On air bubble size and air concentration entrained through aerator

Aerator for air entrainment has been adopted in spillway structures to prevent possible cavitation errosion on the surface of concrete. So far, many model studies and field measurement have been carried out. This paper describes a measurement of air bubble entrained through aerator in tunnel spillway model. Air bubble sizes were read from visualized air-water flow pictures, the result of which was consistent with ones measured by electric probe method. As a result, it became clear that, by a few visualized pictures, air bubble size distribution after aerator could be estimated.