› › Comparison Of Far