Effect of conjugate heat exchange of flame holder on laminar premixed flame stabilization in a meso-scale diverging combustor

The present work investigates the effect of heat exchange of flame holder on the premixed flame stabilization in a diverging channel through numerical simulation. When the heat exchange of flame holder exists, the flame can remain stable and presents a "V" shape. A majority of the heat flux that enters the flame holder is used to preheat the incoming fresh mixture, which can induce and enhance the initiation of reactions. Moreover, three different zones are found and defined, including the free reaction zone, the quenching zone, and the enhanced reaction zone. However, when the heat exchange of flame holder is absent, the flame pulsates up and down instead of remaining stable, and shows a cone "Lambda" shape. Subsequently, the pulsating mechanisms of flame are quantitatively analyzed in terms of local flow velocity, the angle between flow direction and flame front, and the stretch rate. The pulsation is a dynamic process where the flame speed self-adjusts to match the normal component of flow velocity. In summary, the present study indicates that the heat exchange of flame holder can significantly suppress the flame instability and improve the flame anchoring performance. (C) 2020 Elsevier Ltd. All rights reserved.