【作者】 张峰；

【导师】 刘伟强；

【作者基本信息】 国防科学技术大学 ， 航空宇航科学与技术， 2008， 博士

【摘要】 层板发汗冷却概念提出后的四十多年以来,已有数百种层板装置问世。层板装置是指将若干蚀刻有流动通道的金属或非金属薄片按预定的结构形式叠放,借助扩散焊或其他成型工艺,形成的一种装置。层板技术具有热防护能力强、精确分流、设计和制作灵活、便于自动化生产等优势,目前随着激光光刻技术、尤其是随着抗腐蚀的金属层板蚀刻与扩散焊技术的发展而呈现出了极大的活力。在典型层板发汗冷却装置应用于液体火箭发动机推力室热防护研究工作的带动下,层板技术应用于流体流动控制和燃料发汗喷注等方面的研究也在迅速发展。如在整个层板式流体混合器的内壁上通过相邻的层板微小缝隙,将不同的流体以交替形式实施交错分层发汗喷注,利用层板的控制流道来控制各部位的发汗喷注流强,使得各缝隙层的不同流体交错排列吹出,实现小容腔混合均匀,并可根据需要实现所期望的混合温度和压强。近二十年来,层板技术的理论研究也有一些进展,这些研究工作基本上都是围绕同一种流动介质的层板发汗冷却而开展,对不同的流体的层板交错发汗混合、发汗喷注暂未涉足,这方面的研究工作迫切需要着手开展,因此,本文对层板发汗冷却理论进行了深入研究,针对层板交错发汗孔隙与缝隙结构进行了初步的探讨,并开展了层板微小缝隙交错分层发汗喷注装置的应用研究。本文主要开展了以下几个方面的研究工作:(1)对典型层板发汗冷却技术及相关理论、国内外层板装置研究进展和层板制作经验进行了总结。回顾了国内外对层板发汗冷却技术的研究工作,对层板发汗冷却等典型层板装置以及层板式混合器、高速船推进装置等国内外新型层板装置进行了介绍,并对层板装置的制作工艺进行了简述。(2)对典型层板发汗冷却结构壁内流道流动与传热特性的研究。基于高温宏观尺度理论,建立了典型层板发汗冷却散布流道的高温传热模型,研究了求解结构层板温度和散布流道发汗介质温度的解析方法,得出了层板材料的导热系数、冷却剂参数、壁面热流流强、散布流道几何参数与结构层板温度以及热浸深度之间的关系;给出了壁内层板控制流道一般设计方法,探讨了控制流道以及主通道等流道的流阻特性。(3)基于微观尺度理论数值分析了散布流道的传热特性。以不可压缩流体或可压缩流体的N-S方程及能量方程为基础,采用考虑与近壁面流体速度梯度相关的滑移边界条件,以及与近壁面流体温度梯度相关的温度跳跃边界条件进行流动与传热计算,建立了微尺度计算模型,得到了结构层板与微小通道内的温度分布趋势,并与基于宏观尺度理论得到的分析结论进行了对比。(4)对层板交错孔隙珠状发汗的蒸发与燃烧速率进行了分析。应用双球坐标系解析计算了层板孔隙发汗结构出口处珠状发汗介质的蒸发、燃烧问题,探讨了在层板发汗孔隙密集结构中,发汗液珠的蒸发、燃烧速率与发汗孔隙相邻距离、孔隙大小以及环境温度、发汗介质的物性等之间的关系,得到两个相互作用的任意大小发汗液珠的分子扩散组分分布解析解,计算了发汗液珠在不同条件下的蒸发和燃烧速率变化规律。(5)研究了层板交错分层发汗缝隙结构中的发汗介质流动和燃烧特性,为指导相关的混合器和燃烧装置方面的设计工作提供理论基础和设计参考。为探讨层板微缝交错发汗喷注混合和燃烧机理,选用不同种流体作为发汗介质,经过层板微缝交错发汗喷注结构后进行混合或燃烧,建立了流体混合或燃烧的层板交错发汗缝隙结构的计算模型,得到了层板交错发汗缝隙结构内发汗流体的流动、组分分布、温度分布、表面的火焰特性、壁面热流流强等特征。(6)对典型层板发汗冷却的结构层板进行热力耦合特性研究及试验验证。针对结构层板的热皱损问题,对层板温度、板厚、缝隙宽度与挠曲临界压应力的关系做出了计算分析。采用伽辽金法通过一个严格满足几何边界条件和静力边界条件的屈曲试函数得到了散布流动区层板非均匀受热皱损的解析解;采用有限元法对不同厚度层板的受热变形及小扰动作用下的稳定性、对不同散布流道的高度以及不同夹筋条宽度条件下的层板受热变形等进行了分析;通过由薄膜加热片、V型槽夹具等构成的热皱损试验验证系统对层板热皱损静力分析方法进行了验证。(7)进行了层板发汗冷却分析方法的应用探讨。针对层板发汗冷却装置由许多相同或相似结构组成的特殊性,采用层板发汗冷却单元参数变量化的方法进行自动化设计;基于层板发汗冷却技术,将层板交错孔隙珠状发汗特性分析以及层板分层交错发汗缝隙结构分析等在流体混合机理研究以及交错发汗喷注燃烧研究中进行了应用,对层板式交错发汗混合与燃烧装置的研究提供了设计依据与理论支撑。更多还原

