TY - JOUR
T1 - Three-dimensional measurements and analysis of early-stage non-premixed flame development following spark ignition
AU - Song, Erzhuang
AU - Lei, Qingchun
AU - Li, Xiang
AU - Chi, Yeqing
AU - Fan, Wei
N1 - Publisher Copyright:
© 2023 Elsevier Masson SAS
PY - 2023/11
Y1 - 2023/11
N2 - Igniting pure fuel jets is common in aerospace propulsion systems to organize combustion. A significant issue is that the ignition process is not well understood yet due to its highly localized, transient, dynamic nature. This paper reports a study of early-stage non-premixed flame development following spark ignition based on three-dimensional (3D) measurements. These measurements are obtained by tomographic chemiluminescence, and 3D surface tracking is performed based on the level-set method to calculate the 3D distribution and evolution of flame edge speeds. Measurements are reported for different jet velocities and spark height conditions. The results show that in a typical spark ignition process, after a quick development from a wafer structure to a circular fold, the flame edge propagates along the upstream, downstream, and circular directions simultaneously to form a cylindrical flame. In low-jet-velocity cases, regardless of spark location, the flame edge speeds along the three directions have similar magnitude distributions. The downstream flame edge speeds are slightly higher than the upstream and circular speeds. In high-jet-velocity cases, the flame edge speeds have overall magnitudes larger than those in low-jet-velocity cases, and the dominance of the downstream flame edge speeds over the upstream and circular speeds becomes more obvious. The mean flame edge speeds of all tested cases are shown to be comparable to the theoretical stoichiometric laminar speed. For successful ignition, it is found that thermal convection plays a crucial role in the flame growth in low-spark-height cases, whereas in high-spark-height cases, a well-mixed condition driven by turbulence promotes flame growth. Irrespective of jet flow velocity and spark location, the early stage of flame growth after ignition can be precisely described by a logistic function (S curve), which in turn facilitates a better understanding of the process.
AB - Igniting pure fuel jets is common in aerospace propulsion systems to organize combustion. A significant issue is that the ignition process is not well understood yet due to its highly localized, transient, dynamic nature. This paper reports a study of early-stage non-premixed flame development following spark ignition based on three-dimensional (3D) measurements. These measurements are obtained by tomographic chemiluminescence, and 3D surface tracking is performed based on the level-set method to calculate the 3D distribution and evolution of flame edge speeds. Measurements are reported for different jet velocities and spark height conditions. The results show that in a typical spark ignition process, after a quick development from a wafer structure to a circular fold, the flame edge propagates along the upstream, downstream, and circular directions simultaneously to form a cylindrical flame. In low-jet-velocity cases, regardless of spark location, the flame edge speeds along the three directions have similar magnitude distributions. The downstream flame edge speeds are slightly higher than the upstream and circular speeds. In high-jet-velocity cases, the flame edge speeds have overall magnitudes larger than those in low-jet-velocity cases, and the dominance of the downstream flame edge speeds over the upstream and circular speeds becomes more obvious. The mean flame edge speeds of all tested cases are shown to be comparable to the theoretical stoichiometric laminar speed. For successful ignition, it is found that thermal convection plays a crucial role in the flame growth in low-spark-height cases, whereas in high-spark-height cases, a well-mixed condition driven by turbulence promotes flame growth. Irrespective of jet flow velocity and spark location, the early stage of flame growth after ignition can be precisely described by a logistic function (S curve), which in turn facilitates a better understanding of the process.
KW - 3D measurement
KW - Flame edge speed
KW - Flame growth
KW - Spark ignition
KW - Tomography
UR - http://www.scopus.com/inward/record.url?scp=85173606685&partnerID=8YFLogxK
U2 - 10.1016/j.ast.2023.108643
DO - 10.1016/j.ast.2023.108643
M3 - 文章
AN - SCOPUS:85173606685
SN - 1270-9638
VL - 142
JO - Aerospace Science and Technology
JF - Aerospace Science and Technology
M1 - 108643
ER -