船体表面からの空気吹き出しによる船尾変動圧力の低減

概要

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The present paper describes the effect of air injection through the hull at the stern of ship on the reduction of pressure fluctuations induced by cavitating propellers. By using three propeller models and a complete ship model, the reduction rate of the pressure fluctuations due to the air injection was confirmed by measurements in the SRI large cavitation tunnel. Very significant damping effects of between 1/2 and 1/8 on the pressure amplitudes were found, depending on the amount of air injection under the condition without air-drawing. A small amount of injection made the pressure fluctuations locally larger than those without air injection in some cases, while in general the increase of air injection made the damping effect larger. An upper limit of the amount of injection existed with respect to the damping effect on the pressure fluctuations because of air being drawn into the propeller and tip vortex cavitation area. The amount of air to be injected was estimated for the ship at full-scale under the assumption of the similarity law on the air flow rate. The required air flow rates at 31.0 knots and 35.5 knots were roughly estimated to be 46 and 60m^3/min, respectively. An improvement of the air injection method is needed to reduce the amount of air injection from the viewpoint of practical application.
社団法人日本船舶海洋工学会の論文
2000-03-29