Author(s): Wenxue Chen; Guifen Li; Shengzong Xie; Kailin Yang
Linked Author(s): Wenxue Chen
Keywords: Erator; Spillway tunnels; Cavitation
Abstract: Aeration is an effective way for protecting high head spillways from cavitation damage. This beneficial effect of flow aeration has been known for more than two decades. But there are still a lot of problems should be deeply studied, e. g. side wall protection of the ogee-section spillway tunnels, aerator structures of spillway tunnels with low Froude number and small slope etc. In recent years, we have done a lot of research works on the aerators of high head spillway tunnels because of engineering demands. During our studies, two main principles are applied. 1) The geometry of the aerators should be as simple as possible. 2) Aerators should not deteriorate the flow pattern of the spillway tunnels at least. 4 kinds of aerators are presented in this paper: 1) A dustpan-shaped aerator used for connecting an ogee-section U-shaped tunnel and a D-shaped (horseshoe-shaped) diversion tunnel; 2) A circular ramp used in a D-shaped diversion tunnel; 3) A side wall ramp applied for protecting the side walls downstream of the elbow part of an ogee-section spillway tunnel; 4) An M-shaped aerator with sudden lateral enlargement used in a spillway tunnel with low Froude number and small slope. These results are heuristic for study and design of aeration devices. The paper also pointed out that, the impinging angle of the jet is an important factor for the formation of the cavity downstream of an aerator, especially when the Froude number of the incoming flow is small.