不同进气速率下的液体火燃烧特性研究

Research on Combustion Characteristics of Liquid Fire at Different Intake Rates

为研究不同进气速率下可燃物燃烧特性,通过变压力变氧浓度试验舱模拟超低压条件下不同进气速率环境,选取乙醇作为燃料,采用不同尺寸的油盆以及不同质量的燃料做对比试验。试验测量了油盆轴向温度、火焰温度、热辐射通量和燃料失重速率。试验结果表明:对于相同尺寸的油盆和相同质量的燃料,燃烧速率随着进气速率的增加而变大,同时进气速率变化越大燃烧速率变化越明显;在进气过程中轴向距离油盆较近的一段距离内火焰温度呈现“凸状”,小尺寸的油盆火在进气过程的末段火焰温度会发生较大波动,并且随着进气速率的增大,波动也更加剧烈;火焰温度与压强满足ln T~KP的关系式;恒定进气速率下,较高进气速率时的辐射率小于较低进气速率时的辐射率,同时较低进气速率下的碳颗粒体积分数大于较高进气速率下的碳颗粒体积分数。

In order to study the combustion characteristics of combustibles under different air intake rates,the experimental chamber of variable pressure and oxygen concentration was used to simulate the environment of different air intake rates under ultra-low pressure.Ethanol was selected as fuel,and different sizes of oil basins and different masses of fuel were used for comparative experiments.The combustion and flue gas parameters such as temperature above the oil basin,flame temperature,heat radiation flux,and fuel weight loss were measured experimentally.The results show that:for the same size of oil basin and the same mass of fuel,the combustion rate increases with the increase of the intake rate,and the greater the change of the intake rate,the more obvious the change of the combustion rate.During the intake process,the flame temperature in the axial distance from the oil basin is“convex”,and the flame temperature of the small size of the oil basin fire will fluctuate greatly at the end of the intake process,and with the increase of the intake rate,the fluctuation is more severe.The relationship between flame temperature and pressure satisfies ln T~KP.Under the same intake velocity,the emissivity at higher intake velocity is smaller than that at lower intake velocity;at the same time,the volume fraction of carbon particles at lower air intake rate is larger than that at higher air intake rate.