Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Numerical Study of Triple Flames in Partially Premixed Methane and Hydrogen-Air Mixtures
Submission Author:
Rafael Meier , SC
Co-Authors:
Rafael Meier, Thiago Cardoso de Souza, Amir Antonio Martins Oliveira
Presenter: Rafael Meier
doi://10.26678/ABCM.ENCIT2022.CIT22-0593
Abstract
The local burning rate and the associated structural variations of laminar triple flames are investigated using direct numerical simulations (DNS) with detailed chemical reaction mechanisms for two distinct fuel-air mixtures, CH4 −air and the H2−air mixtures. The simulations were performed through a parametric variation based on the mixing layer thickness. The triple flames are initiated by imposing a heat source in the center of a scalar mixing layer of non-uniform thickness. The results show that the methane flame propagation is ruled by the flow that develops at the local stoichiometric condition associated with the triple point. On the other hand, the hydrogen leading edge is dominated by the richer region where the burning rate is higher. The mixing layer thickness causes an impact on the magnitude of the flame deformation where for smaller profile thicknesses the lean flame stabilizes even in the flammability limit conditions. Consequently, the local stretch rate and the displacement speed undergo substantial variations where the front curvature increases for decreasing values of the mixing length. The correlation between the local flame speed and the Karlovitz number, Ka, shows that the expected behavior, related to the Markstein length, M a, is not required in a partially premixed flame according to the premixed properties.
Keywords
triple flames, Direct numerical simulations, stretch rate, burning rate
