Measurements of Self-Aerated Flow on a Spillway

Measurements are made on the spillway on a 36-m high concrete gravity dam. The measurements include the point of inception, and the velocity distribution and air concentration distribution and bubble size in the developing region of the flow. The measurements show that there appears to be a universal velocity distribution which is independent of the mean air concentration for average air concentrations of between 0 and 0.5, and the air concentration becomes progressively more uniform with the distance downstream. However at 200 times the depth at the point on inception downstream of this point it is still growing. At 100 times the depth at the point of inception a significant air concentration has reached the spillway floor. A simplified formulae for computing the position and properties at the point of inception is also presented.