16. The fluid property that remains unchanged across a normal shock wave-

A. Static pressure

B. Mass density

C. Stagnation pressure

D. Stagnation enthalpy

Click for Answer/Explanation

Correct Answer is A

17. In a reaction turbine stage enthalpy drop in the stator blades is 4.62 kJ/kg and that in the rotor blades is 2.38 kJ/kg. The degree of reaction of the stage is-

A. 0.34

B. 0.55

C. 0.53

D. 0.45

Click for Answer/Explanation

Correct Answer is A

18. In rocket propulsion, the oxygen for combustion of its fuel is taken from-

A. Surrounding air

B. Surrounding air and compressed atmosphere air

C. The rocket itself

D. Compressed atmospheric pressure

Click for Answer/Explanation

Correct Answer is C

19. Increasing the number of reheating stages in a gas turbine to infinity makes the expansion tending-

A. Isothermal

B. Isobaric

C. Adiabatic

D. Reversible Adiabatic

Click for Answer/Explanation

Correct Answer is A

20. In a gas turbine cycle, the turbine output is 600 kJ/kg, the compressor work is 400 kJ/kg and the heat supplied is 1000 kJ/kg. Find the thermal efficiency-

A. 20%

B. 40%

C. 65%

D. 80%

Click for Answer/Explanation

Correct Answer is A

Net Work = Turbine Work – Compression Work

So on Substituting the value, We get,

(600 – 400) kJ/kg

Net work = 200 kJ/kg

Now the thermal Efficiency is

Efficiency = (Net Work)/(Heat Supplies)

On Substituting, We get,

(200 / 1000) × 100 = 20% [Answer]

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