| 1. |
- Feuk, Henrik, et al.
(författare)
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Impact of Methane and Hydrogen-Enriched Methane Pilot Injection on the Surface Temperature of a Scaled-Down Burner Nozzle Measured Using Phosphor Thermometry
- 2022
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Ingår i: International Journal of Turbomachinery, Propulsion and Power. - : MDPI AG. - 2504-186X. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- The surface temperature of a burner nozzle using three different pilot hardware configurations was measured using lifetime phosphor thermometry with the ZnS:Ag phosphor in a gas turbine model combustor designed to mimic the Siemens DLE (Dry Low Emission) burner. The three pilot hardware configurations included a non-premixed pilot injection setup and two partially premixed pilot injections where one had a relatively higher degree of premixing. For each pilot hardware configuration, the combustor was operated with either methane or hydrogen-enriched methane (H2/CH4: 50/50 in volume %). The local heating from pilot flames was much more significant for hydrogen-enriched methane compared with pure methane due to the pilot flames being in general more closely attached to the pilot nozzles with hydrogen-enriched methane. For the methane fuel, the average surface temperature of the burner nozzle was approximately 40 K higher for the partially premixed pilot injection configuration with a lower degree of mixing as compared to the non-premixed pilot injection configuration. In contrast, with the hydrogen-enriched methane fuel, the differences in surface temperature between the different pilot injection hardware configurations were much smaller due to the close-to-nozzle frame structure.
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| 2. |
- Liu, Xin, et al.
(författare)
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Investigation of turbulent premixed methane/air and hydrogen-enriched methane/air flames in a laboratory-scale gas turbine model combustor
- 2021
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Ingår i: International Journal of Hydrogen Energy. - : Elsevier BV. - 0360-3199. ; 46:24, s. 13377-13388
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Tidskriftsartikel (refereegranskat)abstract
- Methane and hydrogen-enriched (25 vol% and 50 vol% H2-enriched CH4) methane/air premixed flames were investigated in a gas turbine model combustor under atmospheric conditions. The flame operability ranges were mapped at different Reynold numbers (Re), showing the dependence on Re and H2 concentrations. The effects of equivalence ratio (Φ), Re, and H2 enrichment on flame structure were examined employing OH-PLIF measurement. For CH4/air cases, the flame was stabilized with an M shape; while for H2-enriched cases, the flame transitions to a П shape above a specific Φ. This transition was observed to influence significantly the flashback limits. The flame shape transition is most likely a result of H2 enrichment, occurring due to the increase in flame speed, higher resistance of the flame to the strain rate, and change in the inner recirculation zone. Flow fields of CH4/air flames were compared between low and high Re cases employing high-speed PIV. The flashback events, led by two mechanisms (combustion-induced vortex breakdown, CIVB, and boundary-layer flashback, BLF), were observed and recorded using high-speed OH chemiluminescence imaging. It was found that the CIVB flashback occurred only for CH4 flames with M shape, whereas the BLF occurs for all H2-enriched flames with П shape.
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| 3. |
- Pignatelli, Francesco, et al.
(författare)
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Effect of CO2 dilution on structures of premixed syngas/air flames in a gas turbine model combustor
- 2023
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Ingår i: Combustion and Flame. - : Elsevier Inc.. - 0010-2180 .- 1556-2921. ; 255
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Tidskriftsartikel (refereegranskat)abstract
- The impact of CO2 dilution on combustion of syngas (a mixture of H2, CO, and CH4) was investigated in a lab-scale gas turbine model combustor at atmospheric pressure conditions. Two mild dilution levels of CO2, corresponding to 15% and 34% of CO2 mole fraction in the syngas/CO2 mixtures, were experimentally investigated to evaluate the effects of CO2 dilution on the flame structures and the emissions of CO and NOx. All experiments were performed at a constant Reynolds number (Re = 10000). High-speed flame luminescence, simultaneous planar laser-induced fluorescence (PLIF) measurements of the OH radicals and particle image velocimetry (PIV) were employed for qualitative and quantitative assessment of the resulting flame and flow structures. The main findings are: (a) the operability range of the syngas flames is significantly affected by the CO2 dilution, with both the lean blowoff (LBO) limit and the flashback limit shifting towards fuel-richer conditions as the CO2 dilution increases; (b) syngas flames exhibit flame-pocket structures with chemical reactions taking place in isolated pockets surrounded by non-reacting fuel/air mixture; (c) the inner recirculation zone tends to move closer to the burner axis at high CO2 dilution, and (d) the NOx emission becomes significantly lower with increasing CO2 dilution while the CO emission exhibits the opposite trend. The flame-pocket structure is more significant with increased CO2 dilution level. The low NOx emissions and high CO emissions are the results of the flame-pocket structures. © 2023 The Author(s)
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| 4. |
- Subash, Arman Ahamed, et al.
