THE BIRTH OF JET PROPULSION P M V Subbarao Professor Mechanical Engineering Department Another Beak Through Idea by an Individual….

Working Principle of Propeller

Aerofoil Theory of Propeller

Anatomy of Propeller

Capacity of Propeller

Engines to drive propeller

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 Hans von Ohain was granted a patent for his turbojet engine in However, Hans von Ohain's jet was the first to fly in Frank Whittle's jet first flew in in 1941.

Parallel Invention Doctor Hans Von Ohain was a German airplane designer who 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 the idea of a continuous cycle combustion engine in Hans Von Ohain patented a jet propulsion engine design similar in concept to that of Sir Frank Whittle but different in internal arrangement in Hans Von Ohain joined Ernst Heinkel in 1936 and continued with the development of his concepts of jet propulsion.

A successful bench test of one of his engines was accomplished in September 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, The pilot on this historic first flight of a jet-powered airplane was Flight Captain Erich Warsitz.

Think Different…. A Royal Air Force officer. His first attempts to join the RAF failed as a result of his lack of height, but on his third attempt he was accepted as an apprentice in He qualified as a pilot officer in As a cadet Whittle had written a thesis arguing that planes would need to fly at high altitudes, where air resistance is much lower, in order to achieve long ranges and high speeds.

Piston engines and propellers were unsuitable for this purpose. He concluded that rocket propulsion or gas turbines driving 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 a plane 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 the idea himself.

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 it proved inconclusive. Whittle concluded that a complete rebuild was required, but lacked the necessary finances. Protracted negotiations with the Air Ministry followed and the project was secured in By April 1941, the engine was ready for tests. The first flight was made on 15 May By October the United States had heard of the project and asked 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.

The Americans worked quickly and their XP-59A Aircomet was airborne in October 1942, some time before the British Meteor, which became operational in The jet engine proved to be a winner, particularly in America where the technology was enthusiastically embraced.

The biggest aircraft An-225 Cossack1,322,750 lbL: 275'7";S: 290' The An-225 Cossack is the largest airplane in the world. Powerplant: 6× ZMKB Progress D-18 turbofans, kN each

The popular Biggest Aircrafts in the World #PlaneMax. WeightDimensions 1.Hindenburg *484,400 lbL: 804';D: 135' 2. An-225 Cossack1,322,750 lbL: 275'7";S: 290' The An-225 Cossack is the largest airplane in the world. 3. HK-1 Spruce Goose400,000 lbL: 218'6";S: 320' The HK-1 Spruce Goose has the largest wingspan of all aircraft. 4. Airbus A380F1,305,000 lbL: 239'3";S: 261'8" The Airbus A380F is the largest passenger airliner in the world. 5.KM Caspian Sea Monster1,080,000 lbL: 348';S: 131' 6.An-124 Condor892,872 lb L: 226'8.5";S: 240'5.75" 7.C-5 Galaxy840,000 lbL: 247'10";S: 222'9" 8.Boeing ER775,000 lbL: 242'4";S: 212'7" 9.Airbus A ,400 lbL: 246'11";S: 208'2" 10.Boeing ,000 lbL: 231'10";S: 211'5"

The world's largest aircraft engine, the GE90-115B Max. Thrust: 569kN

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 313kN at 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, The last flight took place on Oct. 24, A 200th flight was never made, even after several attempts.

Course Overview This undergraduate level course teaches the principles of jet propulsion. The primary focus of the course is on the teaching of 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.

Course Objectives Students successfully completing MEL 341 will get: A basic understanding of thermodynamic cycles of jet engines. A basic understanding of the rational behind several types of jet engines. A basic understanding of the compressible fluid flow in inlets and compressors and turbines. A basic understanding of the combustion physics in combustion chambers. The ability to analyze jet engines; determine propulsion efficiency and design inlets and nozzles.

Course Contents UNIT- I: PROPULSION Aircraft Propulsion – introduction -- 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 engine – Study of subsonic and supersonic engine models -- Identification and Selection of optimal operational parameters. Need for further development – Analysis of Turbojet with after burner.

Thermodynamic analysis of turbofan engine – Study of subsonic and supersonic systems -- Identification and selection of optimal operational parameters. Design of fuel efficient engines – Mixed flow turbo fan engine – Analysis of Turbofan with after burner. Thermodynamic analysis of turbo-prop engine – Identification and selection of optimal operational parameters.

