Impact of the Flame-Holder Heat-Transfer Characteristics on the Onset of Combustion Instability
In this article, we investigate the impact of heat transfer between the flame and the flame-holder on the dynamic stability characteristics of a 50-kW backward-facing step combustor. We conducted a series of tests where two backward step blocks were used, made of ceramic and stainless
steel, whose thermal conductivities are 1.06 and 12 W/m/K, respectively. Stability characteristics of the two flame-holder materials were examined using measurements of the dynamic pressure and flame chemiluminescence over a range of operating conditions. Results show that with the ceramic
flameholder, the onset of instability is significantly delayed in time and, for certain operating conditions, disappears altogether, whereas with the higher conductivity material, the combustor becomes increasingly unstable over a range of operating conditions. We explain these trends using
the heat flux through the flame-holder and the change in the burning velocity near the step wall. Results suggest a potential approach using low-thermal-conductivity material near the flame-holder as passive dynamics suppression methods.
Keywords: Combustion instability; Flame speed; Flame-holder; Heat transfer; Thermal conductivity
Document Type: Research Article
Affiliations: Reacting Gas Dynamics Laboratory, Center for Energy and Propulsion Research, Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
Publication date: 03 October 2013
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