Effects of heat release on the near field flow structure of hydrogen jet diffusion flames
- Univ. of Texas, Austin, TX (United States). Dept. of Aerospace Engineering and Engineering Mechanics
- Sandia National Labs., Livermore, CA (United States). Combustion Research Facility
An experimental investigation was conducted on the effects of heat release on the near field flow structure of co-flowing hydrogen/inert gas turbulent jet diffusion flames. The reaction zones were imaged using laser-induced fluorescence (LIF) of the OH radical, while the jet fluid was visualized using LIF of acetone vapor seeded into the fuel stream. Both reacting and nonreacting conditions were studied at jet Reynolds numbers ranging from 2,500 to 50,000. The fuel jet was diluted with nitrogen or helium in order to study the effect of diluent mass fraction and jet/co-flow density ratio. In agreement with previous investigations, organized vortical structures were observed in the near field of the jet for both the reacting and nonreacting conditions. For all of the Reynolds numbers and dilution levels considered, the flame was characterized by a thin reaction zone which was located outside of the turbulent regions and was not severely perturbed by the vortical structures. The proximity of the reaction zone to the turbulent varied depending on the diluent fraction and diluent molecular weight. Evidence is provided that the well documented lengthening of the potential core under reacting conditions is primarily due to the density ratio which reduces the growth rate of the jet shear layer. Furthermore, the best indicator of the degree of shear layer/flame interaction was found to be the density ratio, not the stoichiometric mixture fracture.
- OSTI ID:
- 116433
- Journal Information:
- Combustion and Flame, Vol. 102, Issue 3; Other Information: PBD: Aug 1995
- Country of Publication:
- United States
- Language:
- English
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