1. Irreversibilities in Propulsion Systems
P M V Subbarao
Professor
Mechanical Engineering Department
A Major Criteria for Geometric Design of Components…..

2. Irreversible Turbofan Cycle : Unwanted Entropy Generation
Inlet 7c 2 3 7h 4 1 5 6

3. Irreversible Turbofan Cycle : Unwanted Pressure Loss
Inlet 7c 2 3 7h 4 1 5 6

4. Ideal & Irreversible Turbofan cycle

5. Irreversible Propulsion cycle

6. Classification of Irreversibilities
Internal Irreversibilities : Friction, flow separation & Turbulence
External Irreversibilities: Shocks, Friction, flow separation & Turbulence
Heat loss & incomplete combustion

7. External Irreversibilities due to Intake System

8. Typical External flow at Subsonic Cruising Conditions

9. Geometry of Subsonic Inlet at the Entrance

10. External Flow Irreversibilities in Subsonic Intakes
SupercriticalDesign

11. Control of Additional Drag in Intake Systems

12. Normal Shock Intakes
A sharp lipped subsonic diffuser may be used in supersonic engine without a significant aerodynamic penalty for Mac < 1.6.

13. Modes of Operation of External Compression Inlets

14. Performance of Subsonic Diffuser with NS
PRF

15. Selection of Subsonic Diffuser with NS
The total pressure recovery of a normal shock rapidly deteriorates beyond Mach ~ 1.6.
90% total pressure recovery is achieved at 1.6.

16. External Compression Inlets
Oblique Shock
Normal Shock
Cowl Shock
A single compression ram inlet involves one oblique shock and one normal shock.

17. Performance of External Compression Inlets
PRF

18. Modes of Operation of External Compression Inlets

19. Location of Oblique shock & External Drag
No Slippage but High External drag
Slippage with low External drag

20. Variable Geometry Inlets.

21. A High Quality Interior Geometry