Influence of Burner Material, Tip Temperature, and Geometrical Flame Configuration on Flashback Propensity of H2-Air Jet Flames

Abstract

Flashback is a key operability issue for low emission premixed combustion systems operated on high hydrogen content fuels. Frevious work investigated fuel composition impacts on flasliback propensity and found that burner tip temperature was important in correlating flashback data in premixed jet flames. An enclosure around tiie jet flame was found to enhance the flame-burner rim interaction. The present study further addresses these issues using a jet burner with various geometric configurations and interchangeable materials. Systematic studies addressing the quantitative influence of various parameters such as tip temperature, burner material, enclosure size, and burner diameter on flashback propensity were carried out. A comprehensive overview of the flashback limits for all conditions tested in the current study as well as those published previously is given. Tlie collective results indicate that the burner materials, tip temperature, and flame confinement play significant roles for flashback propensity and thus help explain previous scatter in flashback data. Furthermore, the present work indicates that the upstream flame propagation during flashback is affected by the burner material. The material with lower thermal conductivity yields larger flashback propensity but slower flame regression inside the tube. These observations can be potentially exploited to minimize the negative impacts of flashback in practical applications.

Responses of combustor surface temperature to flame shape transitions in a turbulent bi-stable swirl flame

“…Studies of these systems have traditionally treated the confinement (combustor surfaces) as isothermal or adiabatic, while focusing primarily on its role in combustion aerodynamics and acoustics. In recent years, increasing attention has been drawn to heat loss to the confinement, and its influences on combustion chemistry and flame stabilization [1] as well as on flame flashback [2]. Consideration of heat loss to surfaces have proven critical in improving large eddy simulations (LES) for different combustor configurations [1,3].…”

Experimental investigation of upstream flame propagation during boundary layer flashback of swirl flames

“…Since research on flashback began with the first systematic study by Lewis and von Elbe [1,2], the focus has been on measuring flashback limits in (non-swirling) Bunsen-flame type burners for many years [3][4][5][6][7], including more recent studies carefully testing additional parameters such as confinement, wall temperature and pressure [8][9][10][11][12][13]. High-speed optical diagnostics and advanced simulation tools have been applied more recently to reveal new information about the flame propagation dynamics [14][15][16][17].…”

Accurate Prediction of Confined Turbulent Boundary Layer Flashback Through a Critically Strained Flame Model

“…To flash back, the flame must only propagate through the boundary layer while overcoming local heat loss to the wall. This leads to significantly higher flashback propensity in the confined case [5]. Confined flashback is common in swirling burners because the vortex-breakdown in the combustion chamber affects the flow field upstream and often leads to flame protrusions within the mixing section [6].…”