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Investigation of Effect of Muffler Performance on Environmental Pollutants

Khajvand-Sani, Sajad | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51356 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Nouri-Borujerdi, Ali
  7. Abstract:
  8. The silencer is used to reduce sound in the vehicle, air conditioning channels, power plants and guns. Functional parameters of the sound amplifier are the amount of noise reduction and pressure drop. There are few studies on the flow and pressure distribution in the silencer, and there is no article about the effect of the size of the internal passages on the pressure drop and acoustical performance of the silencer. Few studies have been done on the effect of the absorbent fiber diameter on the acoustic performance of silencer. In this study, the effect of different shapes of internal channels (extended tubes, baffles and number of chambers) on the pressure drop and acoustic performance of silencers are numerically studied. Then, with a few geometries, it tried to improve the pressure drop and the acoustic performance of the sound. Also, the effect of different absorbent parameters on acoustic performance has been studied. In the study of pressure drop, the unconstrained and stable flow is assumed and the k-ω SST model is used.In the present work, it was found that the higher the sound absorption resistance flow leads to more attenuation of inlet sound. Extended tubes such as the resonator will exacerbate the performance of the sounder on some frequencies. In the sample, the buffer diameter, the buffer location and the expansion chamber number increased by a maximum of 14%, 7% and 13%, respectively. With the proper arrangement of internal ducts, the pressure drop of the silencer with a simple expansion chamber is reduced by 45.2% and its acoustic performance has increased sharply. The maximum drop in passage from 14 dB to about 80-100 dB has been increased and has shown a more uniform behavior
  9. Keywords:
  10. Acoustics ; Environmental Pollutant ; Pressure Loss ; Sound Absorbing Material ; Transmission Loss Allocation ; Muffler

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