Journal of Combustion最新文献_第10页

Assessing the Role of Particles in Radiative Heat Transfer during Oxy-Combustion of Coal and Biomass Blends 评估颗粒在煤和生物质混合燃烧过程中辐射传热中的作用

IF 0.7

Journal of Combustion Pub Date : 2015-02-19 DOI: 10.1155/2015/793683

G. Krishnamoorthy, Caitlyn M. Wolf

{"title":"Assessing the Role of Particles in Radiative Heat Transfer during Oxy-Combustion of Coal and Biomass Blends","authors":"G. Krishnamoorthy, Caitlyn M. Wolf","doi":"10.1155/2015/793683","DOIUrl":"https://doi.org/10.1155/2015/793683","url":null,"abstract":"This study assesses the required fidelities in modeling particle radiative properties and particle size distributions (PSDs) of combusting particles in Computational Fluid Dynamics (CFD) investigations of radiative heat transfer during oxy-combustion of coal and biomass blends. Simulations of air and oxy-combustion of coal/biomass blends in a 0.5 MW combustion test facility were carried out and compared against recent measurements of incident radiative fluxes. The prediction variations to the combusting particle radiative properties, particle swelling during devolatilization, scattering phase function, biomass devolatilization models, and the resolution (diameter intervals) employed in the fuel PSD were assessed. While the wall incident radiative flux predictions compared reasonably well with the experimental measurements, accounting for the variations in the fuel, char and ash radiative properties were deemed to be important as they strongly influenced the incident radiative fluxes and the temperature predictions in these strongly radiating flames. In addition, particle swelling and the diameter intervals also influenced the incident radiative fluxes primarily by impacting the particle extinction coefficients. This study highlights the necessity for careful selection of particle radiative property, and diameter interval parameters and the need for fuel fragmentation models to adequately predict the fly ash PSD in CFD simulations of coal/biomass combustion.","PeriodicalId":44364,"journal":{"name":"Journal of Combustion","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2015-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75853530","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}

引用次数: 20

Predicting Radiative Heat Transfer in Oxy-Methane Flame Simulations: An Examination of Its Sensitivities to Chemistry and Radiative Property Models 预测氧-甲烷火焰模拟中的辐射传热:对化学和辐射特性模型敏感性的检验

IF 0.7

Journal of Combustion Pub Date : 2015-02-12 DOI: 10.1155/2015/439520

H. Abdul-Sater, G. Krishnamoorthy, M. Ditaranto

{"title":"Predicting Radiative Heat Transfer in Oxy-Methane Flame Simulations: An Examination of Its Sensitivities to Chemistry and Radiative Property Models","authors":"H. Abdul-Sater, G. Krishnamoorthy, M. Ditaranto","doi":"10.1155/2015/439520","DOIUrl":"https://doi.org/10.1155/2015/439520","url":null,"abstract":"Measurements from confined, laminar oxy-methane flames at different O2/CO2 dilution ratios in the oxidizer are first reported with measurements from methane-air flames included for comparison. Simulations of these flames employing appropriate chemistry and radiative property modeling options were performed to garner insights into the experimental trends and assess prediction sensitivities to the choice of modeling options. The chemistry was modeled employing a mixture-fraction based approach, Eddy dissipation concept (EDC), and refined global finite rate (FR) models. Radiative properties were estimated employing four weighted-sum-of-gray-gases (WSGG) models formulated from different spectroscopic/model databases. The mixture fraction and EDC models correctly predicted the trends in flame length and OH concentration variations, and the O2, CO2, and temperature measurements outside the flames. The refined FR chemistry model predictions of CO2 and O2 deviated from their measured values in the flame with 50% O2 in the oxidizer. Flame radiant power estimates varied by less than 10% between the mixture fraction and EDC models but more than 60% between the different WSGG models. The largest variations were attributed to the postcombustion gases in the temperature range 500 K–800 K in the upper sections of the furnace which also contributed significantly to the overall radiative transfer.","PeriodicalId":44364,"journal":{"name":"Journal of Combustion","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2015-02-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89763015","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}

引用次数: 9

Experimental Study of Gas Explosions in Hydrogen Sulfide-Natural Gas-Air Mixtures 硫化氢-天然气-空气混合物中气体爆炸的实验研究

