共查询到20条相似文献,搜索用时 15 毫秒
1.
A. A. Konnov 《Combustion, Explosion, and Shock Waves》2005,41(5):496-503
A simple phenomenological diffusive-thermal model of cellular instability of premixed flames of ternary mixtures is developed
and presented. The model shows that preferential diffusion can alter stoichiometry of the mixture, i.e., the ratio of the
fuel and oxidizer concentrations, and also its effective dilution by an inert. Key parameters of the model are estimated using
numerical modeling of burning velocities. Laminar burning velocities are calculated for hydrogen-oxygen-nitrogen, methane-oxygen-nitrogen,
and propane-oxygen-nitrogen mixtures. Conditions for the appearance of cellular instability in ternary mixtures are determined
and compared with experiments. In good agreement with experimental observations, the diffusive-thermal instability is predicted
in hydrogen flames with equivalence ratios φ ≲ 1.45, in lean methane flames with φ ≲ 1.02, and in rich propane flames with
φ ≳ 1.03. The magnitude of the change in the local flame velocity due to preferential diffusion is evaluated. It is demonstrated
that nitrogen diffuses faster than oxygen in hydrogen-air and methane-air flames, while oxygen diffuses faster than nitrogen
in flames of propane and other heavier hydrocarbons. In mixtures of air with propane or heavier hydrocarbons, the transition
between stable and unstable regimes is predicted in mixtures that are leaner than the mixture corresponding to the peak of
the burning velocity curve, in agreement with experimental observations.
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Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 5, pp. 14–22, September–October, 2005. 相似文献
2.
V. A. Bunev 《Combustion, Explosion, and Shock Waves》2009,45(3):251-257
The effect of the addition of nitric oxides (NO and NO2) on rich hydrogen-air flames was studied using the tracer method in numerical simulation. It is shown that the effects of
these additives are not similar. Both oxides promote the formation of OH and H2O in the low-temperature zone of the front. The addition of NO reduces the first maximum of the OH profile and the burning
velocity. The addition of NO2 increases the first maximum of the OH profile and does not change the burning velocity.
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Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 3, pp. 19–25, May–June, 2009. 相似文献
3.
Filtration combustion of hydrogen-air, propane-air, and methane-air mixtures in inert porous media 总被引:1,自引:0,他引:1
N. A. Kakutkina A. A. Korzhavin M. Mbarawa 《Combustion, Explosion, and Shock Waves》2006,42(4):372-383
The filtration combustion characteristics of hydrogen-air, propane-air, and methane-air mixtures in inert porous media have
been studied experimentally. It is shown that the dependences of the combustion wave velocity on the fuel-air equivalence
ratio are V-shaped. For hydrogen-air mixtures, the velocity minimum is shifted to the rich region, and for propane-air and
methane-air mixtures, it is shifted to the lean region. For lean hydrogen-air and rich propane-air mixtures, the measured
maximum temperatures in the combustion wave are found to be reduced relative to those calculated theoretically. For methane-air
mixtures, a reduction in the measured temperatures is observed over the entire range of the mixture composition. The results
are interpreted within the framework of the hypothesis of selective diffusion of gas mixture components.
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Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 4, pp. 8–20, July–August, 2006. 相似文献
4.
D. A. Knyazkov S. A. Yakimov O. P. Korobeinichev A. G. Shmakov 《Combustion, Explosion, and Shock Waves》2008,44(1):9-17
The effect of small additives of trimethylphosphate (TMP) on the lean and rich flammability concentration limits of CH4/air gas mixtures were studied using an opposed-flow burner and numerical modeling based on detailed kinetic mechanisms. TMP
was found to narrow the flammability concentration limits of premixed CH4/air mixtures. Modeling using a previously developed model for flame inhibition by phosphorus compounds showed that the model
provides a satisfactory fit to experimental results on the effect of TMP additives on the lean concentration limit.
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Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 1, pp. 12–21, January–February, 2008. 相似文献
5.
V. V Azatyan A. A. Borisov A. G. Merzhanov V. I. Kalachev V. V. Masalova A. E. Mailkov K. Ya. Troshin 《Combustion, Explosion, and Shock Waves》2005,41(1):1-11
This paper studies the effects of small additives of propylene and isopropanol on the hydrogen-air flame speed in the predetonation regime, deflagration-to-detonation transition, and burning rate. It is shown that the difference in the effects of these additives on the combustion is determined primarily by their ability to terminate reaction chains. In hydrogen flames, the additives are consumed as a result of their reactions with the active intermediate products of H2 combustion in which these species are replaced by inactive radicals.Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 1, pp. 3–14, January–February, 2005. 相似文献
6.
