摘要:

The burning rate of a combustible mixture is experimentally found to be maximum when the unburnt mixture is slightly fuel-rich. In Part I the authors explained this neat-stoichiometric behavior purely on the basis of diffusion of the reactants. The usual explanation is based on dissociation of the products, according to which dissociation causes the maximum flame temperature and therefore the maximum burning rate to occur slightly on the fuel-rich side of stoichiometry. However, as indicated in Part I, several aspects of this explanation are unsatisfactory. The purpose of the present paper is to show that while dissociation explains the shift of the maximum temperature onto the fuel-rich side, it has only a subsidiary effect on the maximum burning rate.

ISSN:0010-2202    

DOI:10.1080/00102208108946959

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The mass rate of entrainment is examined for a fire plume in a room. Entrainment rates are inferred from measurements of air flow through a door or window and from room temperature data. The effect of the air flow is to tilt the flame plume, and to increase the entrainment rate over that of a vertical free standing plume. Dimensional analysis and theoretical results for a non-reacting wind blown plume model are used to correlate the flame angle and entrainment rate results.

ISSN:0010-2202    

DOI:10.1080/00102208108946960

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A mechanism consisting of 18 elementary chemical reactions is demonstrated to give a complete quantitative description of the concentration-, temperature-, and pressure-dependence of the flame velocity in H2-O2-N2mixtures. Whereas concentration- and temperature-dependence show the expected behaviour, the pressure dependence is determined by the two different chain mechanisms occurring. At low and at high pressures the pressure exponent of the flame velocity is positive in agreement with simple flame theory. In between there is a transition region with negative pressure exponents due to the change of the chain mechanism, which does not contradict simple flame theory as sometimes asserted in the literature. Furthermore, the partial equilibrium assumption is shown to be valid only at temperaturesT>1700 K, whereas at lower temperatures this hypothesis fails by orders of magnitude. Experiments on NO formation in H2-air flames can be reproduced, if the larger of the two rate constants recommended in the literature is used for the calculations.

ISSN:0010-2202    

DOI:10.1080/00102208108946961

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

The transitional structure of two-phase detonations initiated by strong blast waves in decane sprays in oxygen and in clouds of wheat and RDX particles in air is investigated numerically. A one-dimensional unsteady code based on the flux corrected transport algorithm is employed. Detailed profiles of mass velocity, particle velocity, sound velocity and Mach number are presented for the reaction zone both prior to and after the establishment of fully developed detonations. With heavy particle loading a broad region of near sonic flow is observed and under proper conditions weak secondary shock waves are generated within the reaction zone.

ISSN:0010-2202    

DOI:10.1080/00102208108946962

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

Systematic changes have been observed in the character of diesel exhaust particulates as the engine air/fuel ratio is varied. For air/fuel ratios below 20 the particulates are primarily carbonaceous, cluster into chain-like agglomerates and exhibit high specific optical extinction. Increasing the air/fuel ratio leads to increases in the volatile organic content, to less clustering and to lower specific optical extinction. The specific optical extinction decreases from over 10 m2·g−1at air/fuel ratios below 20 to less than 5 m2·g−1for air/fuel ratios above 30.

ISSN:0010-2202    

DOI:10.1080/00102208108946963

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A universal non-dimensional formula that describes the blow-out stability limit of gaseous jet diffusion flames in still air has been found experimentally. Its validity has been established over a wide range of parameters that affect the blow-out limit. Its extrapolation to cases where the burner exit flow is choked suggests that for a given gas there is a critical burner diameter above which a stable flame can exist at any flow rate.

ISSN:0010-2202    

DOI:10.1080/00102208108946964

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

A non-dimensional stability curve that describes the blow-out stability of diffusion flames in a cross-wind, for different gases, has been established experimentally. For a given burner and a given gas, if the cross-wind speed is greater than a limiting value, a stable flame is not possible. For cross-wind speeds less than this limit, there are usually two blow-out limits which are on either side of the blow-out limit in still air.

ISSN:0010-2202    

DOI:10.1080/00102208108946965

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

摘要:

An analysis is performed of the influence of a catalytic surface reaction on the gas phase ignition of a premixed combustible gas flowing past a hot catalytic flat plate. It is assumed that the catalytic surface reaction is infinitely fast so that chemical equilibrium is reached along the whole length of the plate surface. In the gas phase a finite-rate chemical reaction with a large activation energy is considered. The analysis makes use of the boundary layer approximation to describe the gas flow and of first order matched asymptotic expansions to define ignition. Explicit expressions are derived for the critical gas phase Damköhler number for ignition and for the distance from the plate leading edge to the onset of ignition. The ignition distances for a catalytic and a non-catalytic plate are compared. Longer ignition distances for the former case are predicted. The results of the analysis agree qualitatively with previous experimental observations.

ISSN:0010-2202    

DOI:10.1080/00102208108946966

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor

ISSN:0010-2202    

DOI:10.1080/00102208108946967

出版商:Taylor & Francis Group    

年代:1981

数据来源: Taylor