气液两相条件下含气率对高速离心泵的影响研究

为探究气液两相流中含气率对高速离心泵内部流场的变化规律,基于ANSYS CFX欧拉非均相流模型对高速离心泵进行气液两相数值模拟分析,研究高速离心泵在设计流量下不同含气率对其效率和扬程的变化规律、叶轮流道流场的演变过程、隔舌和叶轮圆周出口监测点压力脉动变化特征。结果表明:效率和扬程特性与含气率呈线性关系,含气率越大,效率与扬程就越低,对高速离心泵性能影响就越严重;气相体积分布从叶片吸力面逐渐向叶片后缘处迁移,在叶轮出口处大量聚集,含气率10%附近出现相态分离现象;在含气率条件下隔舌与叶轮出口监测点的时域在t=0.02 s时压力发生较大波动。各含气率下主要变化幅值均发生在叶频及其倍频处,当含气率高于5%时对隔舌和出口的压力脉动幅值影响较大,即含气率5%是影响高速离心泵压力脉动幅值变化快慢的临界点。高速离心泵比常规转速离心泵所承受的含气率范围更小。

Research on the Influence of Gas Volume Fraction on High-speed Centrifugal Pumps under Gas-liquid Two-phase Conditions

In order to explore the variation of the gas flow rate in the gas-liquid two-phase flow to the internal flow field of the high-speed centrifugal pump,the gas-liquid two-phase numerical simulation analysis of the high-speed centrifugal pumps based on the ANSYS CFX Euler non-uniform flow model are carried out to study the high-speed centrifugal pumps.The results show that the efficiency and head characteristics are linear with the gas content.The higher the gas content,the lower the efficiency and the lift,the more serious the effect on the performance of the high-speed centrifugal pump.The gas volume distribution gradually changes from the suction surface of the blade to the trailing edge of the blade.At the point of migration,a large amount of accumulation occurs at the impeller exit,and phase separation occurs nearly 10%of the gas content.Under the condition of gas content,the time domain of the tongue and impeller outlet monitoring point fluctuates greatly at t=0.02 s.The main change amplitudes of each gas content rate occur at the leaf frequency and its octave.When the gas content is higher than 5%,the pressure pulsation amplitude of the tongue and the outlet is greatly affected,that is,the gas content is 5%.The critical point affects the speed of the high-speed centrifugal pump pressure fluctuation amplitude.High-speed centrifugal pumps have a lower gas content range than conventional high-speed centrifugal pumps.