Analysis of an idealized heat-recirculating microcombustor

The structure and stability of two-dimensional premixed flames in an idealized microcombustor are investigated numerically within the context of a diffusive-thermal model with an imposed flow field satisfying the Navier-Stokes equations. The combustible mixture flows in a straight channel with a bend at its end that forces the flow to turn back and reverts its direction. Heat exchange occurs near the bend along a segment of the wall separating the two opposing streams; the remaining walls are assumed adiabatic. Response curves identifying the dependence of the combustion characteristics on the mass flow rate illustrate the existence of multiple steady states for a certain range of the parameters with hysteresis and bi-stability phenomena. Stable solutions correspond to flames attached to the dividing wall, where intense heat exchange occurs, or stabilized by the flow near the front wall. Depending on the conditions, one or both solutions are physically possible. At high flow rates the flame is quenched by the flow.