Jet impact geometry and plunge pool dimensions effects on dynamic pressures at pool sidewalls

摘要

A plunge pool is one of the energy dissipater structures for high head dams, which ensures stability of the dam under extreme hydrodynamic pressure, due to falling jet impacts. The excess energy of the jet is dissipated, together with significant impact pressure exerted on the floor and pool walls. Thus, appropriate assessment of jet dynamic characteristics in the plunge pool is essential. This research presents experimental results focusing on the distribution of mean and extreme pressure fluctuations on the sidewalls, due to circular and rectangular plunging jets, and the effects of pool dimension, especially in narrow valleys. The experimental variables are discharge, geometry of jet, pool depth, pool width, and sidewall slope. Hydrodynamic pressure on the sidewalls due to decreasing bottom width from 6 to 3 times the jet impact diameter, or width, is quite different for core and developed jets. For core jets, it increases the maximum pressure, while decreasing the minimum and mean dynamic pressure on the sidewalls, while, in cases of developed jet impact, a reverse effect is observed for mean dynamic pressure. Finally, the results of pressure variation on plunge pool walls for different jet geometry and pool dimensions are presented graphically and design suggestions for pool optimum dimensions are provided.