Post-Doctoral Position - 2009 / 2010 - IMFT
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Eulerian models for turbulent spray combustion with polydispersity
Investigations in droplets coalescence in a LES framework (ANR project SIGLE)
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Numerical investigations of combustor wall temperature effect on Flame Describing Functions (FDFs)
Thermal coupling of a solid conduction solver and a reactive LES fluid code,
Acoustic forcing of a laminar flame and determination of corresponding FDFs,
Comparisons with experimental results.
Post-Doctoral Position - 2007 / 2009 - CERFACS
During this post-doctoral position, I worked on different aspects dealing with heat transfer and its application to turbomachinery with Large Eddy Simulation. Thus, the topics of investigation are presented as follow:
- Conjugate Heat Transfer with Large Eddy Simulation
- Aerothermal Computations in Industrial Configurations with Large Eddy Simulation - Work done with Airbus (France)
- Towards the use of Arbitrary Lagrangian Eulerian for turbomachinery applications with Large Eddy Simulation
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Conjugate Heat Transfer with Large Eddy Simulations
Thermal coupling between structure and fluid in motion is of significant importance in many industrial engineering applications. In the context of studies dealing with combustion chamber, this complex effect has a large impact on: the thermal stress of combustors walls submitted to a flame front, the temperature of multiperforated walls and more generally on the life cycle of the different components.
With the access to increasing computer power, numerical simulation is more and more an efficient tool to study this set of themes. Based on its experience on High Performance Computing, CERFACS develops an efficient aero-thermal application using the Large Eddy Simulation code AVBP that solve the reactive Navier Stokes equations and AVTP dedicated to conduction in solids. The code coupler PALM MP is used to easily integrate the codes and make them communicate. The characteristics of the coupler are of importance to fastly generate new configurations as well as to use massively parallel architectures for production cases.
This page shows some results from computations that concern:- Coupled Heat Transfer / Fluid Flow Methods for Large Eddy Simulations for turbomachinery applications :
- Application to the Nasa C3X blade,
- Application to the T120D blade.
- Check the accuracy of Large Eddy Simulation to predict wall heat transfer in detached and turbulent flows :
- Square cylinder,
- Square cylinders in tandem.
- Coupled Heat Transfer / Fluid Flow Methods for Large Eddy Simulations in Multiperforated Plates
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- Coupled Heat Transfer / Fluid Flow Methods for Large Eddy Simulations for turbomachinery applications
Conjugate heat transfer between the hot stream coming from the combustion chamber and the guide vanes play an important role when lifespan of turbine baldes is targeted. To help engine manufacturers to design efficently the blades, computational methods are usefull to provide temperature fields as well as thermal constraints (temperature gradients).
1) Nasa C3X blade
Fig. TM-1 - The computational domains for both the fluid and the structure are assumed to be periodic in the spanwise direction (z-axis). For the fluid, a periodicity condition is also assumed y-direction. The fluid flow is not resolved in the cooling holes inside the blade. Heat transfer coefficient are imposed in this holes.
Fig. TM-2 - The main advantage of Large Eddy Simulation is to provide a very good description of the flow around the blade. For exemple, the isosurface of Q criterion shows the vortex shadding at the trailing edge .
Fig. TM-3 - Zoom on the trailing edge.
Fig. TM-4 - Instantatenous temperature fields in the fluid and in the blade.
2) T120D bladePredicting the vanes temperature field (which are cooled from the inside by cold air) is a major research area (Holmer et al. 2000; Medic & Durbin 2002; Garg 2002). Here an experimental setup (T120D blade) developed within the AITEB-1 European project was used to evaluate the precision of the coupled simulations done with AVBP and AVTP. For more details, see :
F. Duchaine, S. Mendez, F. Nicoud, A. Corpron, V. Moureau and T. Poinsot. Coupling heat transfer solvers and Large Eddy Simulations for combustion applications. In Proceedings of the Summer Program Center for Turbulence Reseach, NASA AMES - Stanford University, USA, 2008.
Fig. TD-1 - The computational domains for both the fluid and the structure contain only one spanwise pitch of the film cooling hole pattern (z-axis)), with periodicity enforced at each end. This simplification assumes no end-wall effects, but retains the three-dimensionality of the flow and greatly reduces the number of tetrahedral cells required to model the blade. A periodicity condition is also assumed in the y-direction. The WALE subgrid model (Nicoud & Poinsot 1999) is used in conjunction with non-slipping wall conditions. As shown on the figure , the three film-cooling holes and the plenum are included in the domain: jet 2 is aligned with the main flow (in the xy-plane) while jets 1 and 3 have a compound orientation.
