Flame stabilization in a model ramjet combustor using a transverse slot jet
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Flame stabilization is the act of maintaining combustion in the presence of a high-speed premixed flow, and continues to be an important process that influences the performance and limitations for propulsion applications. A common approach for current generation flame holders involves the employment of a low-speed recirculation zone where hot combustion products are maintained and act as a continuous ignition source. The recirculation zone is often induced using a wake-generating bluff body that is submerged in the flow, or through the use of a rearward facing step. A fluidic-based flame holder using a transverse slot jet issuing into a cross flow offers potential thrust and efficiency benefits for propulsion. The transverse slot jet flame holder has been shown to develop a low-speed recirculation zone capable of stabilizing a stationary flame, analogous to a rearward-facing step (i.e. a wall-bounded bluff body). Turbulent flame structures were investigated for various flame holders. The role of baroclinic torque on turbulent flame structures evolution and the flowfield will be described. Comparisons will be made to a rearward-facing step flame holder. The details of the turbulent flow with and without combustion will be described, showing the potential advantages achieved using fluidics. The fluidic flame holder provides competitive flame holding performance to the mechanical counterpart, while having enhanced combustion rates that result in higher combustor efficiencies and/or shorter burners.