Computation of spatial submerged hydraulic jump with different abrupt expansion ratios
ZHENG Tie-Gang, DAI Hui-Chao, DING Quan-Lin
(1.Department of Hydraulics,China Institute of Water Resources and Hydropower Research, Beijing 100038, China; 2.State Key Laboratory of HydrologyWater Resources and Hydraulic Engineering, Hohai University,Nanjing, Jiangsu 210098, China; 3.College of Mechanics and Materials, Hohai University, Nanjing, Jiangsu 210098, China)
Abstract Since the abrupt expansion can enlarge turbulence intensity level in a local range of water flow, it can be utilized as kind of important energy dissipaters. In order to study effects of abrupt expansion ratio on hydraulic characteristics of down stream flow, spatial submerged hydraulic jumps with the abrupt expansion ratios of 1.000, 0.833, 0.667, 0.500, 0.333 are simulated numerically based on a nonuniform structured mesh, the RNG k-ε turbulence model and the pressure and velocity coupling algorithmPISO. It was found that the change of abrupt expansion ratio has obvious influence on down stream velocity, turbulence kinetic energy and energy dissipation rate. The smaller the ratio, the more obvious the change in velocity, the faster the primary flow diffuses, and the more clearly the flow pattern transition develops. With decreasing expansion ratio, the smaller the turbulent stresses, the larger the energy dissipation rate. Compared with a typical hydraulic jump, the spatial submerged hydraulic jump possesses greatly improved energy dissipation rate. However, once the ratio is less than 0.5, the dissipation rate on longer is improved obviously yet.
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