关键词: 叶尖泄漏流, 叶尖泄漏涡, 流动结构, 流动损失, 轴流压气机, 转子

Abstract:

This paper presents steady numerical study on a subsonic rotor, to further the knowledge of tip leakage flow/vortex flow structure in the tip clearance of an axial flow compressor rotor. The rotor and its related low-speed large-scale repeating-stage axial compressor are used for the low-speed model testing of a modern high-pressure compressor. The results are first compared with available experimental data to validate the numerical method. Then complex endwall flow structure and flow loss mechanism at the design operation points are studied. Finally, variations of the axial compressor rotor endwall flow structure among no tip clearance and different clearances are investigated. Also comparisons are made for tip leakage vortex structure, the interface of leakage flow and main flow, endwall blockage and loss between the design and near-stall operation points. The results show that flow spilled from the leading edge of the tip clearance will entrain into the tip leakage vortex below 62.5% clearance height, while it doesn't occur for higher positions. The effects of the tip leakage vortex on the flow decrease at higher positions, where secondary leakage flow appears more common and occupies a broader chordwise extent simultaneously. Although tip leakage vortex will expand and mix strongly with the main flow as it propagates downstream, which leads to the rapid reduction of the normalized streamwise vorticity, the value of the normalized helicity shows that the concentrated vortex feature can still be maintained.

Key words: tip leakage flow, tip leakage vortex, flow structure, flow loss, axial compressor, rotor