Abstract
Ships take in seawater as weight to keep its balance. This is called ballast water. Ballast water contains various microbe (planktons, fish eggs and bacteria, etc) in the sea. So discharge of ballast water gives bad influence on ecosystem of other sea area. This paper presents effect of destruction of planktons when cavitating jet impinges on a target body. We researched what kind of target body and distance is more effective on destructing planktons. Target body shapes flat, V-notch and horn-shaped target. Distance between nozzle and target body is 4mm, 6mm and 8mm. We experimented by using both the egg and the larva of plankton. As a result, we succeeded in the destruction of almost the larva. On the other hand, the experimental result using eggs showed that highest destruction rate was 40% at 6mm V-notch. It is more difficult to destroy the eggs than to destroy the larva.
