实验探究周向进气畸变对局部喘振型跨声速轴流压气机进气的影响

Experimental Investigation of Circumferential Inlet Distortion on Partial Surge Type Stall Inception in Transonic Axial Compressor

关键词:  跨声速压气机  稳定裕度  失速先兆  周向进气畸变  局部喘振

Key words:  Transonic axial compressor  Stall margin  Stall inception  Circumferential inlet distortion  Partial surge

摘要:

为深入探究失速点变化机理，采用实验方法探究了三种不同周向畸变强度的进气边界对压气机失稳演化的影响机理。在试验过程中，通过增加动态测试点以测量转子叶尖的静压和静子尾缘的总压，并在压气机出口容腔内增加测点以检测系统响应。结果表明，当进口存在周向畸变时，失稳点流量的减小是由于压气机的失稳演化过程从局部喘振转变成了突尖波。在均匀进气时，该压气机失速演化过程为局部喘振，扰动以低频轴对称的形式出现在静子叶根区域。当进口存在周向畸变时，静子叶根处仍会出现不稳定低频扰动，但由于周向畸变的存在使其不再具备轴对称性，因此该低频扰动无法进一步发展，最终由于转子叶尖出现了突尖波导致压气机失稳。本研究主要结论为周向进气畸变可以通过改变压气机失速过程进而影响压气机失速点变化。

Abstract:

To explore the mechanism of stall point shift in detail， a series of experiments are conducted to explore the effects of circumferential inlet distortions on compressor instability evolutions with three different distortion intensities. During the experiments， the high-response dynamic test points are mounted to measure static pressures at rotor tips and total pressures at stator trailing edges， and an additional test point is set on the wall of the plenum to detect the system response. The results demonstrate that the decrease of mass flow rate near rotating stall under circumferential inlet distortions is due to that it is the occurrence of spike-type stall inception that leads to the flow instability instead of that of the partial surge. The instability inception of partial surge occurs under uniform inlet conditions and it is in the form of axisymmetric low-frequency disturbances localized in the stator hub region. The low-frequency disturbance still can appear under circumferential inlet distortions but the propagation characteristic of axisymmetric is suppressed. Therefore， the low-frequency disturbance cannot be further developed， and the final compressor instability is caused by the spike-type inception at the rotor tip. In conclusion， circumferential inlet distortion can change the stall route so as to extend the stalled operation point.