PTV Measurement of Boundary Conditons at the Phase Interfaces in Gas-Liquid, Liquid-Liquid, Multiphase Flow. PTV measurement

应用PTV技术对油浴中液滴下沉周围和附近的流动进行了测量，其中包括一些新发展的流动显示方法。实验的目的是收集相界面处流动状况的信息。为了测量界面附近的流动，利用了PTV技术，但在相界面和液滴内部的可视化方面还需要解决一些问题。通过结合荧光示踪剂、远心透镜和一种新的照明方法，这些问题得到了解决。众所周知，不可避免的污染现象强烈地影响着界面的特性。通过实验得到了沿液滴方向的剪切条件，揭示了污染对剪切的影响。下沉液滴相界面上的速度分布和剪应力以前从未报道过。在第二年，我们试图测量许多困难的问题来测量气泡周围的瞬变流动，气泡上升时变形。对目标流量的测量在实际应用中显得更为重要和有价值，由于测量误差不能通过平均来减小，因此瞬变流的速度分布应该不那么精确。因此，我们必须从一对PTV图像中恢复尽可能多的矢量。除了加强PTV分析的要求外，气泡的运动和变形边界需要精确地定义一个边界形状，该边界形状对应于作为两个图像之间的平均位移的速度。所有这些问题都得到了解决，并得到了沿两个气泡表面和附近的速度分布。在PIV测量中处理移动和变形边界的新方法已被证实在许多流体力学的实验研究中受到欢迎。

Flows around and in the vicinity of a drop sinking in oil bath are moasured by applying PTV technique, which includes some newly developsd methods of flow visualization. The experiment aimed to colleot information about flow conditions at the phase interface. In order to measure the flow in the vicinity of the interface, the PTV technique is utilized, but some problems on visualization of the phase interface and inside the drop had to be solved. By combining fluorescent tracers, a telecentric lens, and a new illumination method, those problems are solved. It has been well known that the inevitable phenomonon of contamination strongly influences characteristics of the interface. The shearfng condition along the drop has been obtained through the experiment, and it unveiled the influence of the contamination. The velocity distributions along the phase interface of a sinking drop have never been reported before, neither the shearing stress.In the second year, we tried to measure much difficult problem to measure transient flow around a bubble that deforms as it going up. Measuring the target flow is more important and valuable with respect of actual application.Velocity distribution of transient flows ought to be less precise since measurement errors cannot be reduced by averaging. So, We have to recover as many vectors as possible from a pair of PTV pictures. Adding to the demand to the enforced PTV analysis, the moving and deforming boundaries of a bubble requires to define precise a boundary shape that corresponds to velocities obtained as mean displacements between two pictures.All those problems have been solved, and velocity distributions along and near two couiding-bubble surfaces have been obtained. The newly developed method to process moving and deforming boundaries in PIV measurements has been confirmed to be welcomed in many experimental studies of fluid mechanics.