TY - JOUR
T1 - The role of low temperature fuel chemistry on turbulent flame propagation
AU - Won, Sang Hee
AU - Windom, Bret
AU - Jiang, Bo
AU - Ju, Yiguang
N1 - Funding Information:
This work was supported by the Air Force Office of Scientific Research Grant FA9550-12-1-0140. BW is supported by the US Department of Energy, Office of Basic Energy Sciences as part of an Energy Frontier Research Center on Combustion with Grant No. DE-SC0001198. The authors sincerely thank Prof. Alexander Smits and his students at Princeton University for help with the hot-wire anemometry measurements.
PY - 2014/2
Y1 - 2014/2
N2 - A new high temperature, high Reynolds number, Reactor Assisted Turbulent Slot (RATS) burner has been developed to investigate turbulent flame regimes and burning rates for large hydrocarbon transportation fuels, which exhibit strong low temperature chemistry behavior. The turbulent flow characteristics are quantified using hot wire anemometry. The turbulent flame structures and burning velocities of n-heptane/air mixtures are measured by using planar laser induced fluorescence of OH and CH2O with reactant temperatures spanning from 400K to 700K. It is found for the first time that for n-heptane/air mixtures there are four unique turbulent flame regimes, a conventional chemically-frozen-flow regime, a low-temperature-ignition regime, a transitional regime between the low- to high-temperature-ignition regimes, and a high-temperature-ignition regime, depending on the initial reactant temperature and heated flow residence time prior to the flame. The turbulent burning velocities have been measured for the first two regimes, chemically-frozen-flow and low-temperature-ignition regimes, in order to quantitatively address the role of low temperature ignition on the turbulent burning velocity. In the latter case, large amount of CH2O formation has been observed in the pre-flame zone, signaling a significant change in the reactant composition and chemistry. At a given reactant temperature and turbulent intensity, the normalized turbulent burning velocities can be varied depending on the extent of low temperature fuel oxidation by varying the heated flow residence time and reactant temperature. The present results suggest that contrary to the previous studies, the turbulent flame regimes and burning velocities for fuels with low temperature chemistry may not be uniquely defined at elevated temperatures.
AB - A new high temperature, high Reynolds number, Reactor Assisted Turbulent Slot (RATS) burner has been developed to investigate turbulent flame regimes and burning rates for large hydrocarbon transportation fuels, which exhibit strong low temperature chemistry behavior. The turbulent flow characteristics are quantified using hot wire anemometry. The turbulent flame structures and burning velocities of n-heptane/air mixtures are measured by using planar laser induced fluorescence of OH and CH2O with reactant temperatures spanning from 400K to 700K. It is found for the first time that for n-heptane/air mixtures there are four unique turbulent flame regimes, a conventional chemically-frozen-flow regime, a low-temperature-ignition regime, a transitional regime between the low- to high-temperature-ignition regimes, and a high-temperature-ignition regime, depending on the initial reactant temperature and heated flow residence time prior to the flame. The turbulent burning velocities have been measured for the first two regimes, chemically-frozen-flow and low-temperature-ignition regimes, in order to quantitatively address the role of low temperature ignition on the turbulent burning velocity. In the latter case, large amount of CH2O formation has been observed in the pre-flame zone, signaling a significant change in the reactant composition and chemistry. At a given reactant temperature and turbulent intensity, the normalized turbulent burning velocities can be varied depending on the extent of low temperature fuel oxidation by varying the heated flow residence time and reactant temperature. The present results suggest that contrary to the previous studies, the turbulent flame regimes and burning velocities for fuels with low temperature chemistry may not be uniquely defined at elevated temperatures.
KW - Laser induced fluorescence
KW - Low temperature chemistry
KW - N-Heptane
KW - Turbulent burning velocity
KW - Two-stage ignition
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U2 - 10.1016/j.combustflame.2013.08.027
DO - 10.1016/j.combustflame.2013.08.027
M3 - Article
AN - SCOPUS:84890229387
SN - 0010-2180
VL - 161
SP - 475
EP - 483
JO - Combustion and Flame
JF - Combustion and Flame
IS - 2
ER -