Experimental investigation of the auto-ignition of a transient propane Jet-in-Hot-Coflow

Arndt, Christoph M.; Papageorge, Michael J.; Fuest, Frederik; Sutton, Jeffrey A.; Meier, Wolfgang

doi:10.1016/j.proci.2018.06.195

Cited by 18 publications

(7 citation statements)

References 25 publications

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“…Following calibration and estimation of the gas composition, this can provide the local number of molecules per unit volume (number density, n) and, hence, local temperature based on the ideal gas law. In non-reacting flows, results from this method can be accurate to within 1% (Arndt et al, 2019).…”

Section: Principles Of Light-matter Interactionsmentioning

confidence: 97%

“…The occurrence of these structures is largely dependent on the combination of fuel/oxidant composition and temperatures (Medwell et al, 2008(Medwell et al, , 2016Medwell and Dally, 2012a;Evans et al, 2016a,b), which dictates both the stoichiometric and most-reactive mixture fractions, and the underlying flow-field, which governs the local strain-field between the fuel and oxidant streams (Ye et al, 2016). Of these mechanisms, ignition kernel formation and autoignitive triple flames have been examined at significant length, and a full discussion is not provided here (Gordon et al, 2008;Mastorakos, 2009;Yoo et al, 2011;Arndt et al, 2012Arndt et al, , 2019Sidey and Mastorakos, 2015;Macfarlane et al, 2017Macfarlane et al, , 2018Macfarlane et al, , 2019Ramachandran et al, 2019). Observations from OH-PLIF (Medwell et al, 2008), and resulting numerical studies (Medwell et al, 2009b;Evans et al, 2016bEvans et al, , 2017a suggest that the least studied of these mechanisms-the "weak-to-strong transition"anchors as a weakly reacting diffusion flame close to the jet exit, in ≈ 0.2 (Evans et al, 2016a) under temperature and flowfield conditions almost identical to the laminar coflow stream.…”

Section: Reaction-zone Imaging In Understanding Flame Stabilizationmentioning

confidence: 99%

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Understanding and Interpreting Laser Diagnostics in Flames: A Review of Experimental Measurement Techniques

Evans

Medwell

2019

Front. Mech. Eng.

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There is a wealth of existing experimental data of flames collected using laser diagnostics. The primary objective of this review is to provide context and guidance in interpreting these laser diagnostic data. This educational piece is intended to benefit those new to laser diagnostics or with specialization in other facets of combustion science, such as computational modeling. This review focuses on laser-diagnostics in the context of the commonly used canonical jet-in-hot-coflow (JHC) burner, although the content is applicable to a wide variety of configurations including, but not restricted to, simple jet, bluff body, swirling and stratified flames. The JHC burner configuration has been used for fundamental studies of moderate or intense low oxygen dilution (MILD) combustion, autoignition and flame stabilization in hot environments. These environments emulate sequential combustion or exhaust gas recirculation. The JHC configuration has been applied in several burners for parametric studies of MILD combustion, flame reaction zone structure, behavior of fuels covering a significant range of chemical complexity, and the collection of data for numerical model validation. Studies of unconfined JHC burners using gaseous fuels have employed point-based Rayleigh-Raman or two-dimensional Rayleigh scattering measurements for the temperature field. While the former also provides simultaneous measurements of major species concentrations, the latter has often been used in conjunction with planar laser-induced fluorescence (PLIF) to simultaneously provide quantitative or qualitative measurements of radical and intermediary species. These established scattering-based thermography techniques are not, however, effective in droplet or particle laden flows, or in confined burners with significant background scattering. Techniques including coherent anti-Stokes Raman scattering (CARS) and non-linear excitation regime two-line atomic fluorescence (NTLAF) have, however, been successfully demonstrated in both sooting and spray flames. This review gives an overview of diagnostics techniques undertaken in canonical burners, with the intention of providing an introduction to laser-based measurements in combustion. The efficacy, applicability and accuracy of the experimental techniques are also discussed, with examples from studies of flames in JHC burners. Finally, current and future directions for studies of flames using the JHC configuration including spray flames and studies and elevated pressures are summarized.

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Section: Principles Of Light-matter Interactionsmentioning

confidence: 97%

Section: Reaction-zone Imaging In Understanding Flame Stabilizationmentioning

confidence: 99%

Understanding and Interpreting Laser Diagnostics in Flames: A Review of Experimental Measurement Techniques

Evans

Medwell

2019

Front. Mech. Eng.

