Aerodynamic Loading Considerations of Three-Shaft Engine Compression System During Surge

Abstract

Compressor surge imposes a limit on aero-engine operability and can compromise integrity because of significant aerodynamic loads imparted on the engine components. The aim of this paper is to use 3D unsteady CFD to predict the surge loadings on a modern three spool engine. The computations are performed using a whole-assembly approach. In this work, the effect of two types of surge initiation on the maximum loading recorded during surge are studied and a physical explanation of the main phenomena which contribute to those loadings is offered. The engine is matched at a high power condition and the surge inception is via throttling of the high pressure compressor (HPC) or turning of the intermediate pressure compressor (IPC) variable stator vanes. It was found that in an aero-engine surge event, the maximum overpressure are caused by a combined effect of the surge shock wave passing and high pressure gas blown towards the front of the engine during depressurisation. The overpressure is dictated by the compression system exit pressure at the moment of the surge inception. The surge initiation via HPC throttling produces larger overpressure and therefore, should be considered for design considerations.

Experimental validation of a three-dimensional through-flow model for high-speed compressor surge

“…The compressor rig presented in this paper has been previously investigated using single passage highfidelity URANS simulations, reproducing multiple surge events [6]. Three-dimensional full annulus modelling of compressor surge has been performed at Imperial College, using high-fidelity URANS simulations [7,8]. This type of CFD offers the best resolution of the phaenomenon, but the computational cost associated remains in the order of a day per rotor revolution using hundreds of cores running in parallel.…”