|Principal Investigator(s)||Dominique Thevenin|
Combustion phenomena are of essential scientific and technological interest, in particular for the improvement of energy generation and transportation systems. For many decades to come an overwhelming part of human energy needs will still be covered by combustion of fossil fuels. Obviously, combustion-driven devices (Internal Combustion Engines, gas turbines, furnaces...) must be optimized to reduce pollutant emissions and fuel consumption. Direct Numerical Simulations (DNS) have become an essential and well-established research tool to investigate turbulent combustion, since they do not rely on any approximate turbulence model. In this project some of the most powerful supercomputers available in Europe will be used to carry out DNS of turbulent flames at realistic (i.e. high) values of the Reynolds number. These simulations will be used in particular to check the importance of two modelling issues concerning possible extensions or modifications of the Navier-Stokes equations: a) volume viscosity; b) additional terms for non-isothermal flows. For both issues, controversial information can be found in the literature. All computations will employ the reactive Navier-Stokes equations including accurate models for chemistry (complex reaction mechanisms) and molecular transport (mixture-averaged diffusion coefficients). DNS are ideally suited for this purpose since all scales down to the Kolmogorov scale are resolved in the simulation, leading to a ’numerical experiment’. For these investigations the ignition and propagation of turbulent hydrogen and n-heptane flames, modelled using up to 30 chemical species, will be considered. This allows a suitable description of most chemical systems used in practical combustion applications, from simple fuels up to complex hydrocarbon molecules.