摘要:

A study was made of flame propagation along methane-air roof layers using a laboratory scale gallery, 8 feet long by 3 inches wide by 6 to 10 inches high. The effects of various environmental and gas layer factors on the speed of the propagating flame were determined and dimensional analysis techniques were used to develop a relationship between these factors and flame speed. The model was designed to study the early stages of flame propagation along a methane-air layer ignited at the closed end of a tunnel.

ISSN:0010-2202    

DOI:10.1080/00102206908952204

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

An analysis of the effects of entropy or material waves on high frequency pressure oscillations in a liquid rocket combustor is presented. The combustor is assumed to have a concentrated combustion zone and a zero length nozzle. The nonlinear perturbation analysis employs the techniques or multiple scales in order to reduce the governing partial differential equations to an ordinary differential equation describing the pressure oscillation limit cycles. Linear stability limits are also determined. The maximum destabilizing effect of entropy waves on these limits is of the order of 15%. Under certain conditions it is found that the entropy waves can effectively cancel the damping effect of the short nozzle.

ISSN:0010-2202    

DOI:10.1080/00102206908952205

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Starting with prior conclusions that beryllium and aluminum burn primarily by some unspecified vapor-phase mechanism, reaction schemes of two-body collisions accompanied by small heats of reaction are proposed, For beryllium, it is shown that the lowest free energy path to the liquid oxide consists of polymerization reactions as opposed to homogeneous nucleation. This is substantiated by the known existence of beryllia polymers through the hexamer. A similar scheme, employing polymers of AlO, is also proposed for aluminum although the highest known polymer reported to date is the dimer. A search for higher polymers through mass spectrometric studies is recommended.

ISSN:0010-2202    

DOI:10.1080/00102206908952206

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Cellulose decrystallized by swelling in liquid ammonia produced a simpler thermogravimetric analysis curve than obtained from ordinary cellulose—presumably because of a decrease in the intermolecular char-forming reactions. By using a graphical procedure which permits a linear plot of the thermogram, it was possible to resolve the overall curve into two components: the principal reaction by which more than 90% of the weight loss occurred (activation energy = 54.9 kcal/mole; pre-exponential factor = 3.15 × 1019/min), and a second component which may be approximated by a first-order reaction leading to an ultimate 4% char.

ISSN:0010-2202    

DOI:10.1080/00102206908952207

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

During pyrolysis of pure cellulose, the Crystallinity Index (Crl) remained fairly constant over more than 50% weight loss before dropping rapidly as the X-ray pattern deteriorated. With samples first treated with trace quantities of inorganic salts, heating first increased the Crl—the results implying a preferentially catalyzed decomposition of the amorphous regions. Swelling cellulose in liquid ammonia eliminated the crystalline diffraction pattern, but heating restored a considerable degree of order. The initial weight loss rate in the swelled material was considerably accelerated and the ultimate char residue reduced. The results support the suggestion that inter-ring cross-linking leading to enhanced char formation will occur preferentially in the ordered rather than the disordered regions of natural cellulose.

ISSN:0010-2202    

DOI:10.1080/00102206908952208

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The rate of flame spread across the surface of liquid fuels (mainly n-decane, but also n-nonane, n-undecane, dipentene, kerosene, and n-butanol) has been examined in detail for a wide range of laboratory variables. Many hundreds of carefully controlled tests have been performed aimed at elucidating the dependence of the flame spreading velocity on (1) the purity of the fuel, (2) the mode of ignition, (3) the temperature of the fuel. (4) the dimensions and material of the fuel container, and (5) the depth of the fuel layer. The effects of environmental parameters (atmospheric pressure, air temperature and relative humidity) have also been investigated, but non-systematically. The results show that the flame spreading velocity is susceptible to changes in most of these parameters. This work constitutes the first systematic variation of all the laboratory variables with the view to obtaining flame spreading data which are meaningfully applicable to any apparatus and also to ‘real’ liquid fuel fires.

ISSN:0010-2202    

DOI:10.1080/00102206908952209

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Convective heat transfer through the liquid fuel below a spreading flame is considered as a rate controlling mechanism. Thus, a surface-tension-driven liquid flow, induced by the temperature profile ahead of a spreading flame, is analyzed. Velocities, pressures and surface heights are determined for a two-dimensional flame spreading at a steady rate. It is demonstrated that convection can occur near the suface ahead of the flame and in the direction of propagation and, thus, that liquid-phase convective heat transfer can be a plausible rate-controlling mechanism for flame propagation.

ISSN:0010-2202    

DOI:10.1080/00102206908952210

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The nonequilibrium formation of nitric oxide within the internal combustion engine cylinder is examined. A thermodynamic model which predicts the properties of the burnt and unburnt gases during the combustion process is developed. A set of reactions which govern the formation of nitric oxide is proposed, and rate equations for nitric oxide concentrations as a function of time in the post-flame gases are derived. The results of time-resolved measurements carried out on a CFR engine are described, where emitted light intensities at wavelengths selected to record radiation from the CO + O and NO + O continua were used to determine the nitric oxide concentration. The comparison between theoretical and experimental results for fuel-lean mixtures confirms that the important features of the model presented are correct.

ISSN:0010-2202    

DOI:10.1080/00102206908952211

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

ISSN:0010-2202    

DOI:10.1080/00102206908952212

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor