Influence of Surface Roughness on the Pump Performance Based on Computational Fluid Dynamics

The influence of surface roughness on the pump performance was deeply analyzed based on computational fluid dynamics (CFD). A series of numerical calculations with different grid numbers, turbulence models, and surface roughness were made for a typical multistage centrifugal pump. Moreover, the external characteristic experiments were also conducted to verify the numerical calculations. The results show that the surface roughness has enormous influences on the pump performance. With the increase of the surface roughness, the head and the efficiency of the pump decreases continuously, but the decreasing rate slows down gradually, and the surface roughness has a greater influence on the efficiency than that on the head. Moreover, the influence of surface roughness on the disk friction loss power is much greater than that on the hydraulic power. Besides, the total efficiency of the pump reduces mainly by decreasing the hydraulic efficiency and the mechanical efficiency, due to the negative effect of surface roughness. In addition, the surface roughness of the impeller and the diffuser mainly affects the hydraulic effciency, the surface roughness of the shroud's outer wall mainly influences the mechanical efficiency, and the surface roughness of the inner wall of the pump cavity mainly affects the volume efficiency, but the influence of surface roughness on the pump performance is interconnected. Therefore, due to that, it's very difficult to make the precision-machine inside the impeller and diffuser, polishing the impeller shroud and pump cavity is beneficial to improve the pump efficiency and reduce the pump shaft power.