Mechanisms Of Extinction Research Articles

LES/PDF modeling of swirl-stabilized non-premixed methane/air flames with local extinction and re-ignition

Turbulent non-premixed flames with local extinction and re-ignition exhibit multiple combustion modes including ignition waves, diffusion flames, partially premixed flames, and ignition-assisted partially premixed flames. The mechanisms of local extinction and re-ignition are not well understood and numerical modeling of multi-mode combustion is a challenging task. In this work, a specially designed swirl-burner was used to study local extinction and re-ignition of non-premixed turbulent methane/air flames. High speed Particle Image Velocimetry (PIV) and laser induced fluorescence of OH radicals (OH-PLIF) measurements along with Large Eddy Simulation (LES) were carried out to investigate the mechanisms of extinction and re-ignition processes in the burner. LES is based on a transported probability density function model within the framework of Eulerian Stochastic Fields (PDF-ESF). It is found that local extinction occurs when the scalar dissipation rate around the stoichiometric mixture fraction is high. The characteristic time scale for local extinction and re-ignition in the present flames is an order of magnitude longer than the characteristic time scale of diffusion/extinction of laminar flamelets. There are two mechanisms for flame hole re-ignition in the present flames. First, under low degree of local extinction conditions (i.e., for small flame holes surrounded by flames) the flame hole re-ignition is due to the mechanism of turbulent flame folding. Second, under high degree of extinction conditions (i.e., with large regions of extinction and lifted flames), re-ignition of the locally extinguished flame is due to the mechanism of ignition assisted partially premixed flame propagation. The results show that the PDF-ESF model is capable of simulating the quenching and re-ignition process found in the experiments.

Involvement of the bed nucleus of the stria terminalis in initial conditioning and rapid reconditioning following extinction of contextual fear.

Although a great deal is known about neurobiological mechanisms of initial conditioning and extinction, relatively little is known about mechanisms involved in the return of behavior following extinction. In this article, we examine the effects of temporarily inactivating the bed nucleus of the stria terminalis (BNST) on initial conditioning and postextinction reconditioning. We investigate effects in unsignaled contextual fear conditioning, in which animals initially receive strong contextual conditioning, followed by three sessions of nonreinforced context exposure (extinction), and then receive a single context-shock reconditioning trial. In 2 experiments with male Long Evans rats, we evaluated the effects of delivery of a muscimol/baclofen cocktail to the BNST prior to initial conditioning or reconditioning. In Experiment 1, we found that a single context-shock pairing results in more freezing following extinction than when it is the initial conditioning trial. This rapid reconditioning effect was impaired by BNST inactivation. In Experiment 2, we found that BNST inactivation also causes a deficit in freezing after strong initial conditioning. These findings suggest that the BNST is involved in both initial conditioning and postextinction reconditioning. We discuss implications of these findings for current thinking about BNST function in learning and memory processes. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Extinction mechanisms of hyperbolic h-BN nanodisk**Project supported by the National Key Research and Development Program of China (Grant No. 2016YFA0203500), the National Natural Science Foundation of China (Grant No. 11874407), and Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB 30000000).

We applied the finite element method to calculate the extinction spectrum of single hyperbolic hexagonal boron nitride (h-BN) nanodisk. We show that the hyperbolic h-BN nanodisk exhibits two extinction mechanisms in the mid-infrared region. The volume confined phonon polaritons resonances of the nanodisk give rise to a series of weak extinction peaks. The localized surface phonon polaritons lead to a robust dipolar extinction, and the extinction peak position is tunable by varying the size of the h-BN nanodisk. These findings reveal the mechanisms of the interaction between light and resonant h-BN nanodisk, which are essential for h-BN related opto-electromagnetic applications.

Lean Blowoff in a Toroidal Jet-Stirred Reactor: Implications for Alternative Fuel Approval and Potential Mechanisms for Autoignition and Extinction

Sustainable aviation fuels (SAFs) have been identified as a method to reduce the aviation sector’s environmental impact through carbon mitigation. Current certification processes of potential, viab...

