The prediction of laminar jet diffusion flame sizes: Part II. Experimental verification

Abstract

This paper describes experiments to test the diffusion flame theory given in a previous paper. It is shown that diffusion flame sizes can be predicted for two different burner geometries (circular and slotted ports) by taking the diffusion coefficient of oxygen at a characteristic flame temperature of 1500 K. For the slot burner, the flame size is found to be controlled either by momentum or by buoyancy effects. The transition between the two regimes occurs, as predicted, when the modified Froude number is approximately one. In contrast, if the classical Burke-Schumann theory is used, the diffusion coefficient needed to predict the correct flame size varies by about a factor of six, depending upon the burner geometry and flame conditions. The paper goes on to show that gas compositions in the tail of a diffusion flame may be predicted by the theory already given. It also examines previous experimental work on diffusion flame size in relation to the present work.