Abstract
The characteristics of biogas-oxygen diffusion flames were experimentally investigated using small counterflow burners, where the apparent equivalence ratio was set to unity. The flame thickness and flame diameter were determined as functions of the inner diameter of burners, the distance between burners and the flow rate of gases. When burners with large inner diameter were used, diffusion flames were observed in small burner distance. The flame thickness and flame diameter decreased as the burner distance became smaller, and they increased as the flow rate became larger. The flame stretch had a great influence on the flame thickness, i.e. the flame thickness decreased monotonously as the flame stretch rate became larger. In addition, the relation between flame thickness and flame stretch depended strongly on the inner diameter of burners and the flow rate of gases.
