Research on air concentration distribution in self-aerated open channel flow

When the self-aeration occurres in steep chutes, there is an equilibrium region of uniform air concentration, because aeration is the result of the combined actions of the turbulence and buoyance. In this paper Wood's method was improved. The calculating model of the rising velocity of the air bubbles and the turbulent diffusion coefficient was derived. The air concentration distribution formula for upper and lower region was obtained. Results show if the aeration ratio is high, the interaction between air and water should be taken into consideration and the turbulent transport equation be modified properly. The analytical solutions show a good agreement with the measured data.