Detailed structure of tip clearance flow in an isolated axial flow compressor rotor and its effect on compressor performance

Experiments up to now cannot reveal completely the structure of tip clearance flow. Our aim is to study theoretically this detailed structure and its important effect on performance of an isolated axial flow compressor rotor. Experimental and numerical investigations were carried out. We used well-known theoretical methods and numerical simulation to study the above-mentioned detailed structure. At NPU Department of Aeroengines we have engaged in aeroengine research, both theoretical and experimental, for many years; so we need not say anything about our normal experimental procedure in this paper other than stating that we have done considerable contract experimental research for Roll-Royce plc. We arranged our experimental setup in such a way as to make it an isolated axial compressor rotor. For such rotor, the calculated results were compared with experimental data and good agreement was achieved between predicted and experimental values all along the spanwise direction of the rotor blade except in the neighborhood of the casing, where it was almost impossible to make measurements experimentally. Near the casing the theoretically calculated total pressure changes very rapidly. Such abrupt change affects very much the performance of axial-compressor rotor.