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ISSN Online: 2379-1748

7th Thermal and Fluids Engineering Conference (TFEC)
SJR: 0.152 SNIP: 0.14 CiteScore™:: 0.5

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Clarivate CPCI (Proceedings) Scopus
May, 15-18, 2022 , Las Vegas, NV, USA


Get access (open in a dialog) pages 1011-1020
DOI: 10.1615/TFEC2022.the.041330


The dynamics of passively controlled turbulent flames subjected to various initial parameters are studied using large-eddy simulations (LES) applying a commercial ANSYS software and an in-house academic highorder code. For turbulence-chemistry interaction, a model based on the Approximate Deconvolution Model is implemented and the results are compared to the Eulerian Stochastic Fields (ESF) method and 'no model' predictions. Various bluff-body shapes (cylindrical, square, star) with two different wall topologies (smooth, wavy) are considered in non-premixed configurations with nitrogen-diluted hydrogen as the fuel. The present work focuses on the structure of the flame, the size and shape of turbulent vortices, and the size and location of the recirculation zones. It is found that the dynamics of flames and their structures strongly depend on geometrical shaping, however the waviness of the bluff-body walls only slightly affects the flame characteristics compared to the sharp-corners bluff-bodies (square, star). In the case of the bluff-bodies with sharp corners the presence of small-scale vortices generated in their vicinity causes deformation of large vortical structures that amplifies the mixing process and intensifies the combustion. When the square bluff-body is used the shortened recirculation zone is observed as the minimum of the mean axial velocity shifts 15% of the equivalence bluff-body diameter towards the inlet plane. The largest differences in the flame temperature are found at the level of 300 K. It is also shown that in case of the square bluff-body the radial flame size is reduced by 10% compared to the configuration with the cylindrical bluff-body. This, however, is conditioned on the cross cross section considered.