﻿ 基于STAR-CCM+的空投气垫船静水阻力特性研究
 舰船科学技术  2022, Vol. 44 Issue (8): 45-49    DOI: 10.3404/j.issn.1672-7649.2022.08.009 PDF

Research on hydrostatic resistance of drop hovercraft based on STAR-CCM +
NAN Xu, HONG Liang, LIU Xin-yue
School of Mechanical Engineering, Nanjing University of Science and Technology, Nanjing 210094, China
Abstract: The 3D model of air drop hovercraft was established by CATIA, the flow field of it was simulated by STAR-CCM+ calculation fluid software, and overlapping grid strategy. Since the air drop hovercraft involved air and water medium during navigation, multiphase flow and VOF models were selected to simulate the free interface.The changes of the hydrodynamic performance of the wave and gas and the total resistance, we verify the reliability and effectiveness of the STAR-CCM+ platform on the hydrostatic navigation state of the hovercraft and the numerical simulation of total resistance.
Key words: airdrop hovercraft     overlapping grid     virtual drag pool     VOF model     wave-making
0 引　言

1 数学模型

 图 1 气垫船总阻力组成 Fig. 1 Total hovercraft resistance composition

 ${{{R}}_{{a}}} = \frac{1}{2}{C_a}{\rho _a}{S_a}{{{V}}^{{2}}} 。$ (1)

 ${{{R}}_{{m}}} = {\rho _a} \cdot {Q_f} \cdot {{V}} 。$ (2)

 ${{{R}}_{{w}}} = {C_w} \cdot \frac{{P_c^2 \cdot {B_c}}}{{g \cdot {\rho _w}}} 。$ (3)

 ${{{R}}_{{z}}} = W \cdot \alpha 。$ (4)

 ${{{R}}_{{{se}}}} = {K_1} \cdot {10^{ - 6}} \cdot {C_l} \cdot \sqrt {{S_c}} \cdot {q_w} \cdot {\left( {\frac{h}{{{C_l}}}} \right)^{ - 0.34}}。$ (5)

 ${{{R}}_{{{sw}}}} = \left[ {2.817 \cdot {{\left( {\frac{{{P_c}}}{{g{L_c}}}} \right)}^{ - 0.26}} - 1} \right] \cdot {R_w}，$ (6)
 $\Delta {{{R}}_{{a}}} = {C_a} \cdot \frac{{{\rho _a}{{\left( {V + {V_b}} \right)}^2}}}{2}{S_a} - {R_a}。$ (7)

 $\Delta {{{R}}_{{m}}} = {\rho _a} \cdot {{\text{Q}}_f} \cdot {V_b}，$ (8)
 $\Delta {{{R}}_{{{se}}}} = {q_w} \cdot {C_l} \cdot \sqrt {{S_c}} \cdot 2 \times {10^{ - 4}}{\left[ {\frac{{2{H_w}}}{{1.6\left( {{H_c} + {H_f}} \right)}}} \right]^{{5 \mathord{\left/ {\vphantom {5 3}} \right. } 3}}}。$ (9)

2 数值模拟 2.1 实体建模

 图 2 空投气垫船三维模型 Fig. 2 3D model of air hovercraft
2.2 边界条件与物理模型

 图 3 计算域边界条件 Fig. 3 Calculate the domain boundary conditions
2.3 流场创建与网格划分

 图 4 计算域网格 Fig. 4 Computational domain grid
2.4 计算结果分析

 ${{{F}}_{{r}}} = {{{V}} \mathord{\left/ {\vphantom {{\text{V}} {\sqrt {{\text{g}} \cdot {{L}}} }}} \right. } {\sqrt {{{g}} \cdot {{L}}} }} 。$ (10)

1）兴波

 图 5 各傅汝德数Fr对应兴波图 Fig. 5 EachFr corresponds to the wave-making

 图 6 各傅汝德数Fr对应水气两相云图 Fig. 6 EachFr corresponds to water-gas two-phase cloud map

2）水气两相特性

 图 7 各航速阻力曲线特征时刻图 Fig. 7 Characteristic time diagram of each speed resitance curve

 图 8 各航速总阻力变化监测 Fig. 8 Monitoring of total drag of each speed

3）静水航行总阻力

 图 9 不同航速总阻力理论值与仿真值对比 Fig. 9 The theoreyical value of the total drag of different speeds is compared with the simulation value

 图 10 不同Fr总阻力理论值与仿真值对比 Fig. 10 The theoreyical value of the total drag of different Fr is compared with the simulation value
3 结　语

1）随着航速的增加，空投气垫船到达阻力峰值的时间由长到短，拐点出现在Fr=1.817附近，越早跨越阻力峰值也就越早趋于平稳，最终无限收敛于一个定值即为所求总阻力。

2）空投气垫船在静水中形成稳定鸡尾涡的时间规律同上；但航速越高，兴起的波浪越大，绕流场更为复杂，开尔文波系角越小，自由面以下最深处涡团区域距离船体越远这有助于研究此类船舶的隐身性能和波系特征。

3）航速在20～40 kn时，空投气垫船所受总阻力与航速成正比，超过40 kn时，总阻力反而开始减小，这是由于气液两相特性使得船体底部空气体积分数增大、压力上升较快，气体最终从围裙底部逸出，流体运动达到动态平衡，气垫效应愈发显著；此外随着傅汝德数增大，船体表面开始出现部分区域水的体积分数小于1的现象，说明有外部空气进入围裙，有效减小了介质的粘性系数，从而起到减小摩擦阻力的作用。这也是气垫船具有高速性能的主导因素之一。

4）通过傅汝德数对无因次总阻力规律进行体现，同时用气垫船静水总阻力估算公式与STAR-CCM+仿真结果相对比，两曲线变化趋势相同，误差满足工程应用要求。验证了计算流体力学方法对此类气垫船的结构设计和阻力性能预报具有可靠性。

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