Experimental and numerical investigation on spray characteristics of biodiesel/methanol blends in a constant volume chamber

The addition of methanol holds significant potential for enhancing the spray atomization of biodiesel, particularly at high altitudes. The aim of this work is to use experiments and CFD methods to study the effects of methanol addition to biodiesel in different ratios (0 %, 10 %, and 20 % in volume) on the spray characteristics, and compare the differences of those spray and evaporation characteristics under diesel working conditions between various altitudes. The experimental results show that biodiesel/methanol blends have shorter spray tip penetration and larger cone angle compared to biodiesel under non-vaporizing conditions. However, the impact of methanol on the spray characteristics decreases with increased injection pressure. Simulation results show that, at high altitudes, biodiesel/methanol blends have shorter liquid penetration but little change in gas penetration than biodiesel. Sauter mean diameter (SMD) decreases with increasing methanol ratio, furthermore, this trend becomes more pronounced at higher altitudes. The evaporation rate of blends increases with the rise in the methanol ratio; nevertheless, this promotional effect diminishes with increasing altitude.