Session chaired By Pr. Aimee Morgans
The reduction of CO2 and NOx becomes an ever-increasing trend across the globe. The addition of hydrogen (H2) proves to be a favorable candidate in reducing such emissions. However, insights pertaining to the effect of H2 addition over the local interaction dynamics in the turbulent flames are limited. Hence, this study aims at investigating the effect of H2 addition in lab-scale bluff-body burner using time-resolved optical diagnostic tools. We have employed, PIV and chemiluminescence imaging (OH*)/ PLIF (OH) in simultaneous fashion to delineate the flame – flow interaction dynamics across various concentration levels of hydrogen in a CH4-H2 fuel mixture. The operating modes such as constant thermal power and momentum flux ratios are considered. Across the two modes, experiments are carried out with the different H2 volumetric concentration levels viz. 20 %, 50%, 80%, and 100 %. In a global sense, reduction in flame length and increased levels of OH concentration are observed for the hydrogenated flames. Furthermore, a localized extinction event namely hole formation causes the intermittent ejection of flame pockets in the pure methane flame. However, the same phenomenon is ceased with H2 addition. This reveals hydrogenated flames exhibit higher strain resistance than methane flame. Finally, proper orthogonal decomposition (POD) is implemented over the instantaneous flow/scalar fields to capture the dominant flow structures associated with various operating modes.