Investigation of mixing processes of effusion cooling air and main flow in a single sector model gas turbine combustor at elevated pressure
[Display omitted] •Effusion air mixes with main flow in all stages of premixed combustion.•This includes mixing before, during and after reaction.•Effusion air partly dilutes fresh gas in primary zone.•Dilution leads to reduction in post-flame OH concentration.•In the near-wall region, the dominant...
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Veröffentlicht in: | The International journal of heat and fluid flow 2021-04, Vol.88, p.108768, Article 108768 |
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Sprache: | eng |
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•Effusion air mixes with main flow in all stages of premixed combustion.•This includes mixing before, during and after reaction.•Effusion air partly dilutes fresh gas in primary zone.•Dilution leads to reduction in post-flame OH concentration.•In the near-wall region, the dominant effect is adiabatic mixing with exhaust.•Dilution of fresh-gas near liner only observed under certain operating conditions.
Mixing processes between main flow and effusion cooling air are investigated in an effusion cooled, swirl-stabilized pressurized single sector gas turbine combustor using advanced laser diagnostics. Quantitative planar laser-induced fluorescence of the hydroxyl radical (OH-PLIF) and planar laser-induced fluorescence of nitric oxide, seeded to the effusion cooling air, (NO-PLIF) are employed in the primary zone and close to the effusion cooled liner. This data is used to identify mixing events at three stages of premixed combustion, i.e. mixing before reaction, mixing during reaction and mixing after reaction. A parametric study of swirl and cooling air mass flow is conducted to investigate the mutual interaction between flame and cooling air. Within the primary zone, a significant radial asymmetry of OH concentration is observed. This asymmetry is partly explained by the presence of effusion cooling air within the unburned fresh gas, leading to lowered OH concentration within local reaction zones and their post-flame equilibrium concentration. Near the effusion cooled liner, adiabatic mixing after reaction is the dominant process across all investigated operating conditions. Notable mixing before reaction is only observed for the first effusion hole on the center line at low swirl conditions. |
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ISSN: | 0142-727X 1879-2278 |
DOI: | 10.1016/j.ijheatfluidflow.2020.108768 |