気相界面の可視化と船体表面の水中照射による波高の光学的計測

概要

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Two optical methods to measure wave profiles are proposed with some accuracy analysis and examples. Although these are independent two methods, both are new techniques to get clear lines of free-surface boundaries. The methods provide enough contrast there for the boundary to be identified accurately by the image processing manner. The one is the method to measure wave profiles along straight cutlines where the air-side of free-surface is visualized by mist of dry-ice (CO_2 gas) . The mist, which is put on the water surface at upstream of the circulating water channel, covers all the surface in contact by the shearing stress of the moving water surface. The laser light sheet clearly visualizes the edge boundary of the air-side. The second is for the measurement of the hull-side wave profiles by illuminating the wetted surface of the hull through the water. The surface looks brightly white as if some kinds of white paints were painted. It has enough contrast along the free-surface to be identified definitely. Because the original pictures by the both methods have clear change in contrast across the free-surface boundary, the methods can provide relatively accurate results even after image processing. Because both methods are enough simple and automatic, they can be applied for daily measurements of the wave height in the circulating water channel.
社団法人日本船舶海洋工学会の論文