DOI: 10.1016/j.combustflame.2019.11.031
论文题名: DNS study of the global heat release rate during early flame kernel development under engine conditions
作者: Falkenstein T. ; Kang S. ; Cai L. ; Bode M. ; Pitsch H.
刊名: Combustion and Flame
ISSN: 102180
出版年: 2020
卷: 213 语种: 英语
英文关键词: DNS
; Flame area
; Flame Kernel
; Flame stretch rate
; Premixed flame
; Spark-ignition engine
Scopus关键词: Flame research
; Internal combustion engines
; Stochastic systems
; Turbulent flow
; Conventional engine
; Cycle to cycle variation
; Flame area
; Flame kernel
; Flame stretch
; Heat Release Rate (HRR)
; Investigate effects
; Premixed Flame
; Engines
英文摘要: Despite the high technical relevance of early flame kernel development for the reduction of cycle-to-cycle variations in spark ignition engines, there is still a need for a better fundamental understanding of the governing in-cylinder phenomena in order to enable resilient early flame growth. To isolate the effects of small- and large-scale turbulent flow motion on the young flame kernel, a three-dimensional DNS database has been designed to be representative for engine part load conditions. The analysis is focussed on flame displacement speed and flame area in order to investigate effects of flame structure and flame geometry on the global burning rate evolution. It is shown that despite a Karlovitz number of up to 13, which is at the upper range of conventional engine operation, thickening of the averaged flame structure by small-scale turbulent mixing is not observed. After ignition effects have decayed, the flame normal displacement speed recovers the behavior of a laminar unstretched premixed flame under the considered unity-Lewis-number conditions. Run-to-run variations in the global heat release rate are shown to be primarily caused by flame kernel area dynamics. The analysis of the flame area balance equation shows that turbulence causes stochastic flame kernel area growth by affecting the curvature evolution, rather than by inducing variations in total flame area production by strain. Further, it is shown that in local segments of a fully-developed planar flame with similar surface area as the investigated flame kernels, temporal variations in flame area rate-of-change occur. Contrasting to early flame kernels, these effects can be exclusively attributed to curvature variations in negatively curved flame regions. © 2019 Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/158904
Appears in Collections: 气候变化与战略
There are no files associated with this item.
作者单位: Institute for Combustion Technology, RWTH Aachen University, Aachen, 52056, Germany; Department of Mechanical Engineering, Sogang University, Seoul, 121–742, South Korea
Recommended Citation:
Falkenstein T.,Kang S.,Cai L.,et al. DNS study of the global heat release rate during early flame kernel development under engine conditions[J]. Combustion and Flame,2020-01-01,213