Lean Blowout and Ignition Characteristics of Conventional and Surrogate Fuels Measured in a Swirl Stabilized Combustor

Stouffer, Scott D.; Hendershott, Tyler; Monfort, Jeffrey R.; Diemer, Jacob; Corporan, Edwin; Wrzesinski, Paul J.; Caswell, Andrew W.

doi:10.2514/6.2017-1954

Cited by 41 publications

(19 citation statements)

References 14 publications

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“…In addition to chemistry and mixing effects, blowoff is also influenced by atomization and vaporization processes. Available data often generate conflicting or inconclusive results [8][9][10][11][12][13][14][15], likely due to the range of potentially dominant physical processes depending upon atomization quality, air preheat temperature, etc. Early approaches to this problem involved generalizing methods developed from premixed combustors.…”

Section: Introductionmentioning

confidence: 99%

“…Other studies have noted kinetic sensitivities to LBO boundaries. For example, Colket et al [10], Stouffer et al [14], and Allision et al [17] found that blowoff boundaries could be correlated with the derived cetane number (DCN), a kinetic property. Although the DCN is directly related to the mixture's ignition delay time [18], it is also correlated with high-temperature kinetic properties, such as the flame speed and the extinction stretch rate [19].…”

Section: Introductionmentioning

confidence: 99%

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Near-lean blowoff dynamics in a liquid fueled combustor

Rock

Emerson

Seitzman

et al. 2020

Combustion and Flame

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This paper describes an analysis of the near-lean blow off(LBO) dynamics of spray flames, including the influence of fuel composition upon these dynamics. It is motivated by the fact that, while reasonable correlations exist for predicting blowoffconditions, the fundamental reasons for why flames supported by flow recirculation actually blow offare not well understood. Prior work on gaseous systems has shown that the blowoffevent is a culmination of several intermediate processes, initiating with local extinction of reactions ("stage 1"), followed by large scale changes in flame and flow dynamics ("stage 2"), finally leading to blowoff. In this study, near-LBO dynamics were characterized for ten liquid fuels with widely varying kinetic and physical properties. Results were compared at two air inlet temperatures, 450 and 300 K, as this influences the relative importance of physical and kinetic properties in controlling LBO. Extinction, re-ignition, and recovery of the flame are evident from these data, and grow in frequency as blowoffis approached. Results show that after a near-blowoffevent, the flame can move upstream at velocities much faster than the flow velocity, corresponding to re-ignition. Nonetheless, the majority of the flame recovery events appear to be associated with convection of hot products back upstream, not re-ignition. In contrast, downstream motion of the flame faster than the flow, which would correspond to bulk flame extinction, was never observed. This indicates that "extinction events"actually correspond to convection of the flame downstream by the flow when it loses its stabilization point. The dependence of the equivalence ratio when these events appear, their frequency, and event duration were quantified as a function of fuel composition and air inlet temperature. For example, the data shows a higher percentage of recovery from near-blowoffevents through re-ignition for high DCN fuels at the 450 K air temperature condition. These extinction/re-ignition results suggest that high DCN fuels are harder to blow offthan low DCN fuels through two mechanisms: (1) by delaying the onset of LBO precursor events, and (2) because they are able to recover from these precursor events through re-ignition more often.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Near-lean blowoff dynamics in a liquid fueled combustor

Rock

Emerson

Seitzman

et al. 2020

Combustion and Flame

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“…[16]. On comparing kerosene fuels, the kerosene flames with a high derived cetane number (DCN) are more stable than those with a low DCN [15,17,18]. The spray characteristics near blow-off of alternative fuels were compared to A2 in Ref.…”

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confidence: 99%

Lean Blow-Off Scaling of Turbulent Premixed Bluff-Body Flames of Vaporized Liquid Fuels

Pathania

Skiba

Sidey-Gibbons

et al. 2021

Journal of Propulsion and Power

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The lean blow-off (LBO) limits and structure of turbulent premixed flames were investigated with vapourised liquid fuels stabilized by a bluff-body burner. Ethanol, heptane, and two kerosenes were used. In order to facilitate comparisons to gaseous-fueled flames, results were also obtained from methane flames. The measured LBO limits indicate that, for this burner, the ethanol and heptane flames are more resilient to blow-off than the kerosene fuels. Furthermore, a correlation based on a Damköhler number (Da), which is proportional to the laminar flame speed, does not lead to the successful collapse of the different fuels, indicating that the Da correlations based on laminar flame speed is not applicable. Average OH* chemiluminescence images of the ethanol and heptane flames are qualitatively similar to that from methane: the flame brushes of both exhibit an M-shape when close to blow-off. In contrast, the distribution of OH* signal in the kerosene flames is primarily concentrated in regions further downstream of the bluff body. Ultimately, the results of this effort highlight the influence fuel-type has on the LBO of bluff-body stabilized flames. Moreover, this work indicates the LBO behavior of flames produced with complex hydrocarbon fuels cannot be fully understood via high-temperature chemistry concepts such as the laminar flame speed. Turbulent premixed combustion, blow-off scaling, Vapourise kerosene

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“…The referee combustor is experimentally characterized in an apparatus (“referee rig”) that includes an air plenum and bypass flow passages that establish flow splits representative of an engine. 27 Air from compressor outlet splits and enters into numerous air passages within and around the combustor. A fraction of the total air flows through inner axial swirler, outer axial swirler, radial swirler, and swirler cooling slot.…”

Section: Computational Methodologymentioning

confidence: 99%

Numerical simulations and analysis of the turbulent flow field in a practical gas turbine engine combustor

Hasti

Kundu

Som

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part A:

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The turbulent flow field in a practical gas turbine combustor is very complex because of the interactions between various flows resulting from components like multiple types of swirlers, dilution holes, and liner effusion cooling holes. Numerical simulations of flows in such complex combustor configurations are challenging. The challenges result from (a) the complexities of the interfaces between multiple three-dimensional shear layers, (b) the need for proper treatment of a large number of tiny effusion holes with multiple angles, and (c) the requirements for fast turnaround times in support of engineering design optimization. Both the Reynolds averaged Navier–Stokes simulation (RANS) and the large eddy simulation (LES) for the practical combustor geometry are considered. An autonomous meshing using the cut-cell Cartesian method and adaptive mesh refinement (AMR) is demonstrated for the first time to simulate the flow in a practical combustor geometry. The numerical studies include a set of computations of flows under a prescribed pressure drop across the passage of interest and another set of computations with all passages open with a specified total flow rate at the plenum inlet and the pressure at the exit. For both sets, the results of the RANS and the LES flow computations agree with each other and with the corresponding measurements. The results from the high-resolution LES simulations are utilized to gain fundamental insights into the complex turbulent flow field by examining the profiles of the velocity, the vorticity, and the turbulent kinetic energy. The dynamics of the turbulent structures are well captured in the results of the LES simulations.

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Lean Blowout and Ignition Characteristics of Conventional and Surrogate Fuels Measured in a Swirl Stabilized Combustor

Cited by 41 publications

References 14 publications

Near-lean blowoff dynamics in a liquid fueled combustor

Near-lean blowoff dynamics in a liquid fueled combustor

Lean Blow-Off Scaling of Turbulent Premixed Bluff-Body Flames of Vaporized Liquid Fuels

Numerical simulations and analysis of the turbulent flow field in a practical gas turbine engine combustor

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