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Gas Dynamics for Design of Nozzles

Gas Dynamics for Design of Nozzles. P M V Subbarao Professor Mechanical Engineering Department. Better Geometrical Solutions to Convert Microscopic KE to Macroscopic Kinetic Energy to …. Generation of Supersonic Velocity from Rest. Isentropic Nozzle:.

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Gas Dynamics for Design of Nozzles

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  1. Gas Dynamics for Design of Nozzles P M V Subbarao Professor Mechanical Engineering Department Better Geometrical Solutions to Convert Microscopic KE to Macroscopic Kinetic Energy to…..

  2. Generation of Supersonic Velocity from Rest Isentropic Nozzle:

  3. Isentropic Nozzle at Design Exit Pressure pexit-design pthroat pin pin p p* pexit-design

  4. Typical flight mission profile & Nozzle Exit Conditions Turn Cruise Turn Climb in Altitude Descent Takeoff Landing

  5. Isentropic Nozzle under Designed Conditions

  6. End Conditions of an Isentropic Nozzle

  7. Local Properties in an Isentropic Nozzle

  8. The Design Conditions of an Isentropic Nozzle

  9. Isentropic Nozzle at Design Conditions Under design conditions the gas pressure at the exit plane of the nozzle is applied back pressure.

  10. Isentropic Convergent Nozzle The compact Isentropic Nozzle:

  11. Remarks on Isentropic Converging Nozzle Design • Length of the nozzle is immaterial for an isentropic nozzle. • Strength requirements of nozzle material may decide the nozzle length. • Either Mach number variation or Area variation or Pressure variation is specified as a function or arbitrary length unit. • A converging Nozzle Design attains maximum capacity when the exit Mach number is unity.

  12. Full Capacity Converging Nozzle pin P* Can this be A basis for selection of altitude of flying?????

  13. Typical flight mission profile & Nozzle Exit Conditions Engine capacity Turn Cruise Turn Thrust Climb in Altitude Descent Takeoff Landing Flight Velocity

  14. Operational Characteristics of Isentropic C Nozzles • A converging passage designed to accelerate the a gas flow is considered for study. • The concern here is with the effect of changes in the upstream and downstream pressures • on the nature of the flow and • on the mass flow rate through a nozzle. • Four different cases considered for analysis are: • Converging nozzle with constant upstream conditions. • Converging-diverging nozzle with constant upstream conditions. • Converging nozzle with constant downstream conditions. • Converging-diverging nozzle with constant downstream conditions.

  15. Pressure Distribution in Under Expanded Nozzle At all the above conditions, the pressure at the exit plane of nozzle, pexit = pb.

  16. Variation of in Exit Pressure 1 1

  17. Variation of in Mass Flow Rate 1

  18. Low Back Pressure Operation

  19. Frictional Adiabatic Flow in A Variable Area Duct 0 Sonic Point : M=1

  20. Throat Conditions The capacity of Frictional throat is always lower than ideal throat!!!

  21. The Real Nozzle for Sonic Flow • It is impossible to get a sonic flow with real converging nozzle. • The flow is always subsonic (transonic) at the throat. • A compact real converging nozzle can produce transonic jet. • A real nozzle for sonic exit is a CD Nozzle.

  22. Ideal Convergent-Divergent Nozzle Under Design Conditions

  23. Ideal Convergent-Divergent Nozzle with High Back Pressure pb1< pin,but > p* Pthroat>p*

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