Understanding the coupling between nanosecond repetitively pulsed discharges and the thermoacoustic behavior of a swirl flame at 2 bar

摘要: This study experimentally investigates the coupling between nanosecond repetitively pulsed (NRP) discharges and the thermoacoustic behavior of a methane-air swirl flame at 2 bar for different power ratios (ratio of plasma power to flame thermal power), at pulse repetition frequencies of 10 kHz, 30 kHz, and 70 kHz, and applied voltages in the range 7 to 14 kV. The NRP discharges are created in the annular gap between a bluff body and the metal ring located at the tip of the injection tube. The results show that when NRP discharges are applied, the thermoacoustic behavior and the discharges are strongly coupled. At each pulse repetition frequency studied, for low power ratios, a strong thermoacoustic instability (TAI) is induced by the discharges until a critical power ratio beyond which reduction in amplitude of turbulent induced noise (TIN) of the flame is observed. This nonlinear behavior can be attributed to …