A diffuser in a jet engine is designed to decrease the kinetic energy of the air entering the engine compressor without any work of heat interactions. Calculate the velocity at the exit of a diffuser when air at 100 kPa and 30°C enters it with a velocity of 350 m/s and the exit state is 200 kPa and 90°C. For calculation, assume the specific heat is constant at the average temperature of the inlet and the exit.

Question

Physics

Gavyn Robles

3 January, 12:02

A diffuser in a jet engine is designed to decrease the kinetic energy of the air entering the engine compressor without any work of heat interactions. Calculate the velocity at the exit of a diffuser when air at 100 kPa and 30°C enters it with a velocity of 350 m/s and the exit state is 200 kPa and 90°C. For calculation, assume the specific heat is constant at the average temperature of the inlet and the exit.

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Marcus Marshall · Answer 1

Given; P1 = 100 kPa, T1 = 30°C, T2 = 90°C, P2 = 200 kPa, V1 = 350 m/s

From energy conservation at inlet and outlet

h1 + (1/2) v1² = h2 + (1/2) v2²

CpT1 + (1/2) v1² = CpT2 + (1/2) v2²

.718 (90-30) x 103 = 0.5x (350²-v2²)

velocity at the exit of a diffuser; V2=190.63m/s