Influence of longitudinal wind and sidewall restriction on burning rates and thermal feedback of pool fires in a tunnel

This paper presents an experimental study on the burning rates and thermal feedback of pool fires under wind effects and sidewall restrictions in a tunnel. A series of pool fire tests were performed with varying wind speeds. Two fire locations involving centerline fire and sidewall fire were designed considering the different restriction boundaries. The results indicate that the burning rates of the two fire locations both increase rapidly and then decrease sharply with wind speed, and finally increase slowly. For lower wind speeds, the burning rates of sidewall fires are slightly higher than those of centerline fires, but the trend reverses for larger wind speeds. These variations of the burning rates are mainly attributed to the evolution of the thermal feedback to the fuel. Combined with the measurement and calculation of thermal feedback, it was found that the radiative thermal feedback plays an important role in the variations of burning rates for lower wind speeds. In comparison, the conductive thermal feedback becomes dominant in the variations of burning rates for larger wind speeds. Finally, the evolutions of thermal feedback fractions of radiation, conduction and convection with wind speed for the two fire locations were analyzed.