高温高压环境下RP-3航空煤油单液滴的加热与蒸发特性研究OA

RP-3 aviation kerosene is a commercial jet fuel commonly employed in China.The evaporation of aviation kerosene droplets in the aeroengine combustion chamber directly affects the fuel atomization performance,the formation of air-fuel mixture,and combustion quality.To accurately predict the heating and vaporization characteristics of single RP-3 kerosene droplet,the blend of n-dodecane,2,5-dimethylhexane and toluene was selected as the surrogate fuel.And a multi-component droplet evaporation model considering the natural convection effect at elevated temperature and pressure was proposed in the present study.Based on the self-developed experimental apparatus,the temporal variations of the RP-3 kerosene droplet diameter were obtained for an ambient pressure of 1MPa at ambient temperatures of 473K to 673K.The accuracy of the model was validated by the comparison between the simulation results and experimental results.The predictions of the parameters including diameter,internal temperature distribution,component mass fraction distribution and lifetime of three-component surrogate fuel by the new-proposed model were used to quantitatively analyze the effect of ambient pressure on the evaporation characteristics of individual droplet under various ambient temperatures.The results indicated that the heat and mass transfer inside the liquid phase can affect the evaporation rate of multi-component droplets,and the liquid diffusion resistance leads to the heterogeneity of the distribution of internal temperature and component mass fraction inside the liquid phase.The impact of environmental pressure on the RP-3 kerosene droplet lifetime strongly depends on environmental temperature.When the ambient temperature is below the critical temperature of n-dodecane(658.25K),the relationship between droplet lifetime and ambient pressure is not monotonic,but first increases and then decreases with the increase of ambient pressure.When the ambient temperature exceeds 658.25K,the droplet lifetime monotonically decreases as ambient pressure increases.This can be attributed to the fact that in high temperature and pressure environment,the increase of ambient pressure can significantly increase the heat and mass transfer intensity of natural convection.When natural convection exceeds a certain intensity,it can obviously promote droplet evaporation.The study above is conducive to underseand the diffusion process of the internal for the optimized design of future high-performance low-pollution engines from the source.