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

• Published in: Energy (Oxford) Vol. 198; p. 117294
• Main Authors: Wan, Jianlong, Zhao, Haibo
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2020; Elsevier BV
• Subjects: Anchoring; Combustion chambers; Computer simulation; Diverging combustor; Flame holder; Flame holders; Flame propagation; Flame speed; Flame stability; Flow velocity; Heat; Heat exchange; Heat flux; Heat transfer; Local flow; Mathematical models; Premixed flames; Pulsating flame; Diverging combustor; Flame holder; Heat exchange; Flame stability; Pulsating flame
• ISSN: 0360-5442; 1873-6785
• DOI: 10.1016/j.energy.2020.117294

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 “Λ” 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. •The effect of heat exchange of flame holder in a diverging channel is studied.•The heat exchange of flame holder can significantly suppress the flame instability.•Most heat flux entering the flame holder is used to preheat the fresh mixture.•The quenching zone, free reaction zone and enhanced reaction zone are defined.•The flame pulsates up and down when the heat exchange of flame holder is absent.