【作者】 李光霁；

【导师】 潘家祯；

【作者基本信息】 华东理工大学 ， 化工过程机械， 2010， 博士

【摘要】 颗粒细化技术作为支持高新技术工业最重要的技术之一受到学术界和企业界广泛的关注,但是目前对液体颗粒的细化研究无论在理论研究还是应用技术等方面都存在着不足。本文的研究正是以其为出发点,提出一种将超高压技术、微型通道流动技术、撞击流技术三者有机地结合起来的新技术、新方法,用以探讨液体颗粒的细化。超高压技术由于具有瞬间压力、作用均匀、操作安全和耗能低的特点被广泛应用酒类催陈、食品加工等重要领域,微型设备由于其体积小,保压效果好,所能达到的压力高,对超高压能量利用率高,同时由于线尺度小,使得一些物理量的梯度增加很快,传质推动力增加,从而具有混合效果好等特点。撞击流技术是通过两股高速射流的强烈撞击,使颗粒间相互的碰撞、互磨产生的剪切力和挤压力从而使液体颗粒细化。因此如何把三者技术优势进行有效整合并运用到颗粒细化中是本文研究的重点。本文通过对超高压下微型管道流动特性、超高压下微射流撞击壁面的流动特性以及超高压下微射流对撞的流动特性等理论分析研究,对相关理论进行进一步推导和证明,实现了对现有理论的完善和拓展,同时结合超高压技术、微型通道流动技术、撞击流技术的理论研究设计优化了两种超高压微型撞击流装置结构,并对该装置在食品和酒类等领域的应用进行了实验研究。(1)超高压微流道流动特性研究对超高压微流道流动特性、流场进行研究,从尺寸效应、边界层影响和质量和动量传递三方面阐述了微通道流动特性。详细分析了截面为方形时的边长和比表面积的对应关系和截面为圆形时直径和比表面积的对应关系,在圆管中边界层积分方程的基础上,-推导了宏观圆形管内湍流的速度边界层厚度方程和核心区速度方程,微尺寸圆形管内的速度边界层厚度方程和核心区速度方程,在此基础上结合比表面积的计算分析了微尺寸通道中流体的质量传递和动量传递特性。详细分析了在超高压状态下,微尺寸圆管的流动特性,建立了实验模型,进行数值计算,对其在不同介质下、不同压力下的速度分布、压力分布、壁面剪切应力分布的规律及变化趋势进行总结。对比分析了在同等条件下微尺寸圆管和宏观尺寸圆管内流动的差别,得出微尺寸圆管内流动的优势。(2)超高压约束微射流撞击壁面的特性研究总结、推导了超高压轴对称约束微射流轴心速度分布公式和半扩展厚度公式。对超高压微射流撞击壁面用不同的湍流模型进行数值模拟,找出最适合微射流撞击壁面湍动场的湍流模型,研究了总结了超高压微射流撞击壁面的流动行为及其流场结构特点。(3)超高压微型撞击流的特性研究研究了超高压微型撞击流(相撞)的流动特性,详细进行数值计算,分析了轴向方向的速度,径向方向的速度,动压,静压,总压以及湍动能分布曲线图,总结了超高压微型撞击流的流动特性,得出了超高压微型撞击流的流场特性分布的规律,并对其进行分析解释。(4)超高压微型撞击流装置结构的设计优化设计了两种超高压微型撞击流装置结构,阐述了撞击速度作为衡量撞击效果依据的理由,分别对超高压微型撞击流发生器两种结构的尺寸进行优化,比较两种结构的优点和缺点。(5)超高压微型撞击流技术的实验研究根据液体相溶的特性,分别选取油-水混合物、果汁、酒-三类物质,对设计的超高压微型撞击流装置的两种结构进行实验研究,确定最佳结构和适宜的运行参数,分析制备微乳液、处理苹果汁和酒类催陈的机理,提出了将动态和静态处理方式相结合来提高供给压力的新方法,总结经验,为工业化积累必要的原始资料。更多还原

