Department of Mechanical Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2G8.
J Hazard Mater. 2010 Apr 15;176(1-3):199-206. doi: 10.1016/j.jhazmat.2009.11.013. Epub 2009 Dec 11.
This study examines a horizontal wall jet impinging onto a forward facing step in a cross-flow. Planar laser induced fluorescence (PLIF) experiments in a water channel indicate that the wall-jet flow after impinging onto the step, becomes a vertical jet with an elliptical cross section. Experiments indicate that the jet trajectory scales with the perimeter of the elliptical jet issuing vertically into the cross-flow. The trajectory consists of three regions: the near-field region which is well described by a power law with an exponent of 1/2, the mid-field region where the jet is fully bent over which is described by a power law with an exponent of 1/3, and a far-field region where the jet is dominated by the cross-flow. This paper provides a prediction of the plume behaviour based on the geometric and initial conditions of the jet (diameter, step height, distance from jet to step, and velocity ratio) alone. The Briggs entrainment model for a round jet was also used to predict the trajectories of the jet in the cross-flow. It was found that the entrainment coefficients, alpha and beta, for the elliptical jet case had average values of 0.15 and 0.58 respectively.
本研究考察了水平壁射流冲击横流中前向台阶的情况。在水通道中的平面激光诱导荧光（PLIF）实验表明，壁射流冲击台阶后，变成了具有椭圆形横截面的垂直射流。实验表明，射流轨迹与垂直进入横流的椭圆形射流的周长成比例。该轨迹由三个区域组成：近场区域，由幂律很好地描述，指数为 1/2；中场区域，射流完全弯曲，由幂律描述，指数为 1/3；远场区域，射流受横流主导。本文仅基于射流的几何和初始条件（直径、台阶高度、射流与台阶的距离以及速度比）对羽流行为进行了预测。还使用了 Briggs 模型来预测射流在横流中的轨迹。发现椭圆射流情况下的夹带系数α和β的平均值分别为 0.15 和 0.58。
