Combustor-turbine interactions: Hot spot migration and thermal environment prediction for a better understanding and design of helicopter engines

This PhD thesis, funded by SAFRAN Helicopter Engines, focuses on Large Eddy Simulation (LES) of the FACTOR test rig to investigate combustor-turbine interactions in the context of next generation lean combustion engines. The FACTOR test rig is a full annular non-reactive lean combustion simulator with a single staged high-pressure turbine located at the DLR in G�ottingen. Another test rig featuring three sectors or 54_ of the full annular DLR test rig is available at the University of Florence. Both rigs provide a huge amount of validation data. In this thesis, certain aspects of LES in turbomachinery are investigated in detail and the manuscript is divided into two parts dealing respectively with the modeling of cooling systems and an analysis of the ow _eld in the combustion chamber and high-pressure vane passage. First, a heterogeneous and a homogeneous coolant injection model for multiperforated plates in combustion chambers are tested against experimental results. From this _rst study it is shown that the heterogeneous model allows for a more realistic coolant jet representation and should be retained for future simulations. In gas turbine engines the application of coolant systems is not only mandatory in the combustion chamber, but also in the _rst stages of the high-pressure turbine. The next section therefore investigates the previously presented heterogeneous injection model as a mean to model the e_ects of the NGV cooling system on the main ow and compares the simulation to a second one with a fully resolved coolant system. The second part deals with simulations that extend over combustion chamber and high-pressure vanes and speci_cally addresses the impact of the ow _eld in the combustor on the high-pressure vanes. The main objective here is to better understand wall temperature distribution on the turbine blade wall which is obtained by use of higher order statistics analysis to highlight thermally critical areas. Based on such coupled multiple component LES, a discussion is initiated to identify a path allowing to take into consideration the impact of the combustion chamber on isolated high-pressure vane simulations using di_erent reconstructed unsteady inlet conditions