ON THE INTERACTION BETWEEN THE BOUNDARY LAYER AND LONGITUDINAL VORTICES

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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.