Large-eddy simulation of a bluff-body stabilised turbulent premixed flame using the transported flame surface density approach
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Publication Date
2017-03-08Journal Title
Combustion Theory and Modelling
ISSN
1364-7830
Publisher
Taylor & Francis
Language
English
Type
Article
This Version
AM
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Lee, C., & Cant, S. (2017). Large-eddy simulation of a bluff-body stabilised turbulent premixed flame using the transported flame surface density approach. Combustion Theory and Modelling https://doi.org/10.1080/13647830.2017.1293849
Abstract
A premixed propane–air flame stabilised on a triangular bluff body in a model jet-engine afterburner configuration is investigated using large-eddy simulation (LES). The reaction rate source term for turbulent premixed combustion is closed using the transported flame surface density (TFSD) model. In this approach, there is no need to assume local equilibrium between the generation and destruction of subgrid FSD, as commonly done in simple algebraic closure models. Instead, the key processes that create and destroy FSD are accounted for explicitly. This allows the model to capture large-scale unsteady flame propagation in the presence of combustion instabilities, or in situations where the flame encounters progressive wrinkling with time. In this study, comprehensive validation of the numerical method is carried out. For the non-reacting flow, good agreement for both the time-averaged and root-mean-square velocity fields are obtained, and the Karman type vortex shedding behaviour seen in the experiment is well represented. For the reacting flow, two mesh configurations are used to investigate the sensitivity of the LES results to the numerical resolution. Profiles for the velocity and temperature fields exhibit good agreement with the experimental data for both the coarse and dense mesh. This demonstrates the capability of LES coupled with the TFSD approach in representing the highly unsteady premixed combustion observed in this configuration. The instantaneous flow pattern and turbulent flame behaviour are discussed, and the differences between the non-reacting and reacting flow are described through visualisation of vortical structures and their interaction with the flame. Lastly, the generation and destruction of FSD are evaluated by examining the individual terms in the FSD transport equation. Localised regions where straining, curvature and propagation are each dominant are observed, highlighting the importance of non-equilibrium effects of FSD generation and destruction in the model afterburner.
Keywords
large-eddy simulation, turbulent premixed combustion, transported flame surface density model, non-equilibrium effects, FSD generation and destruction
Sponsorship
The authors would like to acknowledge financial support from the Dorothy Hodgkin Postgraduate
Award and Rolls-Royce Plc.
Identifiers
External DOI: https://doi.org/10.1080/13647830.2017.1293849
This record's URL: https://www.repository.cam.ac.uk/handle/1810/263828
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