Download or read book Aerodynamic Sources of Acoustic Resonance in a Duct with Baffles written by Kerry Hourigan and published by . This book was released on 1990 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental and numerical investigations of the generation of resonant sound by flow in a duct containing two sets of baffles and the "feedback" of the sound on the vortex shedding process are reported. The experiments are conducted in a wind tunnel and the numerical simulations are used to predict the sources of resonant sound in the flow. The resonant sound field, which is principally longitudinal, is calculated by the finite element method and a discrete-vortex model is used to predict the observed separated flow. Analysis of the passage of a single point vortex past a baffle indicates that the amount of acoustic energy generated is a function of the phase of the acoustic cycle at which the vortex passes the baffle. A more elaborate model simulates the growth of vortex clouds through the clustering of elemental vortices shed from an upstream baffle, tracks the passage of these vortex clouds past a downstream baffle, predicts the generation of acoustic energy using Howe's theory of aerodynamic sound, and accounts for the feedback of sound on the vortex shedding. Comparison is made between the predicted time-dependent structures and the observed flow structures using smoke visualization. The vortex cloud model predicts the flow conditions under which net acoustic energy is generated by the flow and therefore when resonance can be sustained; the results are consistent with the occurrence of peaks in the observed resonant sound pressure levels.
Download or read book A Study of Resonant cavity and Fiberglass filled Parallel Baffles as Duct Silencers written by Paul T. Soderman and published by . This book was released on 1982 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Acoustical performance and pressure drop were measured for two types of splitters designed to attenuate sound propagating in ducts-resonant-cavity baffles and fiberglass-filled baffles. Arrays of four baffles were evaluated in the 7- by 10-Foot Wind Tunnel Number 1 at Ames Research Center at flow speeds from 0 to 41 m/sec. The baffles were 2.1 m high, 305 to 406 mm thick, and 3.1 to 4.4 m long. Emphasis was on measurements of silencer insertion loss as affected by variations of such parameters as baffle length, baffle thickness, perforated skin geometry, cavity size and shape, cavity damping, wind speed, and acoustic field directivity. An analytical method for predicting silencer performance is described and compared with measurements. Unlike small, single-orifice resonators, the undamped, resonant-cavity baffles attenuated sound over a broad frequency range. With the addition of cavity damping in the form of 25-mm foam linings, the insertion loss above 250Hz of the resonant-cavity baffles was improved 2 to 7dB compared with the undamped baffles; the loss became equal to or greater than the insertion loss of comparable size fiberglass baffles at frequencies above 250Hz. Variations of cavity size and shape showed that a series of cavities with triangular cross-sections (i.e., variable depth) were superior to cavities with rectangular cross sections (i.e., constant depth). In wind, the undamped, resonant-cavity baffles generated loud cavity-resonance tones; the tones could be eliminated by cavity damping. Duct-resonance tones were also generated by configurations that had solid skin over portions of the baffle surfaces. The effects of skin porosity, baffle length, and baffle thickness are documented. (Author).
Download or read book Technical Note written by and published by . This book was released on 1958 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flow induced Vibrations written by and published by . This book was released on 1991 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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Download or read book Proceedings of the Heat Transfer and Fluid Mechanics Institute written by Heat Transfer and Fluid Mechanics Institute and published by . This book was released on 2004 with total page 200 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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Download or read book Inter noise written by and published by . This book was released on 1991 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 4th International Symposium on Fluid Structure Interactions Aeroelasticity Flow Induced Vibration and Noise written by M. P. Paidoussis and published by . This book was released on 1997 with total page 490 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 15th AIAA Aeroacoustics Conference 93 4355 93 4400 written by and published by . This book was released on 1993 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Lecture series written by and published by . This book was released on 2001 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 39th AIAA ASME SAE ASEE Joint Propulsion Conference Exhibit July 20 23 2003 Huntsville Alabama 03 4650 03 4699 written by and published by . This book was released on 2003 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamental Aspects of Fluid structure Interactions written by M. P. Paidoussis and published by American Society of Mechanical Engineers. This book was released on 1992 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 36th Aerospace Sciences Meeting Exhibit written by and published by . This book was released on 1998 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:
