Simulation on the Low-Frequency Acoustic Performance of Noise Attenuation Device in Launch Vehicle Fairings

For a special curved neck Helmholtz resonator that exists in the noise attenuation device used to reduce noise in launch vehicle fairings, its low-frequency acoustic performance was investigated numerically. A virtual impedance tube method was adopted to find out the effect of wall thickness on resonance frequency and sound absorption coefficient of the Helmholtz resonator. The effect of noise attenuation device with different installation locations on the average sound pressure level of a cylindrical cavity was analyzed. The simulation results show that as the wall thickness increases, the resonance frequency increases gradually and tends to the value of rigid wall, but the sound absorption coefficient increases firstly and then decreases. The different installation locations of noise attenuation device can result in 10 dB changes of average sound pressure, so the device should be installed on the larger modal amplitude position of a cavity mode.