경사진 실린더에 작용하는 플런징 쇄파 충격력의 불안정성 고찰

Abstract

Impact on cylinder surface caused by plunging breaking waves is investigated experimentally. The breaking waves are generated in a wave fume by decreasing the wavemaker frequencies linearly and focusing the generated wave components at one specific location. The breaking wave packets are based on Pierson-Moskowitz spectrum. Three forward and one backward inclination angles of cylinder are applied to examine the effect of contact angle between cylinder and front surface of breaking waves. Also, the effect of cylinder diameter on pressure distribution and its peak value is investigated by adopting four cylinders with different diameters. The longitudinal location of cylinder is slightly moved in five different points to find out a probable maximum value of impact pressure. The pressures and total force on cylinder surface are measured by piezo-electric pressure sensors and 3-compoinents load cell with 30kHz sampling rate. The variation of peak impact pressures and force is analyzed in terms of cylinder diameter, inclination angle and location. Also, the pressure distribution on cylindrical surface is examined. The cylinder location and surface position are more important parameters that govern the magnitude and shape of peak pressures, while the diameter and inclined angle are relatively insignificant. In a certain conditions, the impact phenomenon becomes very unstable which results in a large variation of measured values in repeated runs.