2. Introduction to Jet Propulsion P M V Subbarao Professor Mechanical Engineering Department Strong and Reliable Muscles for the Aircraft……

3. Global Momentum Analysis

4. Momentum Equation p inlet p exit V ac V jet Reynolds Transport Theorem: Newton’s Second Law of Motion

5. For a frictionless flight, pressure forces are only the surface forces… Steady state steady flow

6. Pressure ThrustMomentum Thrust At design cruising conditions : Pressure thrust is zero.

7. Generation of Thrust : The Capacity Thrust f : Fuel-air ratio

8. Dynamic Equilibrium : Cruising Vehicle For a cruising vehicle:

9. Drag on Aircraft

10. Generation of Lift

11. Drag Coefficient of an Air Craft

12. Generation of Lift

13. Drag Coefficient of an Air Craft

14. Lift - to - Drag Ratio Flight articleScenarioL/D ratio Virgin Atlantic GlobalFlyer Cruise37 [ Lockheed U-2Cruise~28 Rutan VoyagerCruise [4] [4] 27 Albatross20 Boeing 747Cruise17 Common tern12 Herring gull10 ConcordeM2 Cruise7.14 Cessna 150Cruise7 ConcordeApproach4.35 House sparrow4

15. Minimum Drag Coefficients AircraftTypeAspect RatioC Dmin RQ-2 PioneerSingle piston-engine UAV9.390.0600 North American NavionSingle piston-engine general aviation6.200.0510 Cessna 172/182Single piston-engine general aviation7.400.0270 Cessna 310Twin piston-engine general aviation7.780.0270 Marchetti S-211Single jet-engine military trainer5.090.0205 Cessna T-37Twin jet-engine military trainer6.280.0200 Beech 99Twin turboprop commuter7.560.0270 Cessna 620Four piston-engine transport8.930.0322 Learjet 24Twin jet-engine business jet5.030.0216 Lockheed JetstarFour jet-engine business jet5.330.0126 F-104 StarfighterSingle jet-engine fighter2.450.0480 F-4 Phantom IITwin jet-engine fighter2.830.0205 (subsonic) 0.0439 (supersonic) LightningTwin jet-engine fighter2.520.0200 Convair 880Four jet-engine airliner7.200.0240 Douglas DC-8Four jet-engine airliner7.790.0188 Boeing 747Four jet-engine airliner6.980.0305 X-15Hypersonic research plane2.500.0950

16. Propulsive Power or Thrust Power: Specific Thrust S Measure of compactness of a jet engine:

17. Thrust Specific Fuel Consumption TSFC Measure of fuel economy:

18. Aviation Appreciation Propulsion Efficiency

19. 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.

20. Jet Characteristics of Practical Propulsion Systems SystemJet Velocity (m/s) Turbofan200 - 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 Rocket1500 – 2600 Liquid Rocket2000 – 3500

21. Nozzle : Steady State Steady Flow First Law : No heat transfer and no work transfer & No Change in potential energy. in jet

22. Combined analysis of conservation of mass and first law A SSSF of gas through variable area duct can interchange the enthalpy and kinetic energy as per above equation. Consider gas as an ideal and calorically perfect.

23. Isentropic expansion of an ideal and calorically perfect gas.