﻿ 基于CFD的排水型三体无人艇阻力优化研究
 舰船科学技术  2023, Vol. 45 Issue (7): 93-97    DOI: 10.3404/j.issn.1672-7649.2023.07.019 PDF

Research on optimization of displacement trimaran USV resistance based on CFD
SUN Wen-qi, ZHANG Qi, JIANG Zhao-zhen, WANG Wen-long
Naval Submarine Academy, Qingdao 266199, China
Abstract: To predict the hydrostatic resistance of a trimaran USV, computational fluid dynamics simulation of the hull is performed using STAR-CCM+. Based on the design parameters such as the speed and displacement of the hull, different design solutions are selected for the computation considering two factors: side hull longitudinal position and side hull form. The simulation results are analyzed combining the flow field characteristics obtained from post-processing, the resistance change laws are summarized and the change mechanism of the hull hydrodynamic performance are recognized. The results show that shifting the longitudinal position of the side hull can reduce the wave disturbance between the hulls, and the maximum drag reduction rate is about 6.7%. The computation results of various hulls are also summarized to provide a reference for the subsequent research of this trimaran USV.
Key words: trimaran     hydrostatic resistance     computational fluid dynamics
0 引　言

1 数值计算方法 1.1 数学模型

 $\frac{{\partial \overline {\mathop u\nolimits_i } }}{{\partial \mathop x\nolimits_i }} = 0 ，$ (1)
 $\rho \left[\frac{{\partial \overline {\mathop u\nolimits_i } }}{{\partial t}} + \overline {\mathop u\nolimits_j } \frac{{\partial \overline {\mathop u\nolimits_i } }}{{\partial \mathop x\nolimits_j }}\right] = \rho \overline {\mathop g\nolimits_i } - \frac{{\partial \overline p }}{{\partial \mathop x\nolimits_j }} + \mu \mathop \nabla \nolimits^2 \mathop u\nolimits_i - \rho \frac{{\partial \overline {\mathop u\nolimits_i' \mathop u\nolimits_j' } }}{{\partial \mathop x\nolimits_j }} 。$ (2)

 $\mathop \alpha \nolimits_{\text{i}} = \frac{{\mathop V\nolimits_i }}{V} ，$ (3)
 $\sum\limits_{i = 1}^N {\mathop \alpha \nolimits_i } = 1 。$ (4)

 $\left\{\begin{array}{l}{\alpha }_{i}=0\text{，}单元中没有相i，\\ {\alpha }_{i}=1\text{，}单元由相i完全填充，\\ {0 < \alpha }_{i} < 1\text{，}单元中存在交界面。\end{array}\right.$ (5)

 $\frac{\partial }{{\partial t}}\left( {\int_V {\rho {\rm{d}}V} } \right) + \oint_A {\rho v{\rm{d}}} a = \int_V {S{\rm{d}}V} 。$ (6)

1.2 数值拖曳水池

 图 1 片体布局示意图 Fig. 1 Hull layout diagram

 图 2 计算域 Fig. 2 Computational domain
2 计算方案设置及结果分析 2.1 单个片体阻力分析

 图 3 阻力曲线 Fig. 3 Drag curves

2.2 侧体纵向位置对阻力的影响

 图 4 b值-阻力曲线 Fig. 4 b value-resistance curve

 图 5 不同b值的兴波高程图 Fig. 5 Wave elevation map with different b values

 图 6 船底压力纵向分布曲线 Fig. 6 Longitudinal distribution curves of bottom pressure

 图 7 不同侧体型宽的兴波高程图 Fig. 7 Wave elevation map with different side-hull beam
2.3 侧体型宽对阻力的影响

3 结　语

1)该三体无人艇航速较低，片体间兴波扰动较小，船体兴波幅度较低，最大波峰不超过0.1 m。船体的摩擦阻力占比较大，达总阻力的一半以上。

2)侧体靠后布置可明显改善流场，减小兴波幅度，有利于降低阻力，最大减阻率约为6.7%。

3)减小侧体型宽可以小幅度降低三体船压阻，但由此导致的吃水变化会增大摩阻，船体总阻力降低约1.3%。

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