Strain Rate Effects on Head-on Quenching of Laminar Premixed Methane-air flames

Abstract

Head-on quenching is a canonical configuration for flame-wall interaction. In the present study, the transient process of a laminar premixed flame impinging on a wall is investigated for different strain rates, while previous studies with detailed chemistry and transport focused only on unstrained conditions. Increasing strain rate leads to a reduction in the normalized quenching distance, and an increase in the normalized wall heat flux, both are considered as global flame quantities. Looking more into the local microstructure of the quenching process, CO formation and oxidation near the wall are shifted to higher temperatures under higher strain rates. Further, the local flame structure and the thermochemical state are affected by differential diffusion driven by differences in species' gradients and diffusivities. Quenching leads to increased species' gradients and consequently differential diffusion is amplified near the wall compared to propagating flames. However, this effect is suppressed for increasing strain rates, which is explained in more detail by a source term analysis of the transport equation for the differential diffusion parameter Z HC. Results for the global quantities and the local flame structure show that the impact of the strain rate weakens for higher wall temperatures. Finally, the analyses of the thermo-chemical quantities in the composition space shows that H 2 can be a good parameter to characterize the strain rate both for propagating and quenching flamelet.

Temperature field measurements between a Bunsen flame and flat a cold plate by using PLIF

“…The development of modern planar optical measurement techniques allows for detailed experimental study of flame/wall interactions [1][2][3]. A premixed Bunsen flame, directed against a wall, represents one of the simplest model geometrical cases for the investigation of stationary flames near walls [4][5][6][7].…”

Application of dense neural networks for manifold-based modeling of flame-wall interactions

“…Furthermore, the detailed GRI 3.0 mechanism is used [38]. All flamelet simulations are performed with an in-house solver [39], and the setup has been validated previously by Luo et al [40].…”

Multi Compression-Expansion Process for Chemical Energy Conversion: Transformation of Methane to Unsaturated Hydrocarbons and Hydrogen

“…The products are superior to the reactant (CH 4 ) both in their economic value and in their content of free energy. In addition, CH 4 as a main component of natural gas has been intensively studied and is already well investigated [5,6]. This endothermal conversion cannot run spontaneously at standard conditions for reasons of both equilibrium chemistry and chemical kinetics.…”