Manned spacecraft presents significant acoustics challenges to control the noise aboard, for it is important to provide a satisfactory environment for the living and working for astronauts, and to minimize the risk for temporary and permanent hearing loss. Since the primary noise sources on manned spacecraft include the environmental control system and active thermal control system (fans and airflow, pumps and water flow), the noise level of these devices and system are crucial for the noise control of whole spacecraft. Here we present the challenge of noise reduction of a modularized thermal control system. First the system was tested and analyzed in order to recognize the noise sources, and the treatments are designed, including the application of sound absorbing material and damping coat, etc. The treatments are first optimized and validated with simulation analyze, and applied to the thermal control system. The test results indicated a remarkable decrease of noise level. And the materials were carefully selected in order to ensure the safety and reliability for the use in manned spacecraft. These noise reduction treatments could be reference for further use in environmental control system and active thermal control system on other manned spacecraft.
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