平底突扩三元水跃流场的数值模拟

Numerical simulation on flow field of three dimensional hydraulic jump with flat bottom and abrupt lateral expansion

应用湍流RNG k-ε模型封闭流体力学方程组,VOF法追踪自由表面,采用非定常流动PISO算法对R型水跃,S型临界式水跃和S型淹没式水跃进行了数值模拟。结果表明,采用Fluent软件对平底突扩三元水跃进行数值模拟具有较强的适用性。3种水跃在水流的上部区域均形成逆时针方向的翻滚漩涡。S型临界式水跃(z=0.024 m)发生了对称扩散,并在x=1.00 m断面与x=1.30 m断面之间形成了对称分布的漩涡。发现水流紊动能最大值在水跃中部,R型水跃发生的紊动能较大,S型临界式水跃和S型淹没式水跃两者的紊动能相近。分析中轴立面流速分布后,发现在相同位置的横断面上,R型水跃流速均较大。水跃区内,R型水跃边界层变化不大,S型临界式水跃边界层增长缓慢,S型淹没式水跃边界层增加趋势明显。S型淹没式水跃最大流速值以较快速率减小,并且最大流速值相比另外两种工况时小。

The turbulence RNG k-εmodel used to the fluid dynamical equations,and the VOF method applied to track the free water surface,the numerical simulation of R-type hydraulic jump,S-type critical hydraulic jump and S-type submerged hydraulic jump is carried out by using unsteady flow PISO algorithm.The results show that the Fluent software has strong applicability for three dimensional hydraulic jump with flat bottom and abrupt lateral expansion.Three kinds of hydraulic jump form a counter clockwise swirling vortex in the upper part of the flow.The z=0.024 m plane of S-type critical hydraulic jump had symmetrical diffusion,and a symmetrical distribution vortex is formed between the x=1.00 m section and x=1.30 m section.It is found that the maximum value of turbulent energy of water flow is in the middle of hydraulic jump,the turbulence energy of R-type hydraulic jump is larger,and the turbulent energy of S-type critical hydraulic jump and S-type submerged hydraulic jump are similar.After analyzing the velocity distribution of the vertical plane of the central axis,it is found that the velocity of R-type hydraulic jump is larger on the cross section of the same position.In the hydraulic jump region,the variation of the boundary layer of R-type hydraulic jump is not obvious,the boundary layer of S-type critical hydraulic jump is increasing slowly,and the boundary layer of S-type submerged hydraulic jump is increasing obviously.The maximum velocity of S-type submerged hydraulic jump decreases at a faster rate,which is smaller than that of the other two conditions.