Download or read book Suppression of Refraction in Jet Noise by Cooling written by J. T. Kelsall and published by . This book was released on 1975 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Noise generation in an air jet can be described in terms of a convection factor. The velocity gradients in the flow refract the sound, giving rise to a commonly observed final directivity. In the experiments outlined here the effects of convection and refraction on directivity are examined for a jet of very cold air. An attempt is made to determine whether any interdependence between convection and refraction can be detected experimentally in narrow band jet noise data. In the reported investigation liquid nitrogen was used to cool a jet of air (at nozzle speeds 0.21 to 0.28 of ambient sound speed) down to temperatures (between -110C and -155C) at which the refraction from the opposed velocity and temperature gradients produced cancellation effects.

Download or read book UTIAS Technical Note written by and published by . This book was released on 1975 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aircraft System One Sixth Scale Model Studies Coanda Refraction Noise Suppression Concept Advanced Development written by R. E. Ballard and published by . This book was released on 1976 with total page 125 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proven Coanda/refraction concept is applied to the Navy requirement for effective exhaust noise suppression of aircraft (installed engines) ground run up tests. The technical approach is comprised of analytic studies and one-sixth scale model tests using simulated sources for single and twin-engine aircraft. The results of previous exploratory studies, using simulated static sources, are applied to the more complex situation with the engine tailpipe centerline displaced horizontally, vertically, longitudinally and angularly from the model suppressor inlet. Test runs at varied simulated engine power settings and varied model geometric orientations were conducted to determine the effects on jet attachment to the Coanda surface and on cooling air eduction. The extensive recorded test data were analyzed to identify aero/ thermodynamic trends related to suppressor internal components, ejector geometry and material cooling properties. Results present operational limits and configurations for further development as exhaust systems for aircraft test enclosures and aircraft run up suppressors.

Download or read book Jet Engine Demountable Test Cell Exhaust System Phase Coanda Refraction Noise Suppression Concept Advanced Development written by R. E. Ballard and published by . This book was released on 1979 with total page 91 pages. Available in PDF, EPUB and Kindle. Book excerpt: The successfully demonstrated Coanda/refraction air-cooled exhaust noise suppressor system is applied to the Navy requirement for effective exhaust noise suppression in jet engine demountable test cells. The technical approach consists of analytical studies and one-sixth scale model tests using simulated afterburning engine exhaust. Revisions are made to the previously developed system to improve noise suppression capability while reducing the system overall size and initial cost. Revisions include moving secondary air inlets to reduce enclosure size and improve cooling, shortening the Coanda surface to provide more acoustically treated exhaust stack and providing variations in exhaust stack configuration such as single and dual acoustic splitters and acoustic wedges up the back wall. Extensive data were recorded and analyzed to identify the aerothermodynamic and acoustic trends related to these configuration changes. Results present recommendations for an air-cooled Coanda/refraction exhaust system for application to demountable test cells. (Author).

Download or read book Jet Engine Class C Test Cell Exhaust System Phase Coanda Refraction Noise Suppression Concept Advanced Development written by R. E. Ballard and published by . This book was released on 1979 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: The successfully demonstrated Coanda/refraction air-cooled exhaust noise suppressor system is applied to the Navy requirement for an effective air-cooled retrofit configuration for the class 'C' test cells (concrete enclosure). The technical approach consists of analytically sizing retrofit components to meet both acoustic ad aerothermodynamic requirements and then testing at one-sixth scale using simulated afterburning engine exhaust to verify the design configuration. Model variations included exhaust stack height, exhaust stack inner flow passage configurations (straight walls and diffuser) and removal of a concrete internal partition wall. Extensive data were recorded and analyzed to identify the aerothermodynamic trends related to these configuration changes. Results present recommendations for an air-cooled Coanda exhaust noise suppression system for retrofit of Navy class 'C' test cells. (Author).

Download or read book R D Abstracts written by Technology Reports Centre (Great Britain) and published by . This book was released on 1978 with total page 460 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 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2013-11-21 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and dis seminated by the Center for lnformation and Numerica/ Data Analysis and Synthesis (C/NDAS) * at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the ac tivity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficia! to the academic and general scientific and technical community. After fi ve years of this joint undertaking we had concluded that it was in the interest of ali concerned if the printing and distribution of the volume were handled by an international publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and App/ied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. Ali back issues can also be ordered from Plenum. We have reported in Volume 21 (thesis year 1976) a total of 10,586 theses titles from 25 Canadian and 219 United States universities. We are sure that this broader base for theses titles reported will greatly enhance the value of this important annual reference work.

Download or read book NASA SP written by and published by . This book was released on 1990 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Refraction of Sound by Jet Flow and Jet Temperature Ii written by E. Grande and published by . This book was released on 1966 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The refraction of the sound field of an omnidirectional pure tone 'point' source of sound by the temperature and velocity fields of a 3/4 inch air or nitrogen jet was measured. Several source positions were employed: one within the potential core, others entirely outside the jet. For the source in the on-axis position, the air jet velocity was varied between M = 0.5 and 0.95 at fixed source frequency and ambient jet temperature, yielding a characteristic axial refraction valley, e.g., -35dB at M = 0.95 and 3000 c.p.s. Similar, but asymmetric patterns were obtained with the source outside the jet. Using a very cold nitrogen jet (T = -180C), the sound was found to be refracted inward - a focusing effect - to yield an intensity lobe along the jet axis; e.g. +26dB at M = 0.11 and 7000 c.p.s. For both the cold jet and the ambient jet the ordinary jet noise was measured in narrow filter bands: the respective polar plots exhibited the same general shape near the axis as those for the injected pure tones. The filtered jet noise polar plots were also 'corrected' for refraction (using the pure-tone patterns) and for convection (via theory) to yield the approximate 'basic directivity' of the eddy sources: the polar patterns resemble ellipses of low eccentricity, rather unlike Lighthill's four-leaf-clover. (Author).

Download or read book Technical Abstract Bulletin written by and published by . This book was released on 1979 with total page 1186 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 1975 with total page 408 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aeronautical Engineering written by and published by . This book was released on 1984 with total page 446 pages. Available in PDF, EPUB and Kindle. Book excerpt: A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA).

Download or read book Paper written by and published by . This book was released on 1980 with total page 1016 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Federal Aircraft Noise Abatement Plan written by and published by . This book was released on 1969 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Aeronautical Journal written by and published by . This book was released on 1976 with total page 326 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 1975-09-05 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt: