液体射流泵喷嘴长径比的数值分析

液体射流泵的工作喷嘴一般采用锥直形喷嘴,锥直形喷嘴出口直段的长度与喷嘴出口直径之比即喷嘴长径比,是射流泵的重要几何参数。为了研究喷嘴长径比对液体射流泵性能的影响,采用Realizableκ-ε模型对不同长径比的射流泵内部流动进行三维数值模拟。结果表明,在射流泵的流量比小于0.5时,不同喷嘴长径比所对应的射流泵效率曲线差别不大;在流量比大于0.5时,以射流泵效率为判据,喷嘴长径比范围为0.250~1.000的射流泵性能较好;不同喷嘴长径比对应的射流泵壁面剪切应力相差不大。从湍流耗散率、喷嘴出口断面收缩、核心区长度等方面考虑,喷嘴长径比范围为0.250~1.000的射流泵性能较好。

Numerical Analysis of Nozzle Length-Diameter Ratio in Liquid Jet Pump

Tapered nozzles are generally adopted as working nozzles in water jet pump.Nozzle length-diameter ratio,the ratio of length of the nozzle outlet straight part to the nozzle outlet diameter,is a key parameter of a jet pump.Threedimensional numerical analysis of water jet pumps with different nozzles of various length-diameter ratios is carried out using Realizable k-εmodel to evaluate the influence of it on jet pump performance.The results show that the efficiency curves of jet pumps of various nozzle length-diameter ratios differ negligibly when the flow ratios are less than 0.5.However,with greater flow ratios,the length-diameter ratio range of the jet pump is better to be 0.250-1.000 if judged by the corresponding efficiency.Wall shear stress of jet pumps with different nozzle length-diameter ratio differs slightly.While considering the turbulent dissipation rates,the stream contraction at nozzle outlet and the length of jet core,jet pumps with the nozzle length-diameter ratio range of 0.250-1.000 perform better.