DME/柴油混合燃料闪急沸腾喷雾特性的试验与数值模拟  

Experimental and Numerical Study on Flash Boiling Spray Characteristics of DME/Diesel Blends

作　　者：余敬周[1] 张煜盛 姜光军[1] 邱奎[1] 肖干[1] 

机构地区：[1]华中科技大学能源与动力工程学院,湖北武汉430074

出　　处：《内燃机学报》2010年第4期324-330,共7页Transactions of Csice

基　　金：国家重点基础研究发展规划资助项目(2007CB210001);国家自然科学基金资助项目(50676036;20777023);高等学校博士学科点专项科研基金资助项目(20060487043)

摘　　要：应用激光粒度测试仪研究了二甲醚(DME)/柴油混合燃料的稳态喷雾特性,探讨了不同轴向位置处索特平均直径(SMD)的分布规律,分析了混合燃料中液相DME含量对SMD分布的影响。利用Rosin-Rammler双参数分布函数研究了各种尺寸液滴的分布范围及所占比重;采用高性能数码相机记录并讨论了各种燃料的稳态喷雾形态及其影响因素。同时,应用KIVA-3V2计算软件对混合燃料稳态喷雾的雾化特性进行了多维数值模拟研究,计算结果与实测数据基本吻合。结果表明:各种燃料喷雾SMD的轴向分布在喷孔附近变化较快,随着轴向距离的增加,其变化趋缓;喷雾特性与燃油的物理性质紧密相关,当柴油中掺混液相DME时,燃油黏度及表面张力的降低以及DME的闪急沸腾微爆效应对燃油雾化影响较大。与纯柴油相比,DME/柴油混合燃料喷雾锥角以及喷雾体宽度有较大幅度的增加,SMD明显减小,群平均直径小的油滴占的比例显著增大,且这一变化趋势随DME含量的增大而加剧。Spray atomization characteristics of DME/diesel blends in a diesel engine were investigated and compared with those of diesel fuel. Sauter mean diameter （SMD） was measured by Laser Size Analyzer （LSA）. Effects of axis distance and fraction of DME on SMD were analyzed and discussed. Spray patterns of these fuels were captured using a high performance digital camera. The experimental results were compared with the numerical results using KIVA-3V2 code. Experimental results agree with the numerical ones. The study reveals that the droplet SMD reduces remarkably near nozzle and fuel spray break-up characteristics depend on fuel properties. When diesel blends with DME, spray atomization improves greatly due to the decreased viscosity and DME flash boiling behavior. Spray cone angle increases and SMD distribution moves to small size compared with diesel fuel. These tendencies become more obviously with the increase of DME fraction in DME/diesel blends.

关 键 词：柴油 二甲醚 混合燃料 闪急沸腾 喷雾特性 数值模拟 

分 类 号：TK421.43[动力工程及工程热物理—动力机械及工程]