Abstract: Bidirectional shaft tubular pump, a type of low-head pump device for bidirectional pumping, is widely used in plain urban areas, and the location of its shaft has always been a problem to be considered in engineering practice. In this study, a three-dimensional modeling software is used to construct the model of the pump flow system comprising the shaft runner, straight pipe runner, impeller section, and guide vane section, using structured meshing method to generate the grid of all sections. Steady flows in the two-way shaft tubular pump device are simulated by solving the continuity equation, k-ε turbulence model equations and Reynolds average equations; Hydraulic performances of the pump are calculated for the forward and reverse operation modes of its impeller and two schemes of front shaft and rear shaft. The results show that under the design condition, the forward mode efficiency is higher than that of reverse mode regardless of the rear or front position of the pump shaft. In either forward or reverse operating mode, the flows in the shaft runner and straight pipe runner, when both located at the pump inlet side, manifest relatively smooth patterns, the difference between the hydraulic performance of both modes is small; In forward operating mode, when these two components are located at the outlet side, their flow patterns are different due to different shapes, but the overall head loss of the pump is small. In reverse operating mode, the circulation of the outlet runner cannot be fully suppressed by guide vanes, resulting in a head loss greater than that in forward operating mode. Under this condition, the hydraulic performance of the shaft runner as the outlet runner is worse than the straight pipe runner as the outlet runner.

Key words: bidirectional pump, shaft passage, numerical simulation, hydraulic performance