Abstract
The flow characteristics at a centrifugal pump impeller are significantly affected by the hub inclination angle (HIA). The large eddy simulation turbulence model is employed to simulate the centrifugal pump impeller internal flow at two HIA values under design (1.0 Qd) and off-design (0.55 Qd) conditions. The reliability of the simulation results is verified by comparing the results at a 0° impeller HIA and experimental data. The results show that an increase in HIA has a positive effect on the head of the centrifugal pump impeller, which exhibited a 5% relative deviation between HIA values of 0° and 40°. Under design conditions, there is a good and similar impeller internal flow at the two HIA values. Under off-design conditions, the relative velocity of the 40° impeller HIA channel inlet is 11.7% higher than that of the 0° impeller HIA, which reduces the flow attack angle and effectively suppresses stall. Moreover, for the 0° impeller HIA, fluctuation caused by the stall cells on the blade suction surface is observed, whereas such a phenomenon is not observed for the 40° impeller HIA.
Highlights
Centrifugal pumps are important turbo-machinery components used in industrial production, and their operational stability is directly related to the efficiency of their production
Numerical simulations of a centrifugal pump impeller with different hub inclination angle (HIA) values are performed to investigate the influence of HIA on the hydraulic performance and flow characteristics under design (1.0 Qd) and off-design conditions (0.55 Qd)
(1) An increase in the HIA value has a positive effect on the head of the centrifugal pump impeller, especially under off-design conditions, as the head of 40○ impeller HIA is 5% higher than that of a 0○ impeller HIA
Summary
Centrifugal pumps are important turbo-machinery components used in industrial production, and their operational stability is directly related to the efficiency of their production. Liu et al. experimentally studied unsteady internal flow in a double-blade centrifugal pump impeller at the design flow rate; impeller relative velocity distributions and turbulence intensity distributions under six phase conditions were obtained. Many researchers have conducted detailed studies on centrifugal pump impeller internal flow under design conditions. Pedersen et al and Byskov et al discovered that alternating stall in a six-blade impeller was found when the centrifugal pump operated at 0.25 Qd using PIV experiments and LES simulation.. Zhang et al. studied the relative velocity distribution of the centrifugal impeller blade internal channels under stall conditions and clarified the correlation between the flow structure and pressure spectrum. This paper selects a 0.55 Qd load that provides obvious stall, and the design condition rates of the centrifugal pump impeller are analyzed. The mechanism underpinning the influence of the HIA value on the external characteristics and internal flow of a centrifugal pump impeller is analyzed in detail
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