ABSTRACT:

This study presents the result of investigation of gap effect in slamming experiment. The transverse gap, longitudinal gap, and vertical air gap effects were investigated. The pressure at the center was measured to estimate the variation of pressures. It was found that the smaller the transverse and longitudinal gaps, the larger the pressure is. As the vertical air gap increases, the magnitude of peak pressure increases. It can be concluded that the measured pressure can be very dependent on those gaps.

INTRODUCTION

When it comes to the slamming experiment there are many factors which affect the time history of the impact pressures. They are impact velocity, deadrise angle of the model, length of the model. Not many researchers in this community speak about the effect of the ratio of the water plane area and area of the model bottom. It is anybody's guess that when this ratio gets small, the pressure time history might be affected by the disturbance caused by the nearby wall of the tank. To consider the effect of this ratio, two definitions are introduced in this study. They are transverse and longitudinal gaps. Two different transverse gaps were tested to see its effect. Another gap introduced is the vertical air gap. Therefore horizontal and vertical gap effects were investigated at this investigation. Chuang(1966) carried out slamming experiment at the model basin whose dimension is 7620mm 4572mm ⅹ ⅹ2590.8mm(Length ⅹ Width ⅹ Depth). The size of his model was 508mmⅹ673.1ⅹ12.7mm (LⅹBⅹD). Chung et al. (2006) carried out an experiment to test the LNG insulation system at the tank size of 5000mmⅹ5000mmⅹ3000mm (LⅹWⅹD) while the size of the model was 1655mmⅹ1655mmⅹ500mm (LⅹBⅹT).

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