TY - JOUR
T1 - Soot evolution and flame response to acoustic forcing of laminar non-premixed jet flames at varying amplitudes
AU - Foo, Kae Ken
AU - Sun, Zhiwei
AU - Medwell, Paul R.
AU - Alwahabi, Zeyad T.
AU - Nathan, Graham J.
AU - Dally, Bassam B.
N1 - Generated from Scopus record by KAUST IRTS on 2022-09-12
PY - 2018/12/1
Y1 - 2018/12/1
N2 - New details regarding the soot evolution and its controlling parameters in steady and forced flames have been studied using high spatial resolution laser diagnostic techniques. Steady laminar non-premixed ethylene/nitrogen flames with three different diameters burners were acoustically forced using a loudspeaker. 10-Hz-sinusoidal signals of different amplitudes were transmitted to the loudspeaker to drive the flames. The results reveal that the spatial correlation between the soot field and the temperature profile is influenced by the burner diameter and forcing conditions. The soot field in steady laminar flames is confined to a relatively narrow temperature range, 1500–2000 K. In contradiction, the soot field in forced flames spread across a wider range of temperature, 1400–2100 K. Furthermore, the spatial correlation between the normalised soot concentration and primary particle size can be described with an exponential function. While it is observed that the exponential coefficients vary with burner diameter and forcing conditions, further study is necessary for a better understanding. In general, laminar flames forced at a lower amplitude (α=25%) tend to produce less soot than moderately forced (α=50%) flames. Further increasing the forcing amplitude to α=75% does not increase the soot production in laminar flames; conversely, lower peak and volume-integrated soot volume fraction are observed in the strongly forced flame (α=75%) as relative to the moderately forced counterpart. These findings shed new light on the seemingly contradictory results published in the literature regarding the effect of the forcing intensity on the soot production.
AB - New details regarding the soot evolution and its controlling parameters in steady and forced flames have been studied using high spatial resolution laser diagnostic techniques. Steady laminar non-premixed ethylene/nitrogen flames with three different diameters burners were acoustically forced using a loudspeaker. 10-Hz-sinusoidal signals of different amplitudes were transmitted to the loudspeaker to drive the flames. The results reveal that the spatial correlation between the soot field and the temperature profile is influenced by the burner diameter and forcing conditions. The soot field in steady laminar flames is confined to a relatively narrow temperature range, 1500–2000 K. In contradiction, the soot field in forced flames spread across a wider range of temperature, 1400–2100 K. Furthermore, the spatial correlation between the normalised soot concentration and primary particle size can be described with an exponential function. While it is observed that the exponential coefficients vary with burner diameter and forcing conditions, further study is necessary for a better understanding. In general, laminar flames forced at a lower amplitude (α=25%) tend to produce less soot than moderately forced (α=50%) flames. Further increasing the forcing amplitude to α=75% does not increase the soot production in laminar flames; conversely, lower peak and volume-integrated soot volume fraction are observed in the strongly forced flame (α=75%) as relative to the moderately forced counterpart. These findings shed new light on the seemingly contradictory results published in the literature regarding the effect of the forcing intensity on the soot production.
UR - https://linkinghub.elsevier.com/retrieve/pii/S001021801830419X
UR - http://www.scopus.com/inward/record.url?scp=85054345148&partnerID=8YFLogxK
U2 - 10.1016/j.combustflame.2018.09.022
DO - 10.1016/j.combustflame.2018.09.022
M3 - Article
SN - 1556-2921
VL - 198
SP - 249
EP - 259
JO - Combustion and Flame
JF - Combustion and Flame
ER -