Fundamental Researsh on Structure around a Flame Base and Stability Mechanism of Catalitycally Stabilized Diffusion Flame

本文从实验和数值两方面研究了燃料(甲烷-氮气混合气)喷射的催化和非催化平板边界层中火焰底部的火焰结构和扩散火焰的稳定机理。当燃料浓度降低时，火焰变得不稳定，火焰底部振荡。当使用催化多孔板时，火焰稳定极限处的燃料浓度比非催化情况下的要低。实验结果还表明，在较低的燃料浓度条件下，较高的多孔板温度可以稳定火焰，因为减少了多孔板的热损失。这些结果表明，在火焰底部附近的催化反应应该保持多孔板的较高温度，然后在较低的燃料浓度条件下稳定火焰，减少热损失。火焰位置和温度分布的数值计算结果与实验结果吻合较好。然而，这种振荡现象是无法预测的。

A flame structure around the flame base and a stability mechanism of diffusion flame in a laminar boundary layr ober a catalytic or non-catalytic flat porous plate with fuel (methane-nitrogen mixture) injection have been inverstigated experimentallyn and numerically. When the fuel concentration is decreaed, the flame becomes unstable wiht flame base oscillation. As the cataytic porous plate is used, the fuel concentration at the flame stabilization limit becomes lower compared to non-catalytic case. The experimental results also revealed that the flame can be stabilizud with lower fuel concentration condition for higher porous plate temperature, because the heat loss to the porous plate is reduced. These results suggest that the catalytic reaction near the flame base is supposed to keep the porous plate temperature high, and then, the flame can be stabilizud with lower fuel concentration condition, reducing the heat loss. The numerical results of flame location and the temperature profile show good agreement with experimental ones. The oscillating phenomenon, however, can not be predicted.