A method for noise attenuation in cylindrical cavity with melamine foam lining

The low-medium(100~400 Hz) frequency noise attenuation in cylindrical cavity with melamine foam lining is investigated theoretically, numerically, and experimentally. With the melamine foam being equivalent to the impedance boundary, the formulas of the natural frequency of the cylindrical cavity are deduced. The flow resistance and sound absorption coefficient of the melamine foam with different thickness are tested, and the other acoustic parameters of the melamine foam are validated by simulation. Then the surface impedance data is given by simulation, and the data is used to calculate the theoretical and numerical natural frequencies of the cylindrical cavity with impedance boundary, and these results are compared with the results of the simulation in which melamine foam is 3D solid element. A scale model of the cylindrical section of the payload fairing is fabricated, and the acoustic responses inside the cylinder under noise excitation are tested and simulated. The results show that the melamine foam lining leads to decreasing of the natural frequencies, and these reductions are proportional to the thickness of the melamine foam. The noise attenuation of the melamine foam lining on low-medium frequency can reach to nearly 4~8 dB.