Concentration Limits for n-Butane Low Temperature Flames

Williams, F. W.; Indritz, Doren; Sheinson, Ronald S.

doi:10.1080/00102207508946685

Cited by 14 publications

(3 citation statements)

References 11 publications

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“…This behavior is characteristic of the cool flame of lowtemperature kinetics, in which a high concentration of formaldehyde (CH 2 O * ) is produced. Formaldehyde emits light signals within the CH band but not in the OH band and at longer wavelengths [24,25]. Fig.…”

Section: Analysis Of Autoignition In the End-gas Regionmentioning

confidence: 99%

Influence of temperature inhomogeneities on knocking combustion

Pöschl

Sattelmayer

2008

Combustion and Flame

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Section: Analysis Of Autoignition In the End-gas Regionmentioning

confidence: 99%

Influence of temperature inhomogeneities on knocking combustion

Pöschl

Sattelmayer

2008

Combustion and Flame

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“…On the other hand, it changes appreciably with θ, that is with the flame temperature. Cool flames in n-butane-air mixtures are known to belong to the temperature range 200 − 400 • C [23], but we were unable to obtain a more accurate value by direct measurements because of large fluctuations in the burnt gas temperature. By this reason, the solid curve in Fig.…”

Section: Resultsmentioning

confidence: 95%

Effect of vorticity flip-over on the premixed flame structure: Experimental observation of type-I inflection flames

El-Rabii¹,

Kazakov²

2015

Phys. Rev. E

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Premixed flames propagating in horizontal tubes are observed to take on a convex shape towards the fresh mixture, which is commonly explained as a buoyancy effect. A recent rigorous analysis has shown, on the contrary, that this process is driven by the balance of vorticity generated by a curved flame front with the baroclinic vorticity, and predicted existence of a regime in which the leading edge of the flame front is concave. We report experimental realization of this regime. Our experiments on ethane and n-butane mixtures with air show that flames with an inflection point on the front are regularly produced in lean mixtures, provided that a sufficiently weak ignition is used. The observed flame shape perfectly agrees with that theoretically predicted.

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“…Ignition delay time is defined here by the arrival of the reflected shock wave at the measurement plane and the start of ignition, which is determined by a linear extrapolation from the maximum gradient to the ground level of the OH* chemiluminescence signal. Broad band light emission of the excited species formaldehyde (CH 2 O*) is measured at a wavelength (λ = 405 nm) to detect first stage ignition because chemiluminescence from excited formaldehyde (CH 2 O*) plays a role in cool and blue flames or two stage ignition. − Broad band light emissions from C 2 * , which could distort the chemiluminescence signal, is assumed to be absent during low temperature oxidation important for first stage ignition . First stage ignition is determined by the first local gradient peak of the CH 2 O* chemiluminescence signal.…”

Section: Experimental Methodsmentioning

confidence: 99%

Auto-Ignition of DME/DMM Fuel Blends. Part I: Minimizing Temperature Dependency by Blend Optimization

2022

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Combustion concepts based on auto-ignition are prone to detonation formation and premature ignition in the presence of local spots with increased reactivity, which can be caused by unavoidable temperature inhomogeneities in real technical applications. In this study, a fuel blend optimization approach using a fuel component with negative temperature coefficient (NTC) behavior (dimethyl ether, DME) and a fuel component without NTC behavior (dimethoxymethane, DMM) is employed to reduce the temperature sensitivity of ignition delay times and therefore reduce the tendency of premature ignition and detonation development. First, ignition delay times and first stage ignition of a DMM/air mixture are measured behind reflected shock waves in a high-pressure shock tube (20 and 35 bar, stoichiometric conditions) to select a suited chemical kinetic model. Using these data and additional literature data, a mechanism is chosen, which is used to numerically optimize the blending ratio of DME and DMM to minimize the temperature sensitivity of ignition delay times in the temperature range between 800 and 900 K for both considered pressures. The two optimized fuel blends are investigated in the shock tube regarding their ignition characteristics as before (20 and 35 bar, stoichiometric conditions). Finally, the impact of pressure, equivalence ratio, and temperature range on the optimization result is investigated numerically.

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Concentration Limits for n-Butane Low Temperature Flames

Cited by 14 publications

References 11 publications

Influence of temperature inhomogeneities on knocking combustion

Influence of temperature inhomogeneities on knocking combustion

Effect of vorticity flip-over on the premixed flame structure: Experimental observation of type-I inflection flames

Auto-Ignition of DME/DMM Fuel Blends. Part I: Minimizing Temperature Dependency by Blend Optimization

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