Analysis method for reducing rolling motion of ship

Abstract

The invention discloses an analysis method for reducing rolling motion of a ship. The analysis method comprises the following steps of according to an established three-dimensional stimulation image of the ship, calculating instant restoring force and instant wave incidence force of the ship under any waves, calculating a rolling angle and a ship rolling probability according to the ship heaving, pitching and rolling three degrees of freedom coupling motion differential equation to obtain the probability that the rolling angle of the ship is smaller than a flooding angle, thereby judging whether the ship runs at a safe state; and by regulating a navigational state of the ship, obtaining a numerical simulation result of the motion of the ship in any wave directions under the action of random waves and the probability that the rolling angle is smaller than the flooding angle, so that a navigation state of the ship corresponding to the maximum of the probability that the rolling angle is smaller than the flooding angle can be found out, and the rolling motion of the ship can be reduced by selecting the navigation state or changing the model line of a ship body at a design stage. According to the analysis method for reducing the rolling motion of the ship, which is disclosed by the invention, the rolling angle and the rolling probability are calculated, so that the rolling motion of the ship under any waves is reduced.

Description

technical field [0001] The invention relates to the field of motion response analysis and motion performance evaluation of marine ships, in particular to an analysis method for reducing ship rolling motion. Background technique [0002] As an important means of transportation in the shipping industry, ships have attracted much attention for their motion performance. The International Maritime Organization (IMO) is working on the formulation of the second-generation intact stability specification, aiming at five failure modes (dead ship stability, roll, loss of pure stability, excessive acceleration and parametric roll). There is an urgent need for a set of forecasting techniques and criteria methods that are highly reliable and generally applicable to various types of ships. [0003] Many scholars at home and abroad have conducted research on the problem of large nonlinear roll of ships, and have achieved certain results. Atsuo Maki et al. applied stochastic wave theory an...

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Problems solved by technology

[0004] Although the research at home and abroad has made great progress, there are still some problems. In fact, if a ship encounters a strong storm during navigation, it will try to avoid the ship from bearing the wind and wave load laterally, and choose to adjust to longitudinal or oblique waves. wave sailing state, and the actual sea conditions are random

However, most of the research in the prior art focuses on the large nonlinear rolling phenomenon in longitudinal and transverse waves, while there are few studies on rolling motion in oblique waves

Most of the studies on the rolling motion of ships in oblique waves do not consider the parameter excitation items, which will cause great deviations in the prediction results. Experiments have found that the roll angle of a C11 container ship sailing in a certain oblique sea reaches about 20 degrees, but not Considering the influence of parameter excitation, the roll angle obtained does not exceed 3°, and cannot be used to predict large-scale parameter-induced roll motion in oblique waves

The few methods for predicting the large parametric roll in oblique seas also obtain the time history of the ship's rolling motion through numerical simulation, and cannot predict the capsizing probability of the ship

At present, there is no research on the prediction of the probability density of large-scale rolling motions in random oblique waves considering the influence of parameter excitations at home and abroad, so there are still defects in the analysis methods for measuring the downward roll angle of ships in arbitrary waves and the corresponding roll probability. Therefore, there is still room for improvement in the analysis methods for preventing the overturning of the ship and reducing the rolling motion of the ship.

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