Cerfacs Enter the world of high performance ...

Link YouTube : https://youtu.be/-1A726WNVXU

Abstract :

This thesis, funded by Safran Aircraft Engines, focuses on the optimization and study of the film cooling holes deployed on the first row of stationary turbine blades via the Large Eddy Simulation (LES) formalism. The complex industrial problem is simplified into an academic one and the study and optimization is carried out for a single shaped hole on a flat plate. The manuscript is hence divided into two sections, the first of which focuses on the study of the fluid flow from a shaped cooling hole in comparison to a simpler cylindrical one. Both the flow within the perforation and that over the flat plate is discussed. Spectral techniques such as Dynamic Mode Decomposition (DMD) are used to identify the most important flow modes inside the cooling hole and statistical approaches such as Probability Density Functions (PDFs) are constructed to illustrate the near-wall thermal behavior of the unsteady coolant flow over the flat plate. The 2nd section of the thesis is then dedicated to finding the optimal shaped cooling hole via a computer-aided optimization process in combination with LES. A Bayesian optimization technique called the Efficient Global Optimization (EGO) based on Kriging surrogate approximation and Expected Improvement (EI) function is used to and the best fit of various parameters defining a hole geometry for maximum cooling performance. The LES numerical setup and the optimization setup needed to address such a design problem is also demonstrated. The optimal shaped hole finally obtained is shown to have a far higher cooling performance over a reference shape selected for comparison. The influence of shaped hole design parameters is eventually demonstrated via a response surface analysis and a parameter sensitivity study based on Sobol indices. This is complimented by a flow comparison between the optimal and other shapes to illustrate the influence of shaped hole design on film cooling. Overall, it is shown that the LES successfully captures the unsteady flow phenomena characteristic to jets in cross flow such as film cooling and when used as the preferred choice for parametric design optimization studies gives reliable results.

Keywords : Large Eddy Simulation, shaped cooling holes, film cooling, optimization

Marlène SANJOÉ – ETSML – Referee

Tom VERSTRAETE – Von Karman Institute – Referee

Eva DORIGNAC – ENSMA – Examiner

Laurent GICQUEL – Director

Florent DUCHAINE – Co-director

Damien BONNEAU – Groupe SAFRAN – Invited member