Numerical prediction of cavitation in centrifugal pump using Multi-Process cavitation model

In the present study, numerical simulation of cavitating flow using Multi-Process model, which is one of the homogeneous cavitation models and consists of multiple transport equations of bubbly flow characteristics defined on the basis of the moment method, is conducted for a centrifugal pump toward more accurate prediction. The experiment is also conducted for the same pump to obtain the hydraulic performance including the axial thrust force characteristics as well as the visual aspects of cavitation for the validation of numerical simulation. It is found that the present simulation can qualitatively reproduce the degradation of pump suction performance as well as the change in axial thrust force under cavitation at the design flow rate; thrust forces acting on the impeller and the balance drum decreases with the head drop. The cavity patterns leading to the head drop are also well reproduced; the cavitation on the suction surface extends into the blade passage. At a partial flow rate close to the design one, the simulated cavity patterns with the inception and moderate states of cavitation agree with the observation, but they are not well reproduced perhaps due to the insufficient mesh resolution at the deep partial flow rate where the most of cavitation occurs in the vortical structure, typically in the tip separation vortex.