Parameter variations and the effects of hydrogen: An experimental investigation in a lean premixed low swirl combustor

Emadi, Majid; Karkow, Douglas; Melendez, Antonio J.; Ratner, Albert

doi:10.1016/j.ijhydene.2013.02.096

Cited by 8 publications

(4 citation statements)

References 16 publications

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“…Research studies show that when combustion instability occurs, the flame usually acts as an amplifier in the lower frequency range and its response depends on the acoustic amplitude . Also, the visible flame structure significantly changes with the acoustic frequency varying from 100 to 220 Hz . Thus, experimental conditions including acoustic velocity amplitudes of 0–0.5 and acoustic frequencies from 90 to 240 Hz were used and adjusted by the loudspeaker (JBL A0208A) with the acoustic wave generator (GWINSTEK AFG-2225).…”

Section: Experimental Systemmentioning

confidence: 99%

“…34 Also, the visible flame structure significantly changes with the acoustic frequency varying from 100 to 220 Hz. 27 Thus, experimental conditions including acoustic velocity amplitudes of 0−0.5 and acoustic frequencies from 90 to 240 Hz were used and adjusted by the loudspeaker (JBL A0208A) with the acoustic wave generator (GWINSTEK AFG-2225).…”

Section: Experimental Systemmentioning

confidence: 99%

“…Barbosa concluded that hydrogen addition significantly causes increasing flame length, decreasing flame width and heat release, and declining combustion instability. Emadi , found that the degree of thermoacoustic oscillation at the root position of the mixed gas flame with 40% of hydrogen content at 135 Hz acoustic frequency of sound is significantly reduced. Therefore, the addition of hydrogen is considered to be an effective method to suppress combustion instability.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Acoustic Excitation on the Combustion Instability of Hydrogen–Methane Lean Premixed Swirling Flames

et al. 2020

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Lean premixed flames are useful for low nitrogen oxide (NO x ) emissions but more prone to induce combustion instability in gas turbines. Combustion instability of a lean premixed swirling flame (LPSF) with hydrogen–methane was investigated experimentally. The effects of hydrogen addition on combustion instability with equivalence ratios 0.75–1 were investigated with acoustic frequencies (90–240 Hz) and acoustic amplitudes (the ratio of velocity fluctuation to an average velocity of 0–0.5), respectively, which are characterized by the gain and phase of the flame describing function (FDF). The evolution of vortex and the flame morphologies were observed by the particle image velocimetry (PIV), intensified charge-coupled device (ICCD), photomultiplier tube (PMT), and Cassegrain optical systems. The global and local heat release fluctuations of the LPSF were shown by CH*/OH* chemiluminescence and temperature measurements. Results show that the FDF features maximum and minimum gain values in the acoustic frequency range of 90–240 Hz and reaches local maximum peaks at 110 and 180 Hz and local minimum peaks at 160 Hz. It can also be observed that varying velocity amplitudes (0–0.5) have greater effects on the gain and phase of FDF than changing equivalence ratios (0.75–1) for lean swirling flames. Higher velocity amplitudes more effectively intensified the compression of the flame length, which enhanced the mixing of the high-burning gas and the unburned gas, and then heat release fluctuations increased. However, it is more interesting that the effects of hydrogen addition on the combustion instability of the LPSF show a completely opposite phenomenon due to acoustic frequency under all experimental conditions. The FDFs were compared at typical frequencies of 140 and 180 Hz, and it was found that combustion instability enhanced with increasing hydrogen content at 140 Hz while weakened at 180 Hz. The flow field of PIV images shows that it is related to the location and development of vortices in the flame with varying acoustic frequencies. The intensity of OH*/CH* chemiluminescence, local temperature, and heat release rate show the same changing trend with the flame morphology for two acoustic parameters with the increasing hydrogen content in the LPSF. This directly affects the compression and curvature of the LPSF and thereby changes the mixture and temperature of the combustible gas, which influence the heat release fluctuation of the LPSF.

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Section: Experimental Systemmentioning

confidence: 99%

Section: Experimental Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of Acoustic Excitation on the Combustion Instability of Hydrogen–Methane Lean Premixed Swirling Flames

et al. 2020

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“…However, as the ratio of methane to hydrogen decreases-that is, with increasing the relative fraction of hydrogen in the mixed fuel-the Lewis number is reduced, and the potential for thermal-diffusive instabilities in the system develops. 17,53 Following Sivashinsky's 46…”

Section: Characterization Of the Instabilitymentioning

confidence: 99%

Effect of hydrogen addition and burner diameter on the stability and structure of lean, premixed flames

Kaufman¹

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Low swirl burners (LSBs) have gained popularity in heating and gas power generation industries, in part due to their proven capacity for reducing the production of NO x , which in addition to reacting to form smog and acid rain, plays a central role in the formation of the tropospheric ozone layer. With lean operating conditions, LSBs are susceptible to combustion instability, which can result in flame extinction or equipment failure. Extensive work has been performed to understand the nature of LSB combustion, but scaling trends between laboratory-and industrial-sized burners have not been established. Using hydrogen addition as the primary method of flame stabilization, the current work presents results for a 2.54 cm LSB to investigate potential effects of burner outlet diameter on the nature of flame stability, with focus on flashback and lean blowout conditions. In the lean regime, the onset of instability and flame extinction have been shown to occur at similar equivalence ratios for both the 2.54 cm and a 3.81 cm LSB and depend on the resolution of equivalence ratios incremented. Investigations into flame structures are also performed. Discussion begins with a derivation for properties in a multicomponent gas mixture used to determine the Reynolds number (Re) to develop a condition for turbulent intensity similarity in differently-sized LSBs. Based on this requirement, operating conditions are chosen such that the global Reynolds number for the 2.54 cm LSB is within 2% of the Re for the 3.81 cm burner. With similarity obtained, flame structure investigations focus on flame front curvature and flame surface density (FSD). As flame structure results of the current 2.54 cm LSB work are compared to results for the 3.81 cm LSB, no apparent relationship is shown to exist between burner diameter and the distribution of flame surface density. However, burner diameter is shown to have a definite effect on the flame front curvature. In corresponding flow conditions, a decrease in burner diameter results a broader distribution of curvature and iv an increased average curvature, signifying that compared to the larger 3.81 cm LSB, the flame front of the smaller burner contains tighter, smaller scale wrinkling. v TABLE OF CONTENTS LIST OF TABLES .

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Experimental study on dynamics of a confined low swirl partially premixed methane-hydrogen-air flame

Tong

Shu

Liu

et al. 2017

International Journal of Hydrogen Energy

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Parameter variations and the effects of hydrogen: An experimental investigation in a lean premixed low swirl combustor

Cited by 8 publications

References 16 publications

Effects of Acoustic Excitation on the Combustion Instability of Hydrogen–Methane Lean Premixed Swirling Flames

Effects of Acoustic Excitation on the Combustion Instability of Hydrogen–Methane Lean Premixed Swirling Flames

Effect of hydrogen addition and burner diameter on the stability and structure of lean, premixed flames

Experimental study on dynamics of a confined low swirl partially premixed methane-hydrogen-air flame

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