前后盖板长度对离心泵外特性与非定常特性的影响

为了研究前后盖板保留长度对离心泵外特性以及非定常特性的影响,以一台比转速为80的离心泵为研究对象,在切削叶轮的叶片外径保持不变的情况下,对比了不同前后盖板直径(168、174和180 mm)对外特性、径向力和压力脉动的影响。通过对离心泵进行全流场非定常计算发现,各流量下扬程、效率均随前后盖板保留长度的增加而增大,扬程最大相差2.14 m,效率最大相差3.5%;在设计工况下,3种方案下的径向力呈周期性变化,矢量图呈五芒星分布,前后盖板保留得越多,径向力越大;由于叶轮与隔舌动静干涉的作用,蜗壳内各监测点压力脉动的主频均为叶频,随着叶轮与蜗壳间间隙的减小,隔舌处的压力脉动在叶频处基本保持不变,其倍频逐渐增大,第二断面的压力脉动系数幅值也逐渐增大。

Analysis of the Influence of the Length of the Hub and Shroud in Centrifugal Pump on Performance of the Pump under Unsteady Flow Condition

This work investigated the influence of the length of the hub and shroud in centrifugal pump on pump performance under unsteady flow condition.We took a centrifugal pump at specific speed of 80 as an example.The outlet diameter of the cutting impeller was kept unchanged,and we examined the change in radial force and pressure pulsation when the diameter of the hub and shroud varied from168 mm to 180 mm.The flow field in the pump under unsteady condition was calculated.It was found that the pumping-height and the efficiency increased as the length of the hub and shroud increased,and the maximum difference between pumping-height and efficiency was 2.14 m and 3.5％ respectively.For the pump we examined,the radial forces changed periodically under all conditions,and the vector diagram was pentagram-distributed.The more the hub and shroud were retained,the larger the radial force was.Due to the interaction between the impeller and the tongue,the main frequency of the pressure pulsation at the monitoring point was a leaf-frequency.As the gap between the impeller and the volute decreased,the pressure pulsation at the leaf tongue remained unchanged,while its frequency multiplication increased gradually.Pressure pulsation coefficient also gradually increased.The results provided reference for practical application of the impeller cutting.