ABSTRACT:

This paper presents comparison of pressures due to liquid sloshing in a VLCC cargo hold between experimental results and numerical results. DSME's typical double hull VLCC has a single horizontal cross tie in center tanks. However the conventional cross tie system include difficulties at construction stage and local fatigue damage. For these reasons, DSME developed a new type of mid ship section of VLCC. The cross-tie in the center tanks is removed and the depth of vertical web and stringer is increased. To investigate the effect of internal structure, i.e. cross tie, on sloshing loads of a VLCC, a systematic model tests are carried out using 6-DOF motion platform at PNU. These experimental results, both with and without cross-tie, are compared with results of numerical simulations using a commercial CFD program, STAR-CCM+. The tank model with simplified internal structures is manufactured from acrylic to the scale of 1:50. To compare experimental and numerical results, test conditions are based on regular harmonic motions. It is conclude that the proposed tank configuration without the cross-tie would be acceptable for a VLCC center tank.

INTRODUCTION

In ordinary double hull VLCC, one row of cross-tie is arranged in the center tanks in order to prevent damage on inner wall due to the various loads and stresses. However, cross-tie has some problems. The cross-tie structure is difficult to be constructed and require dangerous jobs of workers at shipyard. So, DSME has developed a new type of mid ship section of VLCC to increase productivity and structural integrity. The cross-tie in the center tanks is removed and the depth of vertical web and stringer is increased in the developed design. To evaluate the safety of the new cargo hold, the evaluation of cross-tie's effect on sloshing loads was required.

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