双吸离心泵叶轮交替加载设计方法

双吸离心泵内部的压力脉动是影响机组运行稳定性的关键因素之一。为了减轻压力脉动,分析了引起双吸离心泵压力脉动的主要原因,研究了不同类型的叶片载荷曲线对双吸离心泵流态的影响,建立了叶片加载方式、叶片出口倾角和叶轮交错角与泵内二次流及压力脉动的关系,提出了能够抑制二次流、降低压力脉动的叶轮交替加载设计方法。在新的设计方法中,叶片载荷曲线具有盖板前加载、轮毂后加载的混合加载模式。基于该方法所生成的双吸叶轮具有轮毂两侧交错布置、叶片出口边正向倾斜、盖板和轮毂包角差小的特点。通过在一大型引黄灌溉泵站的试验表明,该方法可将双吸离心泵压力脉动主频的幅值降低到原来的1/5左右,同时还可改善泵的最优效率和高效区。该方法为大功率双吸离心泵的优化设计和更新改造提供了一种新的技术途径。

Impeller Design with Alternate Loading Technique for Double-suction Centrifugal Pumps

The pressure pulsation in double-suction centrifugal pump is one of the key factors affecting the stability of pump unit operation. In order to reduce the pressure pulsation, the main causes of pressure pulsations in double-suction centrifugal pump were analyzed. The effects of blade loading curves on flow patterns in pumps were investigated. The relations between blade loading, blade outlet obliquity, staggered angle and the flow features including secondary flow and pressure pulsation were established. A new impeller design method with alternate loading was proposed. In the new design method, the main loading point on shroud located at the front of blade loading curve, and the main loading point on hub located at the rear of its curve. The impeller designed by this method was in the type of staggered arrangement in circumferential direction. The blade outlet edge was tilted forward, and the wrap angle difference between shroud and hub was very small. The field test on a large irrigation pumping station showed that the dominant frequency of pressure pulsations in the double-suction centrifugal pump designed by using this method was reduced significantly. The optimum efficiency and high-efficiency-range of the pump were also improved. This method could be used as a new approach to design/redesign double-suction centrifugal pumps with large power.