Study of a low-frequency combustion oscillation in a DLN combustor

This paper presents a low-frequency combustion oscillation observed in a DLN micro gas turbine combustor operated in premixed mode. Its frequency is 1~2 Hz. The oscillation mechanism is investigated by the numerical simulation methods. The results reproduced the low-frequency oscillation occurrence in the experiments. It is shown that the oscillation is due to the unreasonable structure design of the preheating passageway. There is a periodic recirculation flow lead to low-frequency oscillation. By modifying the preheating passageway structure, the oscillation can be suppressed, which further confirms the reason of the oscillation. This kind of low-frequency combustion oscillation has not been reported in the literature, the discovery is of important significance for the DLN combustor design.