离心泵间隙对压力脉动及径向力的影响

针对采用超厚叶片的离心式无过载潜水排污泵非定常流动所引起的蜗壳流道内的压力脉动及壁面受到的径向力的问题,基于标准k-ε湍流模型和SIMPLE算法,研究了间隙对压力脉动及径向力的影响.设计了基圆直径D3分别为390,435,460 mm的3种计算模型,通过对3种模型进行非定常计算,得到由于间隙的变化导致的隔舌处压力脉动的特性及蜗壳壁面所受径向力的变化规律.计算结果表明：由于叶片和隔舌的动静干涉作用,蜗壳流道内各监测点的压力脉动及壁面所受径向力的变化具有明显的周期性;蜗壳内各监测点压力脉动的主频均为叶片通过频率;在相同流量下,间隙越小,压力脉动越剧烈,主频处的脉动幅值越大;同一计算模型,随着流量的增大,在一个旋转周期内蜗壳壁面所受到径向力的平均值先减小后增大;与原始方案相比,在相同流量下,间隙增大或减小,径向力的平均值均会增大.

Influence of gap on pressure pulsation and radial force of centrifugal pumps

The unsteady flow in centrifugal pumps induces a pulsation in fluid pressure inside the volute channel and imposes a radial force on the volute wall too. Thus effect of the gap between the vo- lute tongue and impeller outlet on them was tackled by means of a non-overload submersible sewage pump with extremely thickened-blades. Three pump models with different base circle diameters, such as 390, 435 and 460 mm were designed. The unsteady flow fields in those models were obtained nu- merically based on the standard k -6 turbulence model and SIMPLE algorithm. The characteristics of pressure pulsation on the tongue and the radial force on the wall against gap were obtained. The results showed that the pressure pulsation and the radial force presented an obvious periodicity due to the ro- tor-stator interaction. The dominant frequency of pressure pulsation at the monitor points in the volute was the blade passing frequency. At the same flow rate, the intensity and amplitude of pressure pulsation at the dominant frequency were increased with decreasing gap. The time-averaged radial force imposed on the wall was decreased and then increased with increasing flow rate. Compared with the original pump model, the averaged radial force in the new models was increased regardless of gap at the same flow rate.