Air entrainment and detrainment downstream of a chute aerator

The chute aerators separate the flow from the chute bottom, and the air can enter into the flow through the lower surface. In this study, the air concentration and the pressure along the chute bottom are investigated systematically by a series of model tests with the upper aeration effect being eliminated. The chute downstream the aerator is partitioned into four zones: the cavity zone, the impact zone, the equilibrium zone, and the far zone. It is found that a large amount of air entrained in the cavity zone is only partially entrained into the flow finally. Furthermore, the lower air discharge is decreased sharply in the impact zone, and the detrainment disappearsonthe section of x = Lm. In the equilibrium zone, the lower air discharge is kept unchanged. With the increase of the flow Froude number and with the other parameters kept unchanged, it is found that the dimensionless value of K has a significant increase. Meanwhile, a formula to calculate K is proposed, with results in good agreement with the model and prototype data.