The effect of the temperature difference between the gas and the particles on propagation of premixed flames in a combustible
mixture containing volatile fuel particles uniformly distributed in an oxidizing gas mixture is analyzed in this paper. It
is presumed that the fuel particles vaporize first to yield a gaseous fuel, which is oxidized in the gas phase. The analysis
is performed in the asymptotic limit, where the value of the characteristic Zel’dovich number is large, which implies that
the reaction term in the preheating zone is negligible. Required relations between the gas and the particles are derived from
equations for premixed flames of organic dust. Subsequently, the governing equations are solved by an analytical method. Finally,
the variation of the dimensionless temperatures of the gas and the particles, the mass fraction of the particles, the equivalence
ratio ϕ
g
as a function of ϕ
u
, the flame temperature, and the burning velocities of the gas and the particles are obtained. The analysis shows that the
calculated value of ϕ
g
is smaller than unity for certain cases, even though ϕ
u
⩾1.
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Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 3, pp. 49–57, May–June, 2009. 相似文献
7.
Zuohua Huang Qian Wang Jinrong Yu Yong Zhang Ke Zeng Haiyan Miao Deming Jiang 《Fuel》2007,86(15):2360-2366
Measurement of laminar burning velocity of dimethyl ether-air mixtures was taken under different initial pressures and equivalence ratios using a constant volume bomb and high-speed schlieren photography. The stretched laminar burning velocity increases with the increase of stretch rate. At equivalence ratio of 1.0, low initial pressure gives high stretched flame speed. At initial pressure less than 0.1 MPa, the stoichiometric mixture gives the higher value of stretched flame speed than those at ? = 1.2 and ? = 0.8. The Markstein numbers decrease with the increase of equivalence ratio, and this reveals that lean mixture will maintain higher stability of flame front surface than that of rich mixture in dimethyl ether-air premixed flames. 相似文献
8.
O. P. Korobeinichev V. M. Shvartsberg T. A. Bol'shova A. G. Shmakov D. A. Knyaz'kov 《Combustion, Explosion, and Shock Waves》2002,38(2):127-133
For CH4/O2 flames doped with trimethyl phosphate (TMP), the flame structure is examined and the velocity of flame propagation is determined with the aim of studying the mechanism of inhibition of flames doped with organophosphorus compounds. The structure of a methane–oxygen flame doped with TMP stabilized on a flat burner at a pressure of 1 atm was studied. The dependence of flame propagation velocity on the concentration of TMP is measured using a Mache–Hebra burner to determine the effectiveness of a number of MP as a flame inhibitor. The mechanism of destruction of TMP in flames was used to model the flame structure and calculate the velocities of propagation of a methane–air flame as functions of the initial concentration of TMP. Calculation and experimental results are compared. 相似文献
9.
O. P. Korobeinichev T. A. Bolshova A. G. Shmakov V. M. Shvartsberg 《Combustion, Explosion, and Shock Waves》2014,50(2):130-134
A skeletal mechanism of inhibition and quenching of methane flames by addition of trimethyl phosphate was developed. It includes a mechanism of methane oxidation consisting of 19 elementary steps involving 15 species (including N2), and four elementary reactions involving three phosphorus-containing species (PO2, HOPO, and HOPO2). The developed skeletal mechanism adequately predicts the burning velocity of flames with added inhibitor over a range of equivalence ratio of 0.7–1.4 and can be used to model fire suppression. 相似文献
10.
E. M. Popenko A. A. Gromov Yu. Yu. Shamina A. P. Il’in A. V. Sergienko N. I. Popok 《Combustion, Explosion, and Shock Waves》2007,43(1):46-50
The effect of small additives (1.25–5.00%) of ultrafine aluminum powders (UFAP) on the rheology and combustion of model four-component
energetic condensed systems is studied. It is found that the addition of UFAP decreases the temperature of HMX decomposition.
Small additives of UFAP increase the burning rate of model energetic condensed systems and decrease the exponent ν in the burning rate law without deteriorating the rheological characteristics of the model propellants.
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Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 1, pp. 54–59, January–February, 2007. 相似文献
11.
Experimental measurements of the adiabatic burning velocity in methane + hydrogen + air flames using the Heat Flux method are presented. The hydrogen content in the fuel was varied from 0 to 20%. Non-stretched flames were stabilized on a perforated plate burner from 20 to 100 kPa. The equivalence ratio was varied from 0.8 to 1.4. Adiabatic burning velocities of CH4 + H2 + air mixtures were found in good agreement with the literature results at atmospheric pressure. Also low-pressure measurements in CH4 + air flames performed earlier were accurately reproduced. The effects of enrichment by hydrogen on the laminar burning velocity at low pressures have been studied for the first time. Calculated burning velocities using the Konnov mechanism are in satisfactory agreement with the experiments over the entire range of conditions. Pressure dependences of the burning velocities for the three fuels studied could be approximated by an empirical exponential correlation. 相似文献
12.
