Noise prediction and reduction on interior acoustic field of launch vehicle fairings

During flight, the severe external noise is a major factor threatening the safety of spacecraft and the instruments. It is very important to predict the internal sound field accurately and reduce the interior noise correspondingly. In this paper, the internal acoustic field of a certain launch vehicle fairing is calculated based on statistical energy analysis (SEA). Compared with the reverberation chamber test result, the applicable frequency range of SEA is confirmed, and the models are verified to get a good agreement with the experimental data, which shows that the fairing has a strong response at the cylinder coincident frequency of the fairing. The sound absorption properties of different melamine foams are researched. The optimum acoustical parameters of melamine foam are given to achieve best sound-absorption performance. With melamine foam pasting on the fairing inner wall, the noise attenuation effect is calculated with the SEA model. Results show that 10 dB noise pressure level reduction in applicable frequency range is achieved.