Dynamics of cool flames

Ju, Yiguang; Reuter, Christopher B.; Yehia, Omar R.; Farouk, Tanvir; Won, Sang Hee

doi:10.1016/j.pecs.2019.100787

Cited by 139 publications

(48 citation statements)

References 227 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Besides, fuel stratification is also expected to drive the first stages of the growth of formaldehyde kernels. The cool flame propagation phenomenon was mentioned in other studies [25,26,31,32], and also in DNS of jets of different fuels in hot oxidizer environment [21][22][23][24], eventually in canonical configurations directly related to spray A ignition. Our observations present similarities with the phenomenology described in these works, at the first instants of low temperature ignition: several low temperature kernels form in a leaner region on the spray sides and propagate fast towards richer regions.…”

Section: Interpretation Of Plif Imagesmentioning

confidence: 73%

“…Then non-premixed combustion occurs, propagating towards richer and leaner mixtures until reaching the stoichiometric line. The authors also highlighted the cool flame behavior strongly affects the location and time of hot ignition (see also [25]). This phenomenology is in agreement with the findings of both Dahms et al [20] and Borghesi et al [23].…”

Section: Introductionmentioning

confidence: 94%

See 1 more Smart Citation

Analysis of ECN spray A ignition in a Rapid Compression Machine using simultaneous OH* chemiluminescence and formaldehyde PLIF

Strozzi

Houidi

Sotton

et al. 2020

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

View full text Add to dashboard Cite

The canonical diesel spray A is characterized in an optical Rapid Compression Machine (RCM) at high temperature and density conditions (900 K and 850 K, ρ = 23 kg/m3) using simultaneous high-speed OH* chemiluminescence and two-pulse 355 nm Planar Laser Induced Fluorescence (PLIF). The focus is on the time evolution and the repeatability of the early stages of both cool flame and hot ignition phenomena, and on the time evolution of the fluorescing formaldehyde region in between. In particular, time resolved data related to the cool flame are provided. They show the development of several separated kernels on the spray sides at the onset of formaldehyde appearance. Shortly after this phase, the cool flame region expands at high velocity around the kernels and further downstream towards the richer region at the spray head, reaching finally most of the vapor phase region. The position of the first high temperature kernels and their growth are then characterized, with emphasis on the statistics of their location. These time-resolved data are new and they provide further insights into the dynamics of the spray A ignition. They bring some elements on the underlying mechanisms, which will be useful for the validation and improvement of numerical models devoted to diesel spray ignition.

show abstract

Section: Interpretation Of Plif Imagesmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 94%

Analysis of ECN spray A ignition in a Rapid Compression Machine using simultaneous OH* chemiluminescence and formaldehyde PLIF

Strozzi

Houidi

Sotton

et al. 2020

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

View full text Add to dashboard Cite

show abstract

“…As evident, the nature of such behaviors is very different from conventional "cool" flame or "NTC" phenomena observed for low-molecular-weight paraffins at high pressures (Herzler et al, 2004;Gallagher et al, 2008;Hashemi et al, 2016Hashemi et al, , 2017Hashemi et al, , 2019 or high-molecular-weight paraffins (Sokolov et al, 1996;Basevich and Frolov, 2007;Ju et al, 2019;Wang et al, 2019), where the oxidation chemistry of alkyl-peroxide radicals is fundamental. In particular, for high-molecular-weight paraffins, a double O 2 addition to alkyl-radicals and internal isomerization to ketohydroperoxy radicals, ruled by equilibrium reactions, determine temperature oscillations in time or the NTC behavior (if referred to ignition delay times), coupled with heat exchange mechanisms.…”

Section: Oxidation Process Of Simple Hydrocarbons Under Diluted Condimentioning

confidence: 76%

Critical Issues of Chemical Kinetics in MILD Combustion

Sabia

Joannon

2020

Front. Mech. Eng.

