Simulation of Hydrogen/Air Laminar Diffusion Flame

Abstract

A model as precise as possible both from chemical reactions and fluid mechanics was constructed and applied to simulate a laminar hydrogen/air diffusion flame. The combustion conditions were given as that the burner is 10 mm in diameter, and hydrogen issues with the Poiseuille flow with 10 ml/s of the axial volumetric velocity. The obtained results were as follows. The flame is well-developed as a typical diffusion flame at about 10 mm in height. At this height, the flame-sheet assumption is valid. On the contrary, hydrogen atoms diffusing axially from a downstream region, and oxygen entrained with the radial flow of the environmental air, react at a height as low as 2 mm. This reaction produces hydroperoxyl radicals and releases a fairly large amount of thermal energy at the same time. Thereby, enthalpy is carried to the upperstream region in the form of chemical energy. The flame holding of this flame can be ascribed to these low-temperature reactions.