Experimental and numerical study on heat transfer characteristics for methane/air flame impinging on a flat surface

Heat flux from a premixed methane/air slot laminar flame jet impinging upward to a horizontal target plate is studied experimentally and numerically. Mach-Zehnder interferometer is used to obtain the overall temperature field. The flame jet is produced by a slot nozzle with length of L = 25 mm and width of W = 3 mm. The slot nozzle is parallel to the target plate which has the dimensions of 250 × 130 × 10 mm. The experimentally obtained heat flux distributions were compared for different firing rates and nozzle to plate spacing. A second peak in heat flux to the target surface (an off-center peak with respect to the axis of the nozzle) was observed for the shortest spacing and highest firing rate in the present study. The heat flux distribution and the second peak in it could be successfully simulated using numerical computations. With the help of numerical results and analyzing the velocity components, it was found that the position of the second peak along the plate is in accordance with a second stagnation point caused by the present configuration of the confined flame between the two parallel plates, namely the target plate and the base plate of the two-dimensional nozzle. The results show that the onset of the presence of the second stagnation point could be controlled by the spacing and firing rate.