Bluff-body Thermal Property and Initial State Effects on a Laminar Premixed Flame Anchoring Pattern
Bluff-body stabilized laminar flames remain at the root of many industrial applications. Such a simple flame arrangement although steady results from complex chemical, flow mixing as well as solid body thermal interactions that are still today misunderstood. Numerically, accurate predictions of such non linear problems require Conjugate Heat Transfer (CHT) approaches that are seldom because of the need for complex fluid flow solvers as well as multi-physics coupling strategies that are computationally expensive and difficult to master. Such numerical tools however provide access to fundamental elements otherwise inaccessible. Relying on Direct Numerical Simulation (DNS) CHT based predictions, the following work underlines several key features of importance to predict and understand square bluff-body stabilized flames. In the case of fluid only predictions, where the bluff-body wall temperature is fixed and assumed constant, three possible flame topologies are obtained and respectively qualified as anchored, lifted and bowed flames. Out of these three stable flow solutions, only two topologies are found physically possible whenever computed in a CHT context. Furthermore, depending on the solid material and the initial solution, the non linear CHT problem exhibits multiple solutions highlighting the complex coupling that can arise. As evidenced by these simple flame problems, such a behavior higlights the potential difficulties of predicting flame wall interaction problems where coupling schemes and turbulent closures / modeling will be required.
KeywordsLES Heat transfer Reacting flow CHT Coupling scheme and Convergence
The work presented in this paper has largely benefited from CERFACS supercomputers as well as granted access to the HPC resources of [TGCC/CINES/IDRIS] under the allocation x20162b7525 made by GENCI. These supports are greatly acknowledged. The authors are grateful to SAFRAN HE for partially funding this work. The authors also thank people of the CFD team for helpful discussions.
Compliance with Ethical Standards
Funding: This PhD study was funded by SAFRAN HE (though the funding of S. Berger). The authors declare that they have no conflict of interest.
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