基于大涡模拟的油滴群燃烧特性研究

Studies on group combustion characteristics of liquid droplets based on large eddy simulation

利用Matlab随机生成不同尺寸、位置信息的油滴群,采用一步总包反应机理对其进行大涡模拟,分析了不同来流速度、环境温度工况下不同颗粒数密度油滴群的燃烧特性及燃烧模态,统计出油滴的平均阻力特性、蒸发率以及气体湍流变动。研究表明:油滴群平均阻力系数随来流速度的增加呈现先减小后增大最后趋于稳定的趋势,约为单燃烧油滴的阻力系数的1/2,随环境温度的升高而增大,与来流速度成反比;气相湍流变动随环境温度增大而加剧,随颗粒数密度增加而减小;在油滴群燃烧特性下,蒸发率随环境温度的升高而增大,随数密度的增加而减小,随来流速度的增加而增大。

Liquid droplets group with different sizes and positions were randomly generated by Matlab,and large eddy simulation was carried out using one-step global reaction mechanism.Combustion characteristics and modes o£liquid droplets group with different particle number density at different flow rates and ambient temperatures were analyzed.The average drag characteristics,evaporation rate and gas turbulence variation of liquid droplets group were calculated・Numerical results suggest that the mean drag coefficient decreases firstly,then rise and tends to be stable finally with the increase of the flow velocity which accounts for 1/2 of a single burning liquid droplet.It increases with the increase of ambient temperature,but is inversely proportional to the velocity of incoming flow.The gas phase turbulence modification by liquid droplets intensifies with the increase of ambient temperature and decreases with the increase of the density of the droplets.Under the liquid droplets group combustion,the evaporation rate increases with the increase of ambient temperature,decreases with the increase of particle-number density,and increases with the increase of inflow velocity.