Effect of impeller and diffuser matching optimization on broadening operating range of storage pump

Abstract

A large volute-type centrifugal pump (LVTCP) is a crucial component of a pumped-storage power station. A steady increase in the single-operation power of each large pump station gradually causes unstable operation and substantial energy loss in engineering applications. The Taguchi design and numerical calculations are combined in this study to enhance the efficiency and operational stability of an LVTCP and reduce energy consumption. The impeller blade shape is designed using an inverse design method, whereas the diffuser shape is designed using a positive design method. Optimization is performed to achieve the desired efficiency under 0.9Qd, 1.0Qd, and 1.1Qd using 12 design variables. The significant effect of each design variable on the objective is identified, and the increase in efficiency in the high-efficiency zone after optimization is investigated. The results show that the efficiency of the three optimized schemes improved significantly, with maximum increases of 3.47 %, 2.96 %, and 3.2 % under 0.9Qd, 1.0Qd, and 1.1Qd, respectively. Additionally, the optimized internal flow characteristics of the pump improved significantly, the vortex in the diffuser runner is eliminated, and the energy losses at the diffuser and volute tongue decreased significantly, thus effectively alleviating energy loss in the pump. Based on the efficient house theory, a set of design schemes with the largest range of high-efficiency zones is calculated; these schemes improve the overall operating efficiency and stability of the storage pump under design and non-design conditions. This study shows that multicomponent matching optimization based on the Taguchi is vital to the high efficiency, energy saving, and stability of LVTCP under multi-operating conditions.