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dc.contributor.advisorCarneal, James P.en_US
dc.contributor.advisorJohnson, Marty E.en_US
dc.contributor.advisorFuller, Chris R.en_US
dc.contributor.authorSacarcelik, Ozeren_US
dc.date.accessioned2011-08-06T16:01:37Z
dc.date.available2011-08-06T16:01:37Z
dc.date.issued2004-05-05en_US
dc.identifier.otheretd-05242004-160125en_US
dc.identifier.urihttp://hdl.handle.net/10919/9950
dc.description.abstractThe work presented in this thesis can be divided into two main subjects. First, lightweight designs for acoustic devices such as Helmholtz resonators and loudspeakers used for noise control in rocket payload compartments are developed. Second, active control using a hybrid control system (with structural and acoustic actuators) was tested experimentally. Due to the weight limitations for this application, Helmholtz resonators and loudspeakers are re-designed in order to reduce the device weight as much as possible while maintaining performance. For Helmholtz resonators, this is done by modeling the resonator for different structural shapes, wall materials and wall thicknesses using a finite element analysis software. The final design is then compared to the rigid resonators and is shown to perform effectively. These designs are then successfully applied to the full-scale fairing at Boeing facilities. In order to design a lightweight loudspeaker, a comparative approach was used. A standard 12" loudspeaker is taken as the reference loudspeaker and weight reduction solutions are applied to it while maintaining performance. The loudspeaker is characterized using mechanical, electrical and acoustical theories, and an optimization process is applied in order to minimize a defined cost function, which was taken as the total sound pressure output over a targeted frequency range per mass of the actuator. The results are used to build a lightweight loudspeaker together with a lightweight box, and the new designs are tested for comparison with the reference loudspeaker and shown to increase performance by 1.7 dB over 60-200 Hz band while reducing the mass by 78%. The second part of this thesis investigates the performance of a hybrid active control treatment featuring distributed vibration absorbers (DAVAs) and loudspeakers applied on a scale payload fairing. Several aspects such as causality, reference signals, and maximum controllable levels of this feedforward control scheme are the subjects of analyses. The results show that this active control approach can achieve significant amount of interior noise attenuation, and the total actuator weight required to control an external level of 138 dB can be reduced to 9.2kg using lightweight loudspeakers. However, it is shown that the attenuation levels can still be improved further by actuator positioning that gives more effective coupling of the actuators with the structural and acoustic modes and by using multiple references for the control system.en_US
dc.format.mediumETDen_US
dc.publisherVirginia Techen_US
dc.relation.haspartOzerSacarcelik_thesis_revised.pdfen_US
dc.rightsThe authors of the theses and dissertations are the copyright owners. Virginia Tech's Digital Library and Archives has their permission to store and provide access to these works.en_US
dc.source.urihttp://scholar.lib.vt.edu/theses/available/etd-05242004-160125en_US
dc.subjectactive noise controlen_US
dc.subjectloudspeakeren_US
dc.subjectHelmholtz resonatoren_US
dc.titleAcoustic Devices for the Active & Passive Control of Sound in a Payload Compartmenten_US
dc.typeThesisen_US
dc.contributor.departmentMechanical Engineeringen_US
dc.description.degreeMSen_US


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