Study on effect of hydrogen addition on extinction dynamics of dimethyl ether spherical diffusion flame

In this paper, numerical calculations were conducted to investigate the effect of H2 addition on dimethyl ether (DME) spherical diffusion flames in the hot- and cool-flame conditions, in terms of the S-curve flammability, near-limit oscillatory dynamics, and extinction mechanism. The mole fraction of H2 in the fuel mixture was varied from 0% to 15% gradually, by 5% in increment. The results indicate that the flammability limit of DME spherical diffusion flame, in either hot- or cool-flame condition, was considerably extended due to H2 addition to the fuel mixture. It is interesting to note that with increasing H2 addition, the hot-flame extinction limit was decreased, while that for cool-flame was increased. Additionally, the spherical diffusion flame exhibited a strong oscillation behavior near extinction, which made flame extinguishment happen prior to the extinction turning point of S-curve in either hot- or cool-flame regime. In either H2 addition case, the oscillation dynamics of near-extinction hot flame featured a single oscillatory mode with a constant frequency which was uncorrelated with the ambient oxygen mole fraction (XO2∗), while the cool-flame oscillatory featured the dual oscillatory modes that had fairly distinct frequencies, and its high-frequency oscillatory period was slightly relevant with XO2∗. Furthermore, oscillatory period of the near-extinction hot flame slightly increased with increasing H2 addition. While for the near-extinction cool flame, as H2 addition increased, its high-frequency oscillatory period considerably decreased, and its low-frequency oscillatory period kept nearly unchanged, but its oscillation amplitude attenuated quickly and finally became rather indiscernible. Specially, when H2 addition approached 15%, the dual oscillatory mode of cool flame was nearly disappeared, replaced by a single oscillatory mode. Besides, the sensitivity analysis was conducted to reveal the key reactions that controlled the oscillatory extinction in hot- and cool-flame regimes. It was found that in either hot- or cool-flame regime, the reactions involving H radical became increasingly more significant to the oscillatory extinction with the increment in H2 addition. Additionally, it was further found that the hot-flame oscillatory extinction was governed by the competition between exothermicity/endothermicity and branching/termination involving small molecules, while the cool-flame oscillation extinction was primarily governed by the competition between low-temperature branching and termination reactions involving large molecules in the negative temperature coefficient (NTC) regime.

Pressure gradient tailoring effects on the mechanisms of bluff-body flame extinction

The mechanisms of flame blowout under pressure gradient effects are explored for a bluff-body stabilized flame. The blowout process is induced through equivalence ratio reduction from a lean stabilized flame to complete blowout. Simultaneous high-speed particle image velocimetry (PIV) and C2*/CH* chemiluminescence imaging diagnostics are used to obtain the instantaneous flame structure, vorticity field, equivalence ratio, and local strain rate during the extinction process. The goal is to elucidate the effect of flame-generated vorticity on lean flame extinction. Three test-sections configured as a nozzle, a rectangular duct, and a diffuser, are used to alter the downstream pressure gradient yielding high, nominal, and low magnitudes of flame-generated baroclinic torque. For all three configurations, the flame brush narrows and the shear layer vorticity expands in the transverse direction resulting in flame-shear interactions and extinction. The flame-shear layer interaction increases the strain rate along the flame; however, the strong flame-generated vorticity for the nozzle case delayed the strain rate increase by keeping the flame away from the shear layer the longest. The sharp increase in the Karlovitz number above unity caused by the sudden increase in the strain rate corresponds to the time of flame brush contraction and shear layer width expansion. It is shown that the downstream pressure gradient can either augment or attenuate the time required for the Karlovitz number to reach a critical value of unity, which is associated with local extinctions along the flame. In all of the test-section configurations, the flame-generated vorticity has a weak influence on the Bénard von Kármán (BVK) instability mode and its harmonics. The Strouhal number during blow-out remained relatively constant in all of the cases showing greater sensitivity to the shear layer length than to the BVK frequency.

Chamber volume development, metabolic rates, and selective extinction in cephalopods

Reconstructing the physiology of extinct organisms is key to understanding mechanisms of selective extinction during biotic crises. Soft tissues of extinct organisms are rarely preserved and, therefore, a proxy for physiological aspects is needed. Here, we examine whether cephalopod conchs yield information about their physiology by assessing how the formation of chambers respond to external stimuli such as environmental changes. We measured chamber volume through ontogeny to detect differences in the pattern of chamber volume development in nautilids, coleoids, and ammonoids. Results reveal that the differences between ontogenetic trajectories of these cephalopods involve the presence or absence of abrupt decreases of chamber volume. Accepting the link between metabolic rate and growth, we assume that this difference is rooted in metabolic rates that differ between cephalopod clades. High metabolic rates combined with small hatching size in ammonoids as opposed to lower metabolic rates and much larger hatchlings in most nautilids may explain the selective extinction of ammonoids as a consequence of low food availability at the end of the Cretaceous.

PSYCHOTHERAPY TREATMENT OF NEGATIVE EMOTIONAL EXPERIENCES OF ADULTS WITH THE TECHNIQUE “INTERIORIZATION AND EXTERIORIZATION OF THE FOCUS OF ATTENTION”

PSYCHOTHERAPY TREATMENT OF NEGATIVE EMOTIONAL EXPERIENCES OF ADULTS WITH THE TECHNIQUE “INTERIORIZATION AND EXTERIORIZATION OF THE FOCUS OF ATTENTION”

水基泡沫消光特性实验研究（特约）

Aqueous foam is widely used as a kind of stealth way in the scene of optoelectronic countermeasure. The existing optoelectronic jamming stealth technology has such problems as short acting time, single band and environmental pollution, which makes it difficult to effectively counter dual-mode and multi-mode precision guidance weapons. Aiming at the above problems, the aqueous foam formulation was studied. The extinction performance experiments of aqueous foam against visible light, infrared (3−5 μm, 8−14 μm), laser (1.06 μm, 10.6 μm), millimeter wave (3 mm, 8 mm) and centimeter wave (2 cm, 3 cm)were implemented. The shielding and interference effects of aqueous foam aiming at thermal imagery of 8−14 μm band were measured. The extinction mechanism of aqueous foam was discussed. The study shows that the curtain barrier formed by aqueous foam cloud or compositing with artificial fog is expected to acquire a new type of smokescreen weapon with the advantages such as full-wave band and environment friendly.

Treatment augmentation for posttraumatic stress disorder: A systematic review

This systematic review examined the efficacy of all augmentation approaches for first-line posttraumatic stress disorder (PTSD) interventions. From 9,890 records, 34 trials were eligible for inclusion, covering 28 different augmentation approaches. Overall, augmentation approaches were ineffective if they targeted a mechanism similar to the first-line treatment. Augmentation approaches combining two guideline-recommended treatments were largely ineffective, reflecting ceiling effects. Pharmacological augmentation approaches targeting fear extinction mechanisms were largely ineffective, or worsened outcomes relative to prolonged exposure alone, as these approaches may inadvertently strengthen fear memories. Augmentation approaches targeting general cognitive enhancement showed promise and provided support for augmentation interventions that require little cognitive or emotional work and target mechanisms different than the first-line treatment.

Study on flame structure and extinction mechanism of dimethyl ether spherical diffusion flames

Flame extinction which belongs to one of the most important limit combustion phenomena plays a vital role in the combustion safety, efficiency, and stability, and additionally, it is also important for fire safety research. Hence studies on the flame extinction mechanism is of fundamental and practical significances in the combustion science. In this paper, the structure dynamics and extinction mechanism of dimethyl ether (DME) hot and cool spherical diffusion flames are studied by experiments and simulations using detailed chemistry and transport models. It was found that DME cool flame had an extended flammability limit in terms of the ambient oxygen mole fraction (XO2* = 7.9%) than the hot flame (XO2* = 23.2%). DME hot flame was much more sensitive than the cool flame with respect to the variation in XO2*. Explosive chemical mode with complex eigenvalues with positive real part was observed within the near-extinction region, either for hot or cool flame. Additionally, oscillation-induced extinction was also observed in this region, which would make the practical flame extinction point (XO2* = 24.04%) deviated from the steady-state extinction turning point of the S-curve (XO2* = 23.2%). The hot-flame extinction was mainly governed by high-temperature reactions involving small molecules, while the cool flame mainly by low-temperature reactions involving large hydrocarbons.

Numerical investigation of the local extinction and re-ignition mechanisms of premixed flame in a micro combustor with a flame holder and preheating channels

A novel combustor with a flame holder and preheating channels, which takes advantage of heat and flow recirculation, was developed to improve the stability of the micro flame in our previous work. The results demonstrated that the lean methane/air premixed flame could be stabilized within a wide operating range. Certainly, the flame blows off when the equivalence ratio of the fuel mixture becomes too small or too big or the Reynolds number is too large. The present work reports and analyzes the blow-off dynamics of a methane/air laminar premixed flame at a relatively large Reynolds number under the synergistic effect of heat and flow recirculation. Interestingly, a flame with local extinction and re-ignition appears, which is first found in the micro combustor. The underlying mechanisms of this interesting phenomenon are systematically discussed in terms of the flow recirculation effect, stretch effect, conjugate heat exchange, and preferential transport effect. We find that the counter flow in the recirculation zone and stretch effect induce the local extinction of the flame. The smaller heat loss from the residual flame to the flame holder and the better preferential transport effect contribute to the re-ignition of the fuel mixture. The preheating effect on the unburned fuel mixture is not expected to be insignificant for the local extinction and re-ignition phenomenon. These results mean that the generated mechanism of the flame with local extinction and re-ignition in the micro combustor is different from that in the conventional combustors.

