Unsteady flow simulation through a centrifugal pump

Flow in a typical centrifugal pump is known to be unsteady due to flow instabilities and mutual interactions between the rotating part and the stationary parts. Flow instabilities are mostly viscous phenomena such as boundary layer separation and vortex shedding that produces relatively low frequency and small amplitude pressure fluctuations. Mutual interaction between the impeller blades and the guide vane diffuser produces relatively high frequency and large amplitude pressure fluctuations. This phenomenon is more closely related to compressibility than viscosity. It is important because it may cause structural vibration and noise. In this paper, the steady and unsteady turbulent flow through the whole flow passage of an entire centrifugal pump, has been computed to predict the pressure fluctuation of flow in the pump.