IF 0.7

Journal of Combustion Pub Date : 2014-08-21 DOI: 10.1155/2014/905893

A. Gaathaug, D. Bjerketvedt, Knut Vågsæther, S. Nilsen

引用次数: 3

Augmenting the Structures in a Swirling Flame via Diffusive Injection 通过扩散喷射增强旋转火焰中的结构

IF 0.7

Journal of Combustion Pub Date : 2014-08-13 DOI: 10.1155/2014/280501

Jonathan Lewis, A. Valera-Medina, R. Marsh, S. Morris

引用次数: 13

Testing Vegetation Flammability: The Problem of Extremely Low Ignition Frequency and Overall Flammability Score 植物可燃性测试:极低点火频率和总体可燃性得分问题

IF 0.7

Journal of Combustion Pub Date : 2014-06-26 DOI: 10.1155/2014/970218

Zorica Kauf, A. Fangmeier, R. Rosavec, Ž. Španjol

引用次数: 15

Nonpremixed Counterflow Flames: Scaling Rules for Batch Simulations 非预混逆流火焰:批量模拟的缩放规则

IF 0.7

Journal of Combustion Pub Date : 2014-06-22 DOI: 10.1155/2014/484372

T. Fiala, T. Sattelmayer

引用次数: 23

Development and Parametric Evaluation of a Tabulated Chemistry Tool for the Simulation of n-Heptane Low-Temperature Oxidation and Autoignition Phenomena 模拟正庚烷低温氧化和自燃现象的制表化学工具的开发和参数评价

IF 0.7

Journal of Combustion Pub Date : 2014-06-10 DOI: 10.1155/2014/237049

G. Vourliotakis, D. Kolaitis, M. Founti

{"title":"Development and Parametric Evaluation of a Tabulated Chemistry Tool for the Simulation of n-Heptane Low-Temperature Oxidation and Autoignition Phenomena","authors":"G. Vourliotakis, D. Kolaitis, M. Founti","doi":"10.1155/2014/237049","DOIUrl":"https://doi.org/10.1155/2014/237049","url":null,"abstract":"Accurate modelling of preignition chemical phenomena requires a detailed description of the respective low-temperature oxidative reactions. Motivated by the need to simulate a diesel oil spray evaporation device operating in the “stabilized” cool flame regime, a “tabulated chemistry” tool is formulated and evaluated. The tool is constructed by performing a large number of kinetic simulations, using the perfectly stirred reactor assumption. n-Heptane is used as a surrogate fuel for diesel oil and a detailed n-heptane mechanism is utilized. Three independent parameters (temperature, fuel concentration, and residence time) are used, spanning both the low-temperature oxidation and the autoignition regimes. Simulation results for heat release rates, fuel consumption and stable or intermediate species production are used to assess the impact of the independent parameters on the system’s thermochemical behaviour. Results provide the physical and chemical insight needed to evaluate the performance of the tool when incorporated in a CFD code. Multidimensional thermochemical behaviour “maps” are created, demonstrating that cool flame activity is favoured under fuel-rich conditions and that cool flame temperature boundaries are extended with increasing fuel concentration or residence time.","PeriodicalId":44364,"journal":{"name":"Journal of Combustion","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2014-06-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80097684","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}

引用次数: 4

Combustion Characteristics for Turbulent Prevaporized Premixed Flame Using Commercial Light Diesel and Kerosene Fuels 商用轻柴油和煤油燃料紊流预蒸发预混火焰的燃烧特性

IF 0.7

Journal of Combustion Pub Date : 2014-06-01 DOI: 10.1155/2014/363465

M. Shehata, M. Elkotb, H. Salem

{"title":"Combustion Characteristics for Turbulent Prevaporized Premixed Flame Using Commercial Light Diesel and Kerosene Fuels","authors":"M. Shehata, M. Elkotb, H. Salem","doi":"10.1155/2014/363465","DOIUrl":"https://doi.org/10.1155/2014/363465","url":null,"abstract":"Experimental study has been carried out for investigating fuel type, fuel blends, equivalence ratio, Reynolds number, inlet mixture temperature, and holes diameter of perforated plate affecting combustion process for turbulent prevaporized premixed air flames for different operating conditions. CO2, CO, H2, N2, C3H8, C2H6, C2H4, flame temperature, and gas flow velocity are measured along flame axis for different operating conditions. Gas chromatographic (GC) and CO/CO2 infrared gas analyzer are used for measuring different species. Temperature is measured using thermocouple technique. Gas flow velocity is measured using pitot tube technique. The effect of kerosene percentage on concentration, flame temperature, and gas flow velocity is not linearly dependent. Correlations for adiabatic flame temperature for diesel and kerosene-air flames are obtained as function of mixture strength, fuel type, and inlet mixture temperature. Effect of equivalence ratio on combustion process for light diesel-air flame is greater than for kerosene-air flame. Flame temperature increases with increased Reynolds number for different operating conditions. Effect of Reynolds number on combustion process for light diesel flame is greater than for kerosene flame and also for rich flame is greater than for lean flame. The present work contributes to design and development of lean prevaporized premixed (LPP) gas turbine combustors.","PeriodicalId":44364,"journal":{"name":"Journal of Combustion","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2014-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72920503","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}

