摘要:

A planar steady flame is assumed to propagate through a mixture of fuel, oxidant, diluent and product species, which burns according to a general one-step reversible reaction. On the assumption that the activation energy of the burning reaction is large, the first significant terms in asymptotic series for several quantities of interest are evaluated. As a result it is possible to make some general observations about the effects of mixture strength on a number of features, such as flame propagation speed and reaction-zone behaviour, for example. It is also deduced that chemical-reaction induced amplification of acoustic disturbances is unlikely to occur in pre-mixed flames of this simple type.

ISSN:0010-2202    

DOI:10.1080/00102207508946670

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A short information is given on the results of work carried out at the Branch of the Institute of Chemical Physics, U.S.S.R. Academy of Sciences, since 1967 on studying the combustion processes caused by the interaction of chemical elements in the condensed phase and leading to the formation of refractory compounds. New phenomena and processes are described which are revealed when investigating the combustion of the systems of this class, viz solid-phase combustion.fast combustion in the condensed phase, filtering combustion, combustion in liquid nitrogen, spinning combustion, self-oscillating combustion and repeated combustion. A new direction in employment of combustion processes is discussed, viz. a self-propagating high-temperature synthesis of refractory nitrides, carbides, borides, silicides and other compounds.

ISSN:0010-2202    

DOI:10.1080/00102207508946671

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The thermal decomposition of methyl nitrite (CH3ONO), in excess argon, CH3ONO + M → CH3O + NO + M, was studied behind both incident and reflected shock waves. Kinetic data were obtained in the temperature and total pressure ranges 715-1118 °K and 0.8-5 atmospheres, respectively. The reaction was found to be unimolecular in nature and occurring in the low pressure region, with a rate constant expression, k = 1016.36±0.22exp(-30,400 ± 850/RT), cc/mole-sec.; giving the best least-squares fit to the data. Treatment of the data with R.R.K. theory leads to the conclusion that ΔH1OH3O≅ 9.0 kcal/mole rather than the present literature value of 3.5 kcal/mole. The results of previous investigators are compared to the present findings. The molecular absorption coefficient of methyl nitrite at 2800 ± 30 Å was found to be temperature dependent. The values of the absorption coefficient was fit to the form, ϵT3800 ± 30 Å= 636T - 229,010 cc/mole-cm.

ISSN:0010-2202    

DOI:10.1080/00102207508946672

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A low inductance exploding wire circuit is shown to be a good means for the investigation of variable energy cylindrical blast waves. The circuit was designed so that the energy stored in a large capacitor could be discharged with the energy transferred to the wire in a single pulse with no oscillation and no dwell time or restrike. Voltage and current can then be measured as a function of time so that energy release as a function of time can be determined.

ISSN:0010-2202    

DOI:10.1080/00102207508946673

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Multiple turbulent diffusion flames with swirl have been investigated experimentally. The degreeof swirl was varied from 0.2 to 0.57 and the burner separations were changed from 0.25DEto 1.50DE. Temperature and composition surveys were made at various axial and radial positions. A dilution factor which is a measure of the air entrained into the flame is defined and computed. It was found that the flame stability and length of the flames depended mainly on the swirl level and burner separation. Large interaction between burners with, narrow separation and low swirl number was found.

ISSN:0010-2202    

DOI:10.1080/00102207508946674

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Many problems in practical combustion devices are caused by the need to establish a near-stoichiometric zone which aids in the achievement of stable, highly-efficient combustion. For example, if operation at low equivalence ratios (φ ∼ 0.6) were practical, NOx, emission and combustion chamber cooling requirements could be reduced. The present work describes the results of a large-scale experiment where combustion stability was achieved through the use of a catalytic bed within the reaction zone (i.e., catalytic combustion). Since this scheme requires design of a system which results in uniform fuel-air mixing and a uniform velocity profile, the exhaust gases closely approximate isothermal plug flow, thus avoiding many additional current system disadvantages due to severe temperature gradients. Testing was conducted at pressures up to 10.5 atmospheres and exhaust temperatures up to 1589 °K. Performance trends with fuel-air ratio, inlet temperature, reference velocity and pressure were obtained. A literature search was conducted to collect available catalytic oxidation information. Characteristics of noble metal and transition metal oxides are discussed. Results of the present work are interpreted vis-a-vis possible future applications. A summary of development work required before practical application is offered.

ISSN:0010-2202    

DOI:10.1080/00102207508946675

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Explicit analytical solutions for the radiation from nonluminous regions of hydrocarbon laminar diffusion flames are obtained using a wide band model for nonisothermal, nongray radiation from inhomogcneous mixtures of combustion gases. The spatial distributions of the reactant species, of the combustion products, carbon dioxide and water vapor, and of the temperature in these flames are derived from a one-dimensional model with the Shvab-Zel'dovich assumptions. A wide band, theoretical closed form expression for the total band absorptance of infrared radiating gases, used in conjunction with wide band correlation parameters, allows a simple analytical solution for nongray radiation from nonisothermal and nonuniform distributions of carbon dioxide and water vapor observed in hydrocarbon laminar diffusion flames. The isothermal limit of this solution not only provides good agreement with experimental isothermal emissivity data for carbon dioxide, but also yields the correct functional dependence on temperature, for both carbon dioxide and water vapor. Agreement with absolute water vapor emissivity is reasonable. A tentative soot model to compute soot distribution profiles in diffusion flames is discussed. In the future, the techniques which have been developed here will be applied to soot-containing luminous flames.

ISSN:0010-2202    

DOI:10.1080/00102207508946676

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Two recent approximate analyses of ignition in homogeneous, adiabatic systems with fuel consumption specifically included are discussed and compared with the derived exact solution of the problem. The singularity present in both approximate solutions is shown to be the same as that found in the exact solution, and is characteristic of the time required to establish nearly complete chemical reaction. A similar situation is shown to exist for ignition in non-adiabatic, homogeneous systems—the classical Semenov problem—causing the proposal and discussion of a thesis that a correct description of any ignition event must always include the transient behavior as quasi-steady combustion is approached. Intuitively satisfying, the theoretical and experimental implications of this thesis are discussed.

ISSN:0010-2202    

DOI:10.1080/00102207508946677

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor