamics:

Anderson, J.D., Modern Compressible Flow: With Historical Perspective,McGrawHill, 2002.

Zuker, R.D., and Biblarz, O.,Fundamentals of Gas Dynamics, John Wiley& Sons Inc., 2002.

Thompson, P. A. Compressible Fluid Dynamics.Maple Press Company, 1984. Saad, M.A.,Compressible Fluid Flow,Prentice-Hall, 1993.

Liepmann, H., and A. Roshko.Elements of Gas Dynamics.John WileyPublishers, 1957.

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Propulsion - Overview

What is propulsion?

The word is derived from two Latin words:

promeaning before or forwards and

pelleremeaning to drive.

Propulsionmeans to push forward or drive an object forward.

A propulsion system is a machine that produces thrustto push anobject forward.

On airplanes, thrust is usually generated through some application ofNewton's third law of action and reaction.

A gas, or working fluid, is accelerated by a machine, and the reactionto this acceleration produces a force on the engine.

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Classification of Propulsion Systems

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Jet Propulsion

Operating principle based on Newtons laws of motion. 2nd law - rate of change of momentum is proportional to

applied thrust (i.e.F = m a)

3rd law - every action has an equal and opposite reaction.

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Classification of Systems

Only the practical thermo-chemicalcategory will be consideredfurther in this Course.

This may be split into two main sub-categories:

Rockets (Solid or Liquid Propellant);Air Breathers (Ramjet, Turbojet , Turbofan & Turboprop);

along with a Hybrid Ram rocket.

The fundamental operating principle common in all these cases

is , that ofjetor reaction propulsion, i.e. by generating high-

velocity exhaust gases.

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Jet Characteristics

Quantities defining a jet are:

cross-sectional area;

composition;

velocity.

Of these, only the velocityis a truly characteristic feature and

is of considerable quantitative significance.

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Jet Characteristics of Practical Propulsion Systems

System Jet Velocity (m/s)

Turbofan 200 - 600

Turbojet (sea-level, static) 350 - 600

Turbojet (Mach 2 at 36000 ft) 900 - 1200

Ramjet (Mach 2 at 36000 ft) 900 - 1200

Ramjet (Mach 4 at 36000 ft) 1800 - 2400

Solid Rocket 15002600

Liquid Rocket 20003500

I d i R k

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Introduction to Rockets

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Solid Propellant Rocket - Basic Operating Features

Four basic components:

motor case, nozzle, solid propellant charge, igniter.

Propellant charge comprises combined fuel & oxidizer.

Gaseous combustion products fill void at high pressure(70 bar typically) and sustains combustion.

Hot gases vent through convergent-divergent nozzle to

provide high-speed (supersonic) propulsion jet.

Gases generated and escape at fixed rate for steady

operation by maintaining constant burning surface area.

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Solid Propellant Rocket for GW

Jet velocity: 1500-2600m/s

Most widely used in GW

Short, medium range (< 50 km)

Simple, reliable, easy storage,

high T/W

Rapier

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Solid Rocket Features

High propellant density (volume-limited designs).

Long-lasting chemical stability.

Readily available, tried and trusted, proven in service.

No field servicing equipment & straightforward handling.

Cheap, reliable, easy firing and simple electrical circuits.

But

Lower specific impulses (compared with liquid rockets).

Difficult to vary thrust on demand. Smokey exhausts (especially with composite propellants).

Performance affected by ambient temperature.

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Liquid Propellant Rocket - Basic Operating Features

Fueland oxidanttanked separately and delivered tocombustion chamber at specific rates and pressures.

Propellant flowrates (and hence thrust) variable upondemand.

Disadvantages compared with solid propellant rockets: increased complication;

Storage problems (usually LOX & LH2 which must bemaintained at very low temperatures);

more costly; reduced reliability.

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Liquid Propellant Rocket - Space

Jet velocity: 2000 - 3500m/s.Highest thrust, can be throttled.

Long sustained flight (5mins+).Ariane 5

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Space Transportation System(STS)

Travel Cycle of Modern Spacecrafts

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Travel Cycle of Modern Spacecrafts

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Rentering Space Craft

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Major Knowledge Gains Through Gas Dynamics

Simple principles of Gas Dynamics, it was showed thatthe heat load experienced by an entry vehicle was inversely

proportional to the drag coefficient.

The greater the drag, the less the heat load.

Through making the reentry vehicle blunt, the shock waveand heated shock layer were pushed forward, away fromthe vehicle's outer wall.

Since most of the hot gases were not in direct contact withthe vehicle, the heat energy would stay in the shocked gas

and simply move around the vehicle to later dissipate intothe atmosphere.