UNIFIED ENGINEERING Fall 2004

Ian A. Waitz

Problem T8 (Unified Thermodynamics)

A steady stream of high pressure air flows through a part of an aerospace power system. The velocity at the inlet is 200 m/s, the pressure is 2 x 106 N/m2 and the temperature is 1000K. In between the inlet and the outlet are various components that can extract or inject heat and work into the flowing fluid. Approximate the air as an ideal gas with constant specific heat s, R=287 J/kg-K, c_p=1003.5 J/kg-K, and c_v = 716.5 J/kg-K. (MO# 5)

Suppose the outlet flow is at a pressure of 105 N/m2, a velocity of 1000 m/s, and a temperature of 600K, and the rate of power out of the device to turn a shaft is 100 x 103 J/kg per unit mass flow rate.

a) What, if any, quantities are the same at the inlet and the outlet?

b) What is the change in stagnation enthalpy from inlet to outlet?

c) What is the rate of heat transfer between the inlet and the outlet?

d) If there were no heat transfer, if the process through the components were quasi-static, and if the pressure at the outlet were maintained at the same value, what would now be the temperature and velocity at the outlet?