离心泵叶轮斜切对出口回流及驼峰特性的影响

Influence of oblique trimmed impeller on recirculation at impeller outlet and stability of performance curves

为研究叶轮出口斜切对于离心泵驼峰性能的影响,选用离心泵(IS 65-50-174)作为研究对象,利用试验获得叶轮斜切前后的外特性,并利用SST k-ω模型进行非定常数值模拟以获得内流场以及压力脉动特性.试验结果表明,叶轮出口斜切后,可以消除原模型泵中的驼峰现象,并在小流量区域引起更高的耗功.对驼峰附近工况0. 2,0. 3,0. 4倍设计流量下的内部流动进行分析,可以得到以下结论:随着流量的减小,原模型泵叶轮出口的低能量区,从前盖板转移到后盖板附近;而叶轮斜切之后,回流发生在叶轮后盖板附近,并随着流量的减小出口回流强度逐渐上升,进而形成较为稳定的性能曲线.对叶轮出口的压力脉动进行分析,发现斜切后低频脉动幅值减小,叶轮出口流动不稳定性有所下降.

In order to study the influence of the oblique trimmed impeller on the stability of the performance curves of pumps,the centrifugal pump(IS 65-50-174)was chosen as the research object.The performance curves of the pump with original impeller and the oblique trimmed impeller were obtained by the experiment,while the corresponding internal flow field and the pressure fluctuations were acquired from the unsteady numerical simulation with SST turbulence model.The experimental results show that the centrifugal pump with the oblique trimmed impeller can eliminate the instability of the performance curve and consume more shaft power at the reduced flow rate.By analyzing the internal flow field at 0.2,0.3 and 0.4 times of the designed flow rate,some conclusions can be got:with the decrease of the flow rate,the low energy zone in the original impeller transfers from the front shroud to the rear shroud.While the recirculation zone of the oblique trimmed impeller occurs near the rear shroud and its intensity of the recirculation increases with the decrease of the flow rate.The analysis of the pressure pulsation at the impeller outlet shows that the pulsation at the low frequency becomes lower in the oblique trimmed impeller compared with the original impeller,which indicates that the instability of the flow at the impeller outlet becomes lower.