(författare)
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Flame investigations of a laboratory-scale CECOST swirl burner at atmospheric pressure conditions
- 2020
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361. ; 279
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Tidskriftsartikel (refereegranskat)abstract
- Experimental and numerical studies were performed to understand the stabilization of lean premixed natural gas/air flames in a gas turbine model combustor which was equipped with a swirl burner, known as the CECOST burner, designed to replicate the flow and flame structures in an industrial gas turbine engine. The operability range, flame stabilization, and flashback were investigated employing simultaneous OH– and CH2O-PLIF, and high-speed chemiluminescence imaging. Large eddy simulation (LES) was carried out for analysis of the vortex breakdown structures under non-reacting conditions. It was found that the vortex breakdown structures under isothermal conditions were insensitive to the Reynolds number (Re) for Re ≥ 10000; however, the stability of the flames and operability range of the burner were highly sensitive to Re as well as to equivalence ratio (ϕ). The equivalence ratio was varied at various Reynolds numbers to observe different regimes of the flame ranging from the lean blowout (LBO) limit to the flashback limit. The LBO limit was found to be mainly a function of equivalence ratio while being nearly independent of the Reynolds number, whereas the occurrence of flashback showed distinct characteristics for different ranges of the Reynolds number. At low and moderate Reynolds numbers, (Re ≤ 17000), flashback occurred when increasing ϕ from lean towards stoichiometric conditions. The coupling between the flow field and heat release induces vortex breakdown in the mixing tube and initiates flashback. In contrast, at higher Reynolds numbers (Re > 17000) no flashback was observed even when ϕ was increased to stoichiometric conditions. At these conditions with high Re, the increase in the bulk flow velocity affects the vortex breakdown structure, pushing the vortex breakdown downstream, which in turn prevents the flame from flashing back into the mixing tube.
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| 5. |
- Szász, Robert-Zoltán, et al.
(författare)
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A novel model for glaze ice accretion
- 2022
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Ingår i: Conference proceedings of CMFF’22. - 9789634218814 ; , s. 136-143
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Konferensbidrag (refereegranskat)abstract
- This paper introduces a novel model to predict ice accretion in glaze ice conditions due to supercooled water droplets. Glaze icing is controlled by a large number of interacting physical phenomena. The purpose of the suggested model was to offer a faster alternative to explicitly modelling these phenomena. The paper presents the suggested model and investigates the sensitivity of the predictions on the model parameters for three experimental cases in theliterature. The results indicate a qualitatively correct behaviour. Quantitatively, the model over-predicts the amount of accreted ice, the error being significantly larger in severe icing conditions. The errors are caused partly by the choice of faster numerical approaches and by the lack of possibility to account fordetaching ice from the surface.
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| 6. |
- Szász, Róbert Zoltán, et al.
(författare)
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A novel model for glaze ice accretion
- 2023
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Ingår i: Technische Mechanik. - 0232-3869. ; 43:1, s. 178-188
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Tidskriftsartikel (refereegranskat)abstract
- This paper introduces a novel model to predict ice accretion in glaze ice conditions due to supercooled water droplets. Glaze icing is controlled by a large number of interacting physical phenomena. The purpose of the suggested model was to offer a faster alternative to explicitly modelling these phenomena. The paper presents the suggested model and investigates the sensitivity of the predictions on the model parameters for three experimental cases in the literature. The results indicate a qualitatively correct behavior. Quantitatively, the model over-predicts the amount of accreted ice, the error being significantly larger in severe icing conditions. The errors are caused partly by the choice of faster numerical approaches and by the lack of possibility to account for detaching ice from the surface.
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