The self-preserving mixing properties of steady round nonbuoyant turbulent jets in uniform crossflows were investigated experimentally. The experiments involved steady round nonbuoyant fresh water jet sources injected into uniform and steady fresh water crossflows within the windowed test section of a water channel facility. Mean and fluctuating concentrations of source fluid were measured over cross sections of the flow using planar-laser-induced-fluorescence (PLIF). The self-preserving penetration properties of the flow were correlated successfully similar to Diez et al. [ASME J. Heat Transfer, 125, pp. 1046-1057 (2003)] whereas the self-preserving structure properties of the flow were correlated successfully based on scaling analysis due to Fischer et al. [Academic Press, New York, pp. 315-389 (1979)]; both approaches involve assumptions of no-slip convection in the cross stream direction (parallel to the crossflow) and a self-preserving nonbuoyant line puff having a conserved momentum force per unit length that moves in the streamwise direction (parallel to the initial source flow). The self-preserving flow structure consisted of two counter-rotating vortices, with their axes nearly aligned with the crossflow (horizontal) direction, that move away from the source in the streamwise direction due to the action of source momentum. Present measurements extended up to 260 and 440 source diameters from the source in the streamwise and cross stream directions, respectively, and yielded the following results: jet motion in the cross stream direction satisfied the no-slip convection approximation; geometrical features, such as the penetration of flow boundaries and the trajectories of the axes of the counter-rotating vortices, reached self-preserving behavior at streamwise distances greater than 40-50 source diameters from the source; and parameters associated with the structure of the flow, e.g., contours and profiles of mean and fluctuating concentrations of source fluid, reached self-preserving behavior at streamwise (vertical) distances from the source greater than 80 source diameters from the source. The counter-rotating vortex structure of the self-preserving flow was responsible for substantial increases in the rate of mixing of the source fluid with the ambient fluid compared to corresponding axisymmetric flows in still environments, e.g., transverse dimensions in the presence of the self-preserving counter-rotating vortex structure were 2-3 times larger than transverse dimensions in self-preserving axisymmetric flows at comparable conditions.
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机译：实验研究了稳定的圆形非浮力湍流射流在均匀横流中的自保持混合特性。实验涉及将稳定的圆形非浮力淡水射流源注入水通道设施的窗口测试区内的均匀而稳定的淡水横流中。使用平面激光诱导的荧光（PLIF）测量了流体横截面的平均和波动浓度。与Diez等类似，成功地关联了流的自保护渗透特性。 [ASME J. Heat Transfer，125，pp。1046-1057（2003）]，而基于Fischer等人的结垢分析，成功地关联了流动的自保存结构特性。 [Academic Press，纽约，第315-389页（1979）]；两种方法都假设在横流方向（平行于横流）无滑流对流，并假设自保持的非浮力线膨胀沿流向（平行于初始源流）具有单位长度的动量守恒。 。自保持流动结构由两个反向旋转的涡流组成，它们的轴几乎与横流（水平）方向对齐，由于源动量的作用，它们沿流向远离源移动。当前的测量值分别从水源沿水流方向和横流方向扩展到最大260和440的水源直径，并得出以下结果：沿水流方向的射流运动满足无滑流对流近似；几何特征（例如流边界的穿透和反向旋转涡流的轴的轨迹）在距源的直径大于40-50的流向距离上达到了自保留行为；与流的结构有关的参数（例如，源流体的均值和波动浓度的轮廓和轮廓）在距源的流向（垂直）距离大于源的80个直径的情况下达到了自保持行为。与静止环境中相应的轴对称流相比，自保持流的反向旋转涡流结构导致源流体与环境流体的混合速率显着增加，例如在存在自流的情况下为横向尺寸在可比较的条件下，自保持轴对称流中，保持反向旋转涡流结构比横向尺寸大2-3倍。
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