A Study on the Mechanism of Initiation and Propagation of Rotating Stall

以NACA65（12）10叶栅为例，采用数值模拟和实验相结合的方法，研究了旋转失速发生和发展的流动机理，叶栅安装角为30 °，稠度为1.0。当叶片失速时，在吸力面上形成失速涡，然后在同一吸力面上的后缘附近形成非失速涡。结果表明，这些涡对通过叶片通道的流动产生了限制作用，并在一定时间内引起了相邻叶片的失速，从而使失速得以传播，同时还显示了处于旋转失速下的叶片表面上的非定常压力分布。和小扰动的发展瞬态，直到稳定传播的大扰动的完成，实验是在一个线性叶栅的试验段上用数值模拟中所用的相同叶片进行的风洞试验，测量了旋转失速传播过程中叶片表面的非定常压力分布。本实验的目的是通过比较实验和数值模拟得到的非定常压力分布来确认模拟方法的有效性，但由于无法得到与数值模拟结果相比较的表面压力数据，主要原因是没有找到适当的数据平均方法，用于随机波动旋转失速流中采集的信号。实验计划继续进行。

Flow mechanism which controls initiation and propagation of the rotating stall was studied by means of numerical simulation and experiment.A cascade of NACA65(12)10 blades with stagger angle 30ﾟ and solidity 1.0 was selected as an example for the study. When a blade stalls, a stall vortex is formed on the suction surface and then an unstall vortex near the trailing edge on the same suction surface. It is shown that these vortices restrict the flow through the blade channel and, as a result , cause stall of the neighbouring blade in the course of time-thus the stall propagates.Unstady pressure distribution on the surface of blades exposed to the rotating stall is also shown.Next, the initiation process of the rotating stall is analyzed, and the developing transient of the small disturbance until the completion of the steadily propagating large-auplitude rotating stall is shown.The experiment was carried out with the same blades as used in the numerical simulation placed at the test section of a linear cascade wind tunnel, and the unsteady pressure distribution on the blade surfaces is measured when the rotating stall is propagating. The purpose of the experiment is to confirm the availability of the simulation method by comparing both unsteady pressure distributions obtained each from the experiment and the numerical simulation.However, this purpose was not accomplished because the surface pressure data accurate enough to be compared with the numerical result could not be obtained, the main reason being that the adequate data averaging method was not found for the signals taken in the randomly fluctuating rotating stall flow. The experiment is planned to be continued.