横流中多孔射流的稀释特性实验研究

摘要

横向流动条件下多孔射流是污水排放中的一种常见流动,对其稀释特性研究对于污水排放工程设计具有重要的指导意义.利用激光诱导荧光技术(Laser Induced Florescence)对横向流动条件下1、2和4孔射流的浓度场进行了测量.实验表明:多孔射流可分为未合并区、过渡区和已合并区；在未合并区内,多孔射流中的第一个射流浓度轨迹线和稀释度变化与单个射流情况相近,在射流近区和远区,无量纲浓度轨迹线与下游距离分别呈1/2和1/3指数关系；后面射流的浓度轨迹线和稀释度变化相近,受第一个射流的遮挡和卷吸作用,其弯曲度和稀释度变化小于第一个射流,说明作用于后面射流的横向流速小于第一个射流.%The Laser Induced Fluorescence (LIF) technique is employed to measure the scalar concentration field of a multiple jet group in cross-flow with 1,2,4 nozzles. The results show that the trajectory and dilution change of the leading jet in a multiple jet group is similar with a single jet in cross-flow. Due to the entrainment and sheltering of the front jet, the trajectory and dilution change of the rear jets is similar, and less than the leading jet. It implies there existing a reduced cross-flow velocity in front of the rear jets.