Effects of hydrogen enhancement on mesoscale burner array flame stability under acoustic perturbations. (26th October 2021)

• Record Type: Journal Article
• Authors: Choi, Jeongan; Lee, Wooyoung; Rajasegar, Rajavasanth; Lee, Tonghun; Yoo, Jihyung
• Is Part Of: International journal of hydrogen energy. Volume 46:Number 74(2021)
• Page Start: 37098
• Page End: 37107
• Publication Date: 2021-10-26
• Subjects: Mesoscale burner array -- Hydrogen enrichment -- OH∗ chemiluminescence -- OH planar laser-induced fluorescence -- Spectral proper orthogonal decomposition; Hydrogen as fuel -- Periodicals; Hydrogène (Combustible) -- Périodiques; Hydrogen as fuel; Periodicals; 665.81
• DOI: 10.1016/j.ijhydene.2021.08.192
• Languages: English
• ISSNs: 0360-3199

Abstract

Abstract: Partial substitution of hydrocarbon fuel with hydrogen can effectively improve small-scale combustion system stability and performance, potentially opening the way for novel compact power generation and/or propulsion systems in the future. In this study, the effects of hydrogen enhancement between 0% and 40% hydrogen volumetric fractions in methane fuel were experimentally observed in a mesoscale burner array subjected to external acoustic perturbations. The mesoscale burner array utilizes an array of swirl-stabilized burner elements and their interactions with neighboring elements to improve the overall flame stability and simultaneously reduces the combustor length scale. OH∗ chemiluminescence and OH planar laser-induced fluorescence (OH-PLIF) were used to image various hydrogen-enriched flames at an equivalence ratio of 0.7, subjected to transverse acoustic perturbations at 320 Hz. Two acoustic modes were imposed by controlling the phase difference between two speakers perturbing the flow. OH∗ chemiluminescence images exhibited flame length scale reduction, leading to a denser flame array. Also, flame arrays with higher hydrogen enrichment were found to be more robust against transverse acoustic perturbations, demonstrated by reduced fluctuations in the global heat release rate. OH-PLIF images showed that flames with higher hydrogen enrichment initiated V- to M-shaped flame shape transition even under fuel lean conditions, thereby improving the combustion stability. OH-PLIF images were also used for flame stability analysis through spectral proper orthogonal decomposition (SPOD). The SPOD analysis showed hydrogen enrichment diminished flame fluctuation structures under fuel lean operation. Highlights: The effects of hydrogen enrichment on mesoscale flame arrays were studied under acoustic perturbations. Flame stability was investigated for various volumetric hydrogen fractions from 0 to 40%. Transverse acoustic forcing was employed for perturbing the mesoscale flame array. Axial and lateral flame responses were studied using spectral proper orthogonal decomposition.