摘要:

Liquid hydrocarbon supersonic combustion has been experimentally investigated. Kerosene was burnt in a steady. vitiated Mach 2.15 - air flow of a model scramjet combustor. The fuel is injected into the supersonic air stream by means of pylons. The effervescent atomisation method has been employed such that the liquid fuel is injected as a spray. By means of the Mie scattering technique the fuel jet structure was visualised and the evaporation rate estimated.

ISSN:0010-2202    

DOI:10.1080/00102209908924205

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Driven by the need for a new generation of low emission energy systems, research has been conducted that explores the possibility of using unsteady burners to yield significant reductions in environmentally harmful emissions, specifically NO and NO2. Presented here are the results obtained using a small scale fluidic natural gas burner. This fluidic slot burner was operated to measure the effects of: oscillation frequency, from 0 to 60 Hz; the equivalence ratio Math, varied from 0.6 to 1.4; and the burner diffuser angles Math of 30°, 50° and 70°. When the emissions data obtained from these runs were compared to those obtained using a steady state slot nozzle, dramatic reduction in NOxproduction was found throughout most of the frequency range. Additionally, a region of significant NOxreduction was discovered for many test conditions at oscillation frequencies around the 10-15 Hz range. With the burner operating at an equivalence ratio of 1.0, the maximum observed NOxreductions were 46.5% for Math = 30°, 40.9% for Math = 50° and 46.1% for Math = 70°.

ISSN:0010-2202    

DOI:10.1080/00102209908924206

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The results of both experimental and theoretical research on the Silicon-Red Lead pyrotechnic system are reported. The overall aim of the study was to investigate burning temperatures and to model mathematically the combustion behavior of this system.

ISSN:0010-2202    

DOI:10.1080/00102209908924207

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Extinction strain rates in unsteady methane- and propane-air counterflow diffusion flames were experimentally measured as a function of initial strain rate, oscillation frequency, and amplitude of the imposed fluctuation. The maximum strain rate was found to occur at a temporal phase corresponding to the maximum velocity for the diluted methane flame. However, for the propane flame the maximum strain rate occurred when the imposed velocity fluctuation was zero and decreasing. Above an oscillation frequency of 100 Hz, the diluted methane flame was able to survive peak strain rates exceeding the steady extinction strain rate. The minimum air velocity in the pure methane and propane flames was negative for all cases studied, which is most likely responsible for flame extinction at low frequencies and initial strain rates. However, at high initial strain rates and forcing frequencies peak unsteady strain rates at extinction approached the steady extinction strain rate and flow reversal was much less significant.

ISSN:0010-2202    

DOI:10.1080/00102209908924208

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Past studies using G-equation successfully described the effect of flame stretch on the laminar flame propagation. In those studies, flames were regarded as a passive interface that did not influence the flow field. The experimental evidences, however, suggested that flow field was significantly modified by the flames as the burned gas expanded at the flame. A method using G-equation and Biot-Savart law to approximate induced velocity field is described to estimate the effect of volume expansion. Present method was applied to initially wrinkled and planar flames propagating in an imposed velocity field and the average flame speed was evaluated from the ratio of simulated flame surface area and projected area of unburned stream channel. It was found that the initial wrinkling of flame could not sustain itself without velocity disturbance but decayed into planar flame. The rate of decay of the wrinkles increased as the volume expansion ratio increased. The asymptotic change in the average burning speed occurred only in a disturbed velocity field. The average burning speed was always affected by the volume expansion that directly influenced the velocity field. With relatively small expansion ratio of 3, the average flame speed increased 10%. The comparison of the relative significance of volume expansion and flame stretch suggested that the effect of volume expansion was no less important than that of flame stretch and warranted that both of the effects should be taken into account in the simulation of flame propagation.

ISSN:0010-2202    

DOI:10.1080/00102209908924209

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor