1. Large eddy simulation of combustion recession: Effects of ambient temperature and injection pressure.
- Author
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Zhang, Min, Ong, Jiun Cai, Pang, Kar Mun, Xu, Shijie, Zhang, Yan, Nemati, Arash, Bai, Xue-Song, and Walther, Jens Honore
- Subjects
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LARGE eddy simulation models , *COMBUSTION , *TEMPERATURE effect , *RECESSIONS , *FLAME spraying , *SPRAY combustion , *LEAN combustion - Abstract
In the present study, large eddy simulation is used to investigate combustion recession for the Engine Combustion Network Spray A flame at two ambient temperatures (850 K and 800 K) and two injection pressures (100 MPa and 50 MPa). The present numerical results are able to capture different combustion recession phenomena after the end-of-injection (AEOI). With an injection pressure of 100 MPa , the model predicts a "separated" combustion recession at the ambient temperature of 850 K and no combustion recession at the ambient temperature of 800 K , in which both predictions correspond to the measurements. The combustion recession is mainly controlled by the auto-ignition process at the ambient temperature of 850 K. At the ambient temperature of 800 K , the local temperature within the fuel-rich region is not high enough to promote the high-temperature ignition process. As time progresses, the mixture within the fuel-rich region rapidly transitions to become an overly fuel-lean mixture, which further hinders high-temperature ignition to occur. Nonetheless, it is shown that lowering the injection pressure to 50 MPa causes the combustion recession to occur at the ambient temperature of 800 K. This is likely attributed to the low injection case having a lower air entrainment rate AEOI, which causes the mixtures upstream of the lift-off position to transition slower from fuel-rich to fuel-lean mixtures. • LES model captures the evolution of flame structure during combustion recession. • At high P i n j of 100 MPa, combustion recession occurs at 850 K but not at 800 K. • Lowering P i n j to 50 MPa leads to combustion recession in the 800 K spray case. • Air entrainment after EOI affects the fuel–air mixing and combustion recession. • Lowering P i n j leads to lower entrainment rate after EOI and relatively richer mixture. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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