Numerical investigation of the occurrence of micro-explosion for multi-components blended fuel droplets

As the potential alternative substitutes of petroleum fuels, biofuels have received much attention because they are clean, renewable, and can possibly reduce domestic demand on foreign petroleum. Bio-fuels are generally mixed with petroleum-based diesel or gasoline in the commercial market. Since the volatilities and boiling points of ethanol/butanol and diesel/biodiesel fuels are significantly different, microexplosion can be expected in the blend mixture. Understanding the atomization process and dynamics of secondary droplets in bio-fuel and diesel blends due to micro-explosion is helpful in optimizing bio-fuel engine performances. In this study, a numerical model of micro-explosion in multi-component biofuel droplets is proposed to study the bubble generation, droplet growth and final breakup processes. Based on the simulated results of droplet characteristics at the onset of micro-explosion, together with the predictions from the breakup model, a simple way of estimating the Sauter mean radius (SMR) of the secondary droplets is proposed and verified against limited available experimental data. It is concluded that microexplosion is possible in bio-fuel and diesel blends under engine operation conditions, and it can be enhanced by optimizing the ambient conditions.