燃油喷雾撞击高温壁面的形态特征研究  

Research on Morphology Characteristics of Fuel Spray Impingement under High Temperature Wall Surface

作　　者：颜杰 张卫正[1] 殷勇 何旭[1] 苏帅 靳爽 许锴 YAN Jie;ZHANG Weizheng;YIN Yong;HE Xu;SU Shuai;JIN Shuang;XU Kai(School of Mechanical Engineering,Beijing Institute of Technology,Beijing 100081,China;Dongfeng Commercial Vehicle Company,Limited,Wuhan,Hubei 430056,China;China Academy of Aerospace Aerodynamics,Beijing 100074,China)

机构地区：[1]北京理工大学机械车辆学院,北京100081 [2]东风商用车有限公司,湖北武汉430056 [3]中国航天空气动力技术研究院,北京100074

出　　处：《北京理工大学学报》2023年第7期702-711,共10页Transactions of Beijing Institute of Technology

基　　金：国家自然科学基金资助项目(51976012)。

摘　　要：内燃机的高强化发展导致壁面温度上升,燃油撞壁现象难以避免.燃油喷雾撞击高温壁面对混合气形成有重大作用,进而影响燃烧过程和碳烟排放.文中利用背光法在流动式定容燃烧弹上对柴油喷雾撞击高温壁面的形态特征进行试验研究,分析了喷油压力、背景压力和壁面温度对近壁面喷雾形态特征的影响.结果表明:喷油压力越大,壁面漩涡出现时刻越早,且对铺展半径和卷吸高度的增大起明显的促进作用.背景压力越大,撞壁时刻延迟,铺展半径和卷吸高度下降,背压对铺展半径的影响超过对卷吸高度的影响.壁面温度越高,漩涡出现时刻越早,撞壁油束的铺展半径和卷吸高度越大,但当壁温达到莱顿弗罗斯特温度时,壁面传热模式改变,铺展半径和卷吸高度发生突降.针对所引入的综合影响系数,研究表明喷油压力的变化对卷吸高度的综合影响系数最大,最后文中基于研究规律拟合了结合壁面温度的铺展半径和卷吸高度的经验公式.The high reinforcement of internal combustion engine leads to the rise of wall temperature,and fuel spray impingement is inevitable.The impact of fuel spray on high temperature wall has an important effect on the formation of mixture,and then affects the combustion process and soot emission.In this paper,the morphological characteristics of diesel spray impinging on high temperature wall surface were studied by backlight method on flow constant volume vessel.The influences of injection pressure,background pressure and wall temperature on the spray characteristics of near wall surface were analyzed.The results show that:The higher the injection pressure is,the earlier the wall-jet vortex appears.Moreover,it has obvious promoting effect on the increase of spreading radius and entrainment height.Increasing background pressure leads to delay of spray impingement time.Both the spread radius and the entrainment height are decreasing.The influence of back pressure on the spread radius is greater than that on the entrainment height.The hotter the wall temperature,the earlier the wall-jet vortex appears.The spread radius and entrainment height of fuel spray impingement increase.But when the wall temperature reaches Leidenfrost temperature,wall heat transfer mode changes.The spread radius and entrainment height decrease suddenly.According to the concept of contribution index introduced,the research shows that the change of injection pressure has the largest contribution index to entrainment height.The empiric-al formulae of spreading radius and entrainment height under the wall temperature are fitted based on the re-search law.

关 键 词：柴油机 喷雾撞壁 背光法 壁面温度 壁面漩涡 莱顿弗罗斯特效应 流动式定容燃烧弹 

分 类 号：TK421[动力工程及工程热物理—动力机械及工程]