摘要:

Measurements of dynamic light scattering along with classical scattering/extinction as a function of the wavelength for a rich propane/oxygen flame are presented. Spectral optical properties of soot particles are inferred in the visible and infrared part of the spectrum. Particle size distribution. number densities and volume fractions of soot are determined and comparisons are made with predictions of existing models for the soot optical constants. The effects of agglomeration and temperature in the determination of the optical properties are assessed and a new set of dispersion constants for the optical properties of flame soot is presented.

ISSN:0010-2202    

DOI:10.1080/00102208808947108

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Axial, radial and tangential velocities were measured using an LDV in a field in which a laminar hydrogen jet (6.0 mls at the center of a burner exit) was injected into a co-flowing air stream (6.0 m/s) with or without grid turbulence. The conditional sampling based on the origin of the jet and the co-flowing stream was applied. The interaction between grid turbulence and the flame is discussed in detail. It is found from the radial profile of the mean velocity that with the grid the jet and the coflowing stream are mixed intermittently. Inside the flame the jet flows inward and the co-flowing stream flows outward. The profiles of axial and radial turbulent intensities of the co-flowing stream have a peak near the flame and at this location the histograms of velocity are bimodal. This suggests wrinkled laminar f1amelets; that is, the fuel, the air and the f1amelets are mixed intermittently. Moreover, the mean axial/radial velocities of the air and the f1amelets are different from each other but the mean tangential velocities are the same. Thus, the histograms and the profiles of the turbulent intensity depend on the direction.

ISSN:0010-2202    

DOI:10.1080/00102208808947109

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A detailed calculation of the coagulation kinetics of a soot aerosol has been performed by simulating numerically the coagulation kinetics with the inclusion of van der Waals forces. The van der Waals forces between two soot particles at 1600 K and 1 atmosphere give rise 10 a collision rate enhancement which varies between a maximum of about 2.4 for 1 nm diameter particles to just over 1 for particles of dissimilar sizes. The total coagulation rate with the estimated enhancement factors was about twice the unenhanced rates; this compares favorably with experiment. Over the duration of the computation the soot aerosol size distribution approaches closely the self-preserving form, whether or not the collisional enhancement factors are included.

ISSN:0010-2202    

DOI:10.1080/00102208808947110

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

ISSN:0010-2202    

DOI:10.1080/00102208808947111

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Abstract-In the Bray-Moss model for the thermochemistry of premixed turbulent combustion with reaction confined to thin laminar flamelets the temperature at a fixed point within the turbulent flame, suitably idealized and normalized, can be interpreted as a two-valued, zero-one function. Previous work shows that the time autocorrelation of this function plays an important role in the determination of the mean rate of creation of product in such flames. Our purpose here is to develop the partial differential equations for the several space-time correlations of the two-valued functions associated with flamelet crossings in premixed turbulent combustion. Application of each of these equations requires modelling. However, contrary to earlier work we show that a consistent set of models for the equation describing the time autocorrelation leads to no new information on the integral time scale needed in the mean rate of creation. It is concluded that resort must be made either to an alternative theoretical approachto experiment.

ISSN:0010-2202    

DOI:10.1080/00102208808947112

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The precombustion mixture compositions of CH3CI/CH4/O2/Ar 13.4/26.6/36.7/ 28.9 for Flame A and CH4/O2/Ar 36.0/35.1/28.9 for Flame B reported in our paper [Comb. Sci. and Techn. 1987 54( 1-6), 333] correspond to equivalence ratios of 1.99 and 2.05, respectively, as opposed to the values of 1.79 and 2.05 as printed in the paper. That is, the differences seen in the experimental profiles better illustrate the effects of chlorine on flame chemistry in the two systems studied since the flames are closer in equivalence ratios than indicated.

ISSN:0010-2202    

DOI:10.1080/00102208808947113

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor