摘要:

Ignition energy can be determined by means of electric sparks produced by a transmission-line method. The energy released in the spark discharge is calculated from recordings of the voltage pulses incident onto and reflected by the spark gap. It is shown that the voltage across and the current through the spark gap are proportional to measurable distances in the graphs. By the introduction of a form factor, the spark energy can be calculated without detailed evaluation of the instantaneous spark power as function of time.

ISSN:0010-2202    

DOI:10.1080/00102207208952496

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

An experimental investigation has been made of the properties of high speed enclosed diffusion flames being fed by propane and air. The flames burnt within a rectangular chamber consisted of an array of 2, 3 and 4 air jets, the propane inlets lying in between. The study of the velocity profiles showed interesting results of the stability of the flow fields. Combustion can stabilize an air jet field. The blow off stability of such flames decreases with increasing number of air jets and depends on the width of the air slits. The recirculation velocities within the wakes are slightly higher with combustion than in cold flow. The length of the recirculation zone is independent of the air jet velocity and scarcely influenced by combustion. By using radioactive Kr 85 as tracer gas the path of the fuel and its mixing with the air jet could be followed. The turbulence fluctuations in these diffusion flames are of the same order of magnitude as in premixed flames. The results can qualitatively be explained with a model, by taking into consideration the recirculation flow and an initial flame located at the boundary of the air jet.

ISSN:0010-2202    

DOI:10.1080/00102207208952497

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

An analysis of the temperature distribution in a porous disk burner indicates that the reactants exiting the disk and entering the preparation zone have substantial variation in temperature. Information is presented which allows the user of such a burner to estimate the difference in temperature between the central and peripheral streamlines as a function of reactant velocity, and thermal and geometric parameters.

ISSN:0010-2202    

DOI:10.1080/00102207208952498

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The ignition of single magnesium particles (28 to 120 micron diameter) suspended in cold oxidant atmospheres by means of an electrostatic levitation device, and the incendivity of these particles when suspended in a stoichiometric methane-air mixture, were investigated using pulsed laser radiation to heat the particles. Highspeed Schlieren and direct photographic techniques were used in the study. The critical radiant power density required for particle ignition was found to increase with particle size. Approximately equal radiant power densities were required for ignition of identical particles suspended in air and pure oxygen, although an increase in radiant power density was necessary for particle ignition in a helium-20 percent oxygen mixture. Results indicate that particle ignition occurred in the magnesium vapor shroud following surface vaporization. The incendivity experiments indicate that the critical radiant power densities necessary for the particle to ignite methane-air mixtures increases with decreasing particle diameter. Incendivity depends on the amount and rate of energy released by the irradiated particle. The incendive mechanism is believed to constitute a three-stage process.

ISSN:0010-2202    

DOI:10.1080/00102207208952499

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The point-by-point properties of an ammonia/air opposed-reacting-jet flowfield are described by solving the governing partial differential elliptic equations. Analytical descriptions of the reacting flowfield are compared to experimentally measured profiles of temperature and composition. Calculated distributions of stream function, temperature and fuel mole fraction are also presented.

ISSN:0010-2202    

DOI:10.1080/00102207208952500

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

A kinetic analysis of the published surface ignition behavior of M2 double base propellant is made, using a recently-developed approximate analytical model that assumes ignition to result from an adiabatic, first order surface reaction. It is shown that the values of the kinetic parameters obtained in the analysis are the same as are obtained using the results of numerical solution of the more rigorous ignition equations given in the literature. This agreement provides further support for the general validity of the analytical model. The manner of analyzing experimental data with the analytical model is described in detail.

ISSN:0010-2202    

DOI:10.1080/00102207208952501

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

An analysis has been performed for oscillatory burning of solid propellants including gas phase time lag. The gaseous flame is assumed to be premixed and laminar with a one-step overall chemical reaction. The propellant is assumed to decompose according to the Arrenhius Law, with no condensed phase reaction. With this model, strong gas phase resonance has been found in certain cases at the characteristic gas-phase frequencies, but the peaking of the acoustic admittance is in the direction favoring the damping of pressure waves. At still higher frequencies, moderate wave-amplifying ability was found. The limit of low frequency response obtained previously by Denison and Baum was recovered, and the limitations of the quasi-steady theory were investigated.

ISSN:0010-2202    

DOI:10.1080/00102207208952502

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Experiments have shown that acceleration of metalized composite propellants can affect an increased burning rate. The pressure-time trace of an accelerated propellant, which under static conditions would be neutral, exhibits a rapid increase to a maximum pressure and then decays asymptotically toward a quasi-equilibrium value. The model presented here attributes the augmented burning rate to the inertial retention of metal-metal oxide globules in pits on the propellant surface and the attendant heat transfer from the hot globules to the surface. A burning rate augmentation analysis for the initial period when the globules have near-spherical shapes predicts the burning-rate dependence on internal ballistic parameters and explains the observed transient behavior. As burning continues the globules grow and deform into irregularly shaped platelets and sheets which characterize the quasi-equilibrium period. Extending the model to include platelet shapes yields a functional relationship between burning rate, pressure level and acceleration which is validated by experiment.

ISSN:0010-2202    

DOI:10.1080/00102207208952503

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The effect of KMnO4, Fe23, CuO and copper chromite on the pressure limits of combustion of ammonium perchlorate was investigated. The lower pressure limit in all cases increased with small additions of each catalyst and then decreased at higher concentrations of catalyst. An upper pressure limit was observed in the deflagration of samples with high concentrations of KMnO4. It was further observed that the effect of catalysts depends strongly on the way they are distributed as well as their concentration. The catalysis were found to be much more effective at a smaller particle size.

ISSN:0010-2202    

DOI:10.1080/00102207208952504

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

It is well known that the burning rate of a solid propellant during a rapid pressure excursion is not given by the steady state relation, r = apn, but instead is generally a function of the pressure change rate, the pressure magnitude change, and properties of the propellant. An approximate but explicit relation for the non-steady burning rate as a function of these parameters is derived and compared with other treatments. Use of a current model for composite propellant combustion is made (Krier,et al., 1968). Discussion of the applicability of such explicit equations to predict burning extinction as a function of the pressure decay rate is also included.

ISSN:0010-2202    

DOI:10.1080/00102207208952505

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor