Microexplosion in burning emulsified fuel droplets

Abstract

This paper presents an analytical model for simulating microexplosions in burning emulsified fuel droplets. A key feature of the proposed model is its ability to capture bubble growth within a droplet, which triggers microexplosions, while also incorporating the effects of droplet combustion. The model offers a comprehensive formulation for a single bubble inside a burning droplet, accounting for bubble dynamics, heat transfer, phase change, and combustion processes. The methodology outlining the mathematical framework, governing equations, and underlying assumptions are presented. The model is applied specifically to n-dodecane/water emulsion droplets, and the results are analyzed in detail and validated against experimental data from previous studies. The evolution of the bubble radius reveals two distinct growth stages: an initial thermally controlled phase followed by an inertially controlled phase. Droplet growth also proceeds in two stages—initially independent of bubble growth, and later becoming interdependent. Notably, the microexplosion delay time decreases gradually with increasing initial bubble radius but increases sharply with a larger initial droplet radius. The developed analytical model has the potential for simulating spray combustion of water-emulsified fuels with significantly reduced computational cost while maintaining sufficient fidelity.