Cerfacs Enter the world of high performance ...

Abstract

This PhD thesis, funded by Safran Helicopter Engines, focuses on the application of the Large Eddy Simulation (LES) formalism to cooling systems present in high pressure turbine. The complex industrial problem is simplified into academic test cases for which experimental data are available for the validation process. The manuscript is divided into 3 parts dealing respectively with the impinging jet system on flat and concave plates and with the film cooling at the trailing edge equipped with a cutback on the pressure side. The 1st part deals with a jet impinging on a flat plate representing the impingement at mid-chord. This part focuses on the validation and qualification of the tools and models as well as on the physical analysis of the flow. The unsteadiness present in such an impinging jet flow are linked to the thermal behavior of the wall through the use of statistical analysis and modal decomposition of the flow field. The 2nd part is dedicated to the study of a jet impinging on a concave surface. This study aims at characterizing the effect of curvature for an impinging jet flow. The results found in this study disagreed with the current consensus attributing heat transfer enhancement on concave surface to Görtler instability. Hence, a discussion is proposed in an attempt to explain this discrepancy. Finally, the 3rd part reports an LES of the film cooling at the trailing edge. Group effects, due to the presence of internal ribs, are highlighted for the configuration studied here. These simulations use a spatial periodicity assumption to reduce the size of the computational domain. It is shown that this specific assumption is not suited as it forces the flow and modifies the group effect. The local results, in terms of adiabatic effectiveness, are found to be sensitive to such a forcing. However, the global behavior of the effectiveness is not impacted by this periodic boundary condition.

Jury

Laurent GICQUEL                CERFACS, Toulouse          Advisor
Eric LAMBALLAIS                Université de Poitiers          Referee
Matthieu FéNOT                   ISAE-ENSMA, Poitiers       Referee
Eva DORIGNAC                   Université de Poitiers         Member
Laurent JOLY                        ISAE Toulouse                   Member
Florent DUCHAINE               CERFACS, Toulouse         Co advisor