View full text Add to dashboard Cite

Mild combustion processes occur with mixtures highly diluted and preheated by a strong recirculation of hot exhausted gases (thus mass and sensible enthalpy) within the combustion chamber. This strategy configures a process based on autoignition kernels outside or close to flammability limits transported by convection in the combustion chamber, thus defining a process with unique physical and chemical features drastically different from traditional deflagrative-diffusive flames. The article aims at analyzing the recent issues relative to kinetic aspects involved in moderate or intense low-oxygen dilution (MILD) combustion processes. First, the article comes through the identification of peculiar experimental features of simple hydrocarbons oxidation process induced by highly preheated and diluted conditions in model reactors typical of chemical engineering. Second, the effects of steam and carbon dioxides on fuel oxidation process, whose presence within the combustion chamber is imposed by high levels of hot gas recirculation, are addressed. Third, the article comes through a thorough analysis of recent scientific contributions on kinetic aspects of MILD combustion processes to identify the critical points in modeling activities.

show abstract

“…A special flow reactor design has permitted to study periodic ignition phenomena and flame propagation, thus addressing the transition from "cool" to "hot" reaction regimes [178] . For practical systems, the question arises how LT chemistry influences the combustion behavior of realistic fuels [179] under conditions where coupling between chemical reactions, transport, and heat release must be considered [180 , 181] . Ju et al [181] have recently reviewed the importance of cool flame phenomena for ignition, flame extinction, and knock, and the possibility to study LT chemistry under flame conditions.…”

Section: Selected Combustion Chemistry Advances – Overview and Recentmentioning

confidence: 99%

“…For practical systems, the question arises how LT chemistry influences the combustion behavior of realistic fuels [179] under conditions where coupling between chemical reactions, transport, and heat release must be considered [180 , 181] . Ju et al [181] have recently reviewed the importance of cool flame phenomena for ignition, flame extinction, and knock, and the possibility to study LT chemistry under flame conditions. Ozone addition has been demonstrated as being valuable [182] , [183] , [184] , [185] , [186] , [187] , [188] , [189] , albeit not necessary [190] , to enhance or control the reactivity in cool flames.…”

Section: Selected Combustion Chemistry Advances – Overview and Recentmentioning

confidence: 99%

Combustion in the future: The importance of chemistry

Kohse‐Höinghaus

2021

Proceedings of the Combustion Institute

View full text Add to dashboard Cite

Combustion involves chemical reactions that are often highly exothermic. Combustion systems utilize the energy of chemical compounds released during this reactive process for transportation, to generate electric power, or to provide heat for various applications. Chemistry and combustion are interlinked in several ways. The outcome of a combustion process in terms of its energy and material balance, regarding the delivery of useful work as well as the generation of harmful emissions, depends sensitively on the molecular nature of the respective fuel. The design of efficient, low-emission combustion processes in compliance with air quality and climate goals suggests a closer inspection of the molecular properties and reactions of conventional, bio-derived, and synthetic fuels. Information about flammability, reaction intensity, and potentially hazardous combustion by-products is important also for safety considerations. Moreover, some of the compounds that serve as fuels can assume important roles in chemical energy storage and conversion. Combustion processes can furthermore be used to synthesize materials with attractive properties. A systematic understanding of the combustion behavior thus demands chemical knowledge. Desirable information includes properties of the thermodynamic states before and after the combustion reactions and relevant details about the dynamic processes that occur during the reactive transformations from the fuel and oxidizer to the products under the given boundary conditions. Combustion systems can be described, tailored, and improved by taking chemical knowledge into account. Combining theory, experiment, model development, simulation, and a systematic analysis of uncertainties enables qualitative or even quantitative predictions for many combustion situations of practical relevance. This article can highlight only a few of the numerous investigations on chemical processes for combustion and combustion-related science and applications, with a main focus on gas-phase reaction systems. It attempts to provide a snapshot of recent progress and a guide to exciting opportunities that drive such research beyond fossil combustion.

show abstract

Dynamics of cool flames

Cited by 139 publications

References 227 publications

Analysis of ECN spray A ignition in a Rapid Compression Machine using simultaneous OH* chemiluminescence and formaldehyde PLIF

Analysis of ECN spray A ignition in a Rapid Compression Machine using simultaneous OH* chemiluminescence and formaldehyde PLIF

Critical Issues of Chemical Kinetics in MILD Combustion

Combustion in the future: The importance of chemistry

Contact Info

Product

Resources

About