Experimental Investigation of the Transition Mechanism From Stable Flame to Flashback in a Generic Premixed Combustion System With High-Speed Micro-Particle Image Velocimetry and Micro-PLIF Combined With Chemiluminescence Imaging

Abstract

Sustainable power generation resulting in low pollutant emissions, such as CO2 and NOx, poses a very challenging task in the near future. Premixed combustion of hydrogen-rich fuels in gas turbines is a promising approach to cope with ever more stringent regulations on emission levels. This method, however, involves the risk of flame flashback from the desired flame position into the premixing section, leading to catastrophic failure of the machine components that are not designed for such high temperatures. The objective of the current study was to visualize and describe the transition from stable flame to flashback in a generic H2–air combustion system and develop a physics-based model for the description of the transition. In order to achieve the high temporal and spatial resolution required for capturing the involved effects, high-speed particle image velocimetry (PIV) and high-speed planar laser-induced fluorescence (PLIF) were employed. In order to characterize the interaction of the flame with the flow in detail, both measurement techniques were applied to very small fields-of-view using (UV) long-distance microscopes. The repetition rates were 20 kHz for PLIF and 3 kHz for PIV, respectively. During both the PLIF and the PIV measurements, the flame's OH*-chemiluminescence was captured from a perspective perpendicular to that of the PLIF/PIV camera for further flame characterization. The microscopic measurements revealed that there is a negligible influence of the unconfined flame on the incoming burner flow in stable mode. Upon approaching the flashback conditions, however, the velocity profile of the burner flow is distinctly distorted by the presence of the flame inside the premixing duct. The flow directly upstream of the flame is retarded and deflected around the leading flame tip. Based on the effects observed in the experiments, a new flashback model is proposed, which identifies the heat transfer to the burner rim and the flame speed as the main drivers for the onset of flashback, whereas the flame backpressure is the governing factor for the subsequent upstream flame propagation.

Hydrogen for Cooking: A Review of Cooking Technologies, Renewable Hydrogen Systems and Techno-Economics

“…The study quantified the concept of a safety allowance to preserve the performance of the domestic burner. Even though there are experimental and numerical studies to understand and solve the flashback phenomenon [88][89][90][91][92][93][94][95][96][97][98], these studies are focused on large-scale and high-pressure burners, which highlights the need for studies on domestic burners. For instance, Vance, Goey, and Oijen [98] numerically studied the flashback limits of slit burners.…”

Experimental Investigation of the Confinement Effect on Flashback in Multi Combustion Modes Tangential Swirl Burner

“…Flashback is one of the important operation problems in the lean premixed combustion which occurs when the turbulent propagation flame speed becomes faster than the flow velocity or mixture reactants incoming velocity. This leads to that the flame upstream to the premixed passage either burner tube or pre mixer [1,2] The high temperature of flame Flashback Premixed combustion Tangential swirl burner Liquified petroluim gas…”

Development of a flashback correlation for burner-stabilized hydrogen-air premixed flames

“…The ratio of flame to flow timescale proved to correlate flashback data for turbulent ammonia-hydrogen flames. Experiments have also been conducted for turbulent hydrogen-air unconfined flames by Baumgartner et al [25] . They showed that unconfined flames have higher resistance to flashback than the confined flames and that the flashback propensity was dependent on the burner temperature.…”