TY - JOUR
T1 - On micro-buoyancy spherical diffusion flames and a double luminous zone structure of the hydrogen/methane flame
AU - Sung, C. J.
AU - Zhu, D. L.
AU - Law, C. K.
N1 - Funding Information:
This work was supported by the NASA Microgravity Combustion Program. It is a pleasure to acknowledge useful technical discussion with and suggestions from Professor A. C. Fernandez-Pello of U.C.-Berkeley, Professor C. T. Bowman of Stanford University, Professor H. Wang of University of Delaware, and Dr. K. Sacksteder of NASA-Lewis.
PY - 1998
Y1 - 1998
N2 - Almost spherically symmetry diffusion flames of substantial dimension (diameter ∼ several centimeters) were established in earth gravity by ejecting an O2/N2 mixture from a porous sphere into a subatmospheric pressure environment consisting of low-molecular-weight fuels such as methane and hydrogen. In the present investigation, a double-luminous zone structure, consisting of a green luminous zone near the fuel side, a blue or violet luminous zone near the oxidizer side, and a dark space between the two luminous zones, was observed for subatmospheric diffusion flames of either air or an O2/N2 mixture against a mixture of hydrogen with a small quantity of methane. The two luminous zones eventually merge with increasing methane addition, characterized by the green luminous zone shifting toward the blue luminous zone. Computational simulation using the experimental boundary conditions shows that the blue and green luminous zones respectively correspond to the main consumption layers of H2-O2 and CH4; that the breakdown of CH4 is primarily due to its attack by H, leading to the formation of CO, additional H2, and eventually H2O and CO2; and that the electronically excited CO2 and C2 are respectively responsible for the blue and green luminescence. This double-luminous zone structure also exhibits a secondary peak in the heat release rate profile; important reactions accounting for the two heat release peaks were identified.
AB - Almost spherically symmetry diffusion flames of substantial dimension (diameter ∼ several centimeters) were established in earth gravity by ejecting an O2/N2 mixture from a porous sphere into a subatmospheric pressure environment consisting of low-molecular-weight fuels such as methane and hydrogen. In the present investigation, a double-luminous zone structure, consisting of a green luminous zone near the fuel side, a blue or violet luminous zone near the oxidizer side, and a dark space between the two luminous zones, was observed for subatmospheric diffusion flames of either air or an O2/N2 mixture against a mixture of hydrogen with a small quantity of methane. The two luminous zones eventually merge with increasing methane addition, characterized by the green luminous zone shifting toward the blue luminous zone. Computational simulation using the experimental boundary conditions shows that the blue and green luminous zones respectively correspond to the main consumption layers of H2-O2 and CH4; that the breakdown of CH4 is primarily due to its attack by H, leading to the formation of CO, additional H2, and eventually H2O and CO2; and that the electronically excited CO2 and C2 are respectively responsible for the blue and green luminescence. This double-luminous zone structure also exhibits a secondary peak in the heat release rate profile; important reactions accounting for the two heat release peaks were identified.
UR - http://www.scopus.com/inward/record.url?scp=0032265294&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032265294&partnerID=8YFLogxK
U2 - 10.1016/S0082-0784(98)80108-2
DO - 10.1016/S0082-0784(98)80108-2
M3 - Conference article
AN - SCOPUS:0032265294
SN - 1540-7489
VL - 27
SP - 2559
EP - 2566
JO - Proceedings of the Combustion Institute
JF - Proceedings of the Combustion Institute
IS - 2
T2 - 27th International Symposium on Combustion
Y2 - 2 August 1998 through 7 August 1998
ER -