溢流孔直径对轴流泵系统过渡过程的影响

Influence of Overflow Hole Diameter on Transition Process of Axial Flow Pump System

沿海泵站使用的大型轴流泵系统(LAPS)往往需要配备溢流孔以提高过渡过程的品质,但由于LAPS过渡过程中增设溢流孔的机理尚不明确,因此在设计和应用上存在很多困难。本文设计了6种不同直径的溢流孔,在Flomaster软件二次开发的基础上,用瞬态模拟方法研究了不同直径的溢流孔对LAPS的同步启动、异步启动、同步停机和异步停机过渡过程的影响。结果表明:在异步启动过程中,当溢流孔直径达到2 m时,最大冲击扬程为1.67H_(r),最大冲击功率为1.34P_(r),进一步增加溢流孔直径对降低LAPS的最大冲击扬程和功率无明显增益。在异步停机过程中,溢流孔可以有效延缓LAPS流量的衰减,降低瞬时水头和功率,然而,当溢流孔直径达到2 m时,最大冲击扬程为1.18H_(r),最大冲击功率为1.1P_(r),进一步增加溢流孔直径对降低LAPS异步停机过程中的最大冲击水头和功率没有明显的作用。溢流孔直径越大,对于提高过渡过程质量的效果越好,但是当溢流孔直径增大到一定程度后,继续增加溢流孔直径效果没有明显提高。

The large axial flow pump system(LAPS)used in coastal pump stations often needs to be equipped with overflow holes to improve the quality of the transition process.However,due to the unclear mechanism of adding overflow holes in the transition process of LAPS,there are many difficulties in design and application.Totally six kinds of overflow holes with different diameters were designed.Based on the secondary development of Flomaster software,the effects of overflow holes with different diameters on the synchronous start-up,asynchronous start-up,synchronous shut-up and asynchronous shut-up transition process of LAPS were studied by transient simulation method.The results showed that during the asynchronous start-up process,when the diameter of the overflow hole reached 2m,the maximum impact head was 1.67H_(r),and the maximum impact power was 1.34P_(r).Further increasing the diameter of the overflow hole had no significant gain in reducing the maximum impact head and power of the LAPS.In the process of asynchronous shut-up,the overflow hole can effectively delay the attenuation of LAPS flow and reduce the instantaneous head and power.However,when the diameter of the overflow hole reached 2 m,the maximum impact head was 1.18H_(r) and the maximum impact power was 1.1P_(r).Further increasing the diameter of the overflow hole had no obvious effect on reducing the maximum impact head and power during the asynchronous shut-up of LAPS.The larger the diameter of the overflow hole was,the better the effect on improving the quality of the transition process was,but when the diameter of the overflow hole was increased to a certain extent,the effect of continuing to increase the diameter of the overflow hole was not significantly improved.