Symposium (International) on Combustion最新文献

{"title":"High-temperature reactions of C2 with atomic and molecular oxygen","authors":"T. Kruse,&nbsp;P. Roth","doi":"10.1016/S0082-0784(98)80405-0","DOIUrl":"10.1016/S0082-0784(98)80405-0","url":null,"abstract":"<div><p>The reaction of C₂ radicals with atomic and molecular oxygen were studied behind reflected shock waves in the temperature range 2750 K≤T≤3950 K by using ring-dye-laser absorption spectroscopy. The shock-induced pyrolysis of acetylene was used as a well-defined C₂ source, which was perturbated by the addition of N₂O (O-atom source) or O₂. The addition of these species results in specific changes in the C₂ concentration compared to the unperturbated pyrolysis, mainly caused by the following reactions: {fx1} for which the rate coefficients {fx2} were obtained.</p></div>","PeriodicalId":101203,"journal":{"name":"Symposium (International) on Combustion","volume":"27 1","pages":"Pages 193-200"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0082-0784(98)80405-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"97070283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Multidimensional laser diagnostic and numerical analysis of no formation in a gasoline engine","authors":"Göran Josefsson ,&nbsp;Ingemar Magnusson ,&nbsp;Frank Hildenbrand ,&nbsp;Christof Schulz ,&nbsp;Volker Sick","doi":"10.1016/S0082-0784(98)80055-6","DOIUrl":"10.1016/S0082-0784(98)80055-6","url":null,"abstract":"<div><p>Laser diagnostic imaging techniques were used to obtain detailed in-cylinder data from a commercial gasoline engine. Mean flowfields and turbulence intensities were acquired using particle imaging veloci-metry (PIV). Instantaneous quantitative NO-concentration fields were measured using planar laser-induced fluorescence (LIF). From experimental images of NO, also the flame propagation could be deduced. Combustion and NO formation were simulated with a 3-D computer code SPEEDSTAR. The overall agreement between experimental data and computational results is encouraging in general, with remaining issues to be solved. The mean flow is well predicted, whereas the prediction of turbulence quantities is less satisfactory. Calculated results for flame propagation are in good agreement with measurements. NO concentrations resulting from calculations are close to those measured, both in respect to their spatial distribution and absolute number densities. As could be expected, the highest NO concentrations are found in regions where combustion started earliest. Local concentrations of NO are found be up to 4 times higher than those in the exhaust. The comparison of experimental results with calculations clearly shows that, although the 3-D computer model can predict major features of the in-cylinder processes in agreement with measurements, details such as the exact flow pattern and flame development are difficult to capture and depend critically on some of the models parameters used.</p></div>","PeriodicalId":101203,"journal":{"name":"Symposium (International) on Combustion","volume":"27 2","pages":"Pages 2085-2092"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0082-0784(98)80055-6","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"112315749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combustion-induced pressure effects in supersonic diffusion flames","authors":"K.H. Luo ,&nbsp;K.N.C. Bray","doi":"10.1016/S0082-0784(98)80065-9","DOIUrl":"10.1016/S0082-0784(98)80065-9","url":null,"abstract":"<div><p>A turbulent diffusion flame at a convective Mach number 1.2 was investigated using direct numerical simulation (DNS). The DNS employed the full time-dependent compressible Navier-Stokes equations coupled with a one-step chemical reaction governed by the Arrhenius kinetics. Detailed study of combustion-induced pressure effects on turbulence generation, conserved scalar, and stagnation enthalpy transport was conducted. Local countergradient diffusion (CGD) of a conserved scalar flux was observed for the first time in a diffusion flame where heat release was strong enough while gradient diffusion prevailed when heat release was zero or weak. The CGD occurred in spite of the absence of an externally imposed mean pressure gradient and was attributed to combustion-induced pressure fluctuations. The balance of the turbulent kinetic energy budget was strongly influenced by the pressure dilatation and the (combustion-induced) mean pressure work when heat release was strong. Both terms can be a source or a sink of turbulence, depending on the intricate interactions between turbulence and combustion. However, the temporal change in pressure <em>ϱp/ϱt</em> had an insignificant influence on the stagnation enthalpy transport. A linear relation between the stagnation enthalpy and the mixture fraction was confirmed, which could lead to considerable simplification in modeling high-speed turbulent combustion.