Some Effects of Non-Axisymmetric End Wall Profiling on Axial Flow Compressor Aerodynamics: Part II—Multi-Stage HPC CFD Study

Abstract

Non-axisymmetric end wall profiling is now a well established design methodology in axial flow turbines, used principally to improve their aerodynamic efficiency by reducing secondary loss. However, profiled end walls (PEWs) have yet to find an in-service application in a gas turbine compressor. This two-part paper presents the results of a number of studies, both experimental and computational, into the potential aerodynamic benefits of applying PEWs in axial flow compressors. The second paper describes an investigation into PEWs as a means of suppressing stator hub corner stall. An in-house design optimisation system (SOPHY) was applied to a typical embedded stator row in a multi-stage HP compressor. This enabled a new PEW geometry to be defined which is shown to be an effective alternative to 3-D aerofoil shaping in controlling stator hub corner stall. The results of this new study and of the work described in the first paper have been combined in a further investigation. PEWs were applied to an HPC with purely 2-D blading, which exhibited extensive stator hub corner stall at off-design conditions. CFD analysis showed that stator hub corner stall was successfully suppressed by the PEWs. It is concluded that PEWs can significantly affect the end wall flow field and have similar effects on corner stall as 3-D blading. The potential for improving the performance of axial flow compressors using PEWs is discussed. To successfully achieve any such improvements, extensive computational resources that are dedicated to design optimisation will be required.