导叶式混流泵空化特性优化研究

Study on Cavitation Characteristics Optimization of Vaned Mixed-flow Pump

导叶式混流泵被广泛应用于工农业调水输水中,本研究针对导叶式混流泵临界空化系数不满足设计要求的情况开展空化性能的优化。通过对空化体积与低压区位置的比较,定义“叶片前缘低压控制体”概念作为空化性能的判定标准。采用扩散角积分法进行叶片前缘几何形状的参数化,简化为前缘椭圆弧长短轴比、直线扩散角、厚度积分表达式系数三个优化参数。以0.7、1.0、1.2倍设计工况下的加权“叶片前缘低压控制体”体积系数为优化目标,采用全域动态判据优化算法进行寻优,最终得到空化性能的优化方案。对比分析优化前后的空化性能发现,空化规模有效降低,三个工况下的临界空化系数均满足设计要求,且水力性能不受到显著影响。以“叶片前缘低压控制体”体积作为优化目标来提高水泵空化性能具有合理性及良好的可适性。

Vaned mixed-flow pump is widely used in industrial and agricultural cases because it has wide head,flow rate range and high-efficiency ranges.In this study,cavitation performance optimization was carried out because the critical cavitation coefficient of vaned mixed-flow pump did not meet the design requirement.After the comparison between cavitation ISO-surface and low pressure region,the concept of“low pressure control volume on leading-edge”was defined as the criterion of cavitation.The geometry of leading-edge was deconstructed by Diffusion-angle Integral method.The leading-edge was parameterized and simplified into three optimization parameters that the long/short axis ratio of the leading-edge ellipse arc,the straight thickness diffusion angle and the coefficient of thickness integration expression.The weighted volume under 0.7,1.0 and 1.2 times design conditions was taken as the optimization objective.The Global Dynamic Criterion optimization algorithm is used for optimization.Finally,the optimal impeller was found with better cavitation performance.Comparison showed that the cavitation scale was reduced after optimization.The critical cavitation coefficient meets the design requirement without obvious influences on hydraulic performance.Therefore,it is reasonable and feasible to improve the cavitation performance of pumps with the“low pressure control volume on leading-edge”as the optimization objective.