Numerical Simulation of Combustion Control by Secondary Fuel Injection

摘要

In this study, flame dynamics of secondary fuel injection control is investigated by large eddy simulation (LES) in a lean premixed combustor to elucidate the oscillation suppression phenomenon observed in the previous experiment. Without secondary fuel injection, large amplitude longitudinal oscillations were observed. With constant injection of secondary fuel, the oscillation amplitude reduced and with harmonic feedback injection, is further reduced. In this process, the flame shape and the flame behavior were changed. To understand the flame dynamics, large eddy simulations are carried out. The LES results show that the oscillation is attributed to the roles of both main flame and secondary flame. The interaction of the main flame and vortices is reduced with the injection is on, thus heat fluctuation is reduced. The secondary flame helps the flame base stabilization and directly the heat release in the case of feedback injection. The phase relations between the pressures, secondary heat release velocities are also shown here. With these effects combined, the oscillations are suppressed. The present study indicates that the LES can be a tool to understand flame dynamics with control.