</p></div>","PeriodicalId":101203,"journal":{"name":"Symposium (International) on Combustion","volume":"27 2","pages":"Pages 2165-2171"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0082-0784(98)80065-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"112963113","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simultaneous rayleigh, raman, and LIF measurements in turbulent premixed methane-air flames","authors":"J.H. Frank ,&nbsp;R.S. Barlow","doi":"10.1016/S0082-0784(98)80470-0","DOIUrl":"10.1016/S0082-0784(98)80470-0","url":null,"abstract":"<div><p>Instantaneous measurements of temperature, major species, OH, CO, and NO are performed in turbulent premixed flames using simultaneous Rayleigh scattering, Raman scattering, and laser-induced fluorescence (LIF). Temperature is determined from Rayleigh scattering, and concentrations of CH₄, O₂, N₂, H₂O, CO₂, and H₂ are obtained from Raman scattering. Linear LIF is used to measure OH and NO, while two-photon LIF is used to determine CO concentrations. The two-photon CO-LIF system provides significant improvements over CO-Raman measurements. This combination of diagnostic techniques is used to investigate the detailed compositional structure of turbulent lean premixed methane-air flames. Three turbulent flames having different equivalence ratios are considered. The ratio of rms velocity to laminar flame speed ranges from approximately 6 to 17. The correlation of major species, OH, and CO concentrations with temperature are similar to those predicted by one-dimensional laminar flame calculations. However, NO concentrations in the leaner flames are higher than the predicted values.</p></div>","PeriodicalId":101203,"journal":{"name":"Symposium (International) on Combustion","volume":"27 1","pages":"Pages 759-766"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0082-0784(98)80470-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"96604349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Automatically simplified chemical kinetics and molecular transport and its applications in premixed and non-premixed laminar flame calculations","authors":"T. Blasenbrey,&nbsp;D. Schmidt,&nbsp;U. Maas","doi":"10.1016/S0082-0784(98)80440-2","DOIUrl":"10.1016/S0082-0784(98)80440-2","url":null,"abstract":"<div><p>Among many other methods for simplifying chemical kinetics for laminar and turbulent flame calculations, the method of intrinsic low-dimensional manifolds (ILDM) has shown to be an efficient tool for the development of reduced kinetic schemes. Based on a numerical analysis, it identifies and decouples the fast relaxing timescales of the chemical system. The results, for example, the thermokinetic state of the system or the reaction rates, are then stored in terms of a small number of parameters (mixture fraction, reaction progress variables) for subsequent use in reacting flow calculations. Furthermore, together with the reduced mechanism, information about the coupling of the chemical kinetics with the physical processes (molecular transport, turbulent mixing) is obtained.</p><p>In this paper, we present a method that allows an efficient implementation of the ILDM method in flame calculations and overcomes several problems that had been discussed in previous work. It is based on three ingredients: A robust numerical method to calculate the ILDM, a storage scheme that allows an easy implementation in CFD codes, and a model for the coupling of the chemical kinetics with transport processes. In this way, not only the chemistry can be calculated beforehand but also a reduced set of diffusion coefficients. The method is verified by simulations of laminar syngas-air flames with an emphasis on the non-premixed case.