外来扰动频率对涡轮叶栅流动稳定性的影响

Effect of External Perturbation Frequency on Flow Stability of the Flow in Turbine Cascade

应用非线性PSE方法预测和评价某型超临界蒸汽轮机调节级导叶栅边界层流动的稳定性,研究了扰动频率对叶栅流动稳定性的影响。结果表明,当来流扰动频率变化时,扰动会对叶栅边界层稳定性产生很大的影响,此时存在一个最大扰动频率,在这一频率下流动最容易发生转捩。最大扰动频率受边界层厚度雷诺数的直接影响,其数值沿着流向逐渐减小,即叶片入口流动对高频扰动敏感,叶片出口流动对低频扰动敏感。

This paper apply nonlinear PSE method, develops one numerical solve program, which can greatly predict ,analysis and evaluate the stability of boundary layer. In this paper, the effect about perturbation frequency on the flow stability is studied in the guide vane cascade of governing stage in one supercritical steam turbine. The results show that when perturbation frequency of incoming flow changed, which can bring about large impact on the stability of boundary layer in this cascade;and there is a maximum perturbation frequency, flow transition most likely to happen under this frequency. In this study, we found that the Reynolds number of boundary layer has direct impact on the maximum perturbation frequency, and the frequency gradually decreases along the flow direction, so we can draw the conclusion that inlet flow is sensitive to higher perturbation frequency and outlet flow is more sensitive to lower perturbation frequency in blade.