旋风分离器内旋转流的不稳定性

Instability of swirling flow in cyclone

旋风分离器内的流场是一个复杂的旋转流流场，以往的流场研究主要集中在稳态流场的时均特性上，重点关注流场的时均速度分布和湍流特性方面，从实验测量和模拟两方面进行，而对瞬态速度的分析不够，对流场的不稳定性尚缺乏分析。研究表明，旋风分离器内的旋转流存在着明显的不稳定性，其表现形式为旋转流的旋转中心和旋风分离器的几何中心不同心，旋转中心线是一条摆动曲线，流场呈现非轴对称分布.

The instability characteristics of swirling flow in the cyclone were studied based on measured real tangential velocity by hot wire anemometry velocity fluctuated obviously in the center region （HWA）. The results showed that the real tangential of the cyclone, however, near the wall of the cyclone, the real tangential velocity had a little fluctuation. The real tangential velocity was analyzed with Fast Fourier Transform （FFT）. There was a basic frequency near the center region of the cyclone, which was about 44Hz. And the amplitude in the center region was bigger than that near the wall. The real tangential velocity fluctuation indicated that there existed an instability of swirling flow in the cyclone. This instability resulted in the rotation center of the swirling flow deviating from the geometric center of the cyclone, which produced the quasi-periodic oscillation of swirling flow and gave the real tangential velocity fluctuation.