Spray characteristics of biodiesel: A nonlinear temporal instability analysis

Abstract

As the global demand for sustainable energy sources intensifies due to the dwindling reserves of fossil fuels, the search for alternative fuels compatible with conventional engines becomes paramount. Biofuels emerge as a promising alternative; however, their distinct thermo-physical properties necessitate a comprehensive evaluation before practical implementation. This research delves into the atomization of biofuels, a critical determinant of combustion efficiency, employing weakly non-linear instability analysis. Our investigations reveal that the reduction in viscosity and surface tension of biofuels, achieved through blending with diesel and preheating, induces destabilization of the fuel sheet, leading to enhanced disintegration. Notably, this destabilizing effect becomes more pronounced at higher air-fuel velocity ratios. Within this study, we employ a stochastic model, the Maximum entropy formalism, to predict droplet characteristics. The analysis demonstrates a shift in the droplet size distribution curve toward smaller diameters, accompanied by a narrowing of the droplet size range with increased velocity ratio and preheating temperature. Additionally, the inclusion of a higher proportion of biodiesel in the blends marginally expands the range of droplet diameters. Furthermore, this research quantifies the mass mean droplet diameter. The results indicate a reduction in mean droplet diameter with increasing velocity ratio. In-depth analysis includes a linear energy budget assessment to elucidate the influence of various forces on the instability phenomenon.