Anna University Model Question Paper BE V sem Mechanical GAS DYNAMICS AND SPACE PROPULSION







Time : 3 Hours                                                                                            Max. Marks: 100

Answer All Questions


PART – A  ( 10  x 2 = 20 Marks )


1.         Explain stagnation state and represent static and stagnation state on T-S Diagram.


2.         Indicate variation of flow properties pressure, density and velocity in a convergent divergent nozzle.


3.         Define Machcone in Supersonic flow.


4.         State the effect of friction in subsonic Fanno flow and indicate the variation in properties of T-S Diagram.


5.         Give some application coming under Fanno and Ryleigh Flow – Processes.


6.         Write down expression to indicate effect of Mach number on compressibility with a short note.


7.         How the Match number, pressure and temperature are varying before and after normal shock.


8.         What is ram effect at inlet to diffuser in building up static pressure.


9.         Briefly explain combustion phenomena in aircraft combustor.


10.       Express the rocket performance by charterstics velocity through stagnation state and  divergent exit nozzle.


PART – B (5 x 16 = 80 marks)


11.i)     Get an expression for ratio of stagnation to static pressure


M2] γ/ γ-1

= [1 +

            PO                 γ-1                                                                                                       (3)






11.ii)    A Supersonic nozzle expands air from Po =25 bar and To = 1050 K to an exit pressure of 4.35 bar; the exit area of the nozzle is 100 cm2. Determine : a) throat area; b) pressure and temperature at the throat; c) temperature at exit; d) exit velocity and e) mass flow rate.                                                                                        (13)


12.a)i)  Represent Reyleigh line on T-S Diagram and indicate variation in flow properties during heating and cooling in subsonic flow.                                                               (4)


       ii)  The stagnation temperature of air in a combustion chamber is increased to 3.5 times its initial value. If the air at entry is at 5 bar, 105°C and a Mach number of 0.25 determine.


a)                  the Mach number, pressure and temperature at the exit.

b)                  Stagnation pressure loss, and

c)                  The heat supplied per kg of air.                                                               (12)




12.b)i)  Write an expression for duct length and comment on maximum duct length in Fanno Flow.                                                                                                                  (2)


      (ii)  A circular duct passes 8.25 kg/s of air at an exit mach number of 0.5. The entry pressure and temperature are 3.45 bar and 38°C respectively and the coefficient of friction 0.005. If the Match number at entry is 0.15 determine.


  1. the diameter of the duct,
  2. length of the duct,
  3. pressure and temperature at the exit,
  4. stagnation pressure loss, and
  5. verify the exit Mach number through exit velocity and temperature.



13.a)i)  Derive an expression for Prandtl – Meyer relation as M*x. M*y = 1 in flow across normal shock.                                                                                                            (4)


      ii)   A jet of air at 275 K and 0.69 bar has an initial Mach number of 2.0. If it passes through a normal shock wave determine a) Mach number b) pressure c) temperature d) density e) speed of sound and i) jet velocity downstream of the shock.                                                                                                                      (12)




13.b)i)  With variation in pressure and temperature show that subsonic nozzle is convergent and supersonic nozzle is divergent.                                                (6)


      ii)   A gas (γ=1.3) at P1 = 345 mbar, T1 = 350 K and M1 = 1.5 is to be isentropically expanded to 138 mbar. Determine a) the deflection angle, b) final Mach number and c) the temperature of the gas-in flow with oblique shock.                  (12)


14.a)i)  Give expression for thrust, thrust power, propulsive power, propulsion efficiency and over all efficiency with a note on the terms involved in the equations, in aircraft propulsion.                                                                                               (4)


      ii)   Calculate the air flow rate through the engine, cross-section area of the propelling nozzle exit, thrust, thrust power, propulsive and overall efficiencies for a turbojet engine from the following data :


            flight Mach number = 0.85

            flight altitude = 12000 m

            cross-sectional area of the inlet-diffuser at entry = 0.5m2

            air- fuel ratio = 60

            Conditions at the exit of the exhaust jet;

            Pressure = 477mbar, temperature = 1000 K

            velocity = 660 m/s

            calorific value of the fuel = 43 MJ/kg                                                                  (12)



14.b)i)  Explain the principle of operation gas turbine through cycle analysis assisted with jet of exhaust gas giving a T-S diagram.                                                         (4)


       ii)  Explain the operation and performance of Ramjet, Tubrojet and Turbo prop engine.                                                                                                                            (12)


15.a)i)  Write a brief note on classification of rocket engines based on fuel energy source, space rockets and solid and liquid propellants.


       ii)  A super sonic jet aircraft with flight Mach number 2, has normal shock attached to the nose at entry to its diffuser. Obtain down stream Mach number and shock strength in building up pressure.




15.b)    Write short, critical note any “Four” of the following


  1. Rocket applications in aircraft
  2. Space flight in Indian space research
  3. Propelling payload through multistage rocket vehicle.
  4. Generalized gasdynamics for Fanno flow and Rayleigh flow in ducts.

5.         Importance of governing equation and property relations for static and stagnation states in isentropic relations.










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