Effects of secondary hydrogen injection on thermoacoustic instability of swirling premixed flames in a model combustor
(2024) In Fuel 377.- Abstract
Effects of pilot H2 injection on the thermoacoustic instability of premixed CH4/air flames were experimentally investigated with varied hydrogen injection rates and different injection strategies. The flames were stabilized on a swirl burner with a central pilot-fuel injection tube. The flame structure was captured using high-speed OH* chemiluminescence and OH-PLIF methods, while the CO and NOx emissions were also measured. It is validated that a minimal flow rate of the pilot H2 injection can significantly enhance flame stabilization. Comparatively, the other two strategies, including premixing H2 with CH4 and a pilot injection of the CH4, all exhibit nearly... (More)
Effects of pilot H2 injection on the thermoacoustic instability of premixed CH4/air flames were experimentally investigated with varied hydrogen injection rates and different injection strategies. The flames were stabilized on a swirl burner with a central pilot-fuel injection tube. The flame structure was captured using high-speed OH* chemiluminescence and OH-PLIF methods, while the CO and NOx emissions were also measured. It is validated that a minimal flow rate of the pilot H2 injection can significantly enhance flame stabilization. Comparatively, the other two strategies, including premixing H2 with CH4 and a pilot injection of the CH4, all exhibit nearly no improvement in the flame stabilization. The underlying reason is that the pilot H2 injection can modify the flame anchoring, reduce flame height, and even redistribute heat release in the flame. Moreover, the H2 injection suppresses the flame front roll-up, mitigates the heat release fluctuations, and ultimately leads to decoupled acoustic pressure and unsteady heat release. Furthermore, it appears that the CO emissions decrease with the pilot H2 injection while the NOx emissions significantly increase. Thus, although the pilot H2 injection can be effective to actively suppress the thermoacoustic instability, the elevated pollutant emissions should be a major drawback of this strategy. In the present work, the optimized trade-off between flame stabilization and NOx emission is achieved using a pilot H2 injection at a thermal power fraction of about 5%. These results are helpful to attain stable and clean combustion in the gas turbine based on hydrogen fuel.
(Less)
- author
- Ji, Longjuan LU ; Zhang, Weijie ; Wang, Jinhua ; Huang, Zuohua and Bai, Xue Song LU
- organization
- publishing date
- 2024-12
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Active control, Hydrogen injection, Pollutant emission, Swirl flames, Thermoacoustic instability
- in
- Fuel
- volume
- 377
- article number
- 132722
- publisher
- Elsevier
- external identifiers
-
- scopus:85200982390
- ISSN
- 0016-2361
- DOI
- 10.1016/j.fuel.2024.132722
- language
- English
- LU publication?
- yes
- id
- d3186064-30e4-4097-8947-1488ab4600e9
- date added to LUP
- 2024-08-30 12:58:33
- date last changed
- 2024-08-30 12:58:45
@article{d3186064-30e4-4097-8947-1488ab4600e9,
abstract = {{<p>Effects of pilot H<sub>2</sub> injection on the thermoacoustic instability of premixed CH<sub>4</sub>/air flames were experimentally investigated with varied hydrogen injection rates and different injection strategies. The flames were stabilized on a swirl burner with a central pilot-fuel injection tube. The flame structure was captured using high-speed OH* chemiluminescence and OH-PLIF methods, while the CO and NO<sub>x</sub> emissions were also measured. It is validated that a minimal flow rate of the pilot H<sub>2</sub> injection can significantly enhance flame stabilization. Comparatively, the other two strategies, including premixing H<sub>2</sub> with CH<sub>4</sub> and a pilot injection of the CH<sub>4</sub>, all exhibit nearly no improvement in the flame stabilization. The underlying reason is that the pilot H<sub>2</sub> injection can modify the flame anchoring, reduce flame height, and even redistribute heat release in the flame. Moreover, the H<sub>2</sub> injection suppresses the flame front roll-up, mitigates the heat release fluctuations, and ultimately leads to decoupled acoustic pressure and unsteady heat release. Furthermore, it appears that the CO emissions decrease with the pilot H<sub>2</sub> injection while the NO<sub>x</sub> emissions significantly increase. Thus, although the pilot H<sub>2</sub> injection can be effective to actively suppress the thermoacoustic instability, the elevated pollutant emissions should be a major drawback of this strategy. In the present work, the optimized trade-off between flame stabilization and NO<sub>x</sub> emission is achieved using a pilot H<sub>2</sub> injection at a thermal power fraction of about 5%. These results are helpful to attain stable and clean combustion in the gas turbine based on hydrogen fuel.</p>}},
author = {{Ji, Longjuan and Zhang, Weijie and Wang, Jinhua and Huang, Zuohua and Bai, Xue Song}},
issn = {{0016-2361}},
keywords = {{Active control; Hydrogen injection; Pollutant emission; Swirl flames; Thermoacoustic instability}},
language = {{eng}},
publisher = {{Elsevier}},
series = {{Fuel}},
title = {{Effects of secondary hydrogen injection on thermoacoustic instability of swirling premixed flames in a model combustor}},
url = {{http://dx.doi.org/10.1016/j.fuel.2024.132722}},
doi = {{10.1016/j.fuel.2024.132722}},
volume = {{377}},
year = {{2024}},
}