Simulation and experiments of aerated flow in curve-connective tunnel with high head and large discharge

The cavitation erosion induced by high-speed flow is very prominent in tunnel with high head and large discharge. air entrainment is an effective technology to solve this problem. in this study,numerical simulation and physical model were applied to the comparative study of air-water flows in curve-connective tunnel including ogee segment,steep segment and anti-arc segment,where three aerators were set up for protecting the bottom-floor and sidewall. the flow pattern,aeration cavity,air concentration and pressure distribution were obtained and the calculated results agree with the experimental data. the hydraulic characteristic and aeration effect of the flows in a curve-connective tunnel are analyzed specific to the bottom aerator and the whole cross-section aerator,respectively. when the bottom aerators were only set up,the flows appeared the black water triangle zone near sidewalls in curve-connective segment. the air concentration was observably improved on sidewalls downstream of the ogee section while the added lateral aeration facility on bottom aerator. thus,the black water triangle zone disappeared so that the floor and sidewalls were protected so well. these results indicated that the whole cross-section aerator not only weaken the backwater in bottom aeration cavity and then increase the length of the bottom cavity but also benefit the protection of sidewalls. © iran university of science and technology 2016.