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Research Papers: Gas Turbines: Combustion, Fuels, and Emissions

# Flame Dynamics With Hydrogen Addition at Lean Blowout Limits

[+] Author and Article Information
Shengrong Zhu

Turbine Innovation and Energy
Research (TIER) Center,
Department of Mechanical Engineering,
Louisiana State University,
Baton Rouge, LA 70803
e-mail: shengrong11@gmail.com

Sumanta Acharya

Professor
Turbine Innovation and Energy
Research (TIER) Center,
Department of Mechanical Engineering,
Louisiana State University,
Baton Rouge, LA 70803
e-mail: acharya@me.lsu.edu

1Corresponding author.

Contributed by the Coal, Biomass and Alternate Fuels Committee of ASME for publication in the JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received October 9, 2013; final manuscript received November 27, 2013; published online January 9, 2014. Editor: David Wisler.

J. Eng. Gas Turbines Power 136(5), 051506 (Jan 09, 2014) (12 pages) Paper No: GTP-13-1359; doi: 10.1115/1.4026321 History: Received October 09, 2013; Revised November 27, 2013

## Abstract

Lean premixed combustion is widely used in power generation due to low nitric oxide emissions. Recent interest in syngas requires a better understanding of the role of hydrogen addition on the combustion process. In the present study, the extinction process of hydrogen enriched premixed flames near lean blow out (LBO) in a swirl-stabilized combustor has been examined in both unconfined and confined configurations. High speed images of the flame chemiluminescence are recorded, and a proper orthogonal decomposition (POD) procedure is used to extract the dominant flame dynamics during the LBO process. By examining the POD modes, the spectral information and the statistical properties of POD coefficients, the effect of hydrogen addition on the LBO processes are analyzed and described in the paper. Results show that in unconfined flames, the shear layer mode along with flame rotation with local quenching and reignition is dominant in the methane-only case. For the open hydrogen enriched flames, the extinction times are longer and are linked to the lower minimum ignition energy for hydrogen that facilitates reignition events. In confined methane flames, a conical flame is observed and the POD mode representing the burning in the central recirculation zone appears to be dominant. For the 60% hydrogen enriched flame, a columnar burning pattern is observed and the fluctuation energies are evenly spread across several POD modes making this structure more prone to external disturbances and shorter extinction times.

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## Figures

Fig. 1

Sectional view of the swirl injector

Fig. 2

Time series of normalized light intensity for (a) unconfined CH4, (b) unconfined 60% H2, (c) confined CH4, and (d) confined 60% H2

Fig. 3

Calculated POD modes for unconfined CH4 flame at ΦLBO = 0.65. Contour scale: red-positive maximum (negative maximum for mode 1), blue-negative minimum (positive minimum for mode 0).

Fig. 4

Image sequence for unconfined CH4 flame at ΦLBO = 0.65 captured from top with 30 deg inclination angle (while dot-dash and dash lines denote the burner center line and the boundary of center-body, respectively). Contour scale: red-maximum, blue-minimum.

Fig. 5

Typical image sequence reconstructed with mode 0 and mode 3 for unconfined CH4 flame at ΦLBO = 0.65. Contour scale: red-maximum, blue-minimum.

Fig. 6

Typical image sequence reconstructed with mode 0 and mode 4 for unconfined CH4 flame at ΦLBO = 0.65. Contour scale: red-maximum, blue-minimum.

Fig. 7

Power spectrum for mode 1–6 for unconfined CH4 flame at ΦLBO = 0.65

Fig. 8

Calculated POD modes for unconfined 60% H2 flame at ΦLBO = 0.33. Contour scale: red-positive maximum (negative maximum for mode 1), blue-negative minimum (positive minimum for mode 0).

Fig. 9

Calculated POD modes for confined CH4 flame at ΦLBO = 0.52. Contour scale: red-positive maximum (negative maximum for mode 1), blue-negative minimum (positive minimum for mode 0).

Fig. 10

Amplitudes for first two modes for confined CH4 flame

Fig. 11

Typical image sequence reconstructed with mode 0 and mode 2 for confined CH4 flame at ΦLBO = 0.52. Contour scale: red-maximum, blue-minimum.

Fig. 12

Calculated POD modes for confined 60% H2 flame ΦLBO = 0.22. Contour scale: red-positive maximum (negative maximum for mode 1), blue-negative minimum (positive minimum for mode 0).

Fig. 13

Typical image sequence reconstructed with mode 0 and mode 3 for confined 60% H2 flame at ΦLBO = 0.22. Contour scale: red-maximum, blue-minimum.

Fig. 14

Typical image sequence reconstructed with mode 0 and mode 4 for confined 60% H2 flame at ΦLBO = 0.22. Contour scale: red-maximum, blue-minimum.

Fig. 15

Power spectrum for modes 1–5 for confined 60% H2 flame

Fig. 16

Statistical properties of POD mode amplitudes for confined 60% H2 flame

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