Tip clearance effect on high-pressure compressor stage matching

Abstract

Tip clearance flows have a major impact on both performance and stability of high-pressure compressors (HPC). The purpose of this paper is to underline how tip clearance variations affect the matching of compressor stages, hence modifying the efficiency and stall margin of the compressor. The practical application covered by the scope of this article is a modern highly loaded HPC dedicated to civil aircraft propulsion. The first part of the paper gives a very simple overview of stagewise matching in multistage compressors. Also, this part introduces the subject of the impact of tip clearance on stage matching. The second part of the paper illustrates the effect of increased rear block clearances on performance and stability, using some available experimental data. Finally, it is shown that three-dimensional multi-stage calculations can predict the effect of tip clearance variations on stage pressure-rise characteristics and on stage matching. This validated numerical tool therefore allows the aerodynamic design to be adjusted to the range of in-service clearances, thus providing a more robust compressor design.