引用次数: 7

Numerical Simulation of the Deflagration-to-Detonation Transition in Inhomogeneous Mixtures 非均匀混合物中爆燃-爆轰过渡的数值模拟

IF 0.7

Journal of Combustion Pub Date : 2014-05-19 DOI: 10.1155/2014/686347

F. Ettner, K. G. Vollmer, T. Sattelmayer

{"title":"Numerical Simulation of the Deflagration-to-Detonation Transition in Inhomogeneous Mixtures","authors":"F. Ettner, K. G. Vollmer, T. Sattelmayer","doi":"10.1155/2014/686347","DOIUrl":"https://doi.org/10.1155/2014/686347","url":null,"abstract":"In this study the hazardous potential of flammable hydrogen-air mixtures with vertical concentration gradients is investigated numerically. The computational model is based on the formulation of a reaction progress variable and accounts for both deflagrative flame propagation and autoignition. The model is able to simulate the deflagration-to-detonation transition (DDT) without resolving all microscopic details of the flow. It works on relatively coarse grids and shows good agreement with experiments. It is found that a mixture with a vertical concentration gradient can have a much higher tendency to undergo DDT than a homogeneous mixture of the same hydrogen content. In addition, the pressure loads occurring can be much higher. However, the opposite effect can also be observed, with the decisive factor being the geometric boundary conditions. The model gives insight into different modes of DDT. Detonations occurring soon after ignition do not necessarily cause the highest pressure loads. In mixtures with concentration gradient, the highest loads can occur in regions of very low hydrogen content. These new findings should be considered in future safety studies.","PeriodicalId":44364,"journal":{"name":"Journal of Combustion","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2014-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84187987","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}

引用次数: 86

Consistent Conditional Moment Closure Modelling of a Lifted Turbulent Jet Flame Using the Presumed -PDF Approach 采用假定-PDF方法的升力湍流射流火焰一致条件矩闭合模型

IF 0.7

Journal of Combustion Pub Date : 2014-05-19 DOI: 10.1155/2014/507459

A. E. Sayed, R. Fraser

{"title":"Consistent Conditional Moment Closure Modelling of a Lifted Turbulent Jet Flame Using the Presumed -PDF Approach","authors":"A. E. Sayed, R. Fraser","doi":"10.1155/2014/507459","DOIUrl":"https://doi.org/10.1155/2014/507459","url":null,"abstract":"A lifted turbulent jet flame issuing into a vitiated coflow is investigated using the conditional moment closure. The conditional velocity (CV) and the conditional scalar dissipation rate (CSDR) submodels are chosen such that they are fully consistent with the moments of the presumed probability density function (PDF). The CV is modelled using the PDF-gradient diffusion model. Two CSDR submodels based on the double integration of the homogeneous and inhomogeneous mixture fraction PDF transport equations are implemented. The effect of CSDR modelling is investigated over a range of coflow temperatures () and the stabilisation mechanism is determined from the analysis of the transport budgets and the history of radical build-up ahead of the stabilisation height. For all , the balance between chemistry, axial convection, and micromixing, and the absence of axial diffusion upstream of the stabilisation height indicate that the flame is stabilized by autoignition. This conclusion is confirmed from the rapid build-up of ahead of , , and . The inhomogeneous CSDR modelling yields higher dissipation levels at the most reactive mixture fraction, which results in longer ignition delays and larger liftoff heights. The effect of the spurious sources arising from homogeneous modelling is found to be small but nonnegligible, mostly notably within the flame zone.","PeriodicalId":44364,"journal":{"name":"Journal of Combustion","volume":null,"pages":null},"PeriodicalIF":0.7,"publicationDate":"2014-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85935923","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}

引用次数: 5