Question

Commercial jet aircraft cruise up to high-subsonic Mach numbers, around 0.8, and are powered by turbofan engines. For the fan to operate efficiently, the Mach number upstream of the fan (Mf ) should not be too high (this is to avoid supersonic flow over the fan blades and resulting shock-wave losses). Typical design value is Mf = 0.5. Therefore, an inlet is used to decelerate the flow before it enters the fan. Consider an inlet Mach number Mi = 0.8 and a fan Mach number Mf = 0.5. The flow from the inlet to the fan is Q1D isentropic.

Calculate the following:
(a) The fan-to-inlet diameter ratio, Df /Di , required to decelerate the flow from Mi = 0.8 to Mf = 0.5.
(b) The associated pressure ratio pf /pi.

Answer 1

a) Df /Di = 1.136

b) pressure ratio pf /pi = 1.285

Step-by-step explanation:

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