微型高速泵内空化流动的数值分析

以一台单级微型高速离心泵为研究对象,对其内部空化流动进行全流场数值模拟,分析了3种流动系数和不同空化数时该离心泵叶片流道内的空泡、静压以及相对速度分布规律。研究结果表明:空泡最先在叶片吸力侧前缘产生,该空泡区随着空化数的减小沿着叶片吸力侧向出口尾缘迁移和扩大,且呈非对称分布。在相同空化数下,随着流量系数的增加叶片流道内的空化区域变大;叶片吸力侧中间区域出现低速区并在叶片间流道内发展,同时,叶片尾缘处的高速区向叶轮内延伸,表明空泡造成叶轮内流道的堵塞,阻碍液体的流动;在叶片吸力面侧,空泡体积分数的最大值主要分布在叶片中间靠近轮毂的位置,而在压力面侧位于叶片前缘的机匣附近。初步建立了关于微型高速离心泵内空泡流动的一个较完整的认识。

Numerical Analysis of Cavitation Flow in a High Speed Micro-pump

The cavitation flow fields of a speed high micro centrifugal pump are numerically analyzed.Simulations of the flows at three different flow coefficients are performed.Distributions of vapor,static pressure and relative velocity in the rotation surfaces of the centrifugal pump are presented and analyzed.The results show that vapor bubble is firstly observed to form near the leading edge of the suction side of the blades when cavitation occurs.As the cavitation number is reduced,the vapor bubbles grow in size along the suction side of the blades and extend in the streamwise direction in the flow passages and the cavitation is found to be asymmetric about the axis.By comparing the vapor volume fraction distributions at different flow rates,cavitation is easier to occur at a larger flow-rate.As the inflow total pressure decreases,a significantly low speed zone is observed at the suction side of each blade.Meanwhile,because of the clogging of vapor near the suction side,the local high speed zone behind the trailing edge is observed to expand reversely to the blade passages.In the suction side of the blades,the maximum value of the vapor volume fraction appears near the hub,while in the pressure side,such peak values are seemed to occur near the leading edge and close to the impeller shroud.Cavitation flow in a high speed micro centrifugal pump is initially understood.