The effect of impeller blades number on the performance of a centrifugal pump with complete and trimmed impeller

masoomeh shadab¹ Rasoul Paydar Nobakht²

1) Ph.D. candidate of mechanical engineering (turbomachinery) -
2) Managing Director of Arya Sepehr Kayhan ,

Publication : 3rd International Congress On Engineering, Technology and Innovation(eticong.com/3rd)
Abstract :
This numerical investigation is carried out on a centrifugal pump to show the effect of the impeller blade number on the pump performance in the complete and trimmed impeller conditions. Four different combined conditions with 3, 5, and 7 blades and the impellers diameter of 404mm and 347mm are tested numerically and the centrifugal pump performance is investigated in the terms of pump head (H), hydraulic power (Phydraulic) and torque on the rotating surface (T) due to recognizing the optimum geometry. All numerical tests are conducted at a constant rotational speed of 2950 rpm. The pumps’ impellers and volute are designed in CFTurbo software and analyzed in Ansys CFX as a CFD commercial code. The results demonstrate a strong influence of the trimming on the performance of the centrifugal pump. All performance parameters tend to be sensitive against the change in the impeller diameter rather than the change in the number of blades. It is found that the head coefficient (ψ) and the efficiency (η) are the highest for the case of the impeller with 7 blades and the impeller diameter of 404mm than that for the case of 3 blades with complete impeller and the cases of 7 and 5 blades with trimmed impellers. Eventually, the losses decrease by increasing the blades number due to the reduction of the secondary flow for a certain limit, and then it increases again because of the friction losses in the impeller. All these results are presented in this paper.
Keywords : centrifugal pump pump performance curve impeller trimming blades number of centrifugal pump impeller torque Ansys CFX CFTurbo hydraulic power