【作者】 戴绍仕；

【导师】 姚熊亮；

【作者基本信息】 哈尔滨工程大学 ， 船舶与海洋结构物设计制造， 2009， 博士

【摘要】 随着船舶工业的迅速发展和海军装备建设日新月异,船舶的供水需求日益提高,越来越多的船舶分别在船体艏部、舯部和艉部设置了海底阀箱(即垂向贯穿船底,底部与海水相通,顶面无自由表面的陷落腔结构),以海底阀箱结构为代表的三维陷落腔结构的流激振荡问题又重新受到各国学者的关注。在一定的条件下,流激振荡所产生的交变流体力会诱发“流体力共振现象”和“流激振动现象”,从而使陷落腔结构的的疲劳寿命受损,给船舶的正常运营带来不利的影响。若能够对复杂流场中三维陷落腔的流激振荡特性做出合理的预报,可大大提高三维陷落腔结构的使用寿命,同时为腔体结构的设计提供依据。本论文重点针对以海底阀箱结构为代表的陷落腔流激振荡特性中的若干问题,结合国防科技工业技术基础科研项目,并在追踪了国内外有关陷落腔流激振荡问题的最新研究动态的基础上,采用物理实验的方法展开系列、深入的研究。旨在揭示三维陷落腔流激振荡机理,并合理地给了各种参数对腔体内流激振荡特性影响的规律。本论文的主要工作内容可总结为以下几个方面：1、本文在正确地掌握腔型分离流数值计算方法的基础上,提出了实验方案数值设计的方法。针对实验的影响因素和将出现的现象进行一系列的数值实验。利用CFD方法分别对三维陷落腔模型的FSO问题和实验船模的Green Water问题进行数值实验研究,优化了实验方案,预测了实验现象。2、针对均匀流中三维陷落腔流激振荡问题采用LES湍流模型进行数值研究。根据数值计算结果,结合涡运动学基本理论知识分析了腔体剪切层处和其内部流体运动的机理。3、针对不同结构型式的陷落腔模型,采用对比分析的实验方法开展了均匀流作用和浪流联合作用时,三维陷落腔流激振荡问题的系列实验研究,测量了腔体侧壁上的流体压力信号。同时在实验中分别考虑了来流攻角、波浪周期、波高对陷落腔流激振荡特性的影响及流体力分布的影响,给出了影响规律,给出了Cp和St数的估算公式。4、分别分析了不同来流条件、不同浪流条件时三维陷落腔流体力随Re数／KC数的变化规律及分布规律,同时分析了波高、波频、来流流速、来流攻角对剪切层振荡频率的影响,给出了各种来流条件下剪切层振荡频率随来流流速的变化规律。5、针对腔体内流体与外界存在质量交换的问题分别开展了均匀流场作用和浪流联合作用时,三维陷落腔的质量交换实验研究(即抽水实验),同时考虑了腔型的变化和来流方向的变化,给出了腔内与外界存在质量交换时对腔内侧壁流体力分布的影响规律及质量交换量的变化对腔口剪切层振荡特性的影响规律。更多还原

【Abstract】 With the rapid development of ship industry and quickly changing of naval equipment construction, the need of water supply in ship increases, so more and more ships set up suction boxes which locate in the stem, amidships and stern, in that suction boxes transfix bottom plating and hull bottom connect with sea water. Moreover they are cave-in cavity without free surface at the top. Represented by the suction box the problem of fluid induced oscillation of cave-in cavity is paid close attention again by many researchers.Under certain conditions the alternating force caused by fluid induced oscillation will lead to phenomenon of "fluid force resonance" and "fluid induced vibration", finally fatigue life of cave-in cavity would be damaged, which will have adverse influence on normal operations. If reasonable forecast of fluid induced oscillation characteristic can be given in complex fluid, their fatigue life will be increased greatly, at the same time the foundation of cave-in cavity’design will be put forward.Aiming at many problems of fluid induced oscillation of cave-in cavity, combining basic research projects of national defense science, technology and industry, besides searching many latest research results on fluid induced oscillation of cavity, a series of experimental and contrastive research methods are carried out in this paper. The purpose is to open out mechanism of fluid induced oscillation on cave-in cavity, and the influencing rule of all kinds of parameter on fluid induced oscillation is given. The main content of this thesis includes the following aspects:1、On the basis of validly grasping numerical calculation method of cavity separation numerical design method on experimental project is opened out. Aiming at experimental influencing factors and taking on new phenomena a series of numerical experiment are carried out. The problems of cave-in cavity’s FSO and ship model’s Green Water are studied using CFD method, then experimental project is optimized, forever experimental phenomena is predicted.2、Aiming at the problem of cave-in cavity’s FSO LES calculating model is adopt to complete numerical research in uniform. Based on the calculating results combining basic theory of vortex dynamics, shear layer oscillation and internal dynamic mechanism of cavity flow are analyzed.3、Aiming at different cavity types, experimental method of constructive analysis is adopted to complete a series of experimental research on flow induced oscillation problem of three dimensional cave-in cavity, which subjected to uniform field and wave flow field. Moreover the pressure signals of cavity’s sidewall are measured, and the influence of attack angle, wave cycle and wave height on the characteristics of fluid induced oscillation of cavity are considered. The influencing rule is presented and estimating formula of Cp and St are opened out.4、Considering the conditions at different incoming and wave flow, the rules of flow forces versus Re number and KC number separately are analyzed. At the same time the influence of wave height, wave frequency, incoming velocity and incoming angle on frequency of the shear layer are analyzed. Then the rule of shear layer versus velocity is given.5、Aiming at the problem of flow of cavity inner having the mass exchange with outside, the different cavity type’s experimental research with mass exchange are carried out, which separately subjected to uniform field and wave field. Then the influence rules of mass exchange on the distribution of flow forces of cavity inner and characteristic of shear layer oscillation are given.更多还原