Abstract:

To investigate the flame spread behavior and combustion characteristics of opposed n-butanol spilling fires under various leakage conditions, experiments was conducted using a 100 cm × 20 cm × 8 cm stainless steel channel platform, with leakage rates (9-650 mL/min) precisely controlled by a peristaltic pump. A high-frame-rate camera was employed to record the flame spread dynamics, while mass loss rates and temperature field evolution were synchronously collected using a balance, thermocouples, and a data acquisition system. The results show that as the leakage rate increases from 40 to 120 mL/min, fuel layer thickening reduces heat losses via substrate conduction and radiation transmission, leading to heat accumulation that accelerates the flame spread rate. As the leakage rate further increases to 560 mL/min, the high-speed fuel flow induces a strong forced convective cooling effect that offsets the thermal insulation effect of the fuel layer, resulting in a significant decrease in the spread rate. The burning rate per unit area exhibits four-stage evolution characteristics under low (60 mL/min), medium (120-160 mL/min), and high (290-650 mL/min) leakage rates. A calculation formula for the mass loss rate per unit area in the steady-state combustion phase, constructed based on energy conservation, yields calculation values within a relative error of ±28% compared with experimental data. With further increases in the leakage rate, the proportion of forced convective heat loss in the total energy balance increases from 28% to 57%.

Key words: n-butanol, opposed spilling fire, spreading behavior, quasi-steady burning characteristics, leakage rate, mass loss rate