Pressure Fluctuation Generated by the Interaction of Blade and Tongue

摘要

Pressure fluctuation around the tongue has large effect on the stable operation ofa centrifugal pump.In this paper, the Reynolds averaged Navier-Stokes equations (RANS) and the RNG k-epsilon turbulence model are employed to simulate the flow in a pump.The finite volume method and the SIMPLE algorithm are used to solve the system of equations.The flow field in the centrifugal pump is computed for a range of flow rate.The simulation results have been compared with the experimental data and good agreement has been achieved.Fifteen monitor points are evenly distributed circumferentially at three radii around the tongue.Pressure distribution is investigated at various blade positions while the blade approaches to and leaves the tongue region.Results show that pressure signals fluctuate largely around the tongue, and it is more intense near the tongue surface.Minimum average pressure and maximum standard deviation are obtained at position near the tongue surface within the gap between the impeller and the tongue.Minimum standard deviation is obtained at design condition.At large flow rate, the increased low pressure region at the tailing edge results in the increases of pressure fluctuation amplitude and pressure spectra at the monitor points.It is found that the pressure fluctuation strongly depends on the blade positious at large flow rate, and pressure fluctuation is caused by the relative movement between blades and tongue.Minimum pressure is obtained when the blade is facing to the tongue.