Detonation Waves in Gases

Lewis, Bernard; Elbe, Guenther von

doi:10.1016/b978-0-12-446751-4.50014-7

Cited by 76 publications

(122 citation statements)

References 18 publications

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“…At the peak T TC of 2024 K, the gas is 162 K hotter than the thermocouple and 238 K hotter than the fiber. The highest T gas observed is 2186 K, which is reasonable given the adiabatic flame temperature of methane/air mixtures of 2223 K [32].…”

mentioning

confidence: 67%

Thin-filament pyrometry with a digital still camera

2007

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A novel thin-filament pyrometer is presented here. It involves a consumer-grade color digital still camera with a charged-couple device sensor with 3008 × 2000 pixels and 12 bits per color plane. A blue Schott filter and custom white balance were used to yield similar red, green and blue intensities along the fibers. SiCO fibers with diameters of 13.9 µm were used and scanning-electron microscopy revealed the fibers to be uniform. Measurements were performed in a methane/air coflowing laminar jet diffusion flame with a luminosity length of 72 mm. Calibration of the pyrometer was accomplished with B-type thermocouple measurements. The camera was found to be well suited to thin-filament pyrometry. The pyrometry measurements yielded gas temperatures in the range of 1350 -2200 K with an estimated uncertainty of ± 60 K, a relative temperature resolution of ± 0.215 K, a spatial resolution of 42 µm and a temporal resolution of 0.66 ms. Fiber aging had no effect on the results. Soot deposition was less problematic for the pyrometer than for the thermocouple. THIN-FILAMENT PYROMETRY WITH A DIGITAL STILL CAMERA

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mentioning

confidence: 67%

Thin-filament pyrometry with a digital still camera

2007

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“…One important result of the calculations is that flashback, which corresponds to positive values of U, is not possible for values of the Karlovitz number K above a critical value K c (Le), which increases with decreasing values of Le; the resulting values of K c are not of order unity, as suggested by Lewis and von Elbe [1951], but roughly of order 1/Ze. Of the two branches of the curve V(K, Le), formed for values of K < K c , the one with lower values of V is unstable; even though, we have not carried out a linear stability analysis of the stationary solutions of the problem, which is not an easy task.…”

Section: Discussionmentioning

confidence: 91%

Structure of a Flame Front Propagating Against the Flow Near a Cold Wall

Kurdyumov¹,

Liñán²

2002

Int. J. Bifurcation Chaos

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The flashback or propagation of premixed flames against the flow of a reacting mixture, along the low velocity region near a cold wall, is investigated numerically. The analysis, carried out using the constant density approximation for an Arrhenius overall reaction, accounts for the effects of the Lewis number of the limiting reactant. Flame front propagation and flashback are only possible for values of the near wall velocity gradient below a critical value. The flame propagation becomes chaotic for small values of the Lewis number.

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“…The ion concentration in a hydrocarbon flame is usually low [65], and UV emissions from hydrocarbon flames are primarily due to OH radicals. Ground state molecular oxygen and long-lived excited oxygen molecules were thought to be non-reactive toward saturated polymers such as PE.…”

Section: Oxidation Mechanism By Flame Treatmentmentioning

confidence: 99%

Flame treatment of low-density polyethylene: Surface chemistry across the length scales

Song¹,

Gunst

Arlinghaus

et al. 2007

Applied Surface Science

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The relationship between surface chemistry and morphology of flame treated low-density polyethylene (LDPE) was studied by various characterization techniques across different length scales. The chemical composition of the surface was determined on the micrometer scale by Xray photoelectron spectroscopy (XPS) as well as with time of flight secondary ion mass spectrometry (ToF-SIMS), while surface wettability was obtained through contact angle (CA) measurements on the millimeter scale. The surface concentration of hydroxyl, carbonyl and carboxyl groups, as a function of the ''number'' of the flame treatment passes (which is proportional to the treatment time) was obtained. Moreover, a correlation was found with chemical composition and polarity, emphasizing the role of oxygen-containing functional groups introduced during the treatment. Carboxyl functional groups were specifically identified by fluorescent labeling and the results were compared with the ToF-SIMS data. In addition, atomic force microscopy (AFM) was used to evaluate changes in surface topography and roughness on the nanometer to micrometer length scales. After flame treatment, water-soluble low molecular weight oxidized materials (LMWOM), which were generated as products of oxidation and chain scission of the LDPE surface, agglomerated into small topographical mounds that were visible in the AFM micrographs. After rinsing the flame treated samples with water and ethanol, bead-like nodular surface structures were observed. The ionization state of flame treated LDPE surfaces was monitored by chemical force microscopy (CFM). The effective surface pK a values of carboxylic acid (-COOH) obtained by AFM were revealed by chemical force titration curves and the effective surface pK a values were found to be around 6. #

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Detonation Waves in Gases

Cited by 76 publications

References 18 publications

Thin-filament pyrometry with a digital still camera

Thin-filament pyrometry with a digital still camera

Structure of a Flame Front Propagating Against the Flow Near a Cold Wall

Flame treatment of low-density polyethylene: Surface chemistry across the length scales

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