</p></div>","PeriodicalId":101203,"journal":{"name":"Symposium (International) on Combustion","volume":"27 1","pages":"Pages 505-511"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0082-0784(98)80440-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"96534539","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Two-dimensional failure waves and ignition fronts in premixed combustion","authors":"T.G. Vedarajan ,&nbsp;J. Buckmaster ,&nbsp;P. Ronney","doi":"10.1016/S0082-0784(98)80444-X","DOIUrl":"10.1016/S0082-0784(98)80444-X","url":null,"abstract":"<div><p>This paper is a continuation of our work on edge-flames in premixed combustion. An edge-flame is a two-dimensional structure constructed from a one-dimensional configuration that has two stable solutions (bistable equilibrium). Edge-flames can display wavelike behavior, advancing as ignition fronts or retreating as failure waves. Here we consider two one-dimensional configurations: twin deflagrations in a straining flow generated by the counterflow of fresh streams of mixture; and a single deflagration subject to radiation losses. The edge-flames constructed from the first configuration have positive or negative speeds, according to the value of the strain rate. But our numerical solutions strongly suggest that only positive speeds (corresponding to ignition fronts) can exist for the second configuration. We show that this phenomenon can also occur in diffusion flames when the Lewis numbers are small. And we discuss the asymptotics of the one-dimensional twin deflagration configuration, an overlooked problem from the 70s.</p></div>","PeriodicalId":101203,"journal":{"name":"Symposium (International) on Combustion","volume":"27 1","pages":"Pages 537-544"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0082-0784(98)80444-X","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"99900798","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pyrolysis product absorption by burning benzene droplets","authors":"Nathan D. Marsh,&nbsp;Delin Zhu,&nbsp;Mary J. Wornat","doi":"10.1016/S0082-0784(98)80033-7","DOIUrl":"10.1016/S0082-0784(98)80033-7","url":null,"abstract":"<div><p>By burning droplets of benzene in a single-droplet combustor and performing phase-discriminating sampling of the liquid and gas phases of the droplet system, we have found that gas-phase pyrolysis products arise in the liquid phase of the droplet. The experiments are conducted at 1000 K and 21 mol % O₂ in the postcombustion gas from an oxygen-rich premixed methane flame. Disruptive burning, which has not previously been reported for a pure hydrocarbon in normal gravity conditions, is observed at the end of the droplet residence time (∼92 ms). Samples of the liquid phase have been taken at various times throughout the combustion lifetime and analyzed by high-pressure liquid chromatography. Compositional analysis using ultraviolet-visible absorbance spectra of the separated components of the samples reveals a wide variety of pure polycyclic aromatic hydrocarbons (PAH), substituted PAH, and cyclopenta-fused PAH. In addition, recent synthesis of new reference standards has enabled identification of cyclopenta-fused PAH—cyclopent[<em>hi</em>]acephenanthrylene, cyclopenta[<em>cd</em>]fluoranthene, and dicyclopenta[<em>cd, jk</em>]pyrene—which have never before been identified as benzene products. Because the droplet remains relatively cold (∼350 K) with respect to the gas phase in the oxygen-deficient zone between the droplet and the flame (∼2000 K), we conclude that these compounds are gas-phase pyrolysis products that are obsorbed into the droplet, rather than products of reactions within the droplet. These heavier species may play a role in observed terminal disruptive burning events by acting as additional droplet components that promote multicomponent effects. Analysis of species concentrations over time reveals the dominance of both ring rupture pyrolysis products such as phenylacetylene, triacetylene, and acenaphthylene, and biaryl pyrolysis products such as biphenyl. These four products in particular represent 70% of the identified mass of absorbed pyrolysis products, which accounts for up to 5% of the droplet mass at the end of its lifetime.</p></div>","PeriodicalId":101203,"journal":{"name":"Symposium (International) on Combustion","volume":"27 2","pages":"Pages 1897-1905"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0082-0784(98)80033-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"101226126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Kinetic investigations of the reactions of toluene and of p-xylene with molecular oxygen between 1050 and 1400 K","authors":"R.A. Eng ,&nbsp;C. Fittschen ,&nbsp;A. Gebert ,&nbsp;P. Hibomvschi ,&nbsp;H. Hippler ,&nbsp;A.