Question

Atmospheric air at -45°C, 60 kPa enters the front diffuser of a jet engine with a velocity of 900 km/h and frontal area of 1 m². After the adiabatic diffuser the velocity is 20 m/s. Find the diffuser exit temperature and the maximum pressure possible

Answer 1

C.V. Diffuser, Steady single inlet and exit flow, no work or heat transfer.

Heat capacity and ratio of specific heats from  C_Po = 1.004 kJ /kg K, k = 1.4, the energy equation then gives: 

 1.004[ T_e - (-45)] = 0.5[(900 x 1000/3600)² - 20² ]/1000

= 31.05 kJ/kg => T_e = −14.05 °C = 259.1 K

Constant s for an ideal gas is expressed in