水下爆炸毁伤后期舰船急速进水的空气效应及船体喘息式运动机理研究

At the early stage of a warship subjected to explosive damage, a large breaking and a rigid-body velocity are caused. After that, the water flooding to the cabin will capture the air and thus the air cavity and high-pressure air cushion are formed. In this period, the unstable air flows will be caused and thus results in the breathing-like motion of the ship hull, which poses serious threats to the survivability of the warship. The International Maritime Organization (IMO) and the ITTC conference have repeatedly specified the key word of air effects for the study of damaged ship dynamics. In this study, the breaking and the rigid-body velocity caused by explosion are included as initial conditions. Based on the compressible fluid dynamics and the theory of multiphase interactions, combined with the multi-scale model experiments, firstly the numerical model in full time domain for the air-liquid-body interactions during the warship flooding is established with the meshless method, then taking into account the influences of the explosion-induced rigid-body velocity and the airtightness of the damaged cabin, the flow characteristics of the air cavity during flooding are studied to reveal the formation mechanism of the high-pressure air cushion and its interactions with the ship hull. Furthermore, under the actions of waves and currents, the laws of the unstable air flows and its induced breathing-like motion of the hull are studied. The research contents are as follows: 1) the numerical model of multiphase interactions in full time domain for the damaged cabin flooding; 2) the air capture and air cushion formation during the dynamic flooding; 3) the air effects and its induced breathing-like motion under complicate sea conditions; 4) the model experiments of the air effects during the rapid flooding.

舰船遭遇水下爆炸毁伤前期经常会产生大破口和刚体速度，在后期舱室急速进水过程中流场会捕获空气形成空泡流和高压气垫，造成不稳定的空气动力，引起船体产生喘息式大幅运动，对舰船的生命力造成严重的威胁。国际海事组织和ITTC会议已多次将空气效应作为破损船研究的关键词。为此，本项目将爆炸毁伤破口和刚体速度作为输入条件，基于可压缩流体动力学和流固耦合理论，首先建立舰船破舱进水的气-液-固全时域耦合无网格数值模型，并通过模型实验验证其正确性；然后，计及爆炸诱导刚体速度和舱室气密度的影响，研究破舱进水过程空泡的流动特性，揭示高压气垫形成及其与船体作用规律；进而研究在浪流作用下破舱内空气的不稳定流动及其引起的船体喘息式运动机理。研究内容包括：1）破舱急速进水的气-液-固全时域耦合模型；2）破舱动态进水空气捕获及气垫效应；3）复杂海况下破舱内部空气流动及船体喘息式运动规律；4）破舱急速进水空气效应模型实验研究。

舰船在遭遇近场水下爆炸后经常会产生大破口，且诱导船体产生一定的总体响应速度，导致船体剧烈的摇晃。当水流由破口急速涌入舱室内部时，对内部结构物和舱壁产生剧烈的砰击，形成破碎、翻卷和飞溅等现象；急速涌入的水流会导致舱室内部产生复杂的空泡流动，形成不稳定的强压缩气垫，与舱外的波浪场间形成复杂的耦合效应，对舰船的生命力产生严重威胁。本项目着眼于舰船遭遇爆炸毁伤后期破舱急速进水过程的空气效应及其引起的船体六自由度非线性运动响应，首先，建立了破舱急速进水的气-液-固耦合作用模型，提出多级分辨率自适应插值的无网格delta-plus-SPH方法进行求解，并开展模型试验验证破舱急速进水模型与计算方法的正确性；在此基础上，计及爆炸诱导船体产生的刚体速度，探明了破舱急速进水自由液面翻卷和破碎、空气流动与压缩等现象蕴含的力学机理，掌握了舱室急速进水过程的空泡流动特性，摸清了气垫的形成及其与船体的作用规律；最后，计入波浪场的作用，探究爆炸毁伤参数、舱室气密度等因素对破舱内部空气不稳定流动及船体喘息式运动的影响规律，形成了舰船遭遇水下爆炸及破舱进水的全周期全时域分析的理论基础与技术体系。研究成果应用到多型舰艇近场爆炸结构毁伤、破舱涌流等结构安全性评估和改进设计之中，为型号舰艇的载荷分析、响应预报、风险评估和应急决策制定提供了重要的技术支撑。研究成果支撑获得教育部自然科学奖一等奖等3项学术奖励，在CMAME、POF、OE等学术期刊上发表SCI学术论文13篇，授权发明专利8项，登记软件著作权6项，培养硕博研究生6人。