Numerical Study on Impeller-Diffuser Interactions with Radial Gap Variation

Abstract:- Numerical simulations on impeller-diffuser interactions are performed in CFX-10 to investigate the unsteady phenomena, and the radial gap effects are also studied by calculating two different impeller-diffuser configurations. Computational results show that the leading edge of a diffuser vane acts as a source to the impeller unsteadiness. The diffuser-induced pressure fluctuation in the impeller increases with increasing radius, and the one on the impeller pressure side is much bigger than on the suction side. When increasing the radial gap between the impeller and the diffuser from 3 % to 10 % of the impeller outlet radius, the pressure fluctuation in the impeller decreases significantly. However, it has no evident influence on the time-averaged pressure field in the impeller. Key-Words:- Impeller-diffuser interactions, numerical simulation, pressure fluctuation, radial gap