SELECTING THE MESH FOR MODELLING THE COMBUSTION OF A STATIONARY SOLID FUEL BED IN ANSYS FLUENT

The choice of model parameters and calculation grid for the model of combustion of a fixed layer of solid fuel is considered. The models included in the calculation and their main parameters are presented. The comparison of the obtained modelling results using different meshes is carried out. The adequacy of combustion modelling was checked by comparing the averaged composition of gases and their temperature in the output window with the values obtained by calculation of fuel combustion; the averaged SO2 and NO content in the output window with the results of emission calculations and combustion analysis along the length of current lines. It is found that the multi-area grid used for all areas provides more adequate results, in contrast to the combination of a tetrahedral grid for the gas part and a Cartesian grid for the surfaces, but is characterised by a higher, three times, calculation time. The combinations of the multi-area grid for the gas part and tetrahedron grid for the surfaces and the combination of the tetrahedron grid for the gas part and Cartesian grid for the surfaces had the same quality and comparable results, as well as the same calculation time, but the first variant contains 20% fewer elements and provides better combustion results on individual current lines. As a result, the multi-zone grid for the gas part and the tetrahedral grid for the surfaces were chosen for modelling as providing adequate results with shorter calculation time.