Accession Number:

ADA267911

Title:

Lifted Turbulent Jet Flames

Descriptive Note:

Doctoral thesis 15 Apr 89-14 Jul 93,

Corporate Author:

CALIFORNIA INST OF TECH PASADENA GRADUATE AERONAUTICAL LABS

Personal Author(s):

Report Date:

1993-04-14

Pagination or Media Count:

159.0

Abstract:

Experiments were conducted on lifted, turbulent jet diffusion flames. A linear photodiode array was used to measure the temporal history of the liftoff height bar-h. Measurements of the mean liftoff height bar-h under a wide range of flow conditions, including several fuels, nozzle diameters, and exit velocities U sub s, showed an approximately linear relationship between bar-h and U sub s, with a slight dependence on Reynolds number. A strain-rate model was developed for liftoff, based on far-field scaling of turbulent jets it provides an explanation for the linear dependence of bar-h on U sub s. When the nozzle fluid was diluted with varying amounts of air it was found that the slope of the bar-h vs. U sub s, line increases faster than predicted by the far-field scaling. The discrepancy is attributed to near-field effects. The amplitudes of the fluctuations in bar-h were found to be of the order of the local large scale of the jet but the time scales were found to be much larger than the local large-scale time of the turbulence tau delta. By using fuels of different chemical times to vary tau delta, the measured correlation time tau 1 2 normalized by tau delta was found to collapse with Richardson number xih.... Flame stability, Burning fuel jets, Flame models.

Subject Categories:

  • Physical Chemistry
  • Fluid Mechanics
  • Thermodynamics
  • Combustion and Ignition

Distribution Statement:

APPROVED FOR PUBLIC RELEASE