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) : Hammer, Jay A


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a267911.pdf


Report Date : 14 Apr 1993


Pagination or Media Count : 159


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.


Descriptors :   *STABILITY , *TURBULENT FLOW , *FUELS , *DIFFUSION , *COMBUSTION , *JET FLOW , VELOCITY , DIAMETERS , AIR , ARRAYS , MIXTURES , FLAMES , IGNITION , FLUIDS , OXIDIZERS , NOZZLES , SLOPE , CHEMICAL REACTIONS , SCALE , CORRELATION , RICHARDSON NUMBER , REYNOLDS NUMBER , NEAR FIELD , HEIGHT , EXITS , PHOTODIODES , AMPLITUDE , LIFT , TIME , STRAIN RATE , FAR FIELD , THESES , RATES , MODELS , MEASUREMENT


Subject Categories : Physical Chemistry
      Fluid Mechanics
      Thermodynamics
      Combustion and Ignition


Distribution Statement : APPROVED FOR PUBLIC RELEASE