摘要
采用动力模态分解(DMD)对离心压气机无叶扩压器内的复杂流场进行分析,选取1.8kg/s设计工况和1.4kg/s非稳定工况下的非定常数值计算结果为基础数据,得到这2种工况下10%叶高平面上切向速度、径向速度的模态云图以及特征频率,评估了DMD方法分析离心压气机非定常流动特征的能力.对不同特征频率下的流场进行重构,直观深入地再现了无叶扩压器内部非定常流动的变化过程.结果表明:在小质量流量下,叶片扫描频率的影响效果虽然仍占据主导,但受到抑制;捕捉到失稳频率约为193Hz,失稳模态在扩压器内沿周向占据3个固定的位置交替波动,不稳定波动沿扩压器周向并不存在旋转.
Taking the simulation results under design condition 1.8 kg/s and unsteady condition 1.4 kg/s as the basic data, an analysis was conducted on the complex flow field in the vaneless diffuser of a centrifugal compressor using dynamic mode decomposition （DMD）, so as to obtain the contours of tangential and radial velocity modes at 10% span plane as well as the characteristic frequencies, and to evaluate the applicability of DMD method in analyzing the unsteady flow within the vaneless diffuser. In addition, flow field reconstruction was conducted at different characteristic frequencies to figure out the transformation of unsteady flow in the diffuser. Results show that at small mass flow rates, the predominant effect of blade passing frequency is suppressed; the eigen mode corresponding to stall does not rotate along the circumferential direction, where three stall cells can be observed, and the frequency of stall is about 193 Hz.
出处
《动力工程学报》
CAS
CSCD
北大核心
2017年第6期447-453,共7页
Journal of Chinese Society of Power Engineering
关键词
离心压气机
无叶扩压器
非定常流动
动力模态分解
centrifugal compressor
vaneless diffuser
unsteady flow
dynamic mode decomposition