-N. Unterreiner","doi":"10.1016/S0082-0784(98)80407-4","DOIUrl":"10.1016/S0082-0784(98)80407-4","url":null,"abstract":"&lt;div&gt;&lt;p&gt;The reaction of toluene with molecular oxygen was studied behind reflected shock waves. Mixtures of 0.5–1 mol% toluene and 5–10% oxygen in argon were investigated in the temperature range between 1050 and 1400 K at total pressures between 2 and 4 bar. We followed the rate of formation of the benzyl radicals by time-resolved UV absorption at 257 nm. The measured concentration-time profiles of the benzyl radicals were numerically reproduced using a simple reaction mechanism. For the initial reaction&lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mo&gt;C&lt;/mo&gt;&lt;mn&gt;6&lt;/mn&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mo&gt;H&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;C&lt;/mo&gt;&lt;msub&gt;&lt;mo&gt;H&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mo&gt;O&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;→&lt;/mo&gt;&lt;msub&gt;&lt;mo&gt;C&lt;/mo&gt;&lt;mn&gt;6&lt;/mn&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mo&gt;H&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;C&lt;/mo&gt;&lt;msub&gt;&lt;mo&gt;H&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mo&gt;H&lt;/mo&gt;&lt;msub&gt;&lt;mo&gt;O&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mo&gt;R&lt;/mo&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt; a rate coefficient&lt;em&gt;k&lt;/em&gt;&lt;sub&gt;1&lt;/sub&gt; of &lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;mn&gt;1&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msup&gt;&lt;mrow&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mn&gt;14&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;exp&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mrow&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;180&lt;/mn&gt;&lt;mo&gt;kj&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;mol&lt;/mo&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;/mrow&gt;&lt;mo&gt;]&lt;/mo&gt;&lt;/mrow&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mo&gt;cm&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;mol&lt;/mo&gt;&lt;mo&gt;s&lt;/mo&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;1050&lt;/mn&gt;&lt;mo&gt;K&lt;/mo&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mn&gt;1400&lt;/mn&gt;&lt;mo&gt;K&lt;/mo&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;was determined with an accuracy of 30%. The rate constant &lt;em&gt;k&lt;/em&gt;&lt;sub&gt;2&lt;/sub&gt;of the subsequent reaction &lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;math&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mo&gt;C&lt;/mo&gt;&lt;mn&gt;6&lt;/mn&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mo&gt;H&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;C&lt;/mo&gt;&lt;msub&gt;&lt;mo&gt;H&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;mo&gt;H&lt;/mo&gt;&lt;msub&gt;&lt;mo&gt;O&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;→&lt;/mo&gt;&lt;msub&gt;&lt;mo&gt;C&lt;/mo&gt;&lt;mn&gt;6&lt;/mn&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mo&gt;H&lt;/mo&gt;&lt;mn&gt;5&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;C&lt;/mo&gt;&lt;msub&gt;&lt;mo&gt;H&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;+&lt;/mo&gt;&lt;msub&gt;&lt;mo&gt;H&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;msub&gt;&lt;mo&gt;O&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mo&gt;R&lt;/mo&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/mrow&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;was determined to be.&lt;span&gt;&lt;span&gt;&lt;span&gt;&lt;math&gt;&lt;msub&gt;&lt;mi&gt;k&lt;/mi&gt;&lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt;&lt;mo&gt;=&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;mo&gt;×&lt;/mo&gt;&lt;msup&gt;&lt;mn&gt;10&lt;/mn&gt;&lt;mrow&gt;&lt;mn&gt;14&lt;/mn&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;mo&gt;exp&lt;/mo&gt;&lt;mo&gt;⁡&lt;/mo&gt;&lt;mrow&gt;&lt;mo&gt;[&lt;/mo&gt;&lt;mrow&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;mo&gt;−&lt;/mo&gt;&lt;mn&gt;92&lt;/mn&gt;&lt;mo&gt;kj&lt;/mo&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mo&gt;mol&lt;/mo&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;R&lt;/mi&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;/mrow&gt;&lt;mo&gt;]&lt;/mo&gt;&lt;/mrow&gt;&lt;mfrac&gt;&lt;mrow&gt;&lt;msup&gt;&lt;mo&gt;cm&lt;/mo&gt;&lt;mn&gt;3&lt;/mn&gt;&lt;/msup&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mo&gt;mol&lt;/mo&gt;&lt;mo&gt;s&lt;/mo&gt;&lt;/mrow&gt;&lt;/mfrac&gt;&lt;mo&gt;(&lt;/mo&gt;&lt;mn&gt;1150&lt;/mn&gt;&lt;mo&gt;K&lt;/mo&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mi&gt;T&lt;/mi&gt;&lt;mo&gt;&lt;&lt;/mo&gt;&lt;mn&gt;1250&lt;/mn&gt;&lt;mo&gt;K&lt;/mo&gt;&lt;mo&gt;)&lt;/mo&gt;&lt;/math&gt;&lt;/span&gt;&lt;/span&gt;&lt;/span&gt;The