Design and Optimization of Low-Specific Speed Centrifugal Pump

Abstract

Centrifugal pumps find applications in a wide range of industries, such as rocketry, oil and gas, petroleum, etc. A main property used to characterize the design of pumps is the specific speed, which relates the flow properties of the pump at its operating point. Pumps in the low-specific speed range have been of particular interest. These are characterized by the high head value (representative of mechanical energy) produced at a relatively low flow rate. A lower flow rate reduces the power requirements required to operate the shaft that rotates the impeller. However, the design of such pumps presents many challenges. Most of the existing design methodologies are developed for pumps in a normal specific speed range--low specific-speed pumps fall out of this range. These methods, when applied for the design of low-specific speed pumps, can result in dimensions that are not physically realizable. The work done herein combines empirical relations based on experimental measurements and theory for the optimal design of a low-specific speed pump. This is done by delineating a baseline design for the design flow rate of 253 USGPM based on these relations and then optimizing the baseline design based on its performance features obtained using numerical simulations. Each design was simulated with both a tangential diffuser and an axial diffuser to assess the impact of these diffuser options on performance characteristics.