UNIT –III: 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 -- The adiabatic 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 shock – oblique shocks – Study of special supersonic nozzles and diffusers.

UNIT –IV: STUDY OF COMPRESSORS Design and Analysis of compressors – Classification – analysis of centrifugal compressors – velocity triangles – design of impellers and diffusers – analysis of axial flow compressor – analysis of stage – characterization of stage – design of multistage axial flow compressor – Performances analysis of centrifugal and axial flow compressors.

UNIT –V: GAS DYNAMICS OF COMBUSTORS Stoichimetry of combustion – calculation air-fuel ratio – gas dynamics of combustors – thermal loading factors – design and selection of combustors. UNIT –VI: STUDY OF TURBINES Concept of gas turbine – analysis of turbine stage – velocity triangles and characterization of blades and stages – Design of multistage axial flow turbine – Performance analysis of turbines. UNIT –VI: ADDITIONAL TOPICS Thermodynamic analysis real turbo engine cycles – performance analysis and thermodynamic optimization. Introduction to ramjets – study of rocket engines – study of missile engines.

Books & References Jet Propulsion: Flack, R.D.., “Fundamentals of Jet Propulsion”, Cambridge University Press, Baskharone, E.A., “Principles of Turbomachinery in Air-Breathing Engines”, Cambridge University Press, Kerrebrock J.L., “Aircraft Engines and Gas Turbines”, MIT Press, Mattingly, J.D., “Elements of Gas Turbine Propulsion”, McGraw-Hill Inc., Gas Dynamics: Anderson, J.D., “Modern Compressible Flow: With Historical Perspective”, McGrawHill, Zuker, R.D., and Biblarz, O.,”Fundamentals of Gas Dynamics”, John Wiley & Sons Inc., Thompson, P. A. Compressible Fluid Dynamics. Maple Press Company, Saad, M.A.,”Compressible Fluid Flow”, Prentice-Hall, Liepmann, H., and A. Roshko. Elements of Gas Dynamics. John Wiley Publishers, 1957.

Propulsion - Overview What is propulsion? The word is derived from two Latin words: pro meaning before or forwards and pellere meaning to drive. Propulsion means to push forward or drive an object forward. A propulsion system is a machine that produces thrust to push an object forward. On airplanes, thrust is usually generated through some application of Newton's third law of action and reaction. A gas, or working fluid, is accelerated by a machine, and the reaction to this acceleration produces a force on the engine.

Classification of Propulsion Systems

Jet Propulsion Operating principle based on Newton’s 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.

Classification of Systems Only the practical thermo-chemical category will be considered further 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 of jet or reaction propulsion, i.e. by generating high- velocity exhaust gases.

Jet Characteristics Quantities defining a jet are: –cross-sectional area; –composition; –velocity. Of these, only the velocity is a truly characteristic feature and is of considerable quantitative significance.

Jet Characteristics of Practical Propulsion Systems SystemJet Velocity (m/s) Turbofan Turbojet (sea-level, static) Turbojet (Mach 2 at ft) Ramjet (Mach 2 at ft) Ramjet (Mach 4 at ft) Solid Rocket1500 – 2600 Liquid Rocket2000 – 3500

Introduction to Rockets

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.

Solid Propellant Rocket for GW Jet velocity: m/s Most widely used in GW Short, medium range (< 50 km) Simple, reliable, easy storage, high T/W Rapier

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.

Liquid Propellant Rocket - Basic Operating Features Fuel and oxidant tanked separately and delivered to combustion chamber at specific rates and pressures. Propellant flowrates (and hence thrust) variable upon demand. Disadvantages compared with solid propellant rockets: –increased complication; –Storage problems (usually LOX & LH2 which must be maintained at very low temperatures); –more costly; –reduced reliability.

Liquid Propellant Rocket - Space Jet velocity: m/s. Highest thrust, can be throttled. Long sustained flight (5mins+). Ariane 5

Space Transportation System (STS)

Travel Cycle of Modern Spacecrafts

Rentering Space Craft

Major Knowledge Gains Through Gas Dynamics Simple principles of Gas Dynamics, it was showed that the 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 wave and heated shock layer were pushed forward, away from the vehicle's outer wall. Since most of the hot gases were not in direct contact with the vehicle, the heat energy would stay in the shocked gas and simply move around the vehicle to later dissipate into the atmosphere.