基于动态模式分解的离心压缩机动态流场分析

动静流道相互作用引起的非定常流动是离心式压缩机内流的主要特征,借助模态分解方法可以有效提取出该流场中相干结构,进而可以说明该动静干涉流场的主要特征。本文将动态模式分解(Dynamic Mode Decomposition,DMD)方法应用于带无叶扩压器通道的离心式压缩机流场分析中,通过对动静干涉速度场和压力场的模态提取和分析,直观揭示出动静流道中的流体运动特征。在设计流量工况下,叶轮出口叶顶间隙的流体流动和动静流道干涉效应影响了叶轮出口的速度参数和压力参数的分布。在叶轮和扩压器流道中分别出现了频率1 715和725Hz的湍流相干结构,两频率和叶轮通过频率有关。动静干涉流道中压力沿叶高方向动态规律相似,而速度场沿叶高方向波动规律存在一定的差异。该特征可以为压缩机流场测试提供参考。

Dynamic Flow Field Analysis of Centrifugal Compressor based on DMD

Abstract:The unsteady flow caused by the interaction between the rotating impeller and stationary diffuser is an inherent attribute of the centrifugal compressor.The dynamic mode decomposition (DMD) method can be used to extract the coherent structures which affect the development of the flow field and serve as a new approach to deeply understand the complicated turbulent field.In this paper,the DMD was adopted to analyze the dynamic flow field of centrifugal compressor with vaneless diffuser.The modes of the velocity field and pressure field showed that the distribution of the velocity field and pressure field in the outlet of the impeller is affected by the tip leakage flow and the rotor-stator interaction.The large scale vortexes which move circumferentially are originated from the tip leakage flow in the impeller.The variation trend of the pressure field in the centrifugal compressor is similar along the height of the blade,while that of the velocity field is different to some extent.This feature found is believed to provide a reference for engineering testing.