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Turbulence and Shear Flow Phenomena -1 First International Symposium

ISBN:
1-56700-135-1 (Print)

EXPERIMENTAL STUDY ON MICROBUBBLES AND THEIR APPLICABILITY TO SHIPS FOR SKIN FRICTION REDUCTION

Yoshiaki Kodama
Ship Performance Division, National Maritime Research Institute 6-38-1 Shinkawa, Mitaka, Tokyo 181-0004, Japan

Akira Kakugawa
Ship Research Institute 6-38-1, Shinkawa, Mitaka Tokyo 181-0004, Japan

Takahito Takahashi
Center for Smart Control of Turbulence, National Maritime Research Institute Shinkawa, Mitaka, Tokyo 181-0004, Japan

Hideki Kawashima
Ship Research Institute 6-38-1, Shinkawa, Mitaka Tokyo 181-0004, Japan

Abstract

Microbubble experiments were carried out using a circulating water tunnel specially designed for testing microbubbles. Skin friction was measured using a skin friction sensor, and skin friction reduction by microbubbles up to 40% was obtained. The local void ratio in the bubble condition was measured by putting a suction tube in the test section, and it was found that the local void ratio close to the wall has strong correlation with skin friction reduction. The applicability of microbubbles to full scale ships was discussed, based on experimental results using a long flat plate.