交汇区水流结构对水温分布特征的影响机理

为分析交汇区复杂的水温分布规律及其受水流结构影响的机理,采用Fluent数值模拟软件,通过改变汇流角和汇流比,模拟了不同条件下交汇区的时均流场、紊动特性和水温分布,分析了各工况下交汇区水平面及断面水温分布特征(水温非均匀性指数)和水流结构特征参量(紊动能和涡量)间的关系,探究了不同水流结构对水温分布的影响机理。结果表明:水流剪切影响热掺混层的位置,二次环流影响热掺混层的形态;汇流角或汇流比越大,断面非均匀指数越小,水温掺混越快,热掺混层随剪切层位置的改变越靠近外岸壁(交汇口对侧壁面),热掺混层弯曲程度随二次环流强度增大而增大;紊动能及涡量与断面非均匀指数之间呈现良好的线性关系。

Influence mechanisms of flow structure on water temperature distribution characteristics in junction areas

In order to analyze the complicated water temperature distribution law in the intersection area and the influence mechanism of flow structure on it, the numerical simulation software Fluent was used to simulate the time-mean flow field, turbulence characteristics and water temperature distribution in the river junction area under different conditions by changing the confluence angle and the confluence ratio, and to analyze the relationship between the water temperature distribution characteristics (water temperature non-uniformity index) and the characteristic parameters of the flow structure (turbulence kinetic energy and vorticity) in the intersection area under different working conditions. The influence mechanism of different flow structure on the water temperature distribution was explored. The results show that the flow shear affects the position of the hot mixing layer and the secondary circulation affects the shape of the hot mixing layer. The larger the confluence angle or confluence ratio, the smaller the cross section non-uniformity index and the faster the water temperature mixing. With the change of shear layer location (turbulent kinetic quantization shear), the hot mixing layer is closer to the outer bank wall (intersection to side wall), and the bending degree of the hot mixing layer increases with the increase of secondary circulation strength. It shows a good linear relationship between turbulence kinetic energy and vorticity and section heterogeneity index.