TY - JOUR
T1 - Pressure effects and transition in the stabilization mechanism of turbulent lifted flames
AU - Guiberti, T.F.
AU - Boyette, Wesley
AU - Roberts, William L.
AU - Masri, A.R.
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST).
PY - 2018/10/16
Y1 - 2018/10/16
N2 - This study reports novel measurements on the effects of pressure on the lift-off behavior and the stabilization mechanism of turbulent non-premixed methane jet flames. A high-pressure combustion duct (HPCD) was operated within the range of pressure P = 1-7 bar using jet velocities of 4 m.s≤ U ≤30 m.s and co-flow velocities of 0.23 m.s≤ U ≤0.60 m.s. Lift-off heights were measured from chemiluminescence pictures while joint images of hydroxyl and velocity, performed using joint PLIF-OH/PIV, were used to extract information about the stabilization mechanism. It is shown that while the lift-off height generally increases with pressure, the impact of pressure depends on the magnitude of the co-flow velocity. For U = 0.30 m.s, the flame's base remains near the nozzle over the entire pressure range and the measured flame speeds indicate that edge-flame stabilization is dominant. The slope of the lift-off height vs. jet velocity curves is positive. For U = 0.60 m.s and P > 2 bar, the flame stabilizes further downstream and a transition to turbulent premixed flame propagation appears to have occurred. At these conditions, the slope of the lift-off height vs. jet velocity curves becomes negative. This reversal at high pressure is a new result for methane. More importantly, the transition in the stabilization mechanism with increasing U is consistent with results reported earlier for ethylene and appears to be independent of the fuel.
AB - This study reports novel measurements on the effects of pressure on the lift-off behavior and the stabilization mechanism of turbulent non-premixed methane jet flames. A high-pressure combustion duct (HPCD) was operated within the range of pressure P = 1-7 bar using jet velocities of 4 m.s≤ U ≤30 m.s and co-flow velocities of 0.23 m.s≤ U ≤0.60 m.s. Lift-off heights were measured from chemiluminescence pictures while joint images of hydroxyl and velocity, performed using joint PLIF-OH/PIV, were used to extract information about the stabilization mechanism. It is shown that while the lift-off height generally increases with pressure, the impact of pressure depends on the magnitude of the co-flow velocity. For U = 0.30 m.s, the flame's base remains near the nozzle over the entire pressure range and the measured flame speeds indicate that edge-flame stabilization is dominant. The slope of the lift-off height vs. jet velocity curves is positive. For U = 0.60 m.s and P > 2 bar, the flame stabilizes further downstream and a transition to turbulent premixed flame propagation appears to have occurred. At these conditions, the slope of the lift-off height vs. jet velocity curves becomes negative. This reversal at high pressure is a new result for methane. More importantly, the transition in the stabilization mechanism with increasing U is consistent with results reported earlier for ethylene and appears to be independent of the fuel.
UR - http://hdl.handle.net/10754/629925
UR - https://www.sciencedirect.com/science/article/pii/S1540748918305753
UR - http://www.scopus.com/inward/record.url?scp=85054744197&partnerID=8YFLogxK
U2 - 10.1016/j.proci.2018.08.033
DO - 10.1016/j.proci.2018.08.033
M3 - Article
SN - 1540-7489
VL - 37
SP - 2167
EP - 2174
JO - Proceedings of the Combustion Institute
JF - Proceedings of the Combustion Institute
IS - 2
ER -