Numerical Design and Performance Prediction of Low Specific Speed Centrifugal Pump Impeller

Abstract

Abstract In this paper, Based on Two-dimensional Flow Theory, adopting quasi-orthogonal method and point-by-point integration method to design the impeller of the low specific speed centrifugal pump by code, and using RANS (Reynolds Averaged N-S) Equation with a standard k-e two-equation turbulence model and log-law wall function to solve 3D turbulent flow field in the impeller of the low specific speed pump. An analysis of the influences of the blade profile on velocity distributions, pressure distributions and pump performance and the investigation of the flow regulation pattern in the impeller of the centrifugal pump are presented. And the result shows that this method can be used as a new way in low speed centrifugal pump impeller design. Key words : Low Specific Speed, Centrifugal Pump impeller, Two-dimensional Flow Theory, Numerical Design ， Performance Prediction 1. Introduction Centrifugal pump is the most widely used vane pump, and a wide variety of centrifugal pump types are used in many different applications in industry and other technical sectors. After long-term research and practice in centrifugal pump, a wealth of experience of slope of head-capacity characteristic curve which bring about low flow rate instability and high flow rate power overload [1]. Traditional impeller design methods, which are mainly based on the similarity theory, empirical correlation, combination of model testing, and engineering experience, their design process are difficult task, mainly due to the great number of free geometric parameters. [2, 3, 4] So well hydraulic design of low specific pump impeller becomes more difficult and more necessary. Regardless of the design process used, the final decision of a new pump impeller design is usually made following physical testing. These tests are often time and resources consuming. In addition, the flow field in impeller channels is very complicated, so that no simple mathematic model can be established to well predict the performance of impellers. For these reasons CFD (computational fluid dynamics) analysis is currently being carried out on centrifugal impeller. [5, 6, 7, 8] By using it can provide quite accurate information on the fluid behaviour, and thus helps the engineers to obtain a thorough performance evaluation of the design. In this paper, based on Two-dimensional flow theory low specific speed pump impeller design method, which adopting quasi-orthogonal method and point-by-point integration, is put forward. 3D turbulent flow field in the designed impeller is calculated numerically by using RANS (Reynolds Averaged N-S) Equation with standard k-e turbulence model and log-law wall function. And predicting result of impeller according to the flow is presented.