微小尺度封闭空间内火焰传播特性和动力学研究  

Flame propagation characteristics and dynamics in micro-scale confined spaces

作　　者：霍杰鹏[1,2,3,4] 赵黛青 苏航[1,2,3,4] 蒋利桥 汪小憨 HUO JiePeng;ZHAO DaiQing;SU Hang;JIANG LiQiao;WANG XiaoHan(CAS Key Laboratory of Renewable Energy,Guangzhou 510640,China;Guangzhou Institute of Energy Conversion,Chinese Academy of Sciences,Guangzhou 510640,China;Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development,Guangzhou 510640,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院可再生能源重点实验室,广州510640 [2]中国科学院广州能源研究所,广州510640 [3]广东省新能源和可再生能源研究开发与应用重点实验室,广州510640 [4]中国科学院大学,北京100049

出　　处：《中国科学：技术科学》2020年第10期1329-1338,共10页Scientia Sinica(Technologica)

基　　金：国家重点基础研究发展计划(编号:2014CB239601);国家自然科学基金(批准号:51336010)资助项目。

摘　　要：微小封闭空间内火焰传播速度是决定微型发动机输出功率及热功转换效率的一个关键因素.为了在接近真实微小型发动机状况下研究其火焰传播特性,本文针对微小燃烧室压缩终止时的点火燃烧过程,研制了一个狭缝间距在2.0~5.0 mm可调且可视的圆盘型封闭定容燃烧室,获得了火焰在狭缝中传播速度随预混气当量比和燃烧室间距的变化规律.通过构建狭缝内传播的一维非绝热动力学模型,探究了影响火焰传播的关键物理参数及作用机理.通过二维数值计算模拟了狭缝内火焰传播过程和火焰面形态,实验结果表明,火焰传播速度对间距变化高度敏感,且呈非线性.理论模型和数值计算发现壁面散热速率、燃料热释放率以及火焰面拉伸强度对封闭腔内火焰的传播起了决定性作用,并发现对不同燃料都普遍存在一个最佳狭缝间距,在这个间距下火焰传播速度最快.最佳间距的存在主要取决于火焰面拉伸强度,最佳间距大小受壁面散热和壁面剪切应力的共同影响.本研究结果可为微小型燃烧室设计和火焰传播特性研究提供数据支撑和理论基础.The flame propagation velocity in micro-scale combustion chambers is dominant in determining the output performance and energy transfer efficiency of a miniature power device.A disc-shape combustion chamber with a gap height that can be adjusted from 2.0 to 5.0 mm is developed to simulate the constant volume combustion of a micro-scale engine.The effects of equivalence ratio and the gap height on the flame front propagation velocity are determined.The physical insights of the mechanism and controlling parameters are provided by constructing a 1D non-adiabatic flame dynamics model.The 2D numerical simulation describes the flame propagation process and shows the development of flame front morphology.Experimental results indicate that the flame propagation velocity is highly sensitive and nonlinear to the gap height.The theoretical model and numerical simulations show that the heat loss rate and heat release rate due to combustion and flame stretch intensity determine the flame propagation behavior in a closed chamber.An appropriate gap height for fast propagation is deduced as a general principle.Such appropriate gap height is caused by the flame stretch intensity,and it is determined by the combined effect of heat loss and shear from the wall.This study can provide data support and theoretical basis for the design of micro-combustion chambers and for further research on flame propagation characteristics.

关 键 词：微小尺度燃烧 层流火焰 定容燃烧 壁面热损失 火焰拉伸 

分 类 号：TK16[动力工程及工程热物理—热能工程]