摘要:

This paper reports the results of experimental and theoretical investigations into the effects of thermal radiation upon ignition and deflagration of M-2 double-base solid propellant. The values of the heat of reaction, the frequency factor and the activation energy in the Arrhenius expression describing the chemical reactions in the solid are determined by matching the numerical solutions of the mathematical model with three sets of experimental data. The effect of thermal radiation upon the propellant is only thermal. Theoretically the effect of thermal radiation on the burning rate is shown to be equivalent to an increase in initial temperature of the propellant only when the radiation absorption coefficient is small. For M-2 propellant, thermal radiation has insignificant effect upon the burning rate for a range of fluxes from 0 to 1.5 cal/cm2-sec.

ISSN:0010-2202    

DOI:10.1080/00102207008952235

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

analytical model for the design of tubular gas turbine combustors is developed by combining the desirable portions of several models from the literature. A literature survey covering the three major theories of combustor analysis, turbulent flame speed, microvolume burning, and stirred reactors is briefly summarized. Based on the results of the literature survey a combustor model composed of stirred reactors is proposed. A kinetic formulation for the combustion of propane in a single-staged stirred reactor is developed, and limited results are presented.

ISSN:0010-2202    

DOI:10.1080/00102207008952236

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Local similarity and related methods are used to analyze the heterogeneous ignition mechanism of solid fuels. Analytic solutions are derived for the surface temperature history in order to determine the time and nature of the transition from a weak combustion mode to a strong one. The existence of the various burning modes is attributed to a time-dependent Damkohler number. It is then shown that non-unique solutions in the local similitude transform plane correspond to discontinuities in the physical plane. The ignition phenomenon is readily associated with the discontinuity so that it is not necessary to resort to arbitrary ignition criteria. The solutions are shown to compare favorably with exact numerical solutions. Finally, the existence of discontinuities suggests that ignition problems may be amenable to asymptotic analysis.

ISSN:0010-2202    

DOI:10.1080/00102207008952237

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A method was developed for measuring the size distribution of particles condensed from metal vapor, at ambient conditions. Particles were collected on a carbon coated surface of mica cleaved along its crystal plane and were shadowed with chromium. The collected samples were photographed through an electron microscope. Size distributions were determined by actual count of the particle images in the photographs after enlargement. The metal vapor was obtained by evaporating metal wires electrically (exploding) at ambient conditions. Primarily platinum wire was used but some zinc and iron were also employed. While the kind of metal and the amount of energy transferred play a role, in all cases it was shown that the particle size distribution is much wider than the distribution of particles from condensation in supersonic nozzles. There appear to be definite limits to the flow fields for which the common assumption that condensed particles are uniform in size is valid.

ISSN:0010-2202    

DOI:10.1080/00102207008952238

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Equations of the kind used in lubrication theory have been developed in order to examine the fluid mechanics of a thin layer of liquid fuel near a burning wick. Under the simplifying assumption made, the problem can be characterised by two dimensionless parameters. An extinction condition is defined and the relationship between the parameter at extinction is obtained. Some numerical solutions are presented for the variations of surface tension and fuel depth with distance from the wick.

ISSN:0010-2202    

DOI:10.1080/00102207008952239

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Hydrogen gas is assumed to be injected through the surface of a ‘fuel spher’ into a pure oxygen atmosphere, and so to give rise to a spherical diffusion flame. The combustion process is presumed to be sustained by a set of five reactions which involve the six species H2, O2, O, H, OH and H2O, and a proper multi-component, variable diffusion-coefficient, description of the diffusion processes is therefore adopted. Use of the method of matched asymptotic expansions to solve the governing conservation equations makes it possible to deal analytically with this problem and, by focussing attention on the dominance of certain physical phenomena in special regions of the field, reveals the influence of chemical kinetics on flame structure. For example, inner region (i.e. intense reaction zone) behaviour indicates the crucial role played on the O2-rich side of the flame by the reaction OH + H; in one case it may produce O + H2and in the other (with the aid of a third body) it may result in H2O and so act as a chain-breaking step. The relative rate of progress of these two reactions is shown to have an essential effect on the flame structure.

ISSN:0010-2202    

DOI:10.1080/00102207008952240

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The development of a diffusion flame at a stagnation point when hydrogen is injected into the hot on coming air flow is studied by treating finite rate chemistry for several sets of flow conditions. The limiting cases of frozen and equilibrium behaviour are presented. Relatively accurate descriptions of the chemical steps, and the thermodynamic and transport properties of the species are employed.

ISSN:0010-2202    

DOI:10.1080/00102207008952241

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

ISSN:0010-2202    

DOI:10.1080/00102207008952242

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

In order to understand the interaction of the physical and chemical processes which result in cool flames, a theoretical investigation of flame propagation has been undertaken. For this study, a mathematical model has been formulated which takes into account the conservation of mass, momentum, and energy; and assumes Fick's law for mass diffusion. To account for the flame separation property associated with these flames, a chemical model consisting of two exothermic, monomolecular, series reactions has been considered in order to have several chemical reactions proceeding at different rates. The resulting flame equations have been solved analytically for an ignition temperature approximation to the chemical kinetics and numerically for Arrhenius kinetics. The results for the two kinetics models compare favorably for the cases in which double flames are produced. A general comparison of the theoretical results to experimental results appearing in the literature shows a general agreement in the shape of the temperature profiles. The conclusion is drawn that the two flame phenomenon can be viewed as literally two flames with weak but sufficient interaction to maintain a separation distance.

ISSN:0010-2202    

DOI:10.1080/00102207008952243

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

An experimental and analytical investigation of the oxidation of methane and ethane behind shock waves has been carried out. Mixtures of methane/oxygen and ethane/oxygen dilute in argon were shock-heated by both incident and reflected waves. The progress of the reaction was followed by monitoring infrared emission from CO2, CO and H2O and the density gradient. The experimental data were expressed in terms of reaction times which were correlated with initial fuel and oxygen concentrations and temperature. To determine oxidation mechanisms for methane and ethane, measured reaction times were compared with calculated reaction times obtained from an analytical study of the two reactions. In the analytical study the time rates of change of species concentration and thermodynamic properties during reaction were calculated by numerically integrating the coupled reaction kinetic, state and gas dynamic equations. A 14-step mechanism for the high-temperature oxidation of methane was suggested which gave good agreement between calculated and measured reaction times. A simplified 11-step mechanism for the high-temperature oxidation of ethane was proposed. In the proposed mechanism ethane reacts only via the decomposition reaction, forming two methyl radicals. The methyl radicals react via the reactions of the methane mechanism. Using the simplified mechanism, reasonable agreement between calculated and measured reaction times was obtained.

ISSN:0010-2202    

DOI:10.1080/00102207008952244

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor