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The 16 September 2021 at 14h00

PhD defense: Julien CARMONA – “Modelling of two-phase flow phenomena in aeronautical Airblast injectors”

Marie LABADENS |  Cerfacs, Toulouse - salle séminaires et webex |  

Web link: https://cerfacs.webex.com/cerfacs/j.php?MTID=m80cd1664853c4618fe56dda8ca79fffd


The aeronautical sector must reduce its pollutant emissions and its fuel consumption to face the ever more stringent environmental standards. To achieve this goal, lean combustion technologies, allowing a good combustion efficiency while limiting nitrogen oxides (NOx) and carbon monoxide (CO) emissions, are being developed. Those new generation combustors are nevertheless more likely to destabilize and the fuel injection system plays a significant part in stabilizing the flame, and thus maintaining an efficient combustion process. Because of their ability to offer stable performances for a large range of operating conditions, Airblast injectors have attracted much attention from the engine manufacturers. In such injectors, the fuel is introduced in the combustor as a thin liquid film flowing along the injector wall towards the diffuser lip, where it is finally atomized into small droplets. This PhD aimed at numerically studying the physical phenomena involved in Airblast injectors, and at developing the numerical tools allowing their characterization. With that objective, a methodology allowing to perform some direct numerical simulations of academic configurations has first been proposed. It was then applied in two distinct configurations to the study the liquid film dynamics and its atomization process using a Volume Of Fluid method and the NGA incompressible solver. In parallel, a simpler modelling method relying on phenomenological models has been developed in the Lagrangian solver of the compressible code AVBP. This approach allows to predict the atomization dynamics given the flow topology. Our main work consisted in developing and integrating the AutomaticPAMELA (Primary Atomization Model for prEfilming airbLAst injectors) model which proposes a local formulation and an automated determination of the PAMELA primary atomization model inputs (Chaussonet, 2016). Once validated on a well characterized experimental configuration, the model was applied to an industrial Airblast injector configuration and allowed us to predict spray characteristics in line with experimentally measured. While very efficient, this approach is valid for a restricted operating range, thus limiting its application to flows where the physical phenomena involved are well known. To address this issue, a twophase flow numerical method based on a multifluid diffuse interface approach has also been developed in AVBP during this PhD. It relies on the combination of a 4-equations multifluid model to describe the flow behavior, and a Noble-Able-Stiffened-Gas (NASG) thermodynamic closure able to represent the thermodynamic evolution in both the gaseous and the liquid phase. To avoid numerical diffusion of strong gradients at liquid/gas interface while ensuring the numerical stability, a Godunov numerical scheme with a HLLC Riemann solver designed for “node-centered” formulations has been integrated in the AVBP code. It required an important algorithmic work specially to implement a MUSCL reconstruction methodology in a high-performance computing framework, and thus ensuring a global second order accuracy. After some 1D and 2D validations, the method has finally been used to perform 2D simulations of a gas sheared liquid film and of a prefilming Airblast atomization process, highlighting its ability to address physical phenomena representative of real Airblast injector configurations.

keywords: CFD, two-phases flow, Airblast injector, atomisation


Stéphane VINCENTProfessor – Laboratoire de Modélisation et Simulation Multi Echelle Referee
Olivier LE METAYER    Professor – Institut Universitaire des Systèmes Thermiques et Industriels Referee
Jean-Philippe MATASProfessor – Laboratoire de Mécanique des Fluides et d’AcoustiqueMember
Olivier DESJARDINSProfessor – Sibley School of Mechanicaland Aerospace EngineeringMember
 Bénédicte CUENOTSenior Researcher – CERFACSAdvisor
Pierre BOIVINScientist Researcher –

Laboratoire de Mécanique, Modélisation & Procédés Propres

Nicolas ODIERSenior Researcher – CERFACSInvited
Alain CAYREEngineer – Safran Aircraft EnginesInvited


The AVBP code from CERFACS at the heart of three PRACE projects from the 23rd call

CERFACS |  30 September 2021

Cerfacs is involved in three PRACE projects of the 23rd call for which hour allocation runs from 01/10/2021 to 30/09/2022. Researchers from ECL/LMFA UMR5509 (Ecole Centrale de Lyon) and IMFT (UMR 5502) laboratories have earned projects entirely based on the use of the LES solver developed by Cerfacs AVBP and involve the support of experts from the CFD and COOP teams underling the importance and effectiveness of collaborations between French labs and Cerfacs. Alexis Giauque from ECL/LMFA UMR5509 (Ecole Centrale de Lyon) has obtained not only one but two PRACE projects! The first project LESFAN (RA0101, 30 000 000 CPU hours on Irene/Rome TGCC) is based on the use of AVBP in the turbomachinery version to study the generation of noise by a fan of a real airplane engine. The second, PRACE-EDGES (RA0101, 40 000 000 CPU hours on Irene/Rome TGCC) focuses on LES modeling of dens gas in complex geometries. To do so, the LMFA Team has developed advanced thermodynamic closures in AVBP allowing the direct simulation of such flows. Laurent Selle from IMFT (UMR 5502) has received CPU hours for the GASTON project (RA0061, 30 000 000 CPU hours on Marenostrum BSC) which aims to study the structure of hydrogen flames in porous materials. For this, IMFT and Cerfacs will perform coupled simulations considering the reactive flow with AVBP as well as the conduction in the porous medium with AVTP which is known to play an central role in the flame stabilization process.Read more

watch the online contest ”my thesis in 180 sec” organized for Marie Curie actions

CERFACS |  24 September 2021

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