CFD simulation and experimental validation of inflow/outflow structure serving retrofitted pumped hydropower storage plant

A three-dimensional CFD (numerical) hydraulic model for free surface flow through an intake/outlet structure in the lower reservoir of a retrofitted pumped storage hydropower plant was developed, pertaining to power generation activities. The ReNormalization Group (RNG) K-Epsilon version of Reynolds Averaged Navier Stokes (RANS) turbulence model and Large Eddy Simulation (LES) model were used to develop the near field flow dynamics and other turbulence parameters. A dedicated sediment transport model was developed to obtain the sediment entrainment, suspension and bed-load movement data. A scaled experimental/physical model for this numerical model was constructed in the laboratory. The turbining experiments were performed on this scaled model with the use of Ultrasonic Velocity Profiler (UVP) and velocity and shear stress data were extracted. These data were then compared with the numerical data in terms of time averaged and instantaneous velocity profiles and shear stress at three different regions of interest. From these comparisons, it was observed that the LES model was able to reproduce the experiment data with higher fidelity than the RANS model. Furthermore, a comparison between the LES model and RANS model was developed in terms of sediment transport, which will be validated through the sediment transport data from the experimental model in near future. This study can provide guidance in terms of hydraulic modelling of the reservoirs in PSH plants as well as the design of intake/outlet structure and potential limitations on water levels, inflows and outflows.