Numerical Analysis of Shaft Tubular Pumping Systems

In order to supply better flow conditions for pump and improve pumping system efficiency, numerical simulations were conducted in this paper on 3 design schemes of a shaft tubular pumping system to compare their energy performances and investigate the relationship between the design scheme and the system characteristics. With the same design of suction box and discharge passage, the head losses of the outlet discharge passage and the pumping system efficiencies were compared between 2 design schemes of different size and shape of the shaft (pit). The flow conditions of pump, in terms of distribution uniformity of axial velocity and velocity-weighted bias angle of outflow field in the outlet cross-section of suction box, and the pumping system efficiencies were compared between the front and rear arrangement of the shaft while keeping the shaft and the pump unchanged. The computational results show that for the rear arrangement of shaft schemes the size and shape of the shaft affect not only the head loss of the discharge passage but also the pumping system efficiency. If just simply turning the pump around 180 degrees without changing pump and flow passages, the pumping system can be operated both in the rear arrangement scheme of shaft and front arrangement scheme. However, the flow conditions of pump become deteriorated in terms of distribution uniformity and bias angle when the rear arrangement scheme of shaft changed to front arrangement. As a result, the hydraulic losses of suction box and discharge passage in front arrangement increases, the best efficiency point drops and high efficiency zone moves toward smaller flow rates.