Modeling flow characteristics of a low specific-speed centrifugal pump with different volute shapes

Abstract

A centrifugal pump is typically designed for a specific operating condition. The pump's shape and size are fine-tuned so that it can produce a specified output pressure and flow rate at the maximum possible efficiency. When a pump begins operating off of its design flow rate, its efficiency drops. Pumping systems often involve dynamic demands. They may have a fluctuating flow rate demand throughout the day, or the system may evolve and change size over time. In these cases, pumps with a single operating point are inefficient and insufficient. This thesis assesses the effects of changing a pump's volute casing geometry on the volute's internal flow characteristics. All analysis is performed on a low-specific-speed, radial flow centrifugal pump. 2D flow models from literature and CFD are analyzed and compared to experimental data. With properly-chosen solution methods, a 2D CFD simulation is found to match well with experimental results. Efficiency estimates and life-cycle cost changes due to changing flow characteristics in the variable volute system are presented.