Abstract:

 According to both the model tests and numerical simulations with realizable k-ε turbulence model and VOF model, analysis and calculations of the spiral flow in a compound internal energy dissipation spillway tunnel are presented, focusing on velocity distribution, rotational flow angle, turbulence kinetic energy, turbulence dissipation rate, and energy dissipation rate. The results show that radial flow velocity occurs in the vortex generator as a result of unfavorable tangential flow at the generator inlet. Over radial direction, the axial velocity is distributed symmetric with its peak close to the tunnel wall, while the tangential component is anti-symmetric with its peak close to the core water-air interface suggesting a combined eddy. Rotational flow angle in the vortex generator and blocking-expansion device changes more rapidly along the tunnel than that in the spiral-flow tunnel at middle section. Turbulence kinetic energy and turbulence dissipation rate are greater in the vortex generator and blocking-expansion device. The calculated total energy dissipation rate of about 83% is split into 5% in shaft section, 28% in swirl-flow section, and 50% in blocking-expansion device. The blocking device can not merely reduce cavitation potential, but increase energy dissipation rate.