TY - JOUR
T1 - An experimental study of vortex-flame interaction in counterflow spray diffusion flames
AU - Santoro, V. S.
AU - Kyritsis, D. C.
AU - Gomez, A.
N1 - Funding Information:
The authors wish to thank the following colleagues: Mr. Ernst Ebert, for the design and construction of the vortex generation system and its retrofitting to the counterflow burner; Mr. Mikhail Noskov, for preliminary calculations that enabled us to use HCHO as a flame marker; Dr. Adon-ios N. Karpetis, for helping with aspects of the data acquisition; and Professor Amable Linan, for enhancing our understanding of flame structure issues. The support of the National Aeronautics and Space Administration, under the Microgravity Science and Applications Program, grant no. NAG3-1688 (Mr. Dennis Stocker, contract monitor), and of the National Science Foundation, grant no. CTS-9904296 (Dr. Farley Fisher, contract monitor), is gratefully acknowledged.
PY - 2000
Y1 - 2000
N2 - The combination of formaldehyde PLIF and Phase Doppler measurements was used to study the extinction behavior of methanol counterflow spray diffusion flames. Extinction was quasi-steadily caused by progressively increasing the flow rates of oxidizer and fuel side, and unsteadily, by generating a vortex on the oxidizer side. Vortex-induced extinction yielded values of extinction strain rates a factor of two larger than the quasi-steady values. The time scales involved in the process were estimated to phenomenologically explain the greater ″robustness″ of the spray flame under unsteady perturbation. The vortex showed unsteady effects in the outer diffusive-convective flame layer. Since the characteristic chemical time was much smaller than the characteristic unsteady time, the inner reactive-diffusive layer behaved in a θuasi-steady″ manner. A measurement of the thickness of the mixing layer based on formaldehyde PLIF provided a convenient way of comparing the scalar dissipation rate and the Damkhoeler number between the two extinction modes, avoiding the need of detailed species measurements for the evaluation of the scalar dissipation and its gradients. This comparison revealed that the difference between the two extinction modes was reduced to 25% on the average. The comparison of the time delay between the onset of extinction and re-ignition between spray flames and gaseous flames exhibited that spray flames have much longer time delays. Original is an abstract.
AB - The combination of formaldehyde PLIF and Phase Doppler measurements was used to study the extinction behavior of methanol counterflow spray diffusion flames. Extinction was quasi-steadily caused by progressively increasing the flow rates of oxidizer and fuel side, and unsteadily, by generating a vortex on the oxidizer side. Vortex-induced extinction yielded values of extinction strain rates a factor of two larger than the quasi-steady values. The time scales involved in the process were estimated to phenomenologically explain the greater ″robustness″ of the spray flame under unsteady perturbation. The vortex showed unsteady effects in the outer diffusive-convective flame layer. Since the characteristic chemical time was much smaller than the characteristic unsteady time, the inner reactive-diffusive layer behaved in a θuasi-steady″ manner. A measurement of the thickness of the mixing layer based on formaldehyde PLIF provided a convenient way of comparing the scalar dissipation rate and the Damkhoeler number between the two extinction modes, avoiding the need of detailed species measurements for the evaluation of the scalar dissipation and its gradients. This comparison revealed that the difference between the two extinction modes was reduced to 25% on the average. The comparison of the time delay between the onset of extinction and re-ignition between spray flames and gaseous flames exhibited that spray flames have much longer time delays. Original is an abstract.
UR - http://www.scopus.com/inward/record.url?scp=0033668901&partnerID=8YFLogxK
M3 - Article
AN - SCOPUS:0033668901
SP - 44
JO - International Symposium on Combustion Abstracts of Accepted Papers
JF - International Symposium on Combustion Abstracts of Accepted Papers
IS - A
T2 - 28th International Symposium on Combustion
Y2 - 30 July 2000 through 4 August 2000
ER -
