Abstract: A coupled casing treatment was designed and optimized with three-dimensional numerical simulation to improve the stall margin of a two-stage high-loaded axial flow compressor. The design was based on the understanding of the failure of traditional slot-type casing treatment in the experiment. The flow mechanism of stability improvement was analyzed with the method of unsteady simulations for the optimized coupled casing treatment， and the compressor’s stall mechanism under the effect of the casing treatment was also studied. The results show that the stall of the two-stage compressor is induced by the boundary layer separation that is caused by the passage shock at the rotor tip of the first stage. The slot-type casing treatment cannot effectively diminish the blockage induced by the boundary layer separation， and thus cannot improve the compressor’s stability. The coupled casing treatment， which takes advantage of slot-type casing treatment and recirculating casing treatment， bleeds the low-energy fluid at the rotor tip into the passage of inlet guide vanes and improves extremely the flow condition of the rotor tip. The stable operating range of compressor is improved by 49.3% and the adiabatic efficiency at the design point is improved by 0.54%. The compressor’s stall is triggered by the blockage induced by the concentrated shedding vortex in the stator rather than the rotor under the effect of coupled casing treatment.

Key words: Axial flow compressor；Slot-type casing treatment；Coupled casing treatment；Stall margin；Concentrated shedding vortex

摘要： 为了提升高负荷两级轴流压气机的失速裕度，在分析传统缝式机匣处理无法扩稳的流动机理基础上，设计了一种耦合型机匣处理结构，采用三维数值模拟对该结构进行了优化设计。针对优化的耦合型机匣处理进行了非定常数值模拟，阐述了该机匣处理的扩稳机理以及机匣处理作用下压气机新的失速机制。研究表明，两级高负荷压气机的失速由第一级转子叶顶强激波诱发的附面层分离引起，缝式机匣处理无法有效消除该附面层分离引起的通道堵塞，因而无法提高该压气机的失速裕度。耦合型机匣处理结合了缝式机匣处理和自循环机匣处理各自的优势，将第一级转子叶顶的低能流体抽吸至进口导叶通道，极大改善了转子叶顶的流动状况，使压气机的稳定工作范围提高了49.3%，设计点效率提升了0.54%。在耦合型机匣处理的作用下，静子通道内集中脱落涡诱发的通道堵塞成为触发压气机失速的新因素。

关键词: 轴流压气机；缝式机匣处理；耦合型机匣处理；失速裕度；集中脱落涡