抄録
LES (Large-eddy simulation) of swirling cold-flows in a pulverized coal combustion furnace is performed and validated by comparing with experiment and RANS (Reynolds-Averaged Navier-Stokes) simulation with the standard k-ε model. Unstructured grids and energy-conserving scheme are employed to obtain robust and accurate solutions at high swirl numbers. The results show that the LES is in good agreement with the experiment in terms of the recirculation flow, though the RANS simulation overestimates it. This is considered due to the capability of prediction of turbulent mixing. The effect of secondary and tertiary swirler vanes' angles on the behavior of the recirculation flow are also well predicted by the LES. The recirculation flow affects the flame stabilization and combustion efficiency related to the particle residence time in the furnace. It can be said, therefore, that the LES is strongly recommended for the accurate prediction of the strong swirling flows in such furnaces.
