Compared to a pure turbojet of identical core size, a high-bypass ratio turbofan engine achieves:

(A) Higher propulsive efficiency $\eta_p$

(B) Lower thrust specific fuel consumption (TSFC)

(C) Lower jet exhaust noise

(D) Higher exhaust jet exit velocity

Answer Key:

A,B,C

### Solution: High bypass engines move a larger mass of air at lower jet velocity, which dramatically increases propulsive efficiency $\eta_p = \frac{2 u_0}{u_0 + u_j}$, lowers TSFC, and reduces jet shear noise ($I \propto u_j^8$). Exhaust velocity is lower, not higher. Correct: A, B, C.

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