摘要:

In order to provide confirmed experimental Favre averaged data for the validation of a new one-dimensional integral model of turbulent diffusion flame with large buoyancy effects, temperature and velocity fluctuation measurements have been carried out on the axis of a gas-fuelled burner at low Froude number. Temperature fluctuations have been measured by instantaneous compensation of the thermal inertia of fine wire thermocouples. Simultaneous measurements of temperature and velocity have pointed out that, on the burner axis, LDV results are not significantly biased toward hotter gas velocities, even if only the fuel is seeded. Results are used to calculate Favre averaged values of temperature and velocity, as well as velocity-temperature correlations.

ISSN:0010-2202    

DOI:10.1080/00102208608923894

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

We have measured the concentration profiles of the major products in fuel-rich pre mixed CH4/O2flames. Optical measurements were performed to measure soot number densities, volume fraction and particle size distributions. We have shown that the increase in the soot volume fraction is due to surface growth and that acetylene is the source of the carbon involved in this process. We have also been able to determine the importance of coagulation versus surface growth in the increase of soot particle radius with time in these flames.

ISSN:0010-2202    

DOI:10.1080/00102208608923895

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Flammability limits for methane-air and propane-air mixtures were measured using the counterflow type burner which consisted of a couple of converging-diverging nozzles made of quartz glass. As several types of flames other than the usual twin flames were obtained in this burner, a simple theoretical analysis on the shape and nature of the flame developing in the counterflow field was first made, and flame stability and correspondence between the theoretically obtained and experimentally observed flame shapes were discussed. Flammability limits were then discussed with respect to the flame stretch effect and the preferential diffusion effect.

ISSN:0010-2202    

DOI:10.1080/00102208608923896

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The ignition process of liquid fuel droplets and its impact on the formation of soot and nitrogen oxides have been studied. The system studied consists of a laboratory flame maintained by a vertical, monosized liquid fuel droplet array surrounded by a laminar flow of a mixture of helium and oxygen. It was found that the formation of soot and nitrogen oxides closely correlates with the ignition of liquid fuel droplets. It has been shown that the soot formation can be suppressed by delaying ignition, and thus vaporizing as much fuel as possible prior to the ignition. But delaying ignition favors the conversion of fuel-bound nitrogen to nitric oxide. The control of the emission of both soot and nitrogen oxides can be achieved by use of low oxygen concentrations in the oxidation gas to delay ignition and suppress soot formation by using a high fuel/air ratio to reduce NOx.

ISSN:0010-2202    

DOI:10.1080/00102208608923897

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Laser velocimetry and Rayleigh scattering diagnostics are applied simultaneously to measure velocity-density correlations, Favre averaged velocities, and the conditioned velocities of reactants and products in a premixed turbulent flame. Details of the experimental procedure are described, as well as the effects of velocity biasing. The flamelets within the flame are visualized and a significant amount of “flame generated turbulence” is measured. A number of assumptions in the Bray-Moss-Libby theory are found to be valid which is in agreement with several previous experiments that employed different diagnostics. However, one difference between the measurements and theory is that the velocity PDF of products is found to be non-Gaussian because a significant amount of low speed products exist within the flame. The low speed products are believed to be due to non-uniform acceleration induced by the curved flamelets that are observed. This non-uniform acceleration appears to represent an additional source of turbulence within the flame and contributes to flame generated turbulence.

ISSN:0010-2202    

DOI:10.1080/00102208608923898

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

This paper treats the initial value problem of the shock initiation of a condensed phase explosive, which consists of an explosive, initially at rest, that is suddenly struck by a piston (flyer plate). The forward reaction rate is assumed to be sensitive; small changes in the thermodynamic state lead to moderate to large changes in the rate. A large parameter, such as a dimensionless activation energy, characterizes the rate.

ISSN:0010-2202    

DOI:10.1080/00102208608923899

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor