Influence of Blade Shape Geometry on Very Low Specific Speed Centrifugal Pump Performance

Direct or inverse design methods for centrifugal pumps play an important role in investigating their performance. In this paper, a very low specific speed centrifugal pump impeller of ns = 9.5 (metric), three blades and 222° wrap angle. This pump was investigated using the direct design method to achieve the blade shape geometry and examine the blade angle distribution. As the blade angle progression affects the pump performance, four models with different blade angle distribution were used to perform the hydrodynamic and suction performance of the pump. The linear and non-linear derived correlation models were designed firstly using ANSYS-BladeGen module then studied numerically using ANSYS-CFX module to solve the three-dimensional Navier-Stokes equations. Validation of the numerical simulation of the investigated centrifugal pump was done using experimental data. Numerical results show that the change in the blade angle distribution has an influence on the blade wrap angle. Consequently, the variation in the blade wrap angle affects the pump head and the relative velocity distribution. The pressure gradient varies in the pump with changing the blade length. Using the velocity streamline and the velocity vector, the eddies existence and distribution in the blade suction side affect the relative velocity distribution and the pump performance. It was found that the blade with the smallest length decreases the pump head and have best velocity distribution.