摘要
为了研究轴流泵空化问题,利用CFX软件二次开发技术对湍流模型进行了修正,通过编写CCL语言实现了PANS模型中参数f_(k)的动态定义,使其可以瞬时地根据当地网格条件和湍流长度尺度修改其值;利用修正后的湍流模型对轴流泵全流道进行空化数值计算,得出临界汽蚀余量为5.37 m,经试验可知,实际临界汽蚀余量为5.68 m,两者误差是由试验条件及试验系统引起的,且在合理范围内,并通过拍摄空泡图验证了该湍流模型在轴流泵空化计算中的可靠性.分析数值计算结果,得出了不同工况下轴流泵的空化特性,随着汽蚀余量的减小,轴流泵叶轮内空泡体积分数变大,涡量变大,叶片表面压力和流速在空泡产生和溃灭的位置处发生相应波动;随着流量的增大,轴流泵临界汽蚀余量减小,空泡分布的整体量变大,叶轮内部湍动能值变大,湍流耗散变严重,这与空化的发生和溃灭有直接关系.
In order to study the cavitation problem of axial-flow pumps,the secondary development technology of CFX software was used to modify the turbulence model,and realize the dynamic definition of the parameter f_(k) in the PANS model by writing CCL language,so that it can be defined according to local grid conditions and turbulence lengths.The revised turbulence model was used to numerically calculate the cavitation in the entire flow channel of the axial-flow pump.According to the calculation results,the critical NPSH of the axial-flow pump is 5.37 m,while the test shows that the actual critical NPSH is 5.68 m.The error between the two values is caused by the test conditions and the test system,and is within a reasonable range.The reliability of the turbulence model in the cavitation calculation of the axial-flow pump was also verified by taking the cavitation diagram in the test.By analyzing the numerical calculation results,the cavitation characteristics of the axial-flow pump under different working conditions were obtained.As the decrease of NPSH,the volume fraction of cavitation in the impeller of the axial-flow pump increases,the vorticity increases,and the surface pressure and flow velocity of the blade fluctuate correspondingly at the position where the cavitation occurs and collapses.With the increase of flow rate,the critical NPSH of axial-flow pump decreases,the overall amount of cavitation distribution becomes larger,the value of turbulent kinetic energy inside the impeller becomes larger,and the turbulent flow dissipation becomes serious,which is directly related to the occurrence and collapse of cavitation.
作者
俞芸芸
周大庆
于安
刘佳佳
YU Yunyun;ZHOU Daqing;YU An;LIU Jiajia(Jincheng College,Nanjing University of Aeronautics and Astronautics,Nanjing,Jiangsu 211100,China;College of Energy&Electrical Engineering,Hohai University,Nanjing,Jiangsu 211100,China;Yangzhou Branch of Jiangsu Water Source Company Ltd.of the Eastern Route of the South-to-North Water Diversion Project,Yangzhou,Jiangsu 225000,China)
出处
《排灌机械工程学报》
CSCD
北大核心
2022年第12期1204-1211,共8页
Journal of Drainage and Irrigation Machinery Engineering
基金
国家自然科学基金资助项目(51979086,51839008)。
关键词
轴流泵
修正PANS
空化特性
试验验证
axial-flow pump
modified PANS
cavitation characteristics
experimental verification