V. A. Bunev 《Combustion, Explosion, and Shock Waves》2006,42(4):367-371
A laminar flame propagating in a rich homogeneous hydrogen-air mixture with addition of propylene is numerically simulated.
Small amounts of propylene are shown to reduce the concentrations of HO2 and OH in the low-temperature zone of the flame front, which effectively reduces the laminar burning velocity. In the flame
front, propylene is consumed completely with formation of CO, CO2, CH4, C2H2, H2, and H2O, whereas hydrogen undergoes little oxidation compared to propylene.
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Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 4, pp. 3–7, July–August, 2006. 相似文献
13.
V. V. Zamashchikov 《Combustion, Explosion, and Shock Waves》2012,48(4):382-386
This paper presents experimental results on the effect of pressure on the flame propagation velocity in a tube with diameter close to the critical diameter. An important feature of the investigated combustion regime is heat transfer along the tube wall from the combustion products to the fresh mixture. Methane-air and hydrogen-air mixtures were used. The experiments show that with increasing pressure, the burning velocity of methane-air flames decreases whereas the burning velocity of hydrogen-air flames is almost unchanged. This behavior is explained by the pressure dependence of the laminar burning velocity. 相似文献
14.
The possibility of increasing the laminar flame velocity in a hydrogen-air mixture by excitation of O2 molecules into the a
1Δ
g
singlet state. The presence of 10% of O2(a
1Δ
g
) molecules in oxygen is demonstrated to result in noticeable (up to 50%) enhancement of mixture burning. The temperature
of combustion products and also the concentrations of H2O, NO, and other constituents increase. The greatest effect of O2(a
1Δ
g
) molecules is manifested in combustion of lean mixtures; the least pronounced effect is observed in rich mixtures. These
effects are caused by intensification of the chain mechanism in the presence of a super-equilibrium amount of excited O2(a
1Δ
g
) molecules in a hydrogen-air mixture.
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Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 4, pp. 3–12, July–August, 2008. 相似文献
15.
The chain reaction mechanism and theoretical approach proposed by Zel’dovich for hydrogen flame propagation are used to describe
the effect of increasing the burning velocity of a low-pressure hydrogen-oxygen flame by the addition of trimethyl phosphate
(TMP), which induce a catalytic recombination of hydrogen atoms. The promotion of a stoichiometric hydrogen-oxygen flame at
subatmospheric pressure by the addition of TMP at a low concentration (0.1–0.5%) is described using a model of the catalytic
recombination of hydrogen atoms. The results of calculation using Zel’dovich’s theory with the proposed simplified kinetic
model are in good agreement with simulation results for the complete kinetic mechanism. It is shown that increasing the recombination
rate of hydrogen atoms in a catalytic reaction involving phosphorus-containing species increases the heat release rate and,
hence, the flame burning velocity. A kinetic analysis was performed of the dependence of the ratio of the recombination and
branching rates, the temperature at the maximum reaction rate, and the maximum mole fraction of hydrogen atoms on the pressure
and additive concentration. The study confirmed Zel’dovich’s prediction that the recombination not only has the harmful effect
of terminating chains, but it also has the beneficial effect of releasing heat. 相似文献
16.
A comprehensive experimental and numerical study has been conducted to understand the influence of CH3Cl addition on CH4/O2/N2 premixed flames under oxygen enrichment. The laminar flame speeds of CH4/CH3Cl/O2/N2 premixed flames at room temperature and atmospheric pressure are experimentally measured using the Bunsen nozzle flame technique
with a variation in the amount of CH3Cl in the fuel, equivalence ratio of the unburned mixture, and level of oxygen enrichment. The concentrations of major species
and NO in the final combustion products are also measured. In order to analyze the flame structure, a detailed chemical kinetic
mechanism is employed, the adopted scheme involving 89 gas-phase species and 1017 elementary forward reaction steps. The flame
speeds predicted by this mechanism are found to be in good agreement with those deduced from experiments. Chlorine atoms available
from methyl chloride inhibit the oxygen-enhanced flames, resulting in lower flame speeds. This effect is more pronounced in
rich flames than in lean flames. Although the molar amount of CH3Cl in the methane flame is increased, the temperature at the post flame is not significantly affected, based on the numerical
analysis. However, the measured concentration of NO is reduced by about 35% for the flame burning the same amount of methyl
chloride and methane at the oxygen enrichment of 0.3. This effect is due to the reduction of the concentration of free radicals
related to NO production within the flame. In the numerical simulation, as CH3Cl addition is increased, the heat flux is largely decreased for the oxygen-enhanced flame. It appears that the rate of the
OH + H2 → H + H2O reaction is reduced because of the reduction of OH concentration. However, the function of CH3Cl as an inhibitor on hydrocarbon flames is weakened as the level of oxygen enrichment is increased from 0.21 to 0.5.
