Effects of wind speed, spacing distance and length-width ratio of burner on flame merging and heat transfer of two-line fires

Abstract This paper investigates the effects of wind speed(V=0.25, 0.5 and 0.75 m/s), length-width ratio(n=5,8,10,15,20,25,30 and 40) and spacing distance(0, 10, 20 and 30 cm) on the burning and flame merging characteristics of two-line fires fueled by n-heptane. Experimental results indicate that the flame merging probability Pm decreases gradually with the increasing length-width ratio. Meanwhile, Pm shows an increasing trend with the groove length(L).The correlation between P m with n and L is found. On the other hand, it is found that,flame height and length decrease with the increasing length-width ratio.The flame height and length of upstream flame are smaller than those of downstream flame for different length-width ratios, at the same n and V. With the length-width ratio increase, the flame inclination angle will increase, and that of upstream flame is consistently smaller than that of downstream flame. Based on heat transfer analysis, under the influence of wind speed, the m '' is closely related to (L+W)/LW, showing an increasing trend with length-width ratio.With the increase of spacing distance, the ṁ '' of downstream flame will be larger, equal and then smaller than that of upstream flame.