基于叶片撞击模型的鱼友好型轴流泵优化设计

为降低鱼类通过大中型泵站后的死亡率,维持生态系统的稳定,研究了一种应用在轴流泵中的叶片撞击数学模型,对某一轴流泵的鱼类通过性能进行了预测,包括叶片撞击概率、撞击死亡率和鱼类死亡率,分析得到设计工况点的鱼类死亡率理论上高达68%。以降低鱼类死亡率为主要目标,兼顾水力性能,通过考虑鱼损伤的关键因素,优化设计了3种方案的鱼友好型轴流泵,对比分析了3个方案的鱼类通过性能和水力性能。研究结果表明,方案1和方案2平均降低鱼类死亡率49%,方案3平均降低鱼类死亡率52%;3个方案在设计点扬程均可满足原型泵使用要求,其中修正叶片进口安放角的方案2效率最高,设计点效率低于原型泵约3%,方案3鱼类通过性能最佳,设计点效率低于原型泵约5%。

Optimization Design of Fish-friendly Axial-flow Pump Based on Blade Strike Model

In order to reduce fish mortality during passage through the large and medium-sized pumping station and maintain the balance of the ecological system, a blade strike model applied to axial-flow pump was analyzed to predict the fish passage capacity of the original pump, including blade strike probability, strike mortality and fish mortality. The theoretical fish mortality of the original pump was only 68% at the design flow point. Thus, a fish-friendly pump was designed based on the original pump to reduce fish mortality and keep hydraulic performance acceptable. Furthermore, three optimization plans were done by reducing the number of blades to two, using the streamline method of nonlinear circulation distribution to design the inlet and outlet blade angles, increasing the chord length of the blade airfoil, optimizing the profile of the leading edge to spiral and thickening the leading edge. The comparison of the three optimization plans showed that the fish mortality of plans 1 and 2 was reduced by 49% on average and that of plan 3 which was better for fish to pass through the pump was reduced by 52%. Meanwhile, the flow through the pump was simulated with ANSYS-CFX, and the numerical results such as head and efficiency were compared with the experimental results to analyze the hydraulic performance. To be specific, the head of all the plans met the operating requirements at the design flow point and the efficiency of plan 2 which corrected the inlet blade angle of plan 1 was 3% lower than that of the original pump at the design flow point, while the efficiency of plan 3 which was better for fish was 5% lower. It was noted that the fish-friendly pump was effective to reduce fish mortality even with the efficiency dropping by 5%, and it can provide a basis for axial-flow pump design of agricultural irrigation works.