旋涡泵进口含气量和叶片数对泵内流场和性能的影响分析

Influence analysis of inlet gas volume fraction and blade number of vortex pump on it’s inner flow field and hydraulic performance

为分析旋涡泵气液混输时进口含气量和叶片数对泵内流场和外特性的影响机理,通过数值计算,对不同进口含气量(5%、10%、15%)和不同叶片数(20、22、24、28)时旋涡泵内流场和外特性进行对比分析.结果表明:旋涡泵的扬程和效率随着进口含气量的增大而减小,扬程从48.98 m减小到36.19 m,效率从34.8%减小到32.4%;在各纵向截面上侧流道内压力大于叶轮流道内压力,从叶轮进口到出口沿圆周方向,各纵向截面内叶轮与壳体的最大压差逐渐增大;纵向截面上气液分离现象越来越严重,叶轮内气体体积分数逐渐增大,而侧流道内气体体积分数逐渐减小,叶轮轮毂处气相聚集越来越严重;随着叶片数的增加,旋涡泵的扬程和效率均呈先增后减的趋势;随着进口含气量的增大,旋涡泵的性能随叶片数变化的敏感度先增后减.

In order to analyze the influence of inlet gas volume fraction and blade number on the inner flow filed and the hydraulic performance of vortex pump during gas-liquid two-phase flow,the inner flow filed and the hydraulic performance of vortex pump with different inlet gas volume fraction(5%,10%,15%)and different blade number(20,22,24,28)were analyzed by numerical simulation.The analysis results show that the head and efficiency of the vortex pump decrease with the increase of inlet gas volume fraction with the head decreased from 48.98 m to 36.19 m,and the efficiency decreased from 34.8%to 32.4%.The pressure in the side channel on each meridional plane is greater than that in the impeller channel.The pressure difference between the maximum pressure in the casing and the minimum pressure in the impeller gradually increases along the circumference from the inlet to the outlet of the impeller,which result that the gas-liquid separation on the meridional plane is becoming more and more serious.The gas volume fraction in the impeller increases gradually while the gas volume fraction in the side channel decreases gradually,and the gas accumulation near the impeller hub becomes more and more serious.With the increase of the blade number,the head and efficiency of the vortex pump increase first and then decrease.With the increase of inlet gas volume fraction,the sensitivity of vortex pump performance with the number of blades increases first and then decreases.