자유 낙하하는 Wigley hull에 작용하는 충격력에 대한 수리모형시험연구

Abstract

Characteristics of impact load and pressure is experimentally investigated. Drop tests have been carried out for a modified Wigley with CB=0.56. Vertical force, pressures, vertical accelerations were measured. 6-component load cell was used for measuring the forces, pie-zo-electric sensors were used for capturing impact pressure, strain-gauge type accelerometers were used for measuring vertical accelerations. 50kHz sampling rate was applied to capture peak values. Repeatability of the measured data was confirmed and basic characteristics of impact load and pressure such as linearity to falling height was observed for all measurements. A simple formula is derived to extract physical impact load from measured force based on a simple mass-sensor-mass diagram, which was validated by comparing impact forces with existing data for a mathematical model of Faltinsen and Chezhian(2005). Effects of elasticity of the model and change of acceleration during the water entry are discussed. It is interesting to observe that the impact loads occurred and reached peak value at the same time duration after water entry for all drop heights.