Abstract: The flow characteristics in an impinging jet mixer were experimentally investigated by using particle image velocimetry (PIV). The inner diameters of two inlet jets and the mixing chamber were 3 and 16 mm, respectively. The effects of flow ratio and distance between the axis of jets and the top wall of the mixing chamber on the distribution of velocity and turbulent kinetic energy were investigated. The results show that the impingement point locates in the middle of the chamber, and normalized velocity and turbulent kinetic energy distribution are almost consistent when the flow rates of two jets are equal. The region with high turbulent kinetic energy is in the vicinity of impingement point, and the maximum normalized turbulent kinetic energy is about 3 times of that near the impeller region of a standard Rushton turbine stirred tank. Flow ratio has significant effect on the location of impingement point. When the distance between the axis of jets and the top wall of mixing chamber decreases, the region with high turbulent kinetic energy is enlarged, which is beneficial for mixing in the chamber. The results are of importance to the design and optimization of industrial impinging jet mixer.

Key words: impinging jet mixer, particle image velocimetry, velocity distribution, turbulent kinetic energy

摘要： 采用粒子图像测速技术对入射管直径为3 mm、混合腔直径为16 mm的T型撞击流混合器内的流动特性进行了研究，考察了不同流速比和撞击轴线上方空间条件下混合腔内的速度和湍流动能分布. 结果表明，在相同入射管直径和流速下，撞击驻点位于混合腔中心处，无因次化的速度和湍流动能分布趋势基本一致. 高湍流动能区主要集中在撞击点附近区域，其无因次化数值是传统Rushton涡轮搅拌槽叶端处的3倍. 流速比对撞击驻点位置影响显著；减小撞击轴线上方空间可增加高湍流动能分布区域，利于物料混合.

关键词: T型撞击流混合器, 粒子图像测速, 速度分布, 湍流动能