Fig. TD-2. Isosurface of vorticity showing the turbulent activity of the three jets as well as the transition to turbulence on the succion side of the blade.
Fig. TD-3. Instantatenous temperature fields in the fluid and in the blade.
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- Check the accuracy of Large Eddy Simulation to predict wall heat transfer in detached and turbulent flows.
Fig. CHT-1 - Heated square cylinder in a cold flow: isosurface of vorticity (from M. Boileau - 2008).
Fig. CHT-2 - Heated square cylinders in tandem in a cold flow: gradient of density.
Fig. CHT-3 - Heated square cylinders in tandem in a cold flow: isosurface of Q criterion colored by the temperature.
Fig. CHT-4 - Heated square cylinders in tandem in a cold flow: isosurface of Q criterion colored by the temperature.
Fig. CHT-5 - Heated square cylinders in tandem in a cold flow: temperature field in the mid-plane.
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- Coupled Heat Transfer / Fluid Flow Methods for Large Eddy Simulations in Multiperforated Plates
Some results of a conjugate simulation between a periodic multiperforated structure and the flow field:
Fig. MP-1 - Configuration for the CFD and solid models.
Fig. MP-2 - Temperature field on the central cut of fluid and solid domains.
Fig. MP-3 - Temperature field on the central cut of fluid and solid domains - Scaling on structure temperature.
Fig. MP-4 - Isosurface of Q criterion and solid frontiers colored by temperature - Top view.
Fig. MP-5 - Isosurface of Q criterion and solid frontiers colored by temperature - Side view.
Fig. MP-6 - Animation of temperature fields in the solid and fluid domain while considering a 2D configuration.
For more details on simulation of multiperforated walls, refer to the PhD of Dr. S. Mendez (pdf).
Fig. MP-7 - Isosurface of Q criterion showing the instantaneous flow structure (S. Mendez and F. Nicoud. Journal of Fluid Mechanics, 598:27-65, 2008).
Aerothermal Computations in Industrial Configurations with Large Eddy Simulation (Airbus france)
Fig. A-1 - Isosurface of Q criterion showing the instantaneous flow structure in a simplified engine nacelle (from M. Boileau - 2008).
Towards the use of Arbitrary Lagrangian Eulerian for turbomachinery applications with Large Eddy Simulations
Fig. ALETM-1 - Animation of the MT1 turbine stage. Left: temperature, right: Mach number.
Fig. ALETM-2 - Animation of the MT1 turbine stage. Temperature
- Coupled Heat Transfer / Fluid Flow Methods for Large Eddy Simulations for turbomachinery applications :
PhD Thesis - 2004 / 2007- CERFACS
- Multiobjective Shape Optimization on Parallel Architectures with Metamodels and Couplers. Application to Aeronautical Combustion Chambers.
Drastic norms on pollutant emissions and the need to reduce times to market encourage aeronautical engine manufacturers to reconsider the concepts of the next generation of combustion chamber as well as their design methodologies. Reactive and turbulent simulation codes based on the RANS approach have been used for a few years by engineers in the design cycle of aeronautical combustion chambers. Their use has allowed to reduce development times and costs mostly by decreasing the number of experimental tests. The way to integrate these tools is still a challenging point when the development of an efficient design framework is considered.
The aim of this work is to provide a multiobjective optimization based methodology to develop a fully automated tool that evaluates design with simulation codes. First, the studies presented in this report deal with the automation of the simulation processes while insisting on the automatic mesh generation aspects. Then, to reduce the overall response time caused by the use of optimization technics with expensive simulation codes, a strategy based on metamodeling is proposed. The resulting tool is developed with a parallel code coupler offering performance and flexibility to the application. Finally, after some validations and evaluations on test cases, an application on an industrial combustor underlines the capacities of the method to identify promising designs.
- PhD Thesis
Optimisation de Forme Multi-Objectif sur Machines Parallèles avec Méta-Modèles et Coupleurs. Application aux Chambres de Combustion Aéronautiques - Institut National Polytechnique de Toulouse, 2007 (pdf) - Posters
- Talks
