Numerical study of the effects of some geometric characteristics of a centrifugal pump impeller that pumps a viscous fluid

摘要

The performance of centrifugal pumps drops sharply during the pumping of viscous fluids. Changing some geometric characteristics of the impeller in these types of pumps improve their performance. In this investigation, the 3-D flow in centrifugal pump along with the volute has been numerically simulated. This numerical solution has been carried out for different cases of primary geometry, and for the changes made to the outlet angle and passage width of the impeller, and also for simultaneous modifications of these parameters. The finite volume method has been used for the discretization of the governing equations, and the High Resolution algorithm has been employed to solve the equations. Also, the "k - ω SST" has been adopted as the turbulence model in the simulation. In the steady state, this simulation is defined by means of the multi-reference frame technique, in which the impeller is situated in the rotating reference frame, and the volute is in the fixed reference frame, and they are related to each other through the "Frozen Rotor". The obtained numerical results are compared with the experimental ones, and the outcome shows acceptable agreement between the two. The flow analysis indicates that with the modification of the original geometry of the pump, at the 30° outlet angle and the passage width of 21 mm, the pump head and efficiency increases compared to the other cases; this improvement is due the reduction of losses arising from the generation of eddies in the passage and outlet of the impeller.