reaction of &lt;em&gt;p&lt;/em&gt;-xylene with molecular oxygen was investigated using the same technique. Mixtures of 0.25–0.5 mol % &lt;em&gt;p&lt;/em&gt;-xylene and 2.5–10 mol% oxygen in argon were shock-heated to temperatures between 1130 and 1380 K. We followed the formation of &lt;em&gt;p&lt;/em&gt;-methyl-benzyl radicals by time-resolved UV a","PeriodicalId":101203,"journal":{"name":"Symposium (International) on Combustion","volume":"27 1","pages":"Pages 211-218"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0082-0784(98)80407-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"98416850","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ignition and combustion of levitated magnesium particles in carbon dioxide","authors":"Benjamin Legrand ,&nbsp;Evgeny Shafirovich ,&nbsp;Michaël Marion ,&nbsp;Christian Chauveau ,&nbsp;Iskender Gökalp","doi":"10.1016/S0082-0784(98)80093-3","DOIUrl":"10.1016/S0082-0784(98)80093-3","url":null,"abstract":"<div><p>This paper considers ignition and combustion of small (50–100 μm) single particles of magnesium and 50-50 magnesium-aluminum alloy in the atmosphere of carbon dioxide or its mixtures with argon. This investigation is of interest for both basic combustion science and applications to rocket engines, including those using Martian CO₂ as an oxidizer, An experimental setup with an electrodynamic levitator inside a high-pressure chamber was employed. A CO₂ laser was used for heating to ignition of the particles. The laser was switched off after ignition. The experiments were conducted with the oxidizer at room temperature over the range of pressures from 0.1 to 2 MPa. Effects of the CO₂ concentration and pressure on the critical ignition conditions, ignition delay times, and burning times have been determined for Mg particles. The results clearly indicate that ignition of Mg in CO₂ is controlled by chemical kinetics and that its combustion is controlled by diffusion in gas phase. Quantitative disagreement of the observed critical ignition pressures with previous experimental data on ignition of Mg disks in CO₂ is explained by the differences in heat-loss mechanisms. The measured values of the burning rate correlate well with previous experimental results on combustion of 2-mm particles and with a quasi-steady model of Mg particle burning in CO₂. In contrast to pure Mg and Al, particles of Mg−Al alloy did not ignite in CO₂ under the present experimental conditions.</p></div>","PeriodicalId":101203,"journal":{"name":"Symposium (International) on Combustion","volume":"27 2","pages":"Pages 2413-2419"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0082-0784(98)80093-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"104606756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling the temperature and pressure dependence of the reaction HO+CO ixHOCO ixH+CO2","authors":"Jürgen Troe","doi":"10.1016/S0082-0784(98)80402-5","DOIUrl":"10.1016/S0082-0784(98)80402-5","url":null,"abstract":"<div><p>The bimolecular reaction HO+CO ixH+CO₂ involves the intermediate formation of HOCO. As a consequence, the rate coefficient shows a complicated temperature and pressure dependence. An optimized <em>E</em>- and <em>J</em>-resolved rigid activated complex RRKM theory, with simplified <em>E</em>- and <em>J</em>-resolved pressure-dependent collision efficiencies, fits the available experimental data and allows for extrapolations to unexplored conditions. Experiments between 80 and 2370 K, between 10⁻³ and 10³ bar in the bath gas He, and below 1 bar in Ar, N₂, CF₄ SF₆, and H₂O at 298 K, serve as the database. A limiting low-pressure rate constant for HO removal of <em>k_o</em>=[1.0×10¹³ exp(−8050 K/<em>T</em>)+9.0×10¹¹ exp(−2300 K/<em>T</em>)+1.01×10¹¹ exp (−30 K/<em>T</em>)] cm³ mol⁻¹ s⁻¹ and a limiting high-pressure rate constant of <em>k_∞</em>=[1.23×10¹⁵ exp (−7520 K/<em>T</em>)+1.1×10¹³ exp(−1850 K/<em>T</em>)+8.0×10¹¹ exp(−120 K/<em>T</em>] cm³ mol⁻¹ s⁻¹ will reproduce the results. The pressure dependence of the rate coefficient as a function of the temperature is represented for the bath gases He, Ar, N₂, CF₄, SF₆, and H₂O. Rate coefficients for HOCO formation and HOCO dissociation are also given.</p></div>","PeriodicalId":101203,"journal":{"name":"Symposium (International) on Combustion","volume":"27 1","pages":"Pages 167-175"},"PeriodicalIF":0.0,"publicationDate":"1998-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0082-0784(98)80402-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"104663521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}