基于非线性时域理论的斜浪下船舶波浪增阻计算方法研究

The wave added resistance will cause speed loss to ships, and has a direct impact on the rapidity and economy of the ship. Therefore wave added resistance has been one of the hot issues of domestic and foreign research. Currently, most of the studies to wave added resistance are carried out in head waves, and only considering the effect of longitudinal movement of the ship. While in the actual situation, the ship is often sailing in oblique waves, and the impact of nonlinear rolling on resistance is obvious. Therefore, this project will firstly establish a nonlinear model of coupled motion with pitch, heave and rolling, which based on potential flow theory and considering the effect of viscous. Secondly, the motions of ship in oblique waves are solved based on a time domain Rankine panel method. Finally, a more accurate calculation method of the wave added resistance of the ship in oblique waves is proposed, by calculating the added resistance of nonlinear rolling based on energy radiation theory, calculating the added resistance of heave and pitch based on direct integration method, and calculating the added resistance of wave diffraction based on empirical formula. The main contents include:1) Research on motion prediction method of the ship in oblique waves based on a time domain Rankine panel method. 2) Research on calculation method of the wave added resistance of the ship in oblique waves considering the effect of longitudinal movement, lateral movement and wave diffraction. 3) Research on model test of the wave added resistance of the ship in oblique waves. The study aims to propose a more accurate calculation method of the wave added resistance of the ship in oblique waves.

波浪增阻会导致船舶失速，直接影响船舶的快速性和经济性，因此一直是国内外研究的热点问题。目前，船舶波浪增阻研究大多针对迎浪航行，只考虑了纵向运动对增阻的贡献，而实际航行中船舶多处于斜浪环境，船体产生的非线性横摇运动对波浪增阻影响明显。鉴于此，本课题首先基于势流理论，考虑运动非线性并引入粘性修正，建立斜浪下垂荡、纵摇、横摇三个关键自由度的耦合运动非线性模型；然后使用基于Rankine源的面元法，对斜浪下船舶摇荡运动在时域内进行求解；最后使用能量辐射法计算非线性横摇运动增阻，使用压力积分法计算垂荡、纵摇运动增阻，并对短波绕射增阻进行修正，建立更加完善的斜浪下船舶波浪增阻计算方法。主要研究内容包括：1）基于Rankine源的斜浪下船舶非线性摇荡运动预报方法；2）综合考虑纵、横向运动增阻及绕射效应的波浪增阻计算方法；3)斜浪下船舶波浪增阻模型试验。旨在为斜浪下船舶波浪增阻建立一种更加准确的计算方法。

波浪增阻对船舶的快速性和经济性能具有重要的影响，是船体线型设计中必须考虑的主要问题之一。随着能源危机和环境保护压力的增大，国际海事组织提出了新建船舶的EEDI公式，对民用船舶的能耗标准进行了更严格的限制。因此，本项目对波浪增阻的计算方法展开了研究。首先，本项目提出了一种基于三维势流理论的面元法，在时域范围内对船舶的运动响应进行求解，然后通过近场压力积分法计算出船舶的波浪增阻。通过对wigely-III船型和S175集装箱船型迎浪下的运动响应和波浪增阻计算，并与试验结果进行对比分析，结果显示计算值的变化趋势和峰值与试验值符合较好，计算精度和效率满足研究需求。然后，利用所提出的方法对某新型单体深V复合船型的运动响应和波浪增阻进行了计算，分析了组合附体的节能减阻机理。计算结果表明，船首底部的组合附体在航行中能够产生垂向阻尼，对船体的纵向运动具有明显的抑制作用，从而减小了船体的运动响应和辐射增阻，起到节能减阻的效果。最后，建立起考虑关键自由度耦合效应的船舶运动模型，应用基于势流理论的面元法，对斜浪下船舶的运动响应和波浪增阻进行了计算分析。对S175集装箱船在多个浪向下的波浪增阻进行了计算，并与试验值进行了比较，验证了该方法在斜浪状态下的有效性和计算精度。通过计算分析研究了傅汝德数、浪向角等参数对波浪增阻的影响规律，为新船型开发、船体型线优化、船舶综合性能评估及航行指导提供了有力的技术支撑。