Experimental study on curvature effects and preferential diffusion for perturbed laminar premixed ammonia-air flames

Karan, Alka, Dayma, Guillaume, Chauveau, Christian and Halter, Fabien 2023. Experimental study on curvature effects and preferential diffusion for perturbed laminar premixed ammonia-air flames. Journal of Ammonia Energy 1 (1) , pp. 118-127. 10.18573/jae.16

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Abstract

Ammonia-air flames are known for low reactivity and have been posing as a huge hindrance in employing the chemical as a sustainable fuel of tomorrow. Curvature is a parameter that could influence the flame structure and so the position of the maximum heat release rate. Flame-acoustic interactions on a Bunsen burner are performed to study the local flame response to highly perturbed flows. NH2* chemiluminescence is used to study the reactivity of these flames. Non-perturbed flames are used as a reference to understand the inherent behaviour of Bunsen ammonia flames. A case study has been chosen for an equivalence ratio ranging between 1.0 and 1.4 at atmospheric conditions to study perturbed flames. The objective is to study the effect of curvature induced by the perturbations on the reactivity of the flame. It was seen that this given case study was quite complex as the flame response was to multiple factors like the effect of Lewis number, convective-diffusion velocities, decomposition of ammonia into hydrogen, thereby, promoting preferential diffusion of hydrogen in both large-scale and locally for certain cases apart from the generated acoustic perturbation which itself dictates the flow regime of the fresh gases, etc. Since the Damköhler number was around 1, the perturbation time scales and the reactivity time scales were comparable and so none of the effects could be ignored. It was concluded that for richer flames where Le>1, the negative curvature promoted the production of hydrogen leading to local enhancement in reactivity. A change in the local thickness due to the induced curvature was seen for all conditions.

Item Type:	Article
Status:	Published
Publisher:	Cardiff University Press
ISSN:	2752-7735
Date of First Compliant Deposit:	13 November 2023
Date of Acceptance:	30 June 2023
Last Modified:	13 Nov 2023 13:53
URI:	https://orca.cardiff.ac.uk/id/eprint/163851

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