喷水推进船舶波浪中操纵运动模拟及规避骑浪/横甩控制研究

Ships with waterjet propulsion often operate at high speeds, thus is vulnerable to the occurrence of surf-riding phenomenon due to the influence of waves. Moreover, such ships have superior turning performance, and the swift turning process is usually accompanied by large degrees of motions. Therefore, if the ship is not properly operated during turning, the broaching phenomenon is likely to be triggered which may lead to ship capsizing and is a huge threat to ship navigation safety. This study aims to establish a high accuracy numerical model for the simulation of maneuvering in waves, targeting ships with waterjet propulsion; and through combining the nonlinear dynamic system bifurcation analysis with the time domain numerical simulation techniques, to reveal the key factors and critical conditions for the occurrence of surf-riding/broaching; on this basis, a controller for the steering and reversing unit of the waterjet propulsion unit is designed based on Model Predictive Control (MPC) method, which enforces constraints on the ship motion during turning process, so as to avoid the occurrence of surf-riding/broaching. This study comprehensively and intensively investigates the mechanism behind the occurrence of surf-riding/broaching for ships with waterjet propulsion, and adopts advanced control method to avoid such hazardous phenomena, which is helpful for improving navigation safety, and can provide technical support for the establishment of surf-riding/broaching regulatory criteria and for the safety design of such high performance ships.

喷水推进船舶一般航速较高，在波浪中航行时可能发生骑浪现象，加之此类船舶的转向性能优越，船体在迅猛转向过程中常伴有大幅的姿态变化。因此，若在改变航向过程中操作不当，存在诱发横甩现象并导致船舶倾覆的风险，严重威胁船舶的航行安全。本课题拟建立高精度的波浪中喷水推进船舶操纵运动数值仿真模型；采用非线性力学分叉分析和时域数值仿真相结合的方法，揭示诱发喷水推进船舶发生骑浪/横甩现象的关键因素和对应的临界条件；在此基础上，基于模型预报控制（MPC）方法设计喷水推进装置的操舵导航机构控制器，通过在控制算法中设置约束条件，限制船舶在改变航向过程中的姿态变化程度，从而避免骑浪/横甩情况的发生。本研究全面深入地探索喷水推进船舶在波浪中发生骑浪/横甩稳性失效的机理，并通过先进的控制算法避免骑浪/横甩情况的发生，有助于提升喷水推进船舶的航行安全性，同时也可为骑浪/横甩衡准研究及高性能船舶安全设计提供技术支撑。

针对喷水推进船在高速急转过程中易产生大角度横倾，在波浪等环境载荷的作用下甚至诱发骑浪/横甩稳性失效的问题，开展了喷水推进船骑浪/横甩运动建模、非线性力学分叉分析、目标喷水推进船在波浪中的操纵运动数值仿真和基于模型预报控制（MPC）的喷水推进船航迹跟踪控制研究，揭示诱发喷水推进船发生骑浪/横甩稳性失效的关键因素和临界阈值，进而通过在控制算法中引入约束条件，限制船舶在航迹跟踪过程中的姿态变化程度，从而避免骑浪/横甩稳性失效的发生。研究选取了一艘2000吨级的四喷泵高速船作为研究对象，针对喷水推进系统的推力形成机理和操舵倒航机构的力学特性，建立起了目标船的操纵运动数学模型。通过平面运动机构（PMM）试验获取了模型中主要的未知操纵性水动力导数并初步探讨了喷水推进系统对操纵性水动力导数的影响。在此基础上，根据双重时间尺度原理建立了目标船的时域六自由度操纵-耐波统一模型，实现了喷水推进船的骑浪/横甩仿真模拟。利用提炼出的骑浪/横甩非线性动力学模型，根据分叉分析方法得到了目标船发生骑浪/横甩的临界参数，指出航速和操舵速率是关键的影响参数。最后，建立了目标喷水推进船的航迹跟踪MPC模型，参照分叉分析的结果确立了模型的约束条件；通过在控制算法中对船舶的横摇运动进行约束有效减小了船舶在操纵运动过程中的横摇幅值，数值模拟证明控制器有助于规避骑浪/横甩稳性失效的发生。通过本项目研究加深了对喷水推进船在波浪中操纵运动特性的理解，基于研究成果形成的2份提案均被国际海事组织接收，为此类船舶的二代稳性衡准制定提供了的技术支撑，增强了我国在该规范制定过程中的话语权；另外，本项目探索了MPC这一先进控制算法在喷水推进船航行操纵中的应用，为提升此类船舶航行操纵安全性提供了有益参考。