Influence of Engine Conditions on the Performance Prediction of a Two-Stage Transonic Low Pressure Compressor

The derivation of application-driven impact factors on the performance of real engine compressors is an essential prerequisite for the development of efficiency-enhanced modern compressor concepts. This study intends to extend the knowledge of the sensitivity of compressor operation simulation on real-engine design conditions, by investigating the impact of upstream and downstream engine components on the prediction of compressor map characteristics. The investigations are conducted on a two-stage transonic low pressure compressor of an unmixed low bypass ratio turbofan engine. Starting from the basic test case of a compressor operation under non-disturbed and homogeneous boundary conditions, the compressor is systematically subjected to aerodynamic conditions deriving from the compressor positioning downstream of the engine intake and upstream of the bypass splitter. The analysis focuses on both global compressor map characteristics and the causal relations in local aerodynamics, in terms of a radial redistribution of the blade loading, local resistance against flow separation and the role of stage interaction depending on the distinguished engine conditions. A strong sensitivity on the spinner geometry is derived and a less pronounced effect of the downstream throttling condition is analysed.