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Aerothermal Lattice Boltzmann Modeling of Bore-Cooling Cavities in High-Pressure Compressors

[Subject to defense authorization]

ED353 Sciences pour l'Ingénieur : Mécanique, Physique, Micro et Nanoélectronique – Aix-Marseille Université

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Next-generation turbofan engines require optimal heat transfer control withinthe rotor disks in the compressor and turbine stages to ensure their efficiency,reliability, and longevity. These engines operate under higher pressure ratiosand turbine inlet temperatures, which subject rotor blades and disks tosignificant thermal stresses. To address these challenges, a bore-cooling system with rotating cavities aroundthe central shaft is used. Predicting heat transfer in these cavities iscomplex due to the dynamic vortex structures induced by both forced convection(from axial throughflow) and natural convection (from centrifugal buoyancy).Advanced Large Eddy Simulation (LES) models have proven more effective incapturing these dynamic processes compared to traditional Reynolds-AveragedNavier-Stokes (RANS) models. However, implementing these simulations at anindustrial scale remains computationally demanding.
This PhD thesis focuses on advancing the compressible lattice Boltzmann methodfor modeling rotating cavity flows, showing promise in capturing this complexflow physics. Key contributions include the extension of the method to modelrotating flows in a local reference frame by incorporating Coriolis andcentrifugal force terms. Furthermore, a direct-coupling refinement algorithm istailored to improve mass conservation at grid interfaces. A newmass-conservative boundary treatment based on the reconstruction of distributionfunctions is proposed to enhance the accuracy of heat transfer predictions. Then, awall model is extended to include thermal effects, enabling the simulation ofconfigurations at higher Rayleigh numbers.
The model’s capabilities were validated against increasingly complexconfigurations, ranging from a sealed annular cavity to a multi-stage cavityrig. Results showed good agreement with temperature measurements, reasonableheat transfer predictions, and the ability to replicate compressibility effectsthat attenuate Rayleigh-Bénard instabilities. This thesis establishes a robustfoundation for future innovations in simulating turbomachinery bore-coolingcircuits at an industrial scale.

Jury

Jonas LATT	Université de Genève	Rapporteur
Adrien TOUTANT	Université de Perpignan	Rapporteur
Bérengère PODVIN	CNRS, EM2C	Examinatrice
Nicolas BINDER	ISAE-SUPAERO	Examinateur, Président du jury
Pierre SAGAUT	Aix-Marseille Université	Directeur de thèse
Jean-François BOUSSUGE	CERFACS	Membre invité
Christophe SCHOLTES	Safran Aircraft Engines	Membre invité