新Omega涡识别法在液体火箭发动机涡轮氧泵中的应用

Application of New Omega Vertex Identification Methodin a Liquid Rocket Engine Oxygen Pump

关键词:  涡轮泵  Omega涡识别  动静干涉  压力脉动  涡脱落

Key words:  Turbopump  Omega vortex identification  Rotor and stator interaction  Pressure pulsations  Vortex shedding

摘要:

离心泵中流动不稳定现象与流场中旋涡的形成及演化过程密切相关。为解决传统涡识别法在高速离心泵流场涡结构捕捉方面的缺陷，引入新Omega涡识别法，对液体火箭发动机涡轮氧泵流场中的涡结构进行了分析。确定了新Omega涡识别法在高速离心泵流场涡结构捕捉方面的优势，利用该方法对涡轮氧泵中离心轮与扩压器之间的动静干涉机理进行了阐释。结果表明：对于高速离心泵，传统Q准则以及λ₂准则涡识别法错误地将壁面强剪切层识别为旋涡，而新Omega涡识别方法能够有效滤除流场中非旋转涡量部分，较好地捕捉流场中涡结构，可作为高速离心泵流场涡结构识别的首选方法。通过离心轮与扩压器动静干涉区域旋涡演化过程分析可知，涡轮氧泵离心轮与扩压器之间的动静干涉效应主要源自于扩压器叶片压力面上的周期性涡脱落现象。

Abstract:

The flow unsteady phenomenon is closely associated with the formation and the evolution process of the vortex in the centrifugal pump. To deal with the issue that traditional vortex identification method cannot capture the vortices correctly in high speed centrifugal pumps, the new Omega vortex identification method was introduced to perform the vortex analysis in a liquid rocket engine oxygen turbopump. The advantages of the new Omega vortex identification method were confirmed and the formation mechanism of the rotor-stator interaction (RSI) between impeller and diffuser was clarified by using this new method. Results show that the traditional Q-criterion and λ₂-criterion method falsely identify the strong shear layers as vortices in the high-speed centrifugal pump. However, the new Omega method can effectively remove this non-vortical vorticity and better capture the vortex structures in the flow field, thus could be a preferable method for vortex identification in high speed centrifugal pumps. The study on the evolution of the vortices in impeller-diffuser interaction region reveals that the RSI effect in the pump is directly derived from the periodic vortices shedding from the diffuser blade pressure surfaces.