Structure and stabilization mechanism of a stratified premixed low swirl flame

Nogenmyr, Karl-Johan; Petersson, Per; Bai, Xue‐Song; Fureby, Christer; Collin, Robert; Lantz, Andreas; Linne, Mark; Aldén, Marcus

doi:10.1016/j.proci.2010.06.011

Cited by 53 publications

(9 citation statements)

References 36 publications

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“…This should be verified by detailed flow field diagnostics. The Kelvin-Helmholtz instability of the shear layer which leads to formation of vortices is shown in unexcited low-swirl flames by Nogenmyr et al [47].…”

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confidence: 93%

Experimental Characterization of Response of Lean Premixed Low-Swirl Flames to Acoustic Excitations

Bagheri-Sadeghi

Shahsavari

Farshchi

2013

International Journal of Spray and Combustion Dynamics

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Acoustically excited lean premixed low-swirl flames were experimentally investigated to gain a better understanding of detrimental thermoacoustic couplings which can occur in applications like low-NO x gas turbines. Propane-air flames were imaged and analyzed at equivalence ratios of 0.6 to 0.8, mean flow velocities of 3.5 to 5.5 m/s and excitation frequencies of 135 Hz to 555 Hz. It was observed that with increasing excitation frequency, mean flame shape gradually became wider up to a Strouhal number of about 2.5 and then slowly reverted back to the unexcited flame shape. Such large changes in mean flame shape and possibly flow field under acoustic excitations can significantly affect flame dynamics. Increased heat release fluctuations were observed in the flame shear layer at Strouhal numbers from 1 to 2. Rolling up of the flame by vortices was suggested as a driving mechanism for these fluctuations which may lead to combustion instabilities.

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confidence: 93%

Experimental Characterization of Response of Lean Premixed Low-Swirl Flames to Acoustic Excitations

Bagheri-Sadeghi

Shahsavari

Farshchi

2013

International Journal of Spray and Combustion Dynamics

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“…It is found that methane fraction in the fuel does not have significant effect on the thermal NO emissions. Nogenmyr and colleagues [17][18][19] carried out LES of low-swirl stratified premixed flames with two-scalar flamelet model. The level-set G-equation was used to track the flame front.…”

Section: Introductionmentioning

confidence: 99%

Flame stability limits of premixed low-swirl combustion

Xiao

Cao

Wang

2018

Advances in Mechanical Engineering

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The objective of this study is to gain a fundamental understanding of the flow-field and flame behaviors associated with a low-swirl burner. A vane-type low-swirl burner with different swirl numbers has been developed. The velocity field measurements are carried out with particle image velocimetry. The basic flame structures are characterized using OH radicals measured by planar laser-induced fluorescence. Three combustion regimes of low-swirl flames are identified depending on the operating conditions. For the same low-swirl injector under atmospheric conditions, attached flame is first observed when the incoming velocity is too low to generate vortex breakdown. Then, W-shaped flame is formed above the burner at moderate incoming velocity. Bowl-shaped flame structure is formed as the mixture velocity increases until it extinct. Local extinction and relight zones are observed in the low-swirl flame. Flow-field features and flame stability limits are obtained for the present burner.

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“…A lot of investigations of flame dynamics and of flame response to perturbations of flow, equivalence ratio and acoustics have been even recently conducted to establish methods for prediction of the thermoacoustic instabilities by experiments [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] and large eddy simulations (LES) [12,[19][20][21][22]. In our previous study [6], a high speed stereoscopic PIV was applied to swirl-stabilized methane-air premixed flame with pressure measurements, and it was shown that periodic large-scale vortical motion plays an important role in combustion oscillations based on phaseaveraged velocity.…”

Section: Introductionmentioning

confidence: 99%