Unsteady response of an axial flow compressor to planar temperature transients

A spatially one-dimensional, time-dependent mathematical model to analyze the effects of pressure and temperature fluctuations on the dynamic response of a compression system is presented. The model accounts for the compressor unsteady response, variation of compressor efficiency with the flow coefficient, and the variation of air specific heats with temperature. The continuity, momentum, and energy equations are written for the inlet, compressor, and outlet duct, together with a first-order relaxation equation describing the unsteady response of the compressor. The resulting system of hyperbolic partial differential equations is solved by the method of characteristics. The model is used to simulate the convection of planar temperature fluctuations (entropy waves) into a compression system.