【Abstract】 As support for one of the most important high-tech industries technologies, Particle refining technology is widely concerned by the academic and business interests, however, the present research on liquid particles refining in both theoretical and applied technology etc.This article is starting point, proposing a new technology, new method combining ultra-high pressure technology, micro-channel flow technology and impinging stream technology for the refinement of liquid particles.Because of characteristics of transient pressure, uniform, safe operation and low power consumption is widely used alcohol on Aging, food processing and other important fields. Micro-devices make better use of the high pressure energy because of its small size, good packing effect, high pressure; Also, because line scale is small, the gradient of some physical quantity increase rapidly, the mass transfer driving force increase, thereby possessing characteristics of good mixed quality; and still the adaptability, micro-devices can be used in conjunction with other systems. Impinging Stream technology is the adoption of two shares of the strong high-speed jet collision, so that inter-particle collisions with each other, extrusion pressure and shear force generated by grinding make liquid particles refining. Therefore, how to effectively integrate the three technical superiority, and apply to the study of grain refinement is the focus of this paper.By the theoretical analysis and study of micro-flow characteristics under ultra-high pressure micro-flow characteristics of jet impact the wall under ultra-high pressure and characteristics of the micro-jet flow to crash under ultra-high pressure, this paper further derive and prove relevant theories, realized improvement and expansion of existing theory, Combined with its theoretical research combining ultra-high pressure technology, micro-channel flow technology and impact streaming technology and design optimization of two ultra-high pressure micro-collision flow structures, and carry on experimental research in food and wine fields.(1) Flow characteristics of micro-channel under ultra-high pressureResearch on micr-channel flow properties and flow field under ultrahigh-pressure. micro-channel flow characteristics described from size effects, boundary layer effects and mass and momentum transfer detailed analysis of relationship of the side length and surface area when the square cross-section and when the corresponding circular cross-section relationship the diameter and surface area. based on the circular tube the boundary layer integral equations, derive turbulent thickness velocity boundary layer equation and velocity equation of the core area in macro-tube, thickness velocity boundary layer equation and velocity equation of the core area in micro-tube, on this basis, combination specific surface area calculation and analyze the quality of fluid transfer and momentum transfer characteristics in micro-size channel. A detailed analysis of the flow characteristics of micro-size pipe under ultra-high pressure state, establishment of an experimental model, numerical calculation, in different media, under different pressure, summary law of the velocity distribution, pressure distribution, wall shear stress distribution pattern and changing trends. Comparative analysis under the same conditions in the micro-tube and macro-size pipe flow differences, come to flow advantage of micro-size pipe.(2) Research of characteristics of the binding micro-jet impact the wall under ultra-high pressureSummary、derivation of symmetry constraints micro-jet ultra-high speed axis distribution formula and half the thickness extension formula. Make simulative analysis of ultra-high-pressure micro-jet impact on the wall with different turbulence models, identify the most suitable for micro-jet impact the wall turbulence model, Study, summarize the flow behavior and flow field of structural characteristics of the ultra-high pressure micro-jet impact the wall.(3) Research of characteristics of ultra-high pressure micro impinging streamStudied flow characteristics of ultra-high pressure micro-impinging flow (the collision), detailed numerical calculation and analysis of distribution curve of the velocity of the axial direction, radial direction velocity, dynamic pressure, static pressure, total pressure and the turbulent kinetic energy. Summed up characteristics of the ultra-high pressure micro impinging stream, reached the distribution law of the ultra-high pressure micro-impinging stream flow characteristics, and make analysis and explanation.(4) Design、optimization of ultra-high pressure micro-impact device structuresDesigned two kinds of ultra-high pressure micro-impinging device structures, presentation measure of knock-on effects based on impact velocity, Ultrahigh-pressure impinging stream, respectively optimize the size of two micro-generator structures to compare the advantages and disadvantages of the two structures.(5) Experimental study of ultra-high pressure micro-impinging stream technologyAccording to the compatibility characteristics of the liquid, respectively select the oil-water mixture, fruit juice, wine three substances, make experimental research on two kinds of designed structures, To determine the best structure and the appropriate operating parameters, make analysis of mechanism of micro-emulsion, apple juice and alcohol mechanism of Aging, put forward a new way combining dynamic and static approach to increase the supply pressure,sum up experience, in order to accumulate the necessary industrial the original data.更多还原