Author(s): W. R. Wei; J. Deng; Z. Tian; F. X. Zhang
Linked Author(s): Jun Deng, Zhouyv Tian, Jiaquan Deng
Keywords: Outlet Sidewall; High-head dam; Impact pressure; Energy dissipation; Experimental study
Abstract: To improve the jet diffusion and energy dissipation for the surface spillway in high-head dams, an optimal design of the outlet structure is studied using scaled experimental model. A symmetrical pair of triangle-wedges is set at the surface spillway outlet to make lateral and vertical contractions at the end cross-sections of the channel. Due to the triangle-wedge shape, the contraction areas with the elevation increase are different for an identical cross-section, and this makes fully contributions to the incoming water head applicability, flow discharge capacity and jet longitudinal diffusion. Based on a series of model tests for different lengths, heights and contraction ratios of the triangle-wedge, the effects of design parameters on the impact pressure on the plunge pool are analyzed. With the increase of the contraction ratio, the mean impact pressure reduces and subsequently increases. An optimal design of contraction ratio can make fully contribution on the energy dissipation in plunge pool. With the increase of the triangle-wedge length, the jet impact gets greater gradually. The contraction effect of triangular-wedge structure on the jet impact is almost established. The deflection of the inclined surface with the increase of triangular-wedge height may improve the lateral contraction, but the reduction on jet impact is limited. The significant decrease of impact for different water discharge confirms the triangular-wedge structure can affect the initial jet shape. This optimal design of outlet sidewalls will give a new option for surface spillways in high-head dams.