Dr. Junji Shinjo
Associate professor, Department of Mechanical, Electrical and Electronic Engineering, Shimane University, Japan.

Speech title: Detailed Numerical Study on Behavior of Blended Biofuel Droplets with Heating, Puffing, Mixing and Combustion

Abstract: The characteristics of blended biofuels, such as heating, puffing mixing and combustion, are investigated in detail by using direct numerical simulation (DNS). The physical properties of blended fuels are different and for the bioethanol/diesel/biodiesel mixture considered here, puffing/microexplosion may happen, which can be positively utilized if properly designed. These small scale phenomena strongly affect the overall fuel spray characteristics and special attention is paid here. First, the detailed physical dynamics of explosive boiling and puffing has been revealed. Droplet heating under convective flow has been also elucidated where the internal circulation plays an important role in determining the inner-droplet temperature distribution, which is important to determine the nucleation locations. Next, the mixing of air, main fuel and ejected vapor has been investigated using the scalar dissipation rates (SDRs) and their evolution. Finally, the combustion characteristics have been investigated. Flame/vapor interactions can be also characterized by the SDRs and droplet grouping may be transiently changed due to puffing. These detailed findings can be utilized for designing and modeling biofuel sprays for practical applications.