摘要:

The limits of stability and extinction of a laminar diffusion flame have been experimentally studied in a two-dimensional laminar boundary layer over a porous flat plate through which n-pentane vapour was uniformly injected. The stability and extinction boundaries are mapped on a plot of free stream oxidant velocity versus fuel injection velocity. Effects of free stream temperature and of dilution of fuel and oxidant on these boundaries have been examined. The results show that there exists a limiting oxidant flux beyond which the diffusion flame cannot be sustained. This limiting oxidant flux has been found to depend_on the free stream oxygen concentration, fuel concentration and injection'velocity of the fuel.

ISSN:0010-2202    

DOI:10.1080/00102208408923728

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Laminar burning velocities of chlorinated methanes, trichloroethylene, and chloro-benzene in mixtures with methane and air were measured using the Bunsen cone method. The effects of mixture composition and precombustion temperature on the measured flame velocities were determined.

ISSN:0010-2202    

DOI:10.1080/00102208408923729

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Measurements have been made of the size, number density, and volume fraction of soot particulates present in a controlled spray flame. The flame was nearly one-dimensional, and resulted from the combustion of a continuous stream of fuel droplets of uniform initial size and spacing. Two independent techniques were applied simullancously to soot sampling. The first was anin-situmethod in which particulate parameters were inferred from the polarization dependence of Mie scattered laser radiation at a fixed angle. The second approach relied on the use of an electrostatic sampling probe for soot collection and, then, an electron microscope for analysis of the soot morphology. The particulate parameters were determined at three burning times for the combustion of 300 urn diameter No. 2 fuel oil droplets. A comparison of the optical and probe results demonstrated quite good agreement between the two approaches; however, in making the comparison, due regard was given to the irregular chain-like structure of the particulates and the different sensitivities of the two methods to the nearly spheroidal components of the chain. The closest agreement was obtained for the volume fraction reflecting its relative insensi-tivity to particulate shape. The results suggest that chain-like agglomeration occurs in the flame and is not, therefore, solely a probe-induced effect.

ISSN:0010-2202    

DOI:10.1080/00102208408923730

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The combustion and coking of isolated, free and suspended droplets of a residual oil have been studied. The combustion history of the free and suspended droplets was found to be characterized by qualitatively similar phenomena. The coke particle was seen to form within the final 9 percent of the droplet burning period and the mass of the coke particle was about 3 percent of the mass of the initial residual oil droplet. Changing the temperature history of a droplet by varying the initial droplet size between 260 and 570 microns or by diluting the residual oil with a more volatile No. 2 fuel oil did not affect the mass fraction of the residual oil in the initial droplet which was converted to coke. The contribution to the coke particle from both the asphaltene and maltenc (residual oil from which the asphaltenes have been removed) components of the oil was found to be significant, and therefore fuel asphaltene content alone will not provide a satisfactory basis for determining the relative coking tendency of different oils. The results indicate that in the combustion of heavy fuel oils coke particles will be formed and that particulate emissions may be best reduced through enahanced particle burnout (through techniques such as improved atomization and oil-water emulsions), and not through an attempted reduction in the formation of coke.

ISSN:0010-2202    

DOI:10.1080/00102208408923731

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The concentrations of the individual hydrocarbon species in the exhaust gases from a single-cylinder CFR engine have been measured. The effects of compression ratio and spark timing on these emissions have been observed using propane, isooctane (2,2,4-trimethylpentanerpar; and indolene clear fuels. The results show that total hydrocarbon emissions increase rapidly as the compression ratio increases and decrease sharply as the spark timing is retarded relative to MBT at a constant compression ratio. Changes in the concentration of unburned fuel in the exhaust contribute the most to these variations. These observations are consistent with the predicted increase in crevice and oil film storage of unburned hydrocarbons at higher compression ratio because of the higher peak pressures. They also agree with the predicted increase in post-flame burnup of stored hydrocarbons in the hotter cylinder gases encountered during low compression ratio or retarded spark operation.

ISSN:0010-2202    

DOI:10.1080/00102208408923732

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

Experimental composition and flammabiliiy-limit data at one atmosphere for samples of dry low-Btu gases containing the major constituents CO, H2, CH4, N2, and CO2, from an actualin-siutcoal gasification test are given. Also shown are composition and flammability-limit data for a synthetic low-Btu gas (simulating a type derived from coalrpar; to which CO2 and N2 were systematically added until the upper and lower flammability limits nearly converged. The flammability limits can be approximated by application of Le Chatelier's law, although it is more inaccurate than previously described in the literature. Fuel concentrations at both the upper and lower limits of the mixtures tested arc consistently leaner than predicted

ISSN:0010-2202    

DOI:10.1080/00102208408923733

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0010-2202    

DOI:10.1080/00102208408923734

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

ISSN:0010-2202    

DOI:10.1080/00102208408923735

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor