基于大涡模拟的混流泵不稳定流动数值研究  

Analysis of instability flow on mixed-flow pump based on LES

作　　者：张琳[1] 施卫东[1] 张德胜[1] 石磊[1] ZHANG Lin Sill Weidong ZHANG Desheng Sill Lei(National Researeh Center of Pumps, Jiangsu University, Zhenjiang, Jiangsu 212013, China)

机构地区：[1]江苏大学国家水泵及系统工程技术研究中心,江苏镇江212013

出　　处：《排灌机械工程学报》2017年第4期303-308,318,共7页Journal of Drainage and Irrigation Machinery Engineering

基　　金：国家自然科学基金资助项目(51579118;51479083);江苏省产学研前瞻性联合研究项目(BY2015064-08)

摘　　要：为了分析某一混流泵在不同工况下运行时的内流场和压力脉动特性,以该混流泵为研究对象,建立流场分析模型,基于CFX软件,采用Large eddy simulation(LES)湍流模型进行不同工况下全流场非定常数值模拟.结果表明:非失速工况下(1.00Q_(opt)),叶轮内流线平稳,没有出现涡团,6个流道内的流态基本一致,仅在导叶出口吸力面附近有一定的流动分离.当旋转失速发生时,在导叶吸力面附近产生了大量的旋涡涡团,从导叶进口到出口,旋涡尺度先增大再减小,涡核附着在压力波动最小的导叶吸力面中间叶高区.对不同点处的压力脉动进行快速傅里叶(FFT)变换,从轮毂到轮缘,压力脉动的幅值逐渐增大.在叶轮出口,压力脉动频率分布情况和叶轮进口类似,但是,低频范围变大,最大脉动频率幅值有所减小,压力脉动主频向低频方向偏移.对不同工况下的压力脉动进行快速FFT变换,3个工况变化规律基本一致,但在0.55Q_(opt)工况下,低频范围较大,频率成分比较复杂,低倍频处的压力脉动幅值比较突出,而在0.75Q_(opt)工况下,低频宽度明显减少,低频脉动的频率集中在1N附近,当达到1.00Q_(opt)工况时,除了6N,12N等主要频率成分外,其他的频率成分均不是特别明显,低频范围的脉动频率幅值显著减小,整体的脉动幅值和另2个工况相比都明显减小.A flow-field analysis model of the mixed-flow pump was established in order to study the flow field and pressure pulsation characteristics under different operating conditions. The unsteady nu- merical simulation of the whole flow field under different operating conditions was carried out by Large eddy simulation（LES）based on the CFX software. The results show that the flow pattern was consis- tent at six channels except that a certain flow separation appeared on the suction surface near the guide vanes outlet at 1.00Qopt. When the rotating stall occurred, a lot of whirlpool developed near the suc- tion surface of the guide vanes and the whirlpool scale increased first and then decreased from the inlet to the outlet at the guide vanes, moreover the vortex core was attached to the suction surface where thepressure fluctuation was the smallest. The pressure pulsationat different points was analyzed by FFT transform, which showed that the amplitude of the pressure pulsation increased gradually from the hub to the rim. The distributiom of the pressure pulsation fi＇equeucy at the outlet was similar to that at the inlet except that the amplitude decreased a little and the dominant frequency shifted to the low-frequency direction. Additionally, the pressure pulsation under different operating conditions was also analyzed. The changing regularity of three operating conditions was consistent. However, the frequency range is lar- ger and the frequency components are more complex at 0. 55Qopt condition than at 0. 75Qopt and 1.00Qopt condition. At 0.75 Qopt the low-frequency width is significantly reduced and tile frequency of low-frequency pulsation was concentrated around 1N,while at 1. 00Qopt ,the frequency was not obvious except 6N and 12N, the amplitude of the pulsation frequency in the low-frequency range was significantly reduced, and the inte- gral pulsation amplitude was significantly smaller than that under the other two operating conditions.

关 键 词：混流泵 压力脉动 傅里叶变换 大涡模拟 

分 类 号：TH32[机械工程—机械制造及自动化]