Numerical investigation of entropy hydraulic loss analysis and vortical structure suppression in mixed flow pump device under lateral inflow

Abstract

To investigate the influence of the lateral inflow on the vortical structures and hydraulic losses inside the mixed-flow pump, entropy production, and Q-criterion were applied to numerical simulation analysis of transient flow. Three inflow runner schemes were designed to compare the effects of the middle-isolated pier and rear wall of the “ω” structure on restraining the occurrence and transmission of a vortex and stabilizing the internal flow state of the pump device. The results showed that when the inflow condition transformed from parallel inflow to lateral inflow, the design efficiency and head deviated toward the over-load flow rate, and the maximum deviations were obtained under the over-load flow rate, reaching 4.79% and 50.35%, respectively. The hydraulic losses and vortical structures increased to a large extent, influenced by the lateral inflow, particularly the flow region near the impeller hub. The setting of the vortex suppression facilities effectively reduced the deviation ratios in the design efficiency and head, which decreased to 1.31% and 7.59%, respectively. The vorticity intensity and entropy dissipation rate were also significantly decreased. By contrast, the rear wall of the “ω” structure had a greater stabilization effect on the internal flow patterns than that of the middle-isolated pier.