Active control of thermoacoustic instability using microsecond plasma discharge

Abstract

The thermoacoustic instability produced in a simple heat-driven-acoustic-oscillation device (so-called Rijke tube) has been controlled by the periodic plasma discharge. A perforated plate is placed at the upstream of the tube as the heater. Due to the interaction between the heat and acoustic waves, thermoacoustic instabilities occur. The high-voltage microsecond pulsed plasma is generated within pin-to-pin electrodes that are used as an actuator since the pressure wave generated by the plasma is quite strong and able to attenuate the thermoacoustic sound wave in the Rijke tube. However, since the pressure waveform generated by the plasma discharge is different from the sinusoidal signal that is generated by a loudspeaker and widely used as a control actuator, it is necessary to derive the new model from the simplified Rijke tube. The time domain oscillation simulation is conducted, and the phase shift method is used to find appropriate control strategy. The discharge pressure waveform is subsequently fitted with an eighth-order Fourier series, and the overall Fourier signal is adjusted so that the first-order waveform in the discharge was similar to the analog sinusoidal control signal; the control is quite effective. It is known that when the sinusoidal control waveform of same frequency as thermoacoustic instability can meet control requirements, the non-sinusoidal signal can also control the thermoacoustic instability. Finally, according to the simulation results, the high-voltage microsecond plasma discharge is adjusted to the suitable amplitude and phase used for closed-loop control on the thermoacoustic oscillation, which significantly suppressed the instability.