Investigation of bicubic flame radiation model of continuously opposed spilling fire over n-butanol fuel

In a real fire accident, the spilling fire probably spreads against the moving direction of liquid flow. The continuously opposed spilling fire experiments were performed under various inclined angles and discharge flow rates of n-butanol. The combustion stage, flame height, flame length and temperature distribution of subsurface flow, and radiant heat flux were examined and analyzed. The behavioral difference involving spill fire spreading is characterized and the fire development undergoes four stages: maintaining – rapidly increasing – quasi-stationary state – rapidly increasing, according to the variation of burning area. The preheating time and the length of subsurface flow is promoted by the flow rate and the steep slope of spilling trench. A bicubic flame model is proposed to quantify the radiation heat flow of opposed spilling fire, and the theoretical values are in acceptable agreement with measurements. The double integral method is established to calculate the incident heat flow from the pioneering flame to the preheating area. The incident radiant heat flow increases nearly linearly with flow rate, and it is extremely large at angle of inclination of θ = 4° owing to the great radiation receiving area and the large flame height. •Unsteady combustion behavior of opposed spilling fire is examined.•A bicubic flame model is proposed to calculate the radiation of spilling fire.•Double integral method is calculated incident heat flux at subsurface flow area.•Radiant heat received by subsurface flow rises linearly with flow rate.