Flow-Field Investigation of an Inter-compressor Duct Under Different Inflows and Their Influence on the Performance of a Low-Pressure Compressor

The present computational study focusses on the flow physics analysis of an aero-derivative inter-compressor duct with struts along with the low-pressure (LP) compressor for a generic small turbofan engine. The transition duct connects the transonic fan to LP compressor. For numerical analysis, four inflows under consideration are Inflow-A (uniform inflow), Inflow-B (fan exit condition with uniform flow at fan inlet), Inflow-C (fan exit condition with radial hub distortion at fan inlet) and Inflow-D (fan exit condition with circumferential distortion at fan inlet). A pair of streamwise counter-rotating pair of vortices forms at the duct-struts-hub corner region for Inflow-A. But, for all other inflows, the vortex formation is deflected on the leeward side of the strut owing to the tangential component generated by the upstream stage. Besides, the exit conditions of the duct are imposed on the LP compressor to estimate its performance and the phenomena that lead to stall. For each inflow, the flow separation at the tip side of the stator leads to compressor stall. In general, the paper briefly elucidates how different inflows ingested by the transonic fan affect the duct and subsequently the LP compressor in a gas-turbine engine.