Study on the effects of ethanol and methanol blending on the explosion characteristics and flame propagation behavior of gasoline vapor

With the widespread application of alcohol additives as clean alternative fuels in gasoline, their potential combustion and explosion safety issues have attracted increasing attention. In this study, a closed-vessel experimental system was used to evaluate the explosion overpressure ( P max ), flame propagation speed, flame temperature, and product composition of ethanol/methanol-blended gasoline vapors, thereby revealing the influence of alcohol addition on the combustion and explosion behavior of gasoline vapor. The results show that both ethanol and methanol blending broaden the flammable concentration range of gasoline and significantly enhance the combustion and explosion intensity. When blended with 10% ethanol, P max reached 0.760 MPa, representing a 15% increase compared with pure gasoline; when blended with 15% methanol, P max reached 0.789 MPa, corresponding to an increase of 18.6%. The ethanol-gasoline blended fuel exhibited higher flame propagation speed, pressure rise rate, and peak flame temperature than the methanol-gasoline blended fuel, indicating stronger combustion and explosion reactivity. Alcohol blending also affects the post-explosion CO/CO 2 product distribution. When blended with 15% ethanol, the CO volume fraction decreased by 30%, while CO 2 increased by 7%. The analysis indicates that ethanol blending leads to a higher flame temperature and a longer combustion duration, thereby promoting the late-stage oxidation of CO. In contrast, although methanol has higher radical activity and oxygen content, which promote flame propagation and broaden the flammable range, its lower unit heat release and higher product heat capacity result in relatively limited flame temperature and complete oxidation degree. The differences between the two blended systems mainly originate from the combined effects of alcohol molecular structure, combustion heat release, and radical chain reaction activity. This study systematically reveals the influence of ethanol and methanol blending on the combustion and explosion characteristics of gasoline vapor and their underlying mechanisms. In confined or semi-confined leakage scenarios, the flammable range, flame propagation, and explosion intensity should be comprehensively evaluated. The results provide a theoretical basis and experimental support for the fire and explosion hazard assessment, safe storage and transportation, and accident prevention and control of clean alternative fuels.