Ventral hippocampus interacts with prelimbic cortex during inhibition of threat response via learned safety in both mice and humans

Heightened fear and inefficient safety learning are key features of fear and anxiety disorders. Evidence-based interventions for anxiety disorders, such as cognitive behavioral therapy, primarily rely on mechanisms of fear extinction. However, up to 50% of clinically anxious individuals do not respond to current evidence-based treatment, suggesting a critical need for new interventions based on alternative neurobiological pathways. Using parallel human and rodent conditioned inhibition paradigms alongside brain imaging methodologies, we investigated neural activity patterns in the ventral hippocampus in response to stimuli predictive of threat or safety and compound cues to test inhibition via safety in the presence of threat. Distinct hippocampal responses to threat, safety, and compound cues suggest that the ventral hippocampus is involved in conditioned inhibition in both mice and humans. Moreover, unique response patterns within target-differentiated subpopulations of ventral hippocampal neurons identify a circuit by which fear may be inhibited via safety. Specifically, ventral hippocampal neurons projecting to the prelimbic cortex, but not to the infralimbic cortex or basolateral amygdala, were more active to safety and compound cues than threat cues, and activity correlated with freezing behavior in rodents. A corresponding distinction was observed in humans: hippocampal-dorsal anterior cingulate cortex functional connectivity-but not hippocampal-anterior ventromedial prefrontal cortex or hippocampal-basolateral amygdala connectivity-differentiated between threat, safety, and compound conditions. These findings highlight the potential to enhance treatment for anxiety disorders by targeting an alternative neural mechanism through safety signal learning.

Extinguishment of sodium fires with Graphite@Stearate core-shell structured particles

Metallic sodium has unique fire hazards for its high chemical reactivity with air and water. Owing to the limitations of existing suppressants for sodium fires, here, a new type of composite particles with expandable graphite as cores and stearate sodium as shells (denoted as EG@SS) was developed for extinguishing sodium fires high efficiently. Laboratory-scale sodium pool fire tests revealed that such graphite powders with stearate sodium coated exhibited much superior performance in comparison to the commonly used raw graphite. The mass ratio (R) of EG@SS composite powders employed over sodium to obtain extinction was 0.7 as opposite to 2.2 of raw EG without surface coating. When applied to sodium fires, the inner expandable graphite would expand rapidly and decrease the flame temperature. Meanwhile the outer stearate sodium would melt and fill the gaps between the loosely packing graphite piles, forming a crust excluding oxygen. Consequently, a fast total extinction was achieved for the combined effects of cooling and suffocation from graphite and stearate sodium. The extinction mechanism was investigated based on experimental results and physicochemical characterizations of the core-shell structured composites.

Effects of hydrogen enrichment of methane on diffusion flame structure and emissions in a back-pressure combustion chamber

In the present study, the effects of hydrogen enrichment of methane are investigated numerically from the diffusion flame structure and emissions aspect. Fluent code is utilised as the simulation tool. In the first part of the study, four experiments were conducted using natural gas as fuel. A non-premixed burner and a back-pressure boiler were utilised as the experimental setup. The natural gas fuel consumption rate was changed between 22 Nm3/h and 51 Nm3/h. After the experimental studies, the numerical simulations were performed. The non-premixed combustion model with the steady laminar flamelet model (SFM) approach was used for the calculations. The methane-air extinction mechanism was utilised for the calculation of the chemical species. The numerical results were verified with the experimental results in terms of the flue gas emissions and flue gas temperature values. In the second part of the study, four different hydrogen-enriched methane combustion cases were simulated using the same methane-air extinction mechanism, which included the hydrogen oxidation mechanism as a sub mechanism. The same energy input (432 kW) was supplied into the boiler for all the studied cases. The obtained results show that the hydrogen addition to methane significantly change the diffusion flame structure in the combustion chamber. The hydrogen-enriched flames become broader and shorter with respect to the pure methane flame. This provides better mixing of the reactants and combustion products in the flame regions due to the use of a back-pressure boiler. In this way, the maximum flame temperature values and thermal NO emissions are reduced in the combustion chamber, when the hydrogen addition ratio is less than 15% by mass. The maximum temperature value is calculated as 2030 K for the case with 15% hydrogen addition ratio by mass, while it is 2050 K for the case without hydrogen enrichment. Therefore, it is determined that the hydrogen-enriched methane combustion in a back-pressure combustion chamber has the potential of reducing both the carbon and thermal NO emissions.

