Experimental Study on the Performance of Sudden Expansion Silencer with Inner Baffle-Wall and Connnecting Duct

• Main Authors: You, Chuan-bei, 游川倍
• Other Authors: Kau Cheng-Hsiung
• Format: Others
• Language: zh-TW
• Published: 1998
• Online Access: http://ndltd.ncl.edu.tw/handle/88445846136011392701

碩士 === 國立中興大學 === 機械工程學系 === 86 === This study investigates the performance of sudden expansion silencer with internal baffle-wall and connecting duct in relation to some design parameters. Such parameters are the length and the asymmetry of input and output ducts, the length and height of the connecting duct as well as the porosity ratio. The inflow frequency ranges from 10Hz to 120Hz. The evaluation is based on the magnitude of pressure variation within and sound level measurement downstream of the silencer . Frequency responses of both pressure variation and the sound level are coincident for frequency lower than 100Hz. However, deviation arises for frequency higher than 100Hz because of the presence of small scale eddy in the exhaust jet. Large porosity ratio can eliminates the noise level at low frequency range. Noise reduction is significant while the internal baffle-wall is inserted. Besides, the longer the connecting duct, the more reduction of the sound level. The height of the connecting duct determines the passage of energy at lower frequency. Thus, small height of the connecting duct can reduce effectively the sound level at low frequency range, and vice versa. Furthermore, longer inlet duct can increase the sound level at frequency higher than 100Hz. On the other hand, the longer outlet duct will decrease the resonant frequency of the flow tone inside the silencer. In the limiting case of no tail duct, the resonant frequency locates beyond 120Hz and the sound level is high within 00z In gnraly, h betperormne o nis reutio ca e atane ifthe veticl bfle-al i intlle isie teasymeti siener Beies, smaller eghtofth conctig uc an uitblelngt o te ilt ad utet ducts cn hlp olocteth reoantfreuncyofth flwton inie tesilencer Hihporsiy ati an lsob faoabl torduc te oun eve atlow frquecyrage.Keyword: suden xpnson iencr、aflewal Bconctig duc、orsit ati