口环间隙泄漏对离心泵空化性能的影响分析
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摘要
以DG-350型多级离心泵次级叶轮为研究对象,研究了口环间隙对离心泵空化性能产生的影响。通过定常数值模拟,计算出了离心泵的扬程和效率,同时得出了口环与进口段交汇处的速度矢量图、涡量云图和空化区域分布图以及叶轮流道内的空化区域分布图。模拟结果与实验结果的对比分析表明:(1)误差都在实际工程所要求的5%左右,说明计算与模拟结果准确;(2)由于口环与进口段交汇处速度旋涡的存在,使得离心泵的进口段与前口环交汇处区域的压力降低,从而导致了空化现象的发生;(3)随着口环间隙的增大叶轮流道上的空化区域也随之增大,从而减小了流体的过流面积,使流体速度和必须的汽蚀余量增大,NPSHR增大,则叶轮进口处的空化区域也就会增大。
Taking the secondary impeller of DG-350 multistage centrifugal pump as a test model,the influence of wear-ring clearance on the cavitation performance of the centrifugal pump was studied. The head and efficiency of centrifugal pump were calculated by steady numerical simulation. The velocity vector,vorticity distribution and cavitation area distribution at the intersection of wear-ring and inlet as well as the cavitation distribution in the impeller channel were obtained. Compared with the simulation results and experimental results,the errors were all about 5% of the engineering requirements,the calculation and simulation results were accurate. Due to the existence of velocity vortices at the intersection of the wear-ring and the inlet section,the pressure at the intersection of the inlet section of the centrifugal pump and the front wear-ring clearance decreased,resulting in cavitation. With the increase of wear-ring clearance,the cavitation area on the impeller channel also increases. Thus,the flowing area reduces,the fluid velocity and NPSHR increase,and then the cavitation area at the inlet section of the impeller increase.
Taking the secondary impeller of DG-350 multistage centrifugal pump as a test model,the influence of wear-ring clearance on the cavitation performance of the centrifugal pump was studied. The head and efficiency of centrifugal pump were calculated by steady numerical simulation. The velocity vector,vorticity distribution and cavitation area distribution at the intersection of wear-ring and inlet as well as the cavitation distribution in the impeller channel were obtained. Compared with the simulation results and experimental results,the errors were all about 5% of the engineering requirements,the calculation and simulation results were accurate. Due to the existence of velocity vortices at the intersection of the wear-ring and the inlet section,the pressure at the intersection of the inlet section of the centrifugal pump and the front wear-ring clearance decreased,resulting in cavitation. With the increase of wear-ring clearance,the cavitation area on the impeller channel also increases. Thus,the flowing area reduces,the fluid velocity and NPSHR increase,and then the cavitation area at the inlet section of the impeller increase.
引文
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[3]廖姣,张兴,张文明,等.分流叶片对离心泵内部固液两相流的影响[J].人民长江,2017,48(10):79-82.
[4]张云蕾,袁寿其,张金凤,等.分流叶片对离心泵空化性能影响的数值分析[J].排灌机械工程学报,2015,33(10):846-852.
[5]谭磊,曹树良,桂邵波,等.带有前置导叶离心泵空化性能的实验及数值模拟[J].机械工程学报,2010,46(18):177-182.
[6]王勇,刘厚林,袁寿其,等.不同叶片包角离心泵空化振动和噪声特性[J].排灌机械工程学报,2013,31(5):391-400.
[7]王勇.离心泵空化及其诱导振动噪声研究[D].镇江:江苏大学,2011.
[8]付燕霞,袁寿其,袁建平,等.叶片数对离心泵小流量工况空化特性的影响[J].农业机械学报,2015,46(4):21-27.
[9]孙帅辉.涡旋式液泵内流场及空化的数值模拟[J].排灌机械工程学报,2017,5(2):100-105.
[10]王洋.开缝叶片低比转数离心泵空化性能的数值模拟[J].排灌机械工程学报,2016,34(3):210-215.
[11]朱荣生.离心式上充泵首级叶轮空化特性与试验研究[J].原子能科学技术,2015,49(10):1778-1785.
[12]邓育轩,李仁年,韩伟,等.螺旋离心泵内回流涡空化特性[J].农业工程学报,2015,31(1):86-90.
[13]周凌九,王占民,江东智,等.离心泵非定常流动计算及性能预测[J].排灌机械工程学报,2010,28(4):286-290.
[14]刘厚林.3种空化模型在离心泵空化流计算中的应用评价[J].农业工程学报,2012,28(16):54-57.
[15]Hssan W,Barre S,Legoupil S.Study of the behavior of vapor fraction in a turbopump inducer usingan X-ray measurement technique[J].Experiments in fluids,2014,55(5):1-14.
[16]Asuaje M,Bakir F,Kergourlay G.3D quasi-unsteady flow simulation in a centrifugal pump-comparison with the experimental results[C]∥Proceedings of the ASMEH Heat Transfer/Fluids Engineering Summer Conference,2004.
[17]Frosina E,Senatore A,Buono D.A tridimensional CFD analysis of the oil pump of an high performance motorbike engine[J].Energy Procedia,2014(45):938-948.
[18]Nobuhiro Y,Shinji F,Xiang Y Q.LES simulation of backflow vortex structure at the inlet of an inducer[J].Journal of Fluids Engineering,2007,129(5):587-594.
[19]Chini S F,Rahimzadeh H,Bahrami M.Cavitation detection of a centrifugal pump using noise spectrum[C]∥Proceedings of IDETC/CIE,USA,California,2005.
[20]GB/T3216-2005回转动力泵水力性能验收实验(1级和2级)[S].北京:中国国家标准化管理委员会,2005.