2018/11/25 by Oliver Schulz, Schulz, Oliver, Nicolas Noiray +1
Chemical Engineering · Engineering · #Advanced Combustion Engine Technologies #Combustion and flame dynamics #FOS: Physical sciences #Fire dynamics and safety research #Fluid Dynamics (physics.flu-dyn) #Fluid Dynamics and Heat Transfer #Particle Dynamics in Fluid Flows
paper · pdf · doi:10.48550/arxiv.1811.10063
openalex publication_date 2018/11/25 · openalex created_date 2022/08/01 · openalex updated_date 2026/07/28
This numerical study investigates the combustion modes in the second stage of\na sequential combustor at atmospheric and high pressure. The sequential burner\n(SB) features a mixing section with fuel injection into a hot vitiated\ncrossflow. Depending on the dominant combustion mode, a recirculation zone\nassists flame anchoring in the combustion chamber. The flame is located\nsufficiently downstream of the injector resulting in partially premixed\nconditions. First, combustion regime maps are obtained from 0-D and 1-D\nsimulations showing the co-existence of three combustion modes: autoignition,\nflame propagation and flame propagation assisted by autoignition. These regime\nmaps can be used to understand the combustion modes at play in turbulent\nsequential combustors, as shown with 3-D large eddy simulations (LES) with\nsemi-detailed chemistry. In addition to the simulation of steady-state\ncombustion at three different operating conditions, transient simulations are\nperformed: (i) ignition of the combustor with autoignition as the dominant\nmode, (ii) ignition that is initiated by autoignition and that is followed by a\ntransition to a propagation stabilized flame, and (iii) a transient change of\nthe inlet temperature (decrease by 150 K) resulting into a change of the\ncombustion regime. These results show the importance of the recirculation zone\nfor the ignition and the anchoring of a propagating type flame. On the\ncontrary, the autoignition flame stabilizes due to continuous self-ignition of\nthe mixture and the recirculation zone does not play an important role for the\nflame anchoring.\n