The noise in the hall has obvious low-frequency characteristics, and mainly comes from the air inlet. Considering the user's requirements for the multi-purpose hall, the overall treatment plan is as follows: (1) Add a soundproof cover to the fan. (2) Sound insulation and sound absorption treatment on the wall of the fan room. (3) Inlet and exhaust cylinders plus muffler. (4) Fan room plus sound insulation door. Figure 3 Sound insulation muffler structure 4 fan sound insulation muffler design Because the fan is in a small position, the hall ceiling has been renovated and cannot be changed.
It is impossible to add a muffler in front of the air inlet of the fan. Therefore, the fan sound insulation cover and the muffler are designed as one body, and become a sound insulator muffler. The front section of the fan soundproof cover muffler is designed as a muffler, which adopts two layers of perforated plates; the rear sound insulation cover adopts a perforated plate. The external structure adopts 018mm galvanized sheet, and the inside adopts micro-perforated plate (the aperture is 018mm, the perforation rate is 2%, 215%, 110%). The air inlet and the air duct of the fan are disconnected, and the air duct and sound insulation cover are used. Is a soft connection.
The purpose of using micro-perforated plate is: (1) The sound absorption structure of micro-perforated plate is higher than that of ordinary perforated plate, the sound absorption frequency band is small, the pressure loss is small, the airflow re-acoustic noise is low, no porous sound-absorbing material is used, no dust Or other fibers are leaked out and cleaned. (2) The micro-perforated plate is not afraid of moisture, is not afraid of water and water vapor, can withstand the impact of high airflow, and is resistant to high temperature and mildew. These features can meet the requirements of the multi-function hall for the muffler. The structure of the specific acoustic enclosure muffler is shown in Figure 3. The treated fan room is shown in Figure 4. Figure 4: Calculation of the noise reduction of the sound box muffler in the fan chamber plane after treatment. Since the structure of the sound insulator muffler is a new type of structure, the advantages of the sound insulation cover and the micro-perforated plate muffler are taken into consideration; The series connection of the perforated plates also broadens the absorption band. The final noise reduction of the sound enclosure muffler is a comprehensive result. According to the actual measured data, the noise reduction effect is obvious, and theoretically, it needs further exploration and improvement.
Governance effect and conclusion Through the comprehensive control of the noise of the axial flow fan, the allowable noise level of the multi-purpose hall of the hotel building in the national standard of the noise value at each point after the treatment is measured, which is close to the first level. At the same time, it also meets the requirements of users, and the noise reduction effect is obvious. About the author: Hu Ping, graduate student, associate professor, mainly engaged in mechanical design, computer control, noise detection and control.
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