摘要:

Flame propagation along linear, vertically-oriented matchstick arrays on inclined base board is studied experimentally. The angles between the base board and the horizontal are 0°, 20°, and 40°. Both uphill burning and downhill burning are studied. The temperature field within the flame zone is measured, which indicates that the preheated region increases as the base board angle increases. Schlieren photographs of burning matchstick arrays also support this observation. Theoretical analysis using the concepts of the ignition temperature and the standoff distance of an envelope flame provides good agreement with the experimental results.

ISSN:0010-2202    

DOI:10.1080/00102208408960366

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Calculations of turbulent diffusion flames are presented and compared with experimental data. In the calculation procedure, the mean continuity and momentum equations are solved by a finite-difference method, and the k-ϵ turbulence model is used to model the Reynolds stresses. The conserved-scalar approach is used so that the local, instantaneous, thermochemical properties of the flame are uniquely related to a single conserved scalar f(x, 1)—the mixture fraction. A modelled transport equation for the probability density function (pdf) offis solved by a Monte Carlo method.

ISSN:0010-2202    

DOI:10.1080/00102208408960367

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The combustion of a fuel droplet in a mixed convective environment once the initial transient heating of the droplet has been completed is analyzed considering the internal motion of the liquid. The coupled gas and liquid phase analyses are solved simultaneously by a series expansion approach in terms of the polar angle. A previously developed mixed convection formulation is used to provide solutions ranging from the forced to the free convective limit. Detailed results are presented for the forced convective combustion of a hexadecane droplet in a standard atmosphere. The pure evaporation of the hexadecane droplet is presented as a particular case of the analysis. The effect on the local mass burning and droplet regression rates of the liquid motion and mixed flow intensities is presented in terms of the parameters that represent the respective processes. It is shown that the internal circulation of the liquid has only a moderate influence in enhancing the evaporation rate of the droplet. A single explicit expression for the droplet regression rate is applicable to the whole range of mixed flow intensity.

ISSN:0010-2202    

DOI:10.1080/00102208408960368

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

A flame extinction model is incorporated in a computational procedure containing the “k-ϵ-g” model of turbulence and applied to the prediction of burner stability features of some furnace trials performed at the International Flame Research Foundation. The fuels are low calorific value gases. As a prelude to the application, the lifting of and blow off of turbulent jet diffusion flames are examined as well as the stability behaviour of baffle stabilized premixed flames. The extinction model presumes that reaction will cease when the diffusional rate between the fine turbulence scales exceeds the reaction rate, both of which quantities are simply characterized. Its performance across the range of flows studied is remarkably good. Diffusion flame blow off is well represented by straightforward considerations of jet similarity and fuel stoichi-ometry.

ISSN:0010-2202    

DOI:10.1080/00102208408960369

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The structure of a wrinkled premixed flame is analysed theoretically. By assuming the reactive mixture diluted in an inert gas and a weak cross-diffusion coupling between the heat and mass fluxes, the effect of the change by the reaction of the physical gas properties (thermal conductivity, specific heat, number of molecules) and Soret and Dufour diffusions have been investigated in the limit of high activation energies. It turns out that Soret mass diffusion cannot be neglected in the study of the flame front dynamics. In contrast, the change of physical properties as well as Dufour heat diffusion generally appears to play a minor role.

ISSN:0010-2202    

DOI:10.1080/00102208408960370

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0010-2202    

DOI:10.1080/00102208408960371

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor