不同工况下混流泵转子径向力及压力脉动
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摘要
为了研究混流泵内部非定常流动特性,基于ANSYS CFX软件对混流泵的外特性和内部流场进行了非定常计算,获得了不同流量工况下转子径向力的分布情况和不同监测点的压力脉动时域、频域响应,分析了不同流量工况对混流泵转子径向力和压力脉动的影响.研究结果表明,数值计算的外特性结果与试验测量结果的趋势基本吻合,说明数值计算的准确度较高. 3种流量工况下径向力的分布均呈现一定的周期性,小流量工况下的瞬态径向力合力最不稳定,设计工况下的瞬态径向力合力规律性最强,大流量工况下混流泵瞬态径向力合力波动性最小.不同流量工况下叶片通过频率始终占主导因素,低频信号是引起设计工况压力脉动的主要原因,流量变化对轮缘间隙进出口压力系数幅值影响较小,对叶轮中间位置处压力系数幅值影响较大.研究结果为揭示导叶式混流泵内部不稳定流动特性及其诱导的转子故障恶化提供理论依据.
In order to study the unsteady flow characteristics of the mixed flow pump,unsteady calculation on the external characteristics and internal flow field was carried out based on the ANSYS CFX software. The radial force distribution of the rotor and the time domain and frequency domain response of the pressure fluctuation at different monitoring points under different flow conditions were obtained.Besides,the influence of different flow conditions on rotor radial force and pressure fluctuation was analyzed. The results show that the numerical results of the hydraulic characteristics are in good agreement with the experimental measurements,which shows that the accuracy of numerical calculation is higher.The distribution of the radial force under three different flow conditions shows a certain periodicity.That is to say,the transient radial force is the most unstable at the small flow rate,the regularity of the transient radial force is the strongest under the rated condition,and the fluctuation of the transient radial force is the smallest under the large flow condition. Under different flow conditions,the blade passing frequency always plays the leading role. Under the rated flow condition,the low-frequency signal is the main cause of the pressure pulse. The change of flow rate has little influence on the pressure coefficient amplitude at the inlet and outlet of the impeller,while it has great influence on the pressure coefficient amplitude at the middle of the impeller. The results provide a theoretical basis for revealing the unsteady flow characteristics and the induced deterioration of rotor faults in the mixed flow pump.
In order to study the unsteady flow characteristics of the mixed flow pump,unsteady calculation on the external characteristics and internal flow field was carried out based on the ANSYS CFX software. The radial force distribution of the rotor and the time domain and frequency domain response of the pressure fluctuation at different monitoring points under different flow conditions were obtained.Besides,the influence of different flow conditions on rotor radial force and pressure fluctuation was analyzed. The results show that the numerical results of the hydraulic characteristics are in good agreement with the experimental measurements,which shows that the accuracy of numerical calculation is higher.The distribution of the radial force under three different flow conditions shows a certain periodicity.That is to say,the transient radial force is the most unstable at the small flow rate,the regularity of the transient radial force is the strongest under the rated condition,and the fluctuation of the transient radial force is the smallest under the large flow condition. Under different flow conditions,the blade passing frequency always plays the leading role. Under the rated flow condition,the low-frequency signal is the main cause of the pressure pulse. The change of flow rate has little influence on the pressure coefficient amplitude at the inlet and outlet of the impeller,while it has great influence on the pressure coefficient amplitude at the middle of the impeller. The results provide a theoretical basis for revealing the unsteady flow characteristics and the induced deterioration of rotor faults in the mixed flow pump.
引文
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[2]李伟,季磊磊,施卫东,等.变流量工况对混流泵转子轴心轨迹的影响[J].农业工程学报,2016,32(4):91-97.LI Wei,JI Leilei,SHI Weidong,et al.Influence of different flow conditions on rotor axis locus of mixed-flow pump[J].Transactions of the CSAE,2016,32(4):91-97.(in Chinese)
[3]ADKINS D R,BRENNEN C E.Analyses of hydrodynamic radial forces on centrifugal pump impellers[J].Asme transactions journal of fluids engineering,1988,110(1):20-28.
[4]BARRIO R,FERNNDEZ J,BLANCO E,et al.Estimation of radial load in centrifugal pumps using computational fluid dynamics[J].European journal of mechanics-B/fluids,2011,30(3):316-324.
[5]袁寿其,周建佳,袁建平,等.分流叶片对螺旋离心泵径向力的影响[J].农业机械学报,2012,43(9):37-42.YUAN Shouqi,ZHOU Jianjia,YUAN Jianping,et al.Numerical simulation on radial hydraulic forces for screw-type centrifugal pump with splitter blade[J].Transactions of the CSAM,2012,43(9):37-42.(in Chinese)
[6]GONZáLES J,SANTOLARIA C,PARRONDO J L,et al.Unsteady radial forces on the impeller of a centrifugal pump with radial gap variation[C]//Proceedings of Joint Fluids Summer Engineering,2003:1173-1181.
[7]JOSé González,JORGE Parrondo,CARLOS Santolaria,et al.Steady and unsteady radial forces for a centrifugal pump with impeller to tongue gap variation[J].Transactions of the ASME,2006,27:454-462.
[8]施伟,李彦军,袁寿其,等.高比转数双蜗壳混流泵设计及流动特性分析[J].农业工程学报,2016,32(S1):57-62.SHI Wei,LI Yanjun,YUAN Shouqi,et al.Design and internal flow field analysis of high specific mixed-flow pump with double volutes[J].Transactions of the CSAE,2016,32(S1):57-62.(in Chinese)
[9]靳栓宝,王永生,常书平,等.混流泵内流场压力脉动特性研究[J].农业机械学报,2013,44(3):64-68.JIN Shuanbao,WANG Yongsheng,CHANG Shuping,et al.Pressure fluctuation of interior flow in mixed-flow pump[J].Transactions of the CSAM,2013,44(3):64-68.(in Chinese)
[10]张德胜,施卫东,王川,等.斜流泵叶轮和导叶叶片数对压力脉动的影响[J].排灌机械工程学报,2012,30(2):167-170.ZHANG Desheng,SHI Weidong,WANG Chuan,et al.Influence of impeller and guide vane blade number on pressure fluctuation in mixed-flow pump[J].Journal of drainage and irrigation machinery engineering,2012,30(2):167-170.(in Chinese)
[11]刘建瑞,郑俊峰,付登鹏,等.混流泵径向间隙对内部非定常流场影响的分析[J].流体机械,2014,42(3):19-23.LIU Jianrui,ZHENG Junfeng,FU Dengpeng,et al.Effect of volute tongue-impeller gaps on the unsteady flow in mixed-flow pump[J].Fluid machinery,2014,42(3):19-23.(in Chinese)
[12]IVERSEN H W,ROLLING R E,CARLSON J J.Volute pressure distribution,radial force on the impeller,and volute mixing losses of a radial flow centrifugal pump[J].Journal of engineering for gas turbines&power,1960,82(2):136.