NUMERICAL INVESTIGATION OF COMBUSTION CHARACTERISTICS IN A LIQUID FUELLED CAN COMBUSTOR

In the present study, reacting flow in a can combustor is numerically simulated and the results are compared with the data available in open literature. Different grids are considered in order to compare air mass-flow distributions through air entry ports. The fuel used for reacting flow calculations is a kerosene surrogate. In combination with continuity and momentum equations, the transport equations for mean mixture fraction (f) and mixture fraction variance (f '') are solved, linking the instantaneous thermo-chemical state of the fluid through this conserved scalar and its variance. Three sets of atomizer air swirls with swirl number (SN) 0.8, 1, and 1.2 have been tested along with different RANS based turbulence models. It is observed that k-omega-sst model appears to exhibit most realistic solutions in terms of the pattern factor and peak exit temperature. This is due to better prediction of turbulence kinetic energy generation at the primary zone of the combustor. However, the swirl in atomizing air plays a critical role in anchoring the flame in the primary zone of the combustor due to formation of recirculation bubble. Moreover, it is observed that the spray stream is convected downstream for a swirl number slightly below 1.0, thereby affecting the pattern factor of the combustor.