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The 6 May 2015

Phd Defense: Dimitrios PAPADOGIANNIS – Coupled Large Eddy Simulations of combustion chamber-turbine interactions

Marie LABADENS |  CERFACS, Conference room Jean-Claude André |  

Modern gas turbines are characterized by compact designs that enhance the interactions between its different components. Combustion chamber-turbine interactions, in particular, are critical as they may alter the aerothermal flow field of the turbine which can drastically impact the engine life duration. Current state-of-the-art treats these two components in a decoupled way and does not take into account their interactions. This dissertation proposes a coupled approach based on the highfidelity Large Eddy Simulation (LES) formalism that can take into account all the potential paths of interactions between components. In the first part of this work, an overset grid method is proposed to treat rotor/stator configurations in a rigorous fashion that is compatible with the LES solver AVBP. This interface treatment is shown not to impact the characteristics of the numerical schemes on a series of academic test cases of varying complexity. The approach is then validated on a realistic high-pressure turbine stage. The results are compared against experimental measurements and the influence of different modeling and simulation parameters is evaluated. The second part of this work is dedicated to the prediction of combustion chamber-turbine interactions using the developed methodologies. The first type of interactions evaluated is the indirect combustion noise generation across a high-pressure turbine stage. This noise arises when combustor-generated temperature heterogeneities are accelerated in the turbine. To simplify the simulations the heterogeneities are modeled by sinusoidal temperature fluctuations injected in the turbine through the boundary conditions. The noise generation mechanisms are revealed by such LES and the indirect combustion noise is measured and compared to an analytical theory and 2D predictions. The second application is a fully-coupled combustor-turbine simulation that investigates the interactions between the two components from an aerothermal point of view. The rich flow characteristics at the turbine inlet, issued by the unsteady combustion in the chamber, are analyzed along with the migration of the temperature heterogeneities. A standalone turbine simulation serves as a benchmark to compare the impact of the fully coupled approach.

Paul G. Tucker                         University of Cambridge      Referee
Edwin T.A. van der Weide        University of Twente            Referee
Pascal Ferrand                        Ecole Centrale de Lyon        Member
Stéphane Moreau                    Université de Sheerbroke    Member
Vincent Brunet                         CFD Team Safran Tech       Member
Gilles Leroy                             Turbomeca                           Industrial member
Laurent Y. Gicquel                   CERFACS                            Advisor
Florent Duchaine                    CERFACS                             Co-advisor


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