高拱坝深潭型水垫塘数值模拟研究

Numerical simulation research on deep plunge pool

高拱坝工程为满足下泄水舌的挑距和淹没水跃长度的要求,水垫塘往往较长,而在水垫塘消能过程中实际参与进来的水体并不多,为此提出一种长度较小且能够集中消能的深潭水垫塘.以溪洛渡水电站为研究对象,采用RNGk-ε三维紊流数学模型对八深孔泄洪工况下反拱和深潭水垫塘进行数值模拟研究,首先把反拱水垫塘的流速及拱底板压强的计算值与相应模型实测值进行了对比验证,再对两种水垫塘塘内的水流流态、近壁流速、壁面压强分布特征以及消能率进行详细分析,结果发现在反拱水垫塘内,下泄水体的巨大能量主要通过淹没射流的紊动扩散和淹没水跃的作用来消除;深潭水垫塘内水体消能主要依靠贴壁流在边壁作用下返回深潭不断紊动耗散的过程;两种水垫塘底板最大冲击压强分别为8.64 mH2O和11.62 mH2O,二道坝顶平均出流流速分别为8.52 m/s和5.34 m/s,消能率分别为90.25%和92.25%.

Taking the Xiluodu Hydropower Station as the research object,a deep plunge pool with a small length and capable of concentrated energy dissipation was proposed to meet the requirements of the tapping distance of the discharge tongue and the length of the submerged hydraulic jump.The RNGk-εmodel was used.The hydraulic characteristics and energy dissipation mechanism of the arch invert plunge pool and the deep plunge pool were compared.The results showed that the water energy of the arch invert plunge pool was mainly eliminated by the turbulent diffusion of the submerged jet and the action of the submerged hydraulic jump.The energy dissipation of the water in the deep plunge pool mainly depended on the adherent flow returning to the deep pool under the action of the side wall to continue to turbulent dissipation process.Respectively,the maximum impact pressures of the bottom plates of the two types of plunge pools were 8.64 mH2 O and 11.62 mH2 O,the average outflow velocities of the auxiliary weir were 8.52 m/s and 5.34 m/s,and the energy dissipation rates were 90.25%and 92.25%.