Abstract: A physical model of slit-type energy dissipator was built to study the water wing through adjusting the shape parameters (Froude number Fr, contraction ratio β, and pick angle θ) to obtain different jet flow conditions. The changes of precipitation intensity and the causes of water wing were analyzed through comparison, and the hydraulic factors which affect the water wing formation and its intensity variation were summarized. Results indicate that the peripheral jet trajectory length and dived length of water tongue increased with the increasing of Fr,and the rainfall distribution in typical areas downstream the bucket changed in correspondence. Moreover, with the increase of contraction angle, shock wave angle became small; the diffusion angle of the water wing to shore was also smaller; the intersection of shock waves became closer to the outlet of narrow slit; and correspondingly the range of rainfall diffusion also decreased. In addition, the contraction ratio was inversely proportional to the peripheral jet trajectory length and dived length of water tongue. The research couldenrich the understanding of hydraulic characteristics, in particular, the water wing formation mechanism of the slit-type energy dissipation and provide basis for the optimization of projects.

Key words: slit-type flip bucket, energy dissipator, water wing, rainfall intensity, hydraulic characteristics