Early Warning Signals of Flashback in CH4/H2 Swirl Flames

Schneider, Christopher E.; Steinberg, Adam M.

doi:10.2514/6.2018-4473

Cited by 4 publications

(2 citation statements)

References 5 publications

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“…This initial transition of the flame into the premix section is supported by the local velocity field near the center body tip, which is affected by the vortex-breakdown downstream of dump plane in such swirl burners. An intermediate, metastable state exists between a stable flame downstream of the center body in the combustion chamber and flashback [12,15,29]. This is different from BLF in non-swirling jet flames where typi-GTP-20-1554 Ebi ASME Journal of Engineering for Gas Turbines and Power cally, once the flame enters the premix tube, it continues to propagate upstream inside the tube [1].…”

Section: Flashback Typementioning

confidence: 99%

Boundary Layer Flashback Limits of Hydrogen-Methane-Air Flames in a Generic Swirl Burner at Gas Turbine-Relevant Conditions

Ebi

Jansohn

2021

Journal of Engineering for Gas Turbines and Power

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Operating stationary gas turbines on hydrogen-rich fuels offers a pathway to significantly reduce greenhouse gas emissions in the power generation sector. A key challenge in the design of lean-premixed burners, which are flexible in terms of the amount of hydrogen in the fuel across a wide range and still adhere to the required emissions levels, is to prevent flame flashback. However, systematic investigations on flashback at gas turbine relevant conditions to support combustor development are sparse. The current work addresses the need for an improved understanding with an experimental study on boundary layer flashback in a generic swirl burner up to 7.5 bar and 300°C preheat temperature. Methane-hydrogen-air flames with 50 to 85% hydrogen by volume were investigated. Flashback limits are reported in terms of the equivalence ratio for a given pressure, preheat temperature, bulk flow velocity and hydrogen content. The wall temperature of the center body along which the flame propagated during flashback events has been controlled by an oil heating/cooling system. This way, the effect any of the control parameters, e.g. pressure, had on the flashback limit was de-coupled from the otherwise inherently associated change in heat load on the wall and thus change in wall temperature. The results show that the preheat temperature has a weaker effect on the flashback propensity than expected. Increasing the pressure from atmospheric conditions to 2.5 bar strongly increases the flashback risk, but hardly affects the flashback limit beyond 2.5 bar.

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Section: Flashback Typementioning

confidence: 99%

Boundary Layer Flashback Limits of Hydrogen-Methane-Air Flames in a Generic Swirl Burner at Gas Turbine-Relevant Conditions

Ebi

Jansohn

2021

Journal of Engineering for Gas Turbines and Power

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“…Numerous experimental studies have investigated the boundary layer flashback in unconfined and confined flame configurations (Lewis & von Elbe 1943;Bollinger & Edse 1956;Fine 1958;Daniele, Jansohn & Boulouchos 2010;Eichler, Baumgartner & Sattelmayer 2011;Eichler & Sattelmayer 2012;Duan, Shaffer & McDonell 2013a;Duan et al 2013b;Baumgartner, Boeck & Sattelmayer 2015;Ebi & Clemens 2016;Kalantari, Sullivan-Lewis & McDonell 2016;Hoferichter & Sattelmayer 2017;Schneider & Steinberg 2018, 2020Goldmann & Dinkelacker 2021. The earliest experimental study of boundary layer flashback can be traced back to the seminal experiment conducted by Lewis & von Elbe (1943), who developed a 'critical velocity gradient' model to predict flame flashback.…”

Section: Introductionmentioning

confidence: 99%

Study of flame–flow interactions in turbulent boundary layer premixed flame flashback over a flat plate using direct numerical simulation

Chen,

Wang,

Gruber

et al. 2023

J. Fluid Mech.

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Lean hydrogen/air premixed flame flashback in a turbulent boundary layer over a flat plate is investigated using three-dimensional direct numerical simulation with detailed chemical kinetics. The upstream propagation of the flame takes place in near-wall turbulence and the interaction between the flame and the approaching reactant flow is studied. It is found that backflow regions are always present immediately upstream of flame bulges that are convex towards the reactants, confirming earlier observations. A flashback speed, including the effects of flame displacement speed and flow velocity, is introduced to quantify the flame flashback behaviour. This analysis indicates that the flashback speed is overall positive and it is considerably affected by the presence of the backflow regions. A budget analysis of the pressure transport equation is performed to explain the presence of the backflow regions. It is suggested that the positive dilatation and thermal diffusion terms near the leading edge of flame bulges are the main reasons for the pressure increase, leading to an adverse pressure gradient. The effects of the flame-induced adverse pressure gradient on the structures of the turbulent boundary layer are also investigated. It is revealed that the near-wall mean velocity and skin-friction coefficient are reduced due to the adverse pressure gradient. The coherent vortical structures of the boundary layer turbulence are lifted by the adverse pressure gradient. The analysis of the Reynolds stress component showed that the ejection event is augmented by combustion while the sweep event is attenuated, which facilitates the occurrence of flame flashback.

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Boundary Layer Flashback Limits of Hydrogen-Methane-Air Flames in a Generic Swirl Burner at Gas Turbine Relevant Conditions

Ebi¹,

Jansohn²

2021

Preprint

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Early Warning Signals of Flashback in CH4/H2 Swirl Flames

Cited by 4 publications

References 5 publications

Boundary Layer Flashback Limits of Hydrogen-Methane-Air Flames in a Generic Swirl Burner at Gas Turbine-Relevant Conditions

Boundary Layer Flashback Limits of Hydrogen-Methane-Air Flames in a Generic Swirl Burner at Gas Turbine-Relevant Conditions

Study of flame–flow interactions in turbulent boundary layer premixed flame flashback over a flat plate using direct numerical simulation

Boundary Layer Flashback Limits of Hydrogen-Methane-Air Flames in a Generic Swirl Burner at Gas Turbine Relevant Conditions

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