离心式上充泵首级叶轮空化特性与试验研究

为研究和改善核电站离心式上充泵首级叶轮空化性能,采用数值模拟方法进行优化分析。将叶片数改为4片,研究了泵的最佳空化性能、扬程和效率。结果表明,最大流量工况点扬程模拟值与试验值的相对误差为2.9%,空化余量相对误差为3.6%,试验结果和模拟结果相吻合。将空化细分为初生空化、发展空化、临界空化、严重空化和断裂空化5个阶段,分析表明:初生空化时汽泡首先出现在叶片进口背面处,临界空化状态以后叶片工作面也开始出现汽泡;在发展空化到严重空化状态之间,空化和叶轮蜗壳动静干涉共同影响叶轮内的压力脉动规律;严重空化状态之后,空化成为主要影响因素,压力脉动变得相对稳定,叶轮进口和中部的压力脉动幅值明显减小,但叶轮出口处仍然保持较高幅值且比较规律的压力脉动。

Cavitation Characteristics and Experimental Study on the First Stage Impeller of Centrifugal Charging Pump

In order to study and improve cavitation performance of the first stage impeller of centrifugal charging pump in nuclear power plant, the numerical simulation was used for optimization and analysis. The number of the blades was changed to 4, and the best cavitation performance, the head and efficiency of pump were studied. The results show that in the maximum flow rate condition, the relative error of head between simulation and experimental results is 2.9% and the relative error of net positive suction head is 3.6%. The numerical results and experiment results are consistent. The cavitation is divided into 5 stages: incipient cavitation, developing cavitation, critical cavitation, severe cavitation and fracture cavitation. The analysis results indicate that the bubbles appear firstly in the inlet of the blade suction surface in incipient cavitation and they appear in the blade pressure surface after critical cavitation. The cavitation and dynamic and static interference in the pump body affect pressure fluctuation in the impeller between developing cavitation and severe cavitation. The cavitation plays a main role after severe cavitation, then pressure fluctuation becomes relatively stable and amplitudes of pressure fluctuation significantly reduce in the inlet and central part of the impeller, but pressure pulsation with relatively high amplitude and regularity still remains in the impeller outlet.