Paper Title
ACOUSTIC DAMPING OF RIJKE TUBE INSTABILITIES USING SOLENOID VALVE PULSATION

Abstract
Thermoacoustic instabilities in combustion systems, including those in a Rijke tube, are quite challenging with their production of high-intensity noise, pressure oscillations, and structural vibrations. This experimental investigation explores the acoustic instability suppression by controlled pulsation of airflow through a solenoid valve. Experiments were performed on an 800 mm long and 80 mm diameter horizontal Rijke tube. Two pulsation frequencies of 8 Hz and 12 Hz were investigated with the same solenoid valve to determine their ability to suppress instability. Periodic airflow perturbations at predetermined frequencies and amplitudes were introduced to interrupt coupling between heat release and acoustic pressure oscillations. The acoustic signals were recorded with a data acquisition (DAQ) system and Lab-view software, which allowed for real-time monitoring and measurement of sound pressure levels (SPL). The findings indicated that both frequencies played a role in instability amplitude reduction, with the 12 Hz pulsation revealing much stronger suppression than that for the 8 Hz case. These results attest to solenoid valve pulsation, particularly at optimized frequencies, being an effective active control method for counteracting thermoacoustic instabilities in industrial burners, gas turbines, and propulsion systems where noise suppression and stability of operation are important. Keywords - Thermoacoustic instabilities; Rijke tube; Solenoid valve pulsation; Sound pressure level (SPL); Data acquisition (DAQ);Active control.