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Direct numerical simulation of inflow boundary-layer turbulence effects on cavity flame stabilisation in a model scramjet combustor.

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Title: Direct numerical simulation of inflow boundary-layer turbulence effects on cavity flame stabilisation in a model scramjet combustor.
Authors: Lin, Minqi1 (AUTHOR), Fang, Jian1,2,3 (AUTHOR) jianfang@imech.ac.cn, Deng, Xi4 (AUTHOR), Gu, Xiaojun3 (AUTHOR), Chen, Zhi X.1,5 (AUTHOR) chenzhi@pku.edu.cn
Source: Aerospace Science & Technology. Oct2025, Vol. 165, pN.PAG-N.PAG. 1p.
Subjects: Combustion, Turbulence, Mass transfer, Supersonic flow, Scramjet engines, Flame stability, Computer simulation
Abstract: Supersonic lean premixed hydrogen/air combustion stabilised by a cavity-flame holder within a model scramjet, characterized by a Mach 1.5 inflow at 1000 K and 50 kPa, is investigated via direct numerical simulation. By separately implementing wall-bounded turbulent and laminar inlet conditions, this work analysis various physical processes of flame stabilization and turbulence-flame interactions to study the influence of inflow boundary layer conditions. Findings indicate that combustion occurred within the cavity shear layer in both cases and propagated downstream along the lower wall. Also, the server impingement at the rear wall in the case with laminar inflow leads to greater cavity resistance. Furthermore, the studies on gas exchange and transport process indicates that with laminar inflow the entered gas accumulates in the back part of the cavity via the intensive mass exchange process and weaker interaction between the primary and secondary vortices. Flame stretch and thickness are further investigated to shed light into turbulence-flame interaction in supersonic flows. Results show that the interaction between the cavity shear layer and the aft wall leads to the increase of flame surface and weaken the correlation between S d and ∇ ⋅ n in both cases. After that, the analysis on flame thickness indicate that the tangential strain rate serves as a dominant factor influencing flame thickness within the preheat layer. In contrast to the case with wall-bounded turbulence inflow, the specific roll-up vortex observed in the cavity shear layer of case with laminar inflow bring different physical phenomenon. Also, the collision at the aft wall exerts a much more significant influence on thickening the flame within oxidation layer due to the intense turbulent effects and increasing the flame stretch in regions characterized by large positive curvature in this case. • Direct numerical simulation is conducted on a laboratory-scale model scramjet combustor operating under supersonic mode. • The influence of inflow boundary-layer turbulence on flame structure and pressure drag is investigated. • Mass transport process in near-cavity region is studied and a specially designed tracer is added to demonstrate this process. • Flame stretch and thickness are investigated to elucidate the flame-vortex interaction under supersonic combustion condition. [ABSTRACT FROM AUTHOR]
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Abstract:Supersonic lean premixed hydrogen/air combustion stabilised by a cavity-flame holder within a model scramjet, characterized by a Mach 1.5 inflow at 1000 K and 50 kPa, is investigated via direct numerical simulation. By separately implementing wall-bounded turbulent and laminar inlet conditions, this work analysis various physical processes of flame stabilization and turbulence-flame interactions to study the influence of inflow boundary layer conditions. Findings indicate that combustion occurred within the cavity shear layer in both cases and propagated downstream along the lower wall. Also, the server impingement at the rear wall in the case with laminar inflow leads to greater cavity resistance. Furthermore, the studies on gas exchange and transport process indicates that with laminar inflow the entered gas accumulates in the back part of the cavity via the intensive mass exchange process and weaker interaction between the primary and secondary vortices. Flame stretch and thickness are further investigated to shed light into turbulence-flame interaction in supersonic flows. Results show that the interaction between the cavity shear layer and the aft wall leads to the increase of flame surface and weaken the correlation between S d and ∇ ⋅ n in both cases. After that, the analysis on flame thickness indicate that the tangential strain rate serves as a dominant factor influencing flame thickness within the preheat layer. In contrast to the case with wall-bounded turbulence inflow, the specific roll-up vortex observed in the cavity shear layer of case with laminar inflow bring different physical phenomenon. Also, the collision at the aft wall exerts a much more significant influence on thickening the flame within oxidation layer due to the intense turbulent effects and increasing the flame stretch in regions characterized by large positive curvature in this case. • Direct numerical simulation is conducted on a laboratory-scale model scramjet combustor operating under supersonic mode. • The influence of inflow boundary-layer turbulence on flame structure and pressure drag is investigated. • Mass transport process in near-cavity region is studied and a specially designed tracer is added to demonstrate this process. • Flame stretch and thickness are investigated to elucidate the flame-vortex interaction under supersonic combustion condition. [ABSTRACT FROM AUTHOR]
ISSN:12709638
DOI:10.1016/j.ast.2025.110463