ON THE INTERACTION BETWEEN THE BOUNDARY LAYER AND LONGITUDINAL VORTICES

本文的目的是研究边界层与纵向涡旋之间的相互作用。用单色LDV系统研究了速度场中湍流或雷诺应力的特性。通过数值计算，明确了纵向涡的影响。涡流是由固定在船体表面或平板上的小机翼的尖端产生的。得到了以下结果：从靠近船面的S、S、I处开始的尖涡使船尾速度分布发生变形。涡发生器的位置和攻角可以控制速度分布的变形。从理论和实验上阐明了涡旋强度的乘积和涡旋发生器与控制平面的距离对平板上边界层畸变的影响是相同的。将相同的理论和实验处理应用于船舶尾部流动，两者之间的结果很好地吻合。利用单色LDV系统对三角金字塔后的湍流进行了测量，以阐明雷诺数应力的特性。并且在三维分离的内外区观察到质的差异。新的图像分析技术被开发用来解释流场的三维畸变。这些技术对于同时得到横截面上的速度场是非常有用的。

The objectives of this paper is to investigate into the interaction between the boundary layer and longitudinal vortices. The characteristics of turbulence or Reynolds' stresses in a velocity field are also studied using one color LDV system. Numerical calculations are performed to make the effects of longitudinal vortices clear. The vortices are generated from the tip of a small wing fixed on the ship hull surface or flat plate.The following results are obtained.1. The tip vortices which start from the S,S, I near the ship surface deform the stern velocity distribution. The deformation of the velocity distributions is controllable by the position and the attack angle of the vortex generator.2. It was clarified theoretically and experimentally that the products of the strength of vortices and the distance between the vortex generator and the control plain have the same effects on the distortion of the boundary layer on the flat plate.3. The same theoretical and experimental treatments are applied to a ship stern flow and the sood agreements were observed between both of the cases.4. Turbulence measurements behind a trigonal pyramid are performed to clarify the characteristics of the Reynolds' stresses by one color LDV system. And qualitative differences are observed between the inner and the outer region of the 3-dimensional separation.5. New image analysis techniques are developed to explain the 3-dimensional distortion of the flow field. These techniques are quite useful to get the celocity field in a cross section simultaneously.