Computational investigation of laminar premixed hydrogen flame past a quenching mesh

Abstract

Purpose The purpose of this study is the computational analysis of atmospheric, laminar, stoichiometric and premixed hydrogen-air flames in the presence of a quenching mesh. The assessment of the predictive capability of different reaction mechanisms, the clarification of the relative importance of the thermal and chemical effects for mesh quenching and the investigation of the influence of the mesh geometry on the quenching effectiveness are the focal points of the investigation. Design/methodology/approach The problem is posed as unsteady, two-dimensional. Differential governing equations are numerically solved by the finite volume method for the reacting hydrogen/air mixture, assuming an ideal gas behaviour. Thermal radiation and buoyancy are neglected. A coupled solver is used to treat the velocity-pressure coupling, along with a stiff-chemistry solver for the chemical kinetics. Second-order discretization schemes are used in space and time. A uniform grid resolution is used, where the grid independence in terms of the flame speed prediction is ensured in preliminary calculations for one-dimensional flames. Findings It is found that a detailed reaction mechanism is necessary for an accurate prediction. Meshes with round openings are found to be more effective that those with slit openings (SOs), by a factor of two in the maximum safe gap size. A perforated plate is observed to have a higher quenching potential compared to a wire mesh, for SOs. It is also found that the heat loss to the wall is the dominating quenching mechanism for the present problem, whereas adsorption of radicals plays a subordinate role. Originality/value In contrast to the previous studies in the field, a detailed reaction mechanism is applied instead of a single-step one, while still using the latter for comparison. The role of wall-radicals interaction for the quenching effectiveness of the mesh is addressed for the first time. Parametric studies are performed on the mesh geometry, which was not done before. Hydrogen is considered as fuel in contrast to the great majority of the previous work.