Computational fluid dynamics study of the spillway and plunge pool at Baihetan hydropower station : Numerical validation of the pressure distribution on the floor of an inverted-arch plunge pool
Abstract: Large-scale hydropower plants with high discharge flow and spillway heads cause high pressure on the downward plunge pool, resulting in erosion of the riverbed, which could ultimately lead to a dam failure. There is an interest of examining the pressure distribution on the plunge pool floor in order to locate where the pressure peaks most frequently occur. A previous experiment was carried out at Tsinghua University, where the pressure location and magnitude of a scaled model of Baihetan was examined. This project aims at investigating the validity of Computational Fluid Dynamic (CFD) modeling compared to the physical scaled model, regarding the pressure distribution. Furthermore, how CFD modeling can be used as a complementary tool to experimental models within this field of study. The geometry was built from blue prints of the ongoing project that is projected to finish in year 2021. The first evaluation involved a mesh independency study of the upper and bottom parts of the geometry. From the mesh independency study, a comparison between the numerical results and experimental results was evaluated. Finally, the pressure contours of different timesteps were studied in the numerical model. The experimental results show that the average pressure, maximum pressure and pressure fluctuation have a difference of 7.4%, 2.2% and 26.6% to the numerical results respectively. Furthermore, the location where the maximum pressure most frequently occurs differs by 9.6% compared to the numerical results. However, what can be examined in the numerical model is that the pressure peaks occur during short periods of time at different locations, which cannot be captured by experimental tests. For some time-steps, a maximum pressure close to 1 MPa was measured in the numerical model; whereas the experimental model shows a maximum pressure around 600 KPa. The numerical model has shown satisfactory agreement to the experimental data. However, further evaluation needs to be tested before numerical modeling can be used as a primary tool for pre-assessment in this field. Furthermore, CFD can serve as a complementary tool to physical scaled models in this field of study, especially when momentary pressure peaks are observed.
AT THIS PAGE YOU CAN DOWNLOAD THE WHOLE ESSAY. (follow the link to the next page)