Static Stability and Combustion Characteristics of Oxy-Propane Flames in a Premixed Fuel-Flexible Swirl Combustor

This study investigates the stability and combustion features of premixed oxy-propane flames in a dry low emission (DLE) model combustor for clean fuel/oxidizer-flexible combustion applications in gas turbines. The stability of the oxy-propane flame is characterized by its blowout and flashback limits over ranges of equivalence ratios (ϕ) from 0.1 to 1.0 and oxygen fractions (OF: volumetric concentration of O2 in the O2/CO2 oxidizer) from 15 to 70%. For better understanding of the physics behind the flame extinction mechanisms, the stability limits were plotted within the ϕ–OF space against the contours of adiabatic flame temperature (Tad), inlet Reynolds number (Re), mixture mass flow rate (ṁmix), and combustor power density (PD). The flame speed (FS) was also estimated at selected operating conditions. It was observed that the FS is contingent to Tad only. A correlation of Tad–FS was developed for better characterization of premixed oxy-propane flames. It was also found that the blowout curve follows a constant Tad contour on the stability map, whereas the flashback curve does not. This implies that Tad is a more relevant controlling parameter choice of combustor stability near the blowout limit, whereas the reaction rate is a suitable indicator of the flame stability limit near flashback. The stability map of the present oxy-propane flame was compared with that of an oxy-methane flame on the same combustor. It was found that, at the same OF, the blowout and flashback limits of the propane flame occur at leaner ϕ, compared to those of methane flame, which was expected for a higher hydrocarbon fuel like propane. Flame shapes at different sets of operating conditions were investigated for inferring key information on the flame behavior and macrostructure while varying ϕ, OF, and hence, Tad. Similar flame shapes were obtained at the same Tad regardless of ϕ and OF values. Flames of similar Tad also demonstrated similar temperature distributions near the flame core. The findings confirm the dependence of the FS on Tad, irrespective of the combinations of ϕ and OF used to achieve any particular Tad.

The first day of the Cenozoic

Highly expanded Cretaceous-Paleogene (K-Pg) boundary section from the Chicxulub peak ring, recovered by International Ocean Discovery Program (IODP)-International Continental Scientific Drilling Program (ICDP) Expedition 364, provides an unprecedented window into the immediate aftermath of the impact. Site M0077 includes ∼130 m of impact melt rock and suevite deposited the first day of the Cenozoic covered by <1 m of micrite-rich carbonate deposited over subsequent weeks to years. We present an interpreted series of events based on analyses of these drill cores. Within minutes of the impact, centrally uplifted basement rock collapsed outward to form a peak ring capped in melt rock. Within tens of minutes, the peak ring was covered in ∼40 m of brecciated impact melt rock and coarse-grained suevite, including clasts possibly generated by melt-water interactions during ocean resurge. Within an hour, resurge crested the peak ring, depositing a 10-m-thick layer of suevite with increased particle roundness and sorting. Within hours, the full resurge deposit formed through settling and seiches, resulting in an 80-m-thick fining-upward, sorted suevite in the flooded crater. Within a day, the reflected rim-wave tsunami reached the crater, depositing a cross-bedded sand-to-fine gravel layer enriched in polycyclic aromatic hydrocarbons overlain by charcoal fragments. Generation of a deep crater open to the ocean allowed rapid flooding and sediment accumulation rates among the highest known in the geologic record. The high-resolution section provides insight into the impact environmental effects, including charcoal as evidence for impact-induced wildfires and a paucity of sulfur-rich evaporites from the target supporting rapid global cooling and darkness as extinction mechanisms.

