TY - JOUR
T1 - Observation of multi-scale oscillation of laminar lifted flames with low-frequency AC electric fields
AU - Ryu, Seol
AU - Kim, Youkyoung
AU - Kim, Minkuk
AU - Won, Sanghee
AU - Chung, Suk Ho
N1 - KAUST Repository Item: Exported on 2020-10-01
Acknowledgements: This work was supported by HKCRC through IAMD/SNU and CCRC/KAUST.
PY - 2010/1
Y1 - 2010/1
N2 - The oscillation behavior of laminar lifted flames under the influence of low-frequency AC has been investigated experimentally in coflow jets. Various oscillation modes were existed depending on jet velocity and the voltage and frequency of AC, especially when the AC frequency was typically smaller than 30 Hz. Three different oscillation modes were observed: (1) large-scale oscillation with the oscillation frequency of about 0.1 Hz, which was independent of the applied AC frequency, (2) small-scale oscillation synchronized to the applied AC frequency, and (3) doubly-periodic oscillation with small-scale oscillation embedded in large-scale oscillation. As the AC frequency decreased from 30 Hz, the oscillation modes were in the order of the large-scale oscillation, doubly-periodic oscillation, and small-scale oscillation. The onset of the oscillation for the AC frequency smaller than 30 Hz was in close agreement with the delay time scale for the ionic wind effect to occur, that is, the collision response time. Frequency-doubling behavior for the small-scale oscillation has also been observed. Possible mechanisms for the large-scale oscillation and the frequency-doubling behavior have been discussed, although the detailed understanding of the underlying mechanisms will be a future study. © 2009 The Combustion Institute.
AB - The oscillation behavior of laminar lifted flames under the influence of low-frequency AC has been investigated experimentally in coflow jets. Various oscillation modes were existed depending on jet velocity and the voltage and frequency of AC, especially when the AC frequency was typically smaller than 30 Hz. Three different oscillation modes were observed: (1) large-scale oscillation with the oscillation frequency of about 0.1 Hz, which was independent of the applied AC frequency, (2) small-scale oscillation synchronized to the applied AC frequency, and (3) doubly-periodic oscillation with small-scale oscillation embedded in large-scale oscillation. As the AC frequency decreased from 30 Hz, the oscillation modes were in the order of the large-scale oscillation, doubly-periodic oscillation, and small-scale oscillation. The onset of the oscillation for the AC frequency smaller than 30 Hz was in close agreement with the delay time scale for the ionic wind effect to occur, that is, the collision response time. Frequency-doubling behavior for the small-scale oscillation has also been observed. Possible mechanisms for the large-scale oscillation and the frequency-doubling behavior have been discussed, although the detailed understanding of the underlying mechanisms will be a future study. © 2009 The Combustion Institute.
UR - http://hdl.handle.net/10754/561434
UR - https://linkinghub.elsevier.com/retrieve/pii/S001021800900279X
UR - http://www.scopus.com/inward/record.url?scp=71649093183&partnerID=8YFLogxK
U2 - 10.1016/j.combustflame.2009.10.001
DO - 10.1016/j.combustflame.2009.10.001
M3 - Article
SN - 0010-2180
VL - 157
SP - 25
EP - 32
JO - Combustion and Flame
JF - Combustion and Flame
IS - 1
ER -