THERMAL EFFECTS ON TRANSIENT PROCESS OF A TURBOJET ENGINE

The mathematical models commonly used for dynamic process of turbojet or turbofan engine consider only the rotor inertia and gas path volume dynamics. Usually the gas path volume of an aeroengine is not great, so the effect of volumedynamics on normal transient process is negligibly small. The thermal effectsinclude transient heat transfer and the component efficiency changes caused by clearance variation with temperature in the components of compressor and turbine.A single-shaft turbojet engine has been tested for cold and hot transient processes. The comparison between the cold and hot transient test results shows that the thermal effects have significant influence on the acceleration time, the changing rate of aerothermodynamic parameters with engine speed, etc. The experimentalinvestigation demonstrates that the thermal effects must be taken into account so as to establish an accurate mathematical model for the transient process of turbine engines.