摘要:

Using the Michelson-Sivashinsky (M.S.) non–linear equation as a starting point to study the dynamics of unstable premixed flames, we propose a way of incorporating an external noise intended to mimic an incoming turbulence. while preserving the possibility of pole-decompositions of the solutions.

ISSN:0010-2202    

DOI:10.1080/00102208808923972

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Laminar burning velocities of stoichiometric mixtures of air and methane with ethane or propane additives have been determined from pressure measurements in a spherical chamber following central ignition. The burning velocities were determined by two methods and correlated in a form

ISSN:0010-2202    

DOI:10.1080/00102208808923973

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Combustion experiments of synthetic gas and pulverized coal were carried out by the method of two free-impinging-streams as shown schematically in configuration "b" of Figure I. In combustion of gas, the complete behaviour of impinging jets versus the fuel/air ratio was revealed and explained on the basis of the dependence of the burning velocity of the gas mixture on the above ratio. This behaviour consists of three distinct and stable modes of operation as follows: In mode I, no combustion takes place along the path of the free jets fed into the reactor (Figure 3a). In mode II, combustion begins roughly near the impingement plane of the two jets (Figures 3b, 4 and 6). Mode III is a third situation in which combustion takes place immediately at the entrance of the jets into the reactor (Figures 3c and 5). For combustion of pulverized coal, a correlation based on a diffusion-convection model was obtained for the prediction of the combustion efficiency as a function of available operational parameters.

ISSN:0010-2202    

DOI:10.1080/00102208808923974

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Abstract A detailed chemical kinetic mechanism for the combustion of CH3CI is presented. This mechanism, together with the better understood mechanism of combustion of CH4, was used to calculate the stable species concentration profiles in atmospheric-pressuresooting CH4CI/CH4/O2/Ar premixed flat flames studied previously (Kana and Senkan, 1987), The agreement between the model and experimental data is reasonable. The major reaction pathways responsible for the formation and destruction of species have been identified via the calculation reaction rates and sensitivity analysis.

ISSN:0010-2202    

DOI:10.1080/00102208808923975

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Abstract The steady combustion of polydispersed sprays of ethanol and kerosene in the stagnation-point flow of lean methane/ air mixtures is experimentally investigated. Using laser Doppler velocimetry, the axial and radial velocity profiles of the dropletsare measured for water sprays in the presence or absence of lean methane/ air flame. These results are then compared with the velocity profiles obtained for small MgO particles under identical flow conditions. The results show the effects of gas expansion on droplet deceleration (acceleration) in the pre-flame (post-flame) regions. Also, it is found that addition of water spray results in the formation of a distributed region of yellow-orange emission downstream of the lean methane flame. In combustion of ethanol spray, certain critical fuel-concentration/ velocity limits are identified above which the flame becomes acoustically unstable. The implications of the study to the modeling of turbulent spray combustion are discussed.

ISSN:0010-2202    

DOI:10.1080/00102208808923976

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Abstract-Combustion in vortex flow fields is of interest in fundamental studies and also because it occurs in many practical situations. Some important analytical contributions to this topic are due to Marble and his students. The Marble problem of a viscous core vortex interacting with a non-premixed flame is treated in the present paper. The analysis is numerical, Detailed calculations of the flame structure are performed.Results obtained confirm intuitive aspects of Marble's analysis. The growth of the core of products is examined. Similarity laws for the radius of this core and for the global reaction rateare verified. Influences of equivalence ratio and Reynolds number are illustrated and discussed.

ISSN:0010-2202    

DOI:10.1080/00102208808923977

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A model is constructed to assess the contribution of fly-ash particles to radiative heat transfer in a coal-tired combustion system. The measured fly-ash optical properties are used to prediet spectral extinction and scattering coefficients as well as the scattering phase function from the Lorenz-Mie theory. Radiative transfer calculations are then performed on the spectral basis for a one-dimensional planeparallel geometry using the Pq/approximation, which is known to be very reliable. The results show that scattering by the fly-ash particles impede the transfer of radiation from the hot flame to the walls of the combustion system and the blockage of radiation is strongly dependent on the wavelength.

ISSN:0010-2202    

DOI:10.1080/00102208808923978

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

Organic peroxides were extracted in a flow system, from the combustion chamber of a motored C.F.R. engine operated as a compressor and running on n-heptane.

ISSN:0010-2202    

DOI:10.1080/00102208808923979

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

A comprehensive study of the stretch response of the Zeldovich-Liñ´n model is made under the new limit of large heat release. As a response to the work of Mikolaitis (1986), in particular, it is shown that the smallness of the concentration of intermediates is due to the ratio of Damköhler numbers and not to the largeness of the heat release, and that the stretch response. including the existence of Seshadri and Peters' stretch-resistant flames, is not affected by the consideration of a large heat release and/or activation energy limit.

ISSN:0010-2202    

DOI:10.1080/00102208808923980

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor

摘要:

The addition of swirl to a non-premixed flame is known to increase the fuel-air mixing rate, which can cause local premixing and thereby increase flame temperature. The present paper quantifies how the flame temperature increases as swirl is systematically increased; it also quantifies how the flame temperature decreases as fuel jet momentum is increased. Of particular interest are two limits which have not been studied previously in much detail. At the high swirl limit, the temperature levels and profile shapes in the non-premixed flame become similar to those of the premixed swirl flame studied by Gouldin. Thus the rapid internal mixing makes the non-premixed flame behave like a premixed flame. A second limit of interest is the transition from a cooler "jet-like" flame to a hotter "strongly recirculating" flame; the temperature change during this transition is reported and the critical level of swirl and fuel jet momentum required to cause such a transition is quantified. Temperatures were measured using non-intrusive laser Rayleigh scattering. It is shown how temperatures can be controlled by systematically varying the swirl and fuel jet momentum, while maintaining good flame stability, which is an advantage of swirl flames over simple jet flames. The paper also quantifies the level of unmixedness, as characterized by temperature fluctuations, in the limit of very high swirl. Even at high swirl the non-premixed flame does not become "well stirred;" temperature fluctuations remain significantly larger than those of the premixed flame reported by Gouldin. A numerical model that includes swirl and combustion is used to help understand the complex balance between centrifugal, inertial and pressure forces.

ISSN:0010-2202    

DOI:10.1080/00102208808923981

出版商:Taylor & Francis Group    

年代:1988

数据来源: Taylor