高海拔模拟环境下喷雾撞壁的燃烧和传热特性研究  

An Investigation on Combustion and Heat Transfer Characteristics of Spray Wall Impingement Under High-Altitude Simulation Conditions

作　　者：刘昌文[1] 朱宸震 潘洁 李卫 卫海桥[1] 潘家营[1] Liu Changwen;Zhu Chenzhen;Pan Jie;Li Wei;Wei Haiqiao;Pan Jiaying(State Key Laboratory of Engines,Tianjin University,Tianjin 300072,China;Weichai Power Co.,Ltd.,Weifang 261041,China)

机构地区：[1]天津大学先进内燃动力全国重点实验室,天津300072 [2]潍柴动力股份有限公司,潍坊261041

出　　处：《天津大学学报（自然科学与工程技术版）》2023年第12期1288-1294,共7页Journal of Tianjin University：Science and Technology

基　　金：国家自然科学基金资助项目(52076149)。

摘　　要：高海拔下低温低压的极端工作环境容易导致发动机燃烧室出现严重的液相喷雾撞壁现象,造成附壁燃烧和池火,是引起活塞或燃烧室壁面烧蚀的重要原因之一.然而,目前关于高海拔环境下发动机喷雾撞壁、附壁燃烧及壁面传热的详细机理尚不完全清楚.本文基于定容燃烧弹模型结合多维数值模拟方法,开展了高海拔模拟环境下喷雾撞壁的燃烧及壁面传热特性研究.结果表明:缸内背景压力通过影响喷雾贯穿能力对喷雾液相撞壁起到主导作用,而背景温度则主要通过影响燃油蒸发速率对油膜演化起显著作用;附壁油膜的质量和蒸发速率对池火燃烧特性具有很大影响,高温高压条件下附壁油膜质量小、蒸发速率快,使得池火出现时间更早、峰值强度最大且持续时间最短;低温低压条件下油膜质量最大且蒸发速率最慢,使得池火出现时间更晚、峰值强度最小且燃烧持续时间最长;而高温低压和低温高压条件下池火的出现时间、峰值强度和持续时间则居于中间;此外,附壁油膜和近壁池火会显著增强定容弹流场对壁面传热的影响作用,附壁燃烧使得壁面长时间处于高热流密度和高温的状态,而油膜分布和蒸发速率的差异会导致池火区壁面热流密度和温度分布不均,且变化剧烈波动,由此引发的热疲劳可能是壁面烧蚀的重要原因.The extreme operating conditions of low temperature and low pressure at high altitudes can easily trigger a serious spray wall impingement in an engine combustion chamber,causing wall-attached combustion and pool fires,which are some of the important causes of ablation damage to the piston and combustion chamber wall.However,the mechanism of spray wall impingement,wall-attached combustion,and wall heat transfer at high altitudes is not completely understood.In this study,the characteristics of spray wall impingement,wall-attached combustion,and wall heat transfer under high-altitude simulation conditions were investigated based on a constantvolume bomb combined with the multidimensional numerical simulation method.The results indicated that background pressure plays a dominant role in liquid spray wall impingement by affecting the spray penetration ability,and background temperature plays a significant role in the evolution of fuel film by affecting fuel evaporation.The mass and evaporation rate of the fuel film considerably affect the combustion characteristics of the pool fire.The mass of the fuel film is small,and the evaporation rate of the fuel film is increased under high temperature and high pressure,resulting in pool fires with early appearance time,highest peak intensity,and shortest duration.The mass of the fuel film is the largest and the evaporation rate of the fuel film is the slowest under low temperature and low pressure conditions,which makes the pool fire appear late,with the smallest peak intensity and the longest duration.The appearance time,peak intensity,and combustion duration of pool fires at high temperature and low pressure and at low temperature and high pressure are between those under the two conditions aforementioned.Moreover,the fuel film and pool fire significantly enhance the heat transfer from the flow field to the wall in the constant-volume bomb.The flame on the wall keeps the wall surface in a state of high heat flux density and high temperature for a long duration.The heat flu

关 键 词：定容弹 喷雾撞壁 油膜 池火 背景工况 

分 类 号：TK401[动力工程及工程热物理—动力机械及工程]