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Transmission loss of silencers with flow from a flow-impedance tube using burst signals

Kim, Hyunsu
http://rave.ohiolink.edu/etdc/view?acc_num=osu1320338533

Abstract Details

2011, Doctor of Philosophy, Ohio State University, Mechanical Engineering.
Acoustic performance of silencers is typically characterized by transmission loss both in the absence and presence of mean flow. The effects of flow on the acoustic characteristics of silencers, however, are not clearly established due to lack of appropriate experimental setups. In addressing this need, the present study develops a flow-impedance tube setup using burst signals for the transmission loss measurement in the presence of flow. By incorporating burst-signal separation with a long tube, an anechoic termination on the downstream side is achieved by separating the transmitted and reflected waves in time domain. Burst sine or burst random is used to enhance the signal-to-noise ratio. By applying wave decomposition in frequency domain on the upstream side, incident waves of the burst signals are effectively obtained. Also discussed in this study are (1) microphone calibration, (2) time domain editing functions, and (3) hydraulic losses either to improve the accuracy or the capacity of the transmission loss setup in the presence of flow. Using the new experimental setup, the effect of flow on various silencers is investigated. The acoustic performance of a Helmholtz resonator is shown to change dramatically in the presence of flow with an increase in the peak transmission loss frequency and a decrease in the magnitude. These varying acoustic characteristics of the Helmholtz resonator with flow are then explained using the lumped parameter model. Complex acoustic behavior of a dual Helmholtz resonator, a turbocharger resonator, and a Helmholtz resonator with leakage are also illustrated first without flow theoretically. The flow effect is then examined on these silencers as well as some additional key silencers such as expansion chamber, perforated tube silencers, and dissipative silencers using the flow-impedance tube setup. Hence, the primary contributions of the present study include (1) the development of methodologies for the transmission loss measurement in the presence of flow by implementing a flow-impedance tube setup and (2) the investigation of the acoustic performance of various silencers subject to flow, thereby establishing the impact of flow on their behavior which, in turn, is expected to provide guidelines toward their design.
Ahmet Selamet (Advisor)
Rajendra Singh (Committee Member)
Ahmet Kahraman (Committee Member)
Junmin Wang (Committee Member)
191 p.
Mechanical Engineering
Transmission loss; flow; Helmholtz resonator

Recommended Citations

Citations

  • Kim, H. (2011). Transmission loss of silencers with flow from a flow-impedance tube using burst signals [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1320338533

    APA Style (7th edition)

  • Kim, Hyunsu. Transmission loss of silencers with flow from a flow-impedance tube using burst signals. 2011. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1320338533.

    MLA Style (8th edition)

  • Kim, Hyunsu. "Transmission loss of silencers with flow from a flow-impedance tube using burst signals." Doctoral dissertation, Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1320338533

    Chicago Manual of Style (17th edition)

osu1320338533
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© 2011, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.