During the development of an aeronautical gas turbine, one of the major concerns is to guaranty a correct reignition in case of extinction during the flight. Whereas manufacturers commonly use CFD (Computational Fluid Dynamics), and in particular LES (Large Eddy Simulation), to predict fuel consumption and pollutant emissions of gas turbines, these tools are rarely used to compute the reignition event due to its complexity and its high CPU cost. This explains why reignition is today essentially studied through experiments which remain extremely expansive and poorly instrumented. In this context, the present PhD proposes to develop LES models and methodologies to calculate reignition in gas turbines with good accuracy and limited CPU cost. In order to fulfil this objective, the study will be based on a CFD code featuring an AMR (Automatic Mesh Refinement) capability which will allow to keep a good resolution of the flame kernel during its growth and convection in the combustion chamber, while maintaining a reasonable number of cells. It will also be based on the thickened flame turbulent combustion model coupled to a reduced chemical mechanism allowing a correct prediction of kinetics in the present complex environment.
The PhD thesis will first consider an ignition case with perfectly premixed gaseous fuel and air in an academic combustion chamber providing good characterization of the flow and of ignition. The aim will be to recover the ignition probability experimentally measured for different spark plug locations. This work will then be extended to a similar two-phase flow configuration thus approaching conditions found in a real aeronautical gas turbine. For this purpose, a thorough study of the impact of the liquid spray characteristics (droplet size, evaporation properties etc…) on the ignition capability will be performed. It will lead to a modelling approach proposal adapted to two-phase ignition. This modelling will finally be applied to a similar case but including not only the ignition phase but also the flame propagation from the first burner to the surrounding ones, as found in annular gas turbines.
Keywords: Large Eddy Simulation, gas turbine, combustion model, ignition
- Academic supervisor Prof. Bruno Renou, CORIA and Dr. Olivier Colin, IFP Energies nouvelles
- Doctoral School ED 591 PSIME, Normandie Université
- IFPEN supervisor Dr Cedric Mehl, engine and vehicle simulation department, firstname.lastname@example.org
- PhD location IFP Energies nouvelles, Rueil-Malmaison, France
- Duration and start date 3 years, starting preferably in October, 2019
- Employer IFPEN Rueil-Malmaison, France
- Academic requirements University Master degree in fluid mechanics, combustion
- Language requirements Fluency in French or English, willingness to learn French
- Other requirements Programming skills (Fortran, C or C++)
IFP Energies nouvelles is a French public-sector research, innovation and training center. Its mission is to develop efficient, economical, clean and sustainable technologies in the fields of energy, transport and the environment. For more information, see www.ifpen.fr. IFPEN offers a stimulating research environment, with access to first in class laboratory infrastructures and computing facilities. IFPEN offers competitive salary and benefits packages. All PhD students have access to dedicated seminars and training se