The effect of flow coefficient on the design of miniature centrifugal impeller

Abstract

A systematic and simple design methodology of miniature centrifugal impeller is proposed. In the design of miniature centrifugal impeller, the flow coefficient ϕ1 plays a significant role. Theoretically, the geometric parameters, including inner radius, blade angles and blade height can be expressed as functions of the flow coefficient. Accordingly, the theoretical head and energy losses are also influenced by the flow coefficient. To investigate the effect of flow coefficient, a series of miniature impellers are designed for different flow coefficients, and CFD simulations are conducted. Both theoretical analysis and CFD simulations show similar trends. Initially, the pressure generated increases with increasing flow coefficient. Upon reaching a maximum, it will subsequently decrease with increasing flow coefficient. Hence, an optimal flow coefficient should be chosen to achieve the best performance. From the theoretical results, the maximum pressure generated occurs when the flow coefficient is approximately 2.8, while for CFD, it is approximately 1.3. The difference between the theoretical analysis and CFD simulation shows that the theoretical model should be further improved to enhance its accuracy.