Pressure fluctuation prediction of a model pump turbine at no load opening by a nonlinear k-ε turbulence model

In this paper, a new nonlinear k-epsilon turbulence model based on RNG k-epsilon turbulence model and Wilcox's k-epsilon turbulence model was proposed to simulate the unsteady flow and to predict the pressure fluctuation through a model pump turbine for engineering application. Calculations on a curved rectangular duct proved that the nonlinear k-epsilon turbulence model is applicable for high pressure gradient flows and large curvature flows. The numerically predicted relative pressure amplitude (peak to peak) in time domain to the pump turbine head at no load condition is very close to the experimental data. It is indicated that the prediction of the pressure fluctuation is valid by the present nonlinear k-epsilon method. The high pressure fluctuation in this area is the main issue for pump turbine design, especially at high head condition.