Author(s): Li Yao; Wen-Li Yang
Keywords: Flow patterns; Energy dissipation; Multiple slit-type energy dissipater (M-STED)
Abstract: Energy dissipation downstream of high dams is a serious concern. Slit-type energy dissipaters (STED) have been frequently used in many hydropower projects since the 1950s in order to take advantage of their dissipation efficiency, aeration characteristics and relative ease of construction. In the present paper, a multiple slit-type energy dissipater (M-STED) was developed, which adopted the functions of both STED and dentated sill energy dissipaters. In the vertical direction of the M-STED, some slits are placed so that the flow is divided into several layers when it leaves the outlet of the M-STED. Two types of those physical models were designed with nine cases, and the flow characteristics were experimentally investigated on the basis of theoretical analises. The main conclusions were drawn as follows: (1) the critical conditions of the flow pattern conversion for working, critical and nonworking flow patterns, which are related to the flow Froude number Fr, slit number n and slit width a1, and the working flow pattern could be formed if large Fr or much more n and small a1; (2) the effects of the flow patterns on the energy dissipation ratio, clearly, which is dominated by the geometric and hydraulic parameters.