횡동요 감쇠 계수의 산출을 위한 감쇠실험 연구

Abstract

In general ship, there are two roll motion's features. One is that wave-making is so small that viscosity effects should be considered to predict roll motion properly. The other is that roll motion's response is large in resonant. To control roll motion, roll motion stabilizers such as a bilge keel, anti-rolling tank and fin-stabilizer are being used. Most of the bilge keel is used bacause bilge keel manufacture is easy and its cost is cheap. Bilge keel's efficiency is shown by roll damping coefficient that was calculated from experimental data. In this study, two procedures to obtain roll damping coefficients are explained. One is roll damping coefficient by using relative decrement, the other roll damping coefficient by using logarithmic decrement. Generally, the former is widely used for evaluation of roll damping coefficient. On the other hand, its calculation is relatively complicated. The latter newly introduced by this research is so simple to calculate. Two roll damping coefficients to be calculated from experimental data are compared. It is shown that roll damping coefficient by logarithmic decrement and roll damping coefficient by relative decrement are similar.