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“…The auto-ignition experiment, which is the subject of the investigations in the present work, has been conducted by Arndt et al [7,9] on the "DLR (Deutsches Zentrum für Luft-und Raumfahrt (Germany Aerospace Center)) JHC (jet in hot coflow)" burner [4,6]. In this experiment, the auto-ignition of a methane jet in a coflow of hot, vitiated air is investigated.…”

Section: Description Of Experimental Setupmentioning

confidence: 99%

Transported PDF simulation of auto-ignition of a turbulent methane jet in a hot, vitiated coflow

Fiolitakis

Arndt

2019

Combustion Theory and Modelling

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In the current work, the auto-ignition of a turbulent round methane jet is studied numerically by means of a transported probability density function (PDF) method. The methane jet is issued into a hot, vitiated coflow, where it ignites to form a steady lifted flame. For this flame, experimental data of hydroxyl, temperature and mixture fraction are provided in the area where the fuel auto-ignites. To model this experiment, the transport equation for the thermochemical PDF is solved using a hybrid finite volume / Lagrangian Monte-Carlo method. Turbulence is modeled using the k-ε turbulence model including a jet-correction. Computational results are compared to experimental data in terms of mean quantities, variances and liftoff height. Moreover, the structure of the one-point, one-time marginal PDF of temperature is analyzed and compared to experimental data which are provided in this work. It is found that the transported PDF method in conjunction with the k-ε model is capable of reproducing these statistical data very well. In particular the effect of ignition on the marginal PDF of temperature can be well reproduced with this approach. To further analyze the relevant processes in the evolution of the temperature PDF, a statistically homogeneous system is studied both numerically and analytically.

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“…So far, quantitative scalar measurements with high spatio-temporal resolution in Jet-in-Hot-Coflow flames are limited to temperature and mixture fraction. Arndt et al and Papageorge et al studied the formation of ignition kernels in a jet-in-hot-coflow (JHC) burner developed at the German Aerospace Center (DLR), the DLR JHC, using planar laser Rayleigh-scattering at a pulse repetition rate of 10 kHz for different fuels [30][31][32]. It was found that the scalar dissipation rate plays a key role in determining the ignition time and location.…”

Section: Introductionmentioning

confidence: 99%

OH planar laser-induced fluorescence measurements with high spatio-temporal resolution for the study of auto-ignition

2019

Self Cite

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For the detailed understanding of transient combustion processes, in particular, of auto-ignition, quantitative measurements with high spatio-temporal resolution are desirable. These can, for instance, serve as validation data for time-resolved numerical simulations, and, in particular for the combustion models used in those simulations. In the current study, a jet-in-hot-coflow (JHC) burner, developed at the German Aerospace Center (DLR), the DLR JHC, was used to inject a turbulent methane jet into the hot exhaust gas of a lean hydrogen/air fame, and a steady state jet flame was established." In addition, fuel could be injected in a transient manner. Here, an auto-igniting jet was observed. The flame stabilization of the steady state jet flame and the auto-ignition during transient fuel injection were studied using high-speed laser-based and optical measurements. A strategy for quantifying high-speed OH planar laser-induced fluorescence (PLIF) is presented and the measurement uncertainties are evaluated. The flame stabilization mechanism in steady state jet flames was assessed using probability density functions (PDFs) of the OH concentration at different axial and radial locations. The formation of auto-ignition kernels during transient fuel injection is evaluated based on time-series of the OH concentration. It is shown how the OH concentration levels and PDF shapes can be used to characterize the chemical state of the reacting flow and to distinguish between auto-ignition and flame propagation.

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Experimental investigation of the auto-ignition of a transient propane Jet-in-Hot-Coflow

Cited by 18 publications

References 25 publications

Understanding and Interpreting Laser Diagnostics in Flames: A Review of Experimental Measurement Techniques

Understanding and Interpreting Laser Diagnostics in Flames: A Review of Experimental Measurement Techniques

Transported PDF simulation of auto-ignition of a turbulent methane jet in a hot, vitiated coflow

OH planar laser-induced fluorescence measurements with high spatio-temporal resolution for the study of auto-ignition

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