Premixed Laminar Flames in Impinging Flows

Abstract

The flat laminar flames arising from the flow of reactants from a jet against a wall are analyzed. If the velocity of the reactants exiting from the jet is suitably high, the flame is adjacent to the wall; this is the case treated in previous studies. However, if either the jet velocity is reduced and/or the chemical kinetics enhanced, the flame is separated from the wall. Here both cases are systematically treated. As a consequence of the generality dealt with a large number of thermo-chemical and aerothermodynamic parameters are shown to be significant in characterizing these flames but two asymptotic analyses simplify their description; one relates to the treatment of chemical reactions and results in a thin reaction zone surrounded by chemically inert regions. The second applies when the Reynolds number is large and separates the flow into one or two viscous regions and one or two inviscid regions. Either when the rate of strain is large and the flame adjacent to the wall or when the Reynolds number is small, heat transfer to the wall is shown to influence the behavior of the flame. Comparison is made with data on the axial velocity in a flame displaced from a separation streamline which can be interpreted as a wall within the context of the present analysis.

Keywords:

• Jet velocity
• chemical kinetics
• aerothermodynamic parameters
• Reynolds number