基于谱分析原理和频率响应法的舰船纵摇运动分析

Analysis of Ship Pitching Motion Based on Spectrum Analysis Principle and Frequency Response Method

摘要:

为了掌握高海况下舰船的纵摇运动规律并对其进行准确预报，分析了舰船的纵摇运动规律。运用谱分析原理和频率响应法，分别在 4 级、5 级和 6 级海况下，根据海浪谱密度函数和舰船的纵摇频率响应函数，求得其纵摇运动谱密度函数；再运用公式推导，得到其纵摇运动的时域函数；使用 MATLAB 仿真软件对舰船进行纵摇运动仿真，得到 3 种高海况条件下的舰船纵摇运动时域函数图像，并验证仿真结果的准确性。 仿真结论：在高海况下，海况等级对舰船纵摇影响显著，海况等级越高，舰船纵摇的角度值范围就越大。以某型舰船为例的预报结果：在 4 级海况下，舰船纵摇的幅度在±6°之间；在 5 级海况下，舰船纵摇的幅度在± 15°之间；在 6 级海况下，舰船纵摇幅度可以达到±30°之间。

关键词:谱分析原理;频率响应法;舰船纵摇

Abstract:

In order to grasp the law of ship pitching motion at abominable sea state and make accurate prediction，this paper analyzes the law of the ship pitching motion. Adopting the principle of spectrum analysis and frequency response method，the ship pitching motion spectral density function is obtained based on the wave spectral density function and the ship pitching frequency response function at sea state 4，5 and 6. Three types of Time-Domain function images of the ship pitching motion at abominable sea state are obtained from the simulation of ship pitching motion using MATLAB，and the accuracy of the simulation has been verified. The simulation result indicates that the sea state level has a significant effect on the ship pitch at abominable sea state，which means the higher the sea state level is，the greater the range of the ship pitch angle value will be. Taking a certain type of ship as an example，the prediction result shows that at sea state 4，the pitch of the ship is within ±6°；at sea state 5，the pitch of the ship is within ±15°；at sea state 6，the pitch of the ship is within ±30°.

Key words:principle of spectral analysis;frequency response;ship pitch