Cerfacs Enter the world of high performance ...

Youtube link : https://youtu.be/GsRG_8fWKIM

Abstract :

The aeronautical industry, and in particular the turbomachinery industry, is constantly seeking to optimize aerodynamics in order to reduce fuel consumption and emissions of pollutants, particularly greenhouse gases. This research involves the precise study of the various modules to verify a certain number of critical elements such as the pumping margin, temperature levels for the behavior of the materials, operating ranges, etc. Unsteady simulations, of which large eddy simulations (LES) are a part, are excellent candidates to be able to account for all this complexity, in particular the interactions between elements and modules of a gas turbine. However, the computational cost for a compressor or a turbine is such that this type of simulation is not accessible for the industrial domain. In order to reduce these costs, different choices are possible. From a purely geometrical point of view, the number of blades of turbomachinery stages being most of the time prime between them, it is necessary to simulate the azimuthal completeness of the machine to correctly predict the flow field. Thus, this thesis investigates two domain size reduction methods for turbomachinery stages using single or dual channel approaches in order to make LES more affordable. The Profile Transformation Approach (PTA) allows information to be transmitted across the rotor-stator interface using geometric scaling. The impact of the assumption is evaluated analytically, and then on cases of increasing complexity from an academic case to an industrial high-pressure turbine. The method based on the spatio-temporal periodicity of the flow, called the chorochronic hypothesis, is then studied. A special boundary condition is designed for the management of azimuthal edges and a first evaluation is carried out on an academic case of translating wakes. The same case is then used to validate the complete method consisting of the chorochronic treatment at the azimuthal edges and at the rotor-stator interface. In the last part, the two methods are compared on an industrial configuration of a high-pressure compressor stage.

Jury :

Sofiane Khelladi – ENSAM Paris – Referee

Marlène Sanjosé – ETS – Referee

Antoine Dazin – ENSAM Paris – Examiner

Stéphane Aubert – EC Lyon – Examiner

Laurent Gicquel – CERFACS – Director

Florent Duchaine – CERFACS Co-director