Structure of a methanol/air coaxial reacting spray near the stabilization region by OH fluorescence imaging and two-component phase-Doppler interferometry
- Centre National de la Recherche Scientifique (CNRS), 230 - Mont-Saint-Aignan (France). URA CORIA
- Sandia National Labs., Livermore, CA (United States)
Planar laser-induced fluorescence and two component phase-Doppler interferometry have been used to study the reaction zone structure near the stabilization region of a coaxial methanol/air spray flame. The configuration of the experiment was chosen to simulate the atomizer geometry, surface tension and Weber number of a single coaxial hydrogen/oxygen rocket injector. The measurements are made in a water-cooled, optically-accessible confinement chamber at a pressure of 1 atm. Data are reported for two operating conditions, one yielding a flame length of approximately 1 meter, the other, half that value. Both the Weber number (characterizing the atomization process) and the Reynolds number (characterizing the gas phase mixing process) vary between the two cases, but the data suggest that it is the Weber number which has the dominant effect. In both cases OH imaging shows that the reaction zone is confined to a narrow region, with the OH field being similar in appearance to that of a single-phase turbulent mixing-controlled (diffusion) flame. Size-classified mean velocity vectors derived from the phase-Doppler data show striking differences in the flow pattern for low and high Stokes number droplets. Droplets 10 {mu}m in diameter and below (Stokes number less than 10) appear to follow the recirculating eddies that provide flame stabilization. Increasing the Weber number by a factor of 2.5 decreased the Sauter mean diameter of the spray by as much as one-third, and the arithmetic mean diameter by as much as one-half. We believe that it is this decrease in the spray droplet diameter that is primarily responsible for the very different flame length in the two cases.
- Research Organization:
- Sandia National Labs., Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC04-76DR00789
- OSTI ID:
- 10112811
- Report Number(s):
- SAND-91-8714; CONF-920707-1; ON: DE92005328
- Resource Relation:
- Conference: 24. international symposium on combustion,Sydney (Australia),5-10 Jul 1992; Other Information: PBD: [1991]
- Country of Publication:
- United States
- Language:
- English
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