开放空腔壳体入水过程多相流动特性研究

发布时间：2018-01-12 04:32

本文关键词：开放空腔壳体入水过程多相流动特性研究　出处：《哈尔滨工业大学》2017年博士论文　论文类型：学位论文

【摘要】：开放空腔壳体是一种含有中空腔体的壳体结构,在以开放端首先撞击自由液面的入水过程中,空腔内气体压缩、液体流入,形成一个气、液两相耦合流动空间,并通过开放端与外部流场连通,形成内、外流场间耦合变化,涉及到固、液、气三相运动和内、外两个流场的多流域耦合运动问题。在这种复杂流动环境下,开放空腔壳体入水流动现象与传统实心运动体入水流动现象截然不同,入水空泡流动特性、流场结构特性、流体动力特性和水下弹道特性均将发生质的改变,因此开展开放空腔壳体入水多相流动特性研究具有重要的理论意义和实用价值。本文采用势流理论、数值模拟和实验相结合的方法,针对开放空腔壳体入水过程中入水空泡流动演化、非定常流场分布、流体动力及入水运动稳定性等问题开展了研究,主要研究内容和成果如下:基于势流理论分析方法,建立了适用于开放空腔壳体入水运动的理论模型。根据开放空腔壳体入水气、液、固耦合运动特征和无旋流动假设,分别建立空腔气体涨缩方程、壳体动力学方程和入水空泡运动学方程;采用势流理论建立入水运动方程组,求解得到入水运动规律和入水空泡扩展规律,并与实验数据对比验证了理论模型的适用性。基于高速摄像实验方法,对开放空腔壳体入水空泡流动方式和演化特性开展研究。开展了不同入水速度条件下的开放空腔壳体入水实验,获得了波动和云化两种流动方式下的入水空泡形态、尺度等特征,分析了Fr数的入水空泡流动方式的影响,并揭示了两种流动方式的形成机理和关系;开展了不同开放端开口面积和空腔体积模型的入水实验,分析了开放空腔结构参数对入水空泡流动方式和演化规律的影响。基于计算流体力学方法,对开放空腔壳体的入水运动规律和流体动力特性开展研究。建立了数值计算模型,参照实验条件开展了相应模拟计算,通过与实验数据对比验证了数值方法的有效性;通过对数值计算结果分析,获得了入水过程壳体轴向阻力演化规律和侧壁面压力分布特征,分析了开放空腔结构在入水运动过程中对流体动力特性的影响;开展了正浮力开放空腔壳体入水仿真,分析了入水后续往复上浮-下沉运动规律和流体动力特性。采用实验和数值模拟相结合的方法,研究了扰动作用下空腔内/外非定常流场结构特性和空泡阶段性局部失稳问题。将入水过程分为冲击阶段和后续的空腔涨缩阶段,分别针对两个阶段的特点分析了内/外流场参数分布和压力波特征;描述了空腔扰动作用下入水空泡的阶段性局部失稳现象,重点分析了空腔扰动作用方式和扰动引起的空泡局部流动特征及作用机理。基于倾斜入水实验方法,研究了开放空腔壳体典型入水弹道特性。开展了不同姿态和入水速度条件下的开放空腔壳体倾斜入水实验,根据实验结果描述了倾斜入水空泡演化规律和典型的入水运动特征,分析了入水空泡和水下弹道的关系,并对入水运动过程进行阶段性划分,分析了运动各阶段的运动特征和流体动力特征;通过对比实验数据分析了初始入水速度和入水姿态对入水弹道和空泡形态等运动特征的影响。
[Abstract]:The open cavity is a hollow cavity containing the shell structure, in the open end of the first collision free surface into the water in the process of cavity gas compression, liquid flow, forming a gas liquid two-phase flow, space coupling, and through the open end and the external flow field of connectivity, form, coupling between outflow changes that relates to solid, liquid, gas phase and movement, multi basin coupling problem of two flow field. In this complex flow environment, open cavity flow into the phenomenon and the traditional solid body into the water flow into the water flow characteristics of different phenomena, cavitation, flow field characteristics, hydrodynamic and water under the ballistic characteristics will be a qualitative change, so the open cavity into the water phase flow characteristics research has important theoretical significance and practical value. This paper uses the theory of potential flow, numerical simulation and experiment combination Method for open cavity flow into the water into the water bubble evolution process, the unsteady flow field, hydrodynamic problems and water movement stability were studied, the main research contents and results are as follows: the analysis method based on potential flow theory, a theoretical model is established for open cavity into the water movement. According to the the open cavity into water vapor, liquid, and solid coupling motion characteristics and irrotational flow assumption, equations were established. The gas cavity, shell dynamics equation and kinematics equation of bubble into the water; the potential flow theory of the water dynamic equations are obtained in the water movement and water entry cavity expansion law, and the applicability is verified. The theoretical model is compared with the experimental data. The experimental method based on high speed camera, open to the cavity into the water cavity flow patterns and evolution characteristics are studied. The different speed of water entry. The open cavity into the water samples, obtained the fluctuation and cloud two flow patterns under the water entry cavity, scale and other characteristics, analyzed the influence of Fr number of the water entry cavity flow, and reveals the formation mechanism and the relationship between the two flow modes; carry out the area and the volume of the cavity model the open end of the opening into the water experiment, analyzes the influence of structure parameters on the open cavity into the water bubble flow mode and evolution. Based on computational fluid dynamics methods, research into the water movement and hydrodynamic characteristics of open cavity. A numerical simulation model is established according to the experimental conditions to carry out the corresponding simulation calculation. By comparison with experimental data to verify the validity of the numerical method; through the analysis of numerical calculation results, obtained in water shell axial resistance evolution and side wall pressure distribution characteristics, divided Influence of open cavity structure on fluid dynamic characteristics in the water movement process; carry out positive buoyancy open cavity into the water simulation, analysis of the follow-up water floating - sinking motion reciprocating and hydrodynamic characteristics. Using the method of experiment combined with numerical simulation, the effects of disturbances in the cavity / non fixed constant flow structure characteristic and cavitation stage local instability problem is studied. The entry process is divided into shock stage and subsequent cavity expansion stage, respectively, according to the characteristics of the two stages of internal / external flow field parameters distribution and pressure wave characteristics; describes the stage of cavity disturbance into the water cavity of the partial loss the stability, focus on the analysis of the cavity perturbation function and disturbance of local flow characteristics and the mechanism of cavitation caused by the tilt. The water entry test method based on the research of open cavity of typical water entry trajectory. The open cavity. The different attitude and speed of water entry under the condition of oblique water entry test, according to the experimental results described oblique water entry cavity evolution and typical water movement characteristics, analysis of the relationship between water and underwater ballistic vacuoles, and stages of the water movement process, analysis the motion characteristics and the hydrodynamic characteristics of each stage of the movement; by comparing the experimental data analysis of the initial water velocity and the influence of water on water entry trajectory and attitude motion characteristics. The cavity shape

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：O359

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