Download or read book Prediction of Jet Noise Shielding with Forward Flight Effects written by Salvador Mayoral and published by . This book was released on 2013 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: Aircraft noise continues to be a major concern among airport-neighboring communities. A strong component of aircraft noise is the jet noise that is generated from the turbulent mixing between the jet exhaust and ambient medium. The hybrid wing body aircraft suppresses jet noise by mounting the engines over-the-wing so that the airframe may shield ground observers from jet noise sources. Subscale jet noise shielding measurements of a scaled-down turbofan nozzle and a model of the hybrid wing body planform are taken with two 12-microphone polar arrays. Chevrons and wedge-type fan flow deflectors are integrated into the baseline bypass ratio 10 (BPR10) nozzle to modify the mean flow and alter the noise source behavior. Acoustic results indicate that the baseline BPR10 nozzle produces a long noise source region that the airframe has difficulty shielding, even when the nozzle is translated two fan diameters upstream of its nominal position. The integration of either chevrons or fan flow deflectors into the nozzle is essential for jet noise shielding because they translate peak intensities upstream, closer to the fan exit plane. The numerical counterpart of this study transforms the system of equations governing the acoustic diffraction with forward flight into the wave equation. Two forward flight formulations are considered: uniform flow over slender body; and non-uniform potential flow at low Mach number. The wave equation is solved numerically in the frequency domain using the boundary element method. The equivalent jet noise source is modeled using the combination of a wavepacket and a monopole. The wavepacket is parameterized using the experimental far-field acoustic autospectra of the BPR10 jets and knowledge of their peak noise locations. It is shown that the noise source compacts with increasing Mach number and consequently there is an increase in shielding. An assessment of the error associated with the non-uniform formulation for forward flight shows that the error is low for Mach numbers less than or equal to 0.2, but can be on the same scale as the acoustic scatter field when the Mach number is 0.6.

Download or read book Some Comments on the Prediction of Forward Flight Effects on Jet Noise written by Frank Obermeier and published by . This book was released on 1981 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Improved Method for Predicting the Effects of Flight on Jet Mixing Noise written by and published by . This book was released on 1979 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Technical Memorandum written by and published by . This book was released on 1982 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Jet shielding of jet noise written by John Charles Simonich and published by . This book was released on 1986 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Near field Noise Prediction for Aircraft in Cruising Flight Methods Manual written by and published by . This book was released on 1979 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Comparison of Foward Flight Effects Theory of A Michalke and U Michel with Measured Data written by John W. Rawls and published by . This book was released on 1983 with total page 64 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 1995 with total page 602 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Download or read book Aeroacoustics of Flight Vehicles written by Harvey H. Hubbard and published by . This book was released on 1991 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Conference Publication written by and published by . This book was released on 1980 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Velocity Jet Noise Source Location and Reduction written by and published by . This book was released on 1977 with total page 582 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Reference Publication written by and published by . This book was released on 1991 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aeroacoustics of Flight Vehicles written by Harvey H. Hubbard and published by . This book was released on 1991 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 High Velocity Jet Noise Source Location and Reduction written by and published by . This book was released on 1977 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Technical Paper written by and published by . This book was released on 1991 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book NASA Scientific and Technical Publications written by and published by . This book was released on 1987 with total page 410 pages. Available in PDF, EPUB and Kindle. Book excerpt: