Various parameters affect the pump performance in which blade number, blade angle, outlet diameter, and volute shape are the most important. In this paper the performance of pumps with different impellers containing blade number and different volute shape containing circular-elliptical and rectangular is evaluated. In this study four different blade numbers 5, 6, 7, and 8 are modeled and two different rectangular and circular-elliptic volute shapes are also studied.Incompressible Navier-Stokes equations over a hybrid grid is solved by commercial software package Fluent. Rotational zone will be simulated by moving reference frame method. For each impeller, the flow pattern and pressure distribution are calculated and finally the head and efficiency curves are compared and discussed. The results show that by increasing the blade number the head increase and efficiency decrease slightly. Also circular-elliptic volute shows better performance especially in higher flow rates than the rectangular one.

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