超大面积比射流泵性能模拟与试验研究

Numerical and experimental investigations on super-large area-ratio jet pumps

根据工程需求并借鉴传统射流泵的设计方法,设计了面积比分别为57.40和60.05的2种超大面积比射流泵.基于有限体积法,采用Realizable k-ε湍流模型和标准壁面函数法,对这两种面积比的射流泵进行三维数值模拟和结构优化,并得到其优化后的性能拟合方程.模拟结果显示,随着面积比在一定范围内增大,最高效率点右移,最优喉管长度增加.按照优化后的结构参数加工射流泵,将2种出口直径的喷嘴和3种直径的喉管进行组合得到6种面积比射流泵,然后在4种不同工作压力下进行水槽试验.试验结果表明:超大面积比射流泵内部流动同样存在自模性;现有汽蚀流量比的预测理论高估了超大面积比射流泵的汽蚀性能,因此需要对该预测理论进行修正;试验数据与数值模拟结果符合较好,验证了数值模拟的可靠性以及采用数值模拟进行结构优化的可行性.对超大面积比射流泵的研究,拓宽了射流泵的应用范围.

Two jet pumps with super-large area-ratios （57.4 and 60.05） , respectively, were designed according to the conventional theory and the engineering requirements. Based on the finite volume method, the Realizable k -s turbulence model with the standard wall function was adopted in the three dimensional flow simulations and structure optimization of the pumps. The simulation results indicated that the best efficiency point moves to a higher flow ratio and the optimum throat length increases with area ratio. Six jet pumps were manufactured according to the optimized parameters; subsequently their performance was tested under different driving pressures. There were six area ratios through the combi- nations of two size nozzles and three throat diameters. The experimental data show that the fluid flow inside those pumps has self-similarity like a conventional jet pump. The existing theory for predicting cavitation flow ratio overestimates the cavitation performance of those pumps, and it needs to be upda- ted. The experimental data agreed well with the simulation results, confirming the reliability of numeri- cal simulation and the feasibility of structure optimization. The investigation into the pumps with superarea ratios has extended the application range of jet pumps.