부가저항의 비선형성에 대한 실험적 연구

Abstract

This study experimentally investigates the nonlinear characteristics of ship motion responses and added resistance under varying wave heights. Two ship models-a bulk carrier (KSUPRAMAX-O) and a liquefied natural gas carrier (KLNG)―were selected for tests. Experiments were conducted in regular wave conditions with varying wave heights to analyze the influence of wave height on the nonlinear behavior of ship motions and added resistance. The validity of the theoretical models applied to the incident wave conditions was first examined, and the characteristics of the incident waves were quantitatively analyzed. The nonlinear behavior of motion responses with respect to wave height variations was then evaluated. The heave response exhibited a decreasing trend with increasing wave height at wavelengths comparable to the ship length, while the pitch response showed relatively low sensitivity to wave height changes. Nonlinear characteristics of added resistance were also analyzed. The KSUPRAMAX-O model exhibited decreasing sensitivity to wave height variations as the wavelength increased, whereas the KLNG model showed a marked increase in sensitivity when the wavelength-to-ship-length ratio (λ/L) exceeded 0.85. Based on the experimental findings, a correction factor was proposed to quantify the nonlinear effects of added resistance. The proposed method also showed applicability to other hull forms with similar geometric characteristics.