GATE_AE_2027_MOCK_05_Q54
GATE 2027 Aerospace Engineering All-India Master Mock 05 (High-Yield Comprehensive Grand Finale)
MSQ · 2 Marks
Propulsion • Thermodynamic Cycles of Gas Turbines • Turbojet and Turbofan Performance
Which of the following statements regarding gas turbine propulsive efficiency \eta_p are TRUE?
(A) \eta_p increases as exit jet velocity V_e approaches flight speed V_0.
(B) \eta_p is maximum when V_e = V_0, but net thrust drops to zero at this condition.
(C) Turbofan engines have higher propulsive efficiency than turbojets at subsonic cruise speeds.
(D) Propulsive efficiency is independent of flight velocity.
Answer Key:
A,B,C
Step-by-Step Verified Solution
### Solution: \eta_p = 2 / (1 + V_e/V_0). As V_e -> V_0, \eta_p -> 1.0 (A, B). Turbofans bypass large airflow at lower jet velocity, giving higher \eta_p at subsonic speeds (C). \eta_p strongly depends on flight velocity (D is false). Correct: A, B, C.