污水自吸泵固体颗粒的流动及分布规律研究

Flows and distribution patterns of solid particles in sewage self-priming pump

为了研究不同颗粒直径下污水自吸泵内固体颗粒的流动及分布规律,以65ZW30-40污水自吸泵为研究对象,基于Mixture多相流模型和RNG k-ε湍流模型,对污水自吸泵全流体域进行了固液两相流数值模拟分析。随颗粒直径的增加,泵的扬程和效率逐渐下降,当颗粒直径d=0.20 mm时,扬程下降13.76%,效率下降12.14%,泵的性能显著变差。同时,分析了不同颗粒直径下自吸泵内固体颗粒的分布情况。结果表明:固体颗粒主要分布于叶片吸力面尾缘,泵体外缘以及回流孔底部区域。研究进一步揭示了当回流孔尺寸较大时,泵内颗粒分布较均匀,回流孔尺寸较小时,颗粒主要分布于回流孔两侧,叶片尾缘及叶片出口靠近压水室的区域,随回流孔尺寸的增大,颗粒体积分数较大的区域向压水室侧迁移,回流孔中心区域颗粒体积分数逐渐减小。

A 65 ZW30-40 sewage self-priming pump is numerically modeled to study its flows of solid particles and their distribution patterns focusing on the effect of different particle diameters. The solidliquid two-phase flows in the pump are simulated using ANSYS Fluent together with a multi-phase flow model the Mixture and a RNG k-ε turbulent flow model. Results show that as the particle diameter increases, the lift head and efficiency of the pump decreases gradually and the decrease in pump performance is significant. Most solid particles are distributed near the trailing edge of the blade suction sides, the outer pump wall, and the back-flow hole inlet. Simulations also reveal that a larger back-flow hole can make the particle pattern closer to uniformly distributed, while a smaller hole results in more particles concentrated on its both sides, near the trailing edge, and over the intersection of impeller and volute. The size of back-flow hole has a crucial effect on its flow rate and thus the particle distribution pattern is sensitive to its variation. As it increases, the particles concentrated zone migrates toward the volute, and the particle volume fraction in the core of the back-flow hole decreases gradually.