Download or read book Interaction Between Air Flow and Airborne Sound in a Duct Propagation of shock fronts and nonlinearity of porus absorbers written by Fridolin P. Mechel and published by . This book was released on 1967 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interaction Between Air Flow and Airborne Sound in a Duct written by and published by . This book was released on 1967 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interaction Between Air Flow and Airborne Sound in a Duct Volume I Propagation of Shock Fronts and Nonlinearity of Porous Absorbers written by P. A. Mertens and published by . This book was released on 1967 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: The sound propagation in moving air with locally varying flow velocity is investigated by means of shock waves from a spark discharge. To accomplish this, the wave fronts were photographed with a schlieren optics in a flow duct with a large flow boundary layer thickness. Results of these experiments agree with the theories of geometrical acoustics and can be incorporated into the design of ducts having air flow and airborne sound. Also investigated were properties of porous absorbers in the presence of an air flow. Results show a penetration of the absorber by the air flow yields a change of the flow resistance compared with still air. The acoustic flow resistance and the differential static flow resistance are experimentally found to have the same value. Moreover, it is proved that turbulent motions along the surface of the absorber do not affect the flow resistance appreciably. (Author).

Download or read book U S Government Research Development Reports written by and published by . This book was released on 1966-11 with total page 1014 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Annual Index written by and published by . This book was released on 1968 with total page 1592 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1985 with total page 1346 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book U S Government Research and Development Reports Index written by and published by . This book was released on 1968 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Bibliography of Scientific and Industrial Reports written by and published by . This book was released on 1968-07 with total page 1150 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1968 with total page 1130 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book U S Government Research and Development Reports written by and published by . This book was released on 1968-10 with total page 1140 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Announcements written by and published by . This book was released on 1968 with total page 1224 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Government Reports Index written by and published by . This book was released on 1968 with total page 864 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book AMRL TR written by and published by . This book was released on 1967-11 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book AGARD Report written by and published by . This book was released on with total page 804 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Report written by and published by . This book was released on 1965 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Research on Sound Propagation in Sound absorbent Ducts with Superimposed Air Streams written by F. MECHEL and published by . This book was released on 1962 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: The possible effects of flow on airborne sound attenuation in ducts are discussed. The theoretical part results in a simple attenuation formula which considers the following: change of the wavelength due to convection of the sound field, change of the sound pressure at the wall caused by the flow profile, change of the characteristic absorber properties by nonlinear effects, and sound scattering by vortices. With porous absorbers another effect is caused by the different curvature of the phase plane at the boundary of the absorber. Measurements with a porous absorber and with damped Helmholtz resonators show reduction of the attenuation for sound propagation in the direction of the flow and an increase of the attenuation for sound propagation against the flow. With the help of pseudo-sound in flow and of partial waves in ducts with a periodic boundary structure, the sound amplification found in ducts coated with reactive absorbers can be explained by analogy to traveling wave tube amplification phenomena. This analogy was confirmed by measurements on resonant absorbers. (Author).