超高压比离心压气机失速机理探究

Stall Mechanism in an Ultra-High-Pressure-Ratio Centrifugal Compressor

喘振和旋转失速代表着通过压气机有序流动的崩溃,是对所有类型压气机性能的固有限制。本文以超高压比离心压气机为研究对象,通过全环数值模拟捕捉失速起始至发展为稳定旋转失速的动态过程。研究发现:在此超高压比离心压气机内,径向扩压器进口为超音速来流并在喉部形成强烈的激波,节流过程中气流攻角逐渐增大,造成了严重的激波附面层分离现象触发了失速;此外,当失速过程发展成熟时,周向形成6个失速区域沿叶轮旋转的反向进行传播,不同于传统失速模型中失速团沿叶轮旋转的方向进行周向传播。

Rotating stall and surge,representing the breakdown of the orderly flow through a compressor,limits the performance of all types of compressors.This paper presents the dynamic process of the stall inception and its development in an ultra-high-pressure-ratio centrifugal compressor based on the full-annulus unsteady simulation.The results indicate that under the condition of supersonic inlet flow,an intensive shock is formed at the radial diffuser throat.In the process of throttling the compressor,the shock-induced boundary-layer separation appears due to the increase of incidence,and thus triggers the stall.In addition,when the stall is mature,the 6 stall cells in the diffuser propagate in the opposite direction of the impeller rotation,which is different from the classic stall model in which the stall cells propagate along the direction of the impeller rotation.