Simulation of a Scramjet Combustor: A Priori Study of Thermochemistry Tabulation Techniques
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Simulation of a Scramjet Combustor: A Priori Study of Thermochemistry Tabulation Techniques J. L. Ruan1 · L. Bouheraoua1 · P. Domingo1 · G. Ribert1 Received: 9 January 2020 / Accepted: 8 June 2020 © Springer Nature B.V. 2020
Abstract Large eddy simulations (LES) of a scramjet combustor are reported in this paper. The case under study is a cavity-based combustion chamber that is experimentally studied at the US Air Force Research Laboratory. The chamber is fed by eleven injectors. The computational domains are either simplified including only one or two injectors or complete with the 11 injectors. A good agreement is found between experimental data (velocities measured by PIV) and results from the LES if the kinetic used is chosen with care. A high temperature is found inside the cavity promoting a reactive zone located in the mixing layer where the flow velocity is high. At this location, the combustion occurs first in a diffusion dominated regime followed by the efficient burning of a well mixed mixture (rich then lean). A significant diffusion dominated burning is also found inside the cavity, mostly at the interface between the two recirculation zones. The simulation of the complete geometry revealed a transverse phenomenon on the temperature and mixing fields, but which had nevertheless little effect on the comparison with the available experimental data. A tabulation of the chemistry based on a premixed flamelet library without compressibility effects has been tested a priori on the results of the simulation with one injector. Good results on temperature and H2 O fields are found. Significant localized discrepancies appeared on CO and CO2 fields due to the complexity of the combustion regimes, while compressibility effects were found to be weak for the configuration studied. Keywords Supersonic combustion · Large-eddy simulation · Cavity-based scramjet · Premixed flamelet tabulation
1 Introduction Despite the increase in high-performance computing, it remains challenging to simulate complete combustion chambers while ensuring accurate numerical methods, reliable description of the thermochemistry and efficient models for the phenomena unresolved by the mesh. In particular, it should be noted that few turbulent combustion models are specifically developed for the supersonic flow regime and the classical subsonic * G. Ribert guillaume.ribert@insa‑rouen.fr 1
CORIA‑CNRS, INSA de Rouen Normandie, Normandie Université, 76000 Rouen, France
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Flow, Turbulence and Combustion
modeling techniques are very often transposed to the supersonic case (Bouheraoua et al. 2017). This is the case for tabulation techniques, that allow for drastically reducing the number of transported scalars (van Oijen et al. 2016; Pope 2013). Indeed, a look-up table contains all information about the chemical system from a well-chosen collection of canonical flames or processes. Thermodynamical variables are then tabulated as functions of a small set of control variables that are transported with the flow (Domin
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