LARGE EDDY SIMULATION OF A TURBULENT HYDROGEN DIFFUSION FLAME

In this work a large eddy simulation (LES) of a turbulent hydrogen jet diffusion flame is presented. The numerical method handles fluctuations of density in space and in time, but assumes density to be independent of pressure (incompressibility). The chemical composition of the fluid is described by solving the transport equation for mixture fraction f. Density, viscosity, temperature and species mass-fractions are evaluated assuming chemical equilibrium. To account for sub-grid fluctuations of f, its sub-grid distribution is presumed to have the shape of a β-function.
The first part of the discussion addresses the influence of inlet boundary conditions and the range close to the nozzle. LES shows to be capable of providing an accurate description of this area. In the second part of the discussion, radial profiles at different axial positions are shown for a complete set of statistically evaluated quantities, i.e. mean velocity, Reynolds-stress tensor, means and variances of mixture fraction and temperature. The results of the LES calculation match experimental data very well. Though the methods applied are of moderate complexity and numerical cost, they prove to be adequate for the considered flow.