动水中含污染物冲击射流横向高浓度聚集区的形成机理和特性分析

采用RNG湍流模型对动水中含污染物冲击射流滞止点下游区域的横向浓度分布特征进行了详细的数值研究,并与相应的实验结果进行了比较。分析了下游过渡区内横向高浓度聚集区的形成机理和扩散特性。计算结果表明,冲击效应和横流绕流对冲击射流下游过渡区内的横向浓度分布具有重要的影响。当流速比相对较小时,在靠近对称面以及底层壁射流与环境横流的横向边界附近出现较为明显的横向高浓度聚集区,计算结果表明,冲击效应产生的横向逆压梯度以及横流绕流导致的Scarf涡结构对横向高浓度聚集区的形成起主导作用。

Formation and characteristics analyses of lateral high concentration convergence zones produced by a pollutant-contained impinging jet in flowing water

The characteristics of lateral concentration distribution in a pollutant-contained impinging jet in the downstream region related to the stagnation point in flowing water are numerically investigated in detail using the RNG turbulence model,and compared with the corresponding experimental results.The formation mechanism and diffusion properties of the lateral high-concentration convergence zones in the downstream transition region are analyzed.The computed results indicate that the impingement action and the circumambient cross-flow play an important role in the lateral concentration distributions of the impinging jet in the transition region.When the velocity ratio is relatively small,there exist distinct lateral high-concentration convergence zones both near the symmetry plane and at the lateral edge between the bottom layer wall jet and the ambient cross-flow,which are dominated by the lateral negative pressure gradient produced by the impingement action and the Scarf vortex structure generated by the circumbient cross-flow,respectively.