系统响应对局部喘振发展影响的实验研究

Experimental Study on Effect of System Response on Development of Partial Surge Initiated Instability

局部喘振型叶根失速先兆是在跨声速压气机中发现的一种起始于叶根的低频轴对称扰动,经研究表明其扰动频率由系统的Helmholtz频率决定,进而猜想系统响应在局部喘振发展过程中有重要作用。本文通过在压气机及出口容腔内新增动态传感器以监测扰动的发展和系统的轴向振荡,从而深入揭示系统响应与局部喘振传播的物理关联。结果表明:系统响应对叶根起始的单个扰动及旋转失速团的形成没有影响,其作用阶段主要在单个扰动发展为连续扰动的过程中。在局部喘振发展过程中,单个扰动首先激励了系统流量的轴向波动,同时容腔内压力也发生了周期性振荡。在系统响应的反馈作用下,单个扰动的幅值被放大,并能持续发展成为连续扰动。

Partial surge is a type of instability inception in transonic axial flow compressors and occurs in the form of axisymmetric low-frequency disturbances localized in the hub region. Previous studies illustrate that the frequency of partial surge disturbances is set by the Helmholtz frequency of entire system, which motivates to propose a hypothesis that the system response performs an important role in the formation of partial surge-type stall inception. To further explore the link between the propagating of partial surge and system feedback in the present study, the dynamic transducers are added in compressor and plenum during the stall evolution to detect the disturbance propagation and system axial oscillation. The results indicate that the system response has no effects on the occurrence of single-pulse and rotating stall cells, the main effect of that is to convert the single-pulse into the continuous disturbances. During the development of partial surge disturbances,the single-pulse first excites the axial oscillation of system mass flow, and the pressure in the plenum oscillates periodically at the same time. The feedback effect of system response is to amplify the amplitude of single-pulse, and further convert it to be continuous disturbances.