﻿ 基于NURBS的模块化三体船总体设计和优化
 舰船科学技术  2022, Vol. 44 Issue (18): 41-44    DOI: 10.3404/j.issn.1672-7649.2022.18.009 PDF

Overall design and optimization of modular trimaran based on NURBS
CHEN Ling, MENG Qiao, ZHOU Chen-yan
Ship Teaching and Research Office, School of Electrical and Energy Engineering, Nantong institute of Technology, Nantong 226002, China
Abstract: Compared with traditional large ships, trimarans have the advantages of good seakeeping, high stability and large cargo capacity. How to improve the design quality of trimarans has become an important research direction in the shipbuilding industry worldwide. The content of this paper is an overall design method of trimaran based on modular theory. The modular design concept is a new design theory emerging in recent years. The reusability of components maximizes the product characteristics of marine products. Based on the modular design theory, this paper uses the NURBS curve to carry out the profile fitting design, completes the optimization design of the characteristic curve of the trimaran, and analyzes the hydrodynamic characteristics of the design scheme based on this.
Key words: modularization theory     trimaran ship     profile design     hydrodynamic characteristics
0 引　言

1 模块化设计理论基本研究

 图 1 模块化设计理论体系的基本原理 Fig. 1 Basic principles of modular design theory system

1）模块化总体设计

2）模块化划分设计

3）模块化重组设计

 图 2 模块化重组设计的流程图 Fig. 2 Flowchart of modular restructuring design

4）模块化产品设计

2 基于NURBS的模块化三体船总体设计与优化 2.1 三体船的特征曲面设计

NURBS曲线模型用下式表示：

 $\bar p\left( m \right) = \frac{{\displaystyle\sum\limits_{i = 0}^n {{w_i}{d_i}{N_{i,j}}\left( u \right)} }}{{\displaystyle\sum\limits_{i = 0}^n {{w_i}{N_{i,j}}\left( u \right)} }} \text{。}$

NURBS曲线的拟合过程用图3表示。

 图 3 NURBS曲线的拟合过程示意图 Fig. 3 Schematic diagram of NURBS curve fitting process

1）确定特征点元素

 $\begin{array}{*{20}{l}} {{f_1} = \min \psi (x,y,z)}，\\ {{f_2} = \max L(t)}，\\ {{f_3} = \min C(t)}，\\ {{f_4} = {F_{x,y,z}}(t)} 。\end{array}$

2）由特征点建立三体船的特征型线

 ${f_s}\left( x \right) = \frac{1}{k}{x_t}gC{\left( t \right)^{{\alpha _0}}}\psi (x,y,z) \text{。}$

 ${f_s}\left( x \right) = \frac{1}{{{F_{x,y,z}}(t)*k}}{x_t}gL{\left( t \right)^{{\alpha _0}}} \text{。}$

3）三体船的型线优化

 $\begin{gathered} \frac{{{\partial ^{}}\psi }}{{\partial \tau }} = 0 ，\\ \frac{{{\partial ^{}}\psi }}{{\partial \tau }} - Vn = 0。\\ \end{gathered}$

 ${F_n}(s) = \frac{{{k_1}{v_x} + {k_2}{v_y} + {k_3}{v_z}}}{{\sqrt {{H_x}^2 + {H_y}^2 + {H_z}^2} }} \text{。}$

4）由三体船型线建立三体船的特征曲面

 图 4 基于SolidWorks产生的三体船特征曲面 Fig. 4 Three body ship feature surface based on SolidWorks
2.2 三体船流体动力学特性分析

 图 5 三体船的运动坐标系 Fig. 5 Trimaran motion coordinate system

 ${\Delta ^2}\psi {\text{ = }}0 \text{，}$

 $m\frac{{\partial \left( {\rho {u_x}} \right)}}{{\partial t}} + m\frac{{\partial \left( {\rho {u_x}{u_y}} \right)}}{{\partial t}} = m\frac{\partial }{{\partial t}}\left[ {\mu \left( {\frac{{\partial {u_x}}}{{\partial y}} + \frac{{\partial {u_y}}}{{\partial x}}} \right)} \right] + {F_i}\text{。}$

 $\alpha \left( {x,t} \right) = \left\{ \begin{gathered} 0\;\;x \in {V_1} ，\\ 1\;\;\;x \in {V_2} 。\\ \end{gathered} \right.$

 $\frac{{\partial \alpha }}{{\partial t}} + u\frac{{\partial \alpha }}{{\partial x}} + v\frac{{\partial \alpha }}{{\partial y}} + w\frac{{\partial \alpha }}{{\partial z}} = 0 \text{。}$

 $\int\limits_S {\frac{\partial }{{\partial {t^{}}}}\left( {{\rho _0}\varphi } \right){\rm{d}}V + \int\limits_{}^{} {{\rm{div}}\left( {{\rho _0}\bar \varphi } \right){\rm{d}}V} = } S\left( V \right) \text{。}$

2.3 三体船流体动力学特性仿真

 $\zeta(t)=\sum_{i=1}^{n} \xi \cos \left(k \psi \pm \omega t+\varepsilon_{i}\right) \text{。}$

 图 6 三体船优化时设计前后的模型兴波阻力曲线对比 Fig. 6 Comparison of wave making resistance curves of trimaran models before and after design
3 结　语

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