Positive and Negative Performance Analysis of the Bi-Directional Full-Flow Pump with an “S” Shaped Airfoil

Abstract

In this study, model tests and numerical simulations are conducted to study the bi-directional full-flow pump (BFFP). Firstly, the head, efficiency and shaft power of the BFFP are significantly higher in the positive operating condition than in the negative operating condition. When the unit operates in the positive direction, the clearance reflux flow rate, the flow uniformity and velocity-weighted average angle of the impeller inlet, and the intensity of pressure pulsation are significantly greater than those during the negative operation. When the pump unit is operating at low flow rates, the clearance reflux produces a significant disturbance to the impeller inlet main flow. Two vortices appear in the near-wall area of the clearance outlet (i.e., impeller inlet), and the range of vortices is larger in the positive operation than in the negative operation. Secondly, at low-flow and design-flow conditions, the total entropy production of the pump unit in the positive direction is greater than that in the negative direction. When at small- and design-flow rates, the amplitude of pressure pulsation in the positive direction is smaller than that in the negative direction. This study will contribute to the research and development of a full-flow pump.