叶片包角对离心泵流场及脉动特性的影响

针对离心泵非定常流动压力脉动特性,采用滑移网格的大涡模拟技术对叶片包角分别为95°,100°,105°,108°的4副叶轮进行数值模拟.分析了叶片包角对离心泵水力性能、叶轮出口"射流-尾迹"、测点压力脉动频谱特性和叶轮径向力的影响关系.结果表明:随着包角的增大,离心泵的水力性能下降;包角适当增大,会使叶轮射流-尾迹流动结构变弱.在设计工况下,蜗舌附近测点压力脉动最大;在蜗壳螺旋段压力脉动强度沿流动方向逐渐变弱,而在叶轮流道内压力脉动沿流动方向逐渐增强,在叶轮出口处达到最大;而离心泵叶轮所受径向力随着包角的增大而减小,适当地增大包角可以提高离心泵运行的可靠性.

Effect of Blade Wrap Angle on the Internal Flow Field and Pressure Pulsation in Centrifugal Pumps

For investigating the pressure pulsation characteristics of the unsteady flow in centrifugal pumps,a single-stage single-suction centrifugal pump was taken as an example to perform a numerical simulation by using the technology of large eddy simulation with sliding grid.The three dimensional flow field was simulated numerically with the blade wrap angle 95°,100°,105° and 108° respectively.The influences of the blade wrap angle on the centrifugal pump hydraulic performance,impeller exit jet-wake,pressure pulsation frequency spectrum characteristics at each measuring point and radial force of the impeller were analyzed.The results show that as the angle increases,the centrifugal pump hydraulic performance degradates.The angle increase will lead to the impeller outlet jet-wake flow structure.Under design conditions,near the volute tongue the pressure pulsation at measuring points is the strongest,at the spiral screw section along the flow direction,the pressure pulsation intensity gradually weaken,and at the impeller passage point along the flow direction,the pressure pulsation gradually enhances and reaches the maximum at the impeller outlet.The radial force of the centrifugal pump impeller decreases with the increase of angle.Therefore,appropriately increasing the wrap angle can improve the reliability of the centrifugal pump running.