Effects of shear inhomogeneities on the structure of turbulent premixed flames

This paper studies the effects of shear inhomogeneities on the structure and stability characteristics of turbulent piloted premixed flames. The shear is introduced by splitting the fuel-air mixture in two stream and feeding each stream at different velocities through two annular concentric tubes residing within the pilot annulus. The shear is varied by varying the proportion of fluid injected through the streams and also by changing the recess distance of the inner tube with respect to the jet exit plane. It is noted that with increasing rates of shear, the Bunsen-like flames become shorter with the flame tip opening downstream of the pilot stream. Measurements of flow fields reveal useful information about the level and location of the shear layers. Joint imaging of Laser-Induced Fluorescence (LIF) of OH and CH show that, with increasing rates of shear, the degree of flame front fragmentation increases implying the occurrence of local extinction even in regions extremely close to the pilot. The flame surface area, marked by LIF-CH is taken as an indicator of consumption rates of reactants. For all flames examined here, the peak flame surface area increases with increasing shear and subsequently decreases as the flame shortens and approaches blow-off. The peak flame surface density decreases with increasing shear. Regime diagrams show that the flames investigated here bridge the regions of broadened preheat thin reactions as well as the distributed reaction zone. While the thickness of the CH layer remain somewhat uniform, the number of flame fragments, as indicated by breaks in the CH profiles, increases with increasing shear before stabilizing at some peak value. The observed mechanism of local extinction in highly sheared Bunsen-like, turbulent piloted premixed flames complements existing results for bluff-body stabilised flames.

Paleogeography and paleoenvironments of the Late Devonian Kellwasser event: A review of its sedimentological and geochemical expression

The Late Devonian (383-359 Ma) was a time of prolonged climate instability with catastrophic perturbation of global marine ecosystems at the Frasnian-Famennian (F-F) and the Devonian-Carboniferous (D-C) boundaries. The causes and mechanisms of anoxia and extinction at the F-F interval are not clearly delineated, and alternative explanations for virtually every aspect of this interval are still intensely debated. In many (but not all) locations, the F-F interval is characterized by two dark, organic-rich lithologies: the Lower and Upper Kellwasser beds (as originally described in Germany) that represent a stepwise ocean anoxia and extinction sequence. The Upper and Lower Kellwasser anoxia event beds are often collectively termed the Kellwasser Event, and the termination of this sequence is within the Upper Kellwasser Event at the F-F boundary. Current knowledge is limited by significant sampling bias, as most previous studies sampled epicontinental seaways or passive continental shelves, primarily from localities across Europe and North America. Together these formed a single equatorial continent with a rising mountain chain during the Late Devonian. Our understanding of the Kellwasser Event is thus based on data and observations from a restricted set of paleoenvironments that may not represent the complete range of Late Devonian environments and oceanic conditions. In the last decade, new methodologies and research in additional paleoenvironments around the world confirm that the Kellwasser Event was global in scope, but also that its expression varies with both paleoenvironment and paleogeography. Studying the many differing geochemical and lithological expressions of the Kellwasser Event using a) a wide variety of paleoenvironments, b) a multiproxy approach, and c) placement of results into the broader context of Late Devonian marine biodiversity patterns is vital for understanding the true scope of ocean anoxia, and determining the causes of the marine biodiversity crisis at the F-F boundary.

Experimental study on flame stability limits of lithium ion battery electrolyte solvents with organophosphorus compounds addition using a candle-like wick combustion system

To evaluate the fire-retardant effectiveness of organophosphorus compounds (OPC) added to Li-ion battery electrolyte solvents, the limiting oxygen concentration (LOC) method is used in conjunction with a wick combustion system, called as wick-LOC method. With the wick-LOC method, two modes of stabilized flame are found, namely, wake flame and full flame. When OPC is added to the electrolyte, two distinct branches of extinction processes occur according to the different flame modes near extinction with no transition from the full flame to the wake flame in the case of higher OPC addition. The flame stability limits are measured as a function of OPC addition for both flame modes. The wake flame is shown to be consistently more stable at low levels of OPC addition. However, once the OPC addition exceeds a critical amount, the full flame shows higher stability with a lower LOC than the wake flame. These phenomena in the two regimes are also found in other cases of high OPC addition (different type of OPC and electrolyte solvent). In the most stable flame mode, the regime switches from the wake flame to the full flame with increasing OPC addition, and they are defined correspondingly as “blow-off regime” and “quenching regime”. To explain the presence of these two regimes, the thermal balance effect is considered in the discussion of flame extinction mechanisms. The difference in flame volume near the extinction limit shows that the quenching mechanism dominates flame extinction under higher OPC addition. The thermal balance effect on flame stabilization or extinction can be the additional impact on the fire retardation abilities of OPC itself.