生物柴油雾化特性仿真模拟及实验研究

Simulation and experimental research on the atomization characteristics of waste oil biodiesel

为了研究风量对地沟油生物柴油在旋流喷嘴中雾化特性的影响规律,本文采用Fluent数值模拟与实验相结合的方法,在供给不同一二次风量的条件下,对地沟油生物柴油进行雾化过程分析。结果表明,在等温等压条件下,控制进入燃油燃烧器的总气量为定值429L/min时,不同一二次风量对油束雾滴的索特平均直径(D_(32))、雾滴速度、雾化锥角和雾化贯穿距有较大的影响。随着一次风量的增大,雾滴的破碎时间变短,D_(32)逐渐减小,速度逐渐增大;雾化贯穿距和雾化锥角呈现先增大后减小的趋势,一次风量50L/min时达到最大值;且湍动能与一次风量大小成正比关系。风量对D_(32)影响存在一定限度,当一次风量达到30L/min时,D_(32)基本趋于稳定。对不同粒径的雾化液滴数量统计分析,得到了生物柴油的不同粒径数量密度分布及拟合经验公式,颗粒直径主要集中在25~75μm之间。

The influence of air volume on the atomization characteristics of waste oil biodiesel in swirl nozzles was studied using a combination of Fluent numerical simulation and experiment.The impact of primary and secondary air volumes on the atomization process of waste oil biodiesel was analyzed.The results show that when the total air volume in the oil burner is set to 429L/min under isothermal and isostatic conditions,the primary and secondary air volumes have a greater impact on the Sauter average diameter(D_(32)),droplet velocity,atomization cone angle and atomization penetration distance of the oil spray droplets.Specifically,with the increase of the primary air volume,the breaking time of the droplets becomes shorter,D_(32) gradually decreases,and the speed gradually increases.While atomization penetration distance and the atomization cone angle firstly increase and then decrease,the maximum values are attained with the primary air volume of 50L/min.Meanwhile,the turbulent kinetic energy is proportional to the primary air volume.However,the D_(32) basically tends to be stable when the primary air volume reaches 30L/min.As for the statistical analysis of the number of atomized droplets of different particle diameters,the distribution of quantity density of different particle diameters of biodiesel and the fitting empirical formula are obtained.The particle diameters are mainly concentrated between 25—75μm.