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Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 6, pp. 103–111, November–December, 2006. 相似文献
17.
A. G. Shmakov V. M. Shvartsberg O. P. Korobeinichev M. W. Beach T. I. Hu T. A. Morgan 《Combustion, Explosion, and Shock Waves》2007,43(5):501-508
The chemical and thermal structure of a Mache-Hebra burner stabilized premixed rich CH4/O2/N2 flame with additives of vapors of triphenylphosphine oxide [(C6H5)3PO], hexabromocyclododecane (C12H18Br6), and ethyl bromide (C2H5Br) was studied experimentally using molecular beam mass spectrometry (MBMS) and a microthermocouple method. The concentration
profiles of stable and active species, including atoms and free radicals, and flame temperature pro.les were determined at
a pressure of 1 atm. A comparison of the experimental and modeling results on the flame structure shows that MBMS is a suitable
method for studying the structure of flames stabilized on a Mache-Hebra burner under near-adiabatic conditions. The relative
flame inhibition effectiveness of the added compounds is estimated from changes in the peak concentrations of H and OH radicals
in the flame and from changes in the flame propagation velocity. The results of the investigation suggest that place of action
of the examined flame retardants is the gas phase.
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Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 5, pp. 12–20, September–October, 2007. 相似文献
18.
L. M. Borodina M. S. Nemirovskii P. A. Tesner 《Combustion, Explosion, and Shock Waves》1999,35(1):8-11
It is shown that when acetylene, ethylene, hexane, octane, benzene, and naphthalene are introduced into natural gas, new soot
particles are not formed in laminar diffusion flames and the hydrocarbon additives are expended only in particle growth. A
similar effect, referred to as the inhibition of soot formation, has been observed previously during isothermal pyrolysis
of hydrocarbon mixtures. Introducing air into the gas sharply reduces the yield of soot. Complete cessation of soot production,
as observed from the disappearance of the luminous flame tip, corresponds to an air/natural gas ratio of 2.1.
Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 1, pp. 11–15, January–February 1999 相似文献
19.
E. N. Volkov A. A. Paletsky A. G. Tereshchenko O. P. Korobeinichev 《Combustion, Explosion, and Shock Waves》2006,42(6):663-671
A study was performed of the chemical and thermal structure of flames of model composite propellants based on cyclic nitramines
(RDX and HMX) and an active binder (glycidyl azide polymer) at a pressure of 1 MPa. Propellant burning rates were measured.
The chemical structure of the flame was studied using molecular-beam mass spectrometry, which previously has not been employed
at high pressures. Eleven species (H2, H2O, HCN, N2, CO, CH2O, NO, N2O, CO2, NO2, and nitramine vapor) were identified, and their concentration profiles, including the composition near the burning surface
were measured. Two chemical-reaction zones were observed. It was shown that flames of nitramine/glycidyl azide polymer propellants
are dominated by the same reactions as in flames of pure nitramines.
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Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 6, pp. 48–57, November–December, 2006. 相似文献
20.
D. A. Knyaz’kov V. M. Shvartsberg A. G. Shmakov O. P. Korobeinichev 《Combustion, Explosion, and Shock Waves》2007,43(2):143-151
The inhibition of atmospheric laminar methane-oxygen flames of various compositions by trimethyl phosphate was studied experimentally
and by numerical modeling using mechanisms based on detailed kinetics. The H and OH concentration profiles in flames with
and without the addition of trimethyl phosphate were measured and calculated. It was shown that the addition of the inhibitor
reduced the maximum (in the reaction zone) concentrations of H and OH in lean and rich flames. The concentration reduction
was higher in rich flames than in lean flames. The concentration profiles of the phosphorus-containing products PO, PO2, HOPO, HOPO2, and (HO)3PO in lean and rich flames stabilized on a flat burner were measured and calculated. Tests of the previously developed model
of flame inhibition by phosphorus compounds showed that the model provides adequate predictions of many experimental results.
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Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 2, pp. 23–31, March–April, 2007. 相似文献