【Abstract】 In the forty years after the concept of platelet transpiration cooling has been introduced, hundreds of platelet devices were invented and adapted. Platelet devices are fabricated by stacking several metallic or non-metallic thin sheets, which are etched with flow passages, into predetermined configuration along with the means of diffusion welding or other molding techniques. The platelet technology has the advantages of high capability of thermal controlling, accurate distributaries, flexible design and fabrication, and convenient for automation in production. And today, it presents extreme vitality because of the development of laser etching, in particular, etching to the corrosion-proofed metal platelet, and technique of diffusion welding. Along with the progress of the thermal protection research of liquid rocket engine chamber, with the adoption of typical platelet diffusion transpiration cooling device, the researches of platelet technology used for fluid flow controlling and fuel transpiration injection are improved further. Take a platelet-style fluid mixer as an example, various fluids flow in from adjacent minute slots of platelet structural wall in turn to realize cross-bedded transpiration injection, metering passages are used to control the flux of those fluids to ensure the process of cross-bedded inflow fluids, then even mixture mixes in small chamber which desired temperature and pressure are is achievable. In the recent two decades, the studies of platelet technology are advanced, however, they are focusing on one fluid mediator only to research the platelet transpiration cooling. Therefore, the researches of platelet cross-bedded transpiration mixing and transpiration injection about different fluids are hardly to be taken and they are waiting to be developed in desperation. Hence, this dissertation takes profound research of the theory of the platelet transpiration cooling, discusses elementarily on the configuration of gaps or slots in the cross-bedded platelet transpiration injection and makes applied research on the minute slots cross-bedded transpiration injection devices.Furthermore, the treatise includes some main researches as follows.1. Summary of the technique and relevant theories of typical platelet transpiration cooling, progress of domestic and foreign research of platelet devices and the experiences of fabricating platelets. It reviews domestic and foreign researches on platelet transpiration cooling technique, introduces late-model platelet devices in our motherland and overseas, such as typical platelet transpiration cooling devices, platelet style mixture and high speed propulsions, and also briefly describes craftwork of platelet devices.2. Study on the thermal transferring feature and fluid flow in passages on inner wall of typical platelet transpiration cooling devices. On the basis of macro-scale theory and the establishment of high temperature thermal transferring model in a typical transpiration cooling device with distributed passages, there are some researches have been done, such as figuring out resolutions to obtain and analyze the temperature of structural platelet and injecting fluid from distributed passages; finding out the relationship among coefficient of thermal conductivity, perimeter of coolant, flux of thermal flow of inner walls, geometric perimeter of distributed passages, structural platelet temperature and depth of hot dip; showing up some designing methods of platelet metering passages and discussing flow resistance character of passages just as metering passages and main passages.3. Analyzing thermal transferring character of distributed passages according to micro-scale theory. Along with the N-S equation and energy equation, micro-scale calculating model for flow and thermal transferring is set up with adoption of shifting edge condition relevant to the speed gradient of close-to-wall fluid and temperature varying edge condition relevant to the temperature gradient of close-to-wall fluid. Under all these, temperature distributing momentum in structural platelets and minute passages are measurable. On the other hand, the same issues are also taking under macro-scale theory, and comparing the outcomes with the ones from prior analysis.4. Taking analysis on the evaporation and combustion rate of hemispherical droplet of cross-bedded platelet transpiration. By utilizing the bispherical coordinates, the evaporation and combustion questions of hemispherical mediators in the outlet of a hole structure platelet transpiration are solved; the relationships among the evaporation and combustion rate of a hemispherical transpiration in a intensive hole structure platelet and the distance of adjacent holes, size of holes, environmental temperature and transpiration mediators are discussed, analytic solution of molecular diffusion of arbitrary hemispherical droplet are obtained, and the evaporation ratio, combustion rate and change momentum of hemispherical droplet transpiration are accounted under various conditions.5. Doing the study of the character of transpiration mediator flow and combustion in cross-bedded platelet transpiration slot structure, and providing theoretic base and design sample for conducting design of relevant mixture and combustion devices. For discussing the mixing and combustion of cross-bedded minute slot platelet transpiration injection, different fluids are chosen, as transpiration fluids, going through the cross-bedded minute slot platelet transpiration injection device to complete thorough mixing and combustion. With the help of setting up a typical cross-bedded minute slot platelet transpiration model, analysis of fluid mixture and combustion are obtainable, as well as the distribution of transpiration fluid constituents, distribution of temperature and fluid flux of inner wall in such a device.6. Thermodynamic coupling researches are carrying on towards sheets in distribution passages of platelet transpiration cooling. As for the thermal wrinkling issues of platelets, the relationships between each of three figures, which are temperature of platelets, thickness of sheets, and width of minute slots, are comparing with the deflexed critical compressive stresses. Analytic solution of unevenly thermal wrinkling issues of platelets in distributed flowing region is gained by using Galerkin method and bulking trial function, which satisfies the need of geometric boundary condition and static boundary condition rigorously. Analysis of the distortion and the stability under minor disturbing forces of be-heated platelets in various thicknesses; the height of different distributing passages; and be-heated platelet distortion under the condition of many diverse widths of rip strips are obtained by the use of finite-element method. The static analyzing method of platelet thermal wrinkling is testified through platelet thermal wrinkling experimental verification system, which is composed of heating-up membranes and clamp apparatus with V-shape vessels.7. Progressing discussion on application of analytic methods of platelet transpiration cooling. With the consideration of the special composition of many identical and similar structures of the construction of the platelet transpiration cooling device, automatic designing researches with perimeter variation methods are taking on platelet transpiration cooling units. Basing on the theory of platelet transpiration cooling, the analysis of cross-bedded platelet hemispherical droplets transpiration and of fluid mixture flow and combustion of cross-bedded platelet transpiration with minute slot structure are used in the studies of fluid mixing mechanism and cross-bedded transpiration injection combustion. And then, design considerations and theory foundations are obtained for the research on the cross-bedded minute slot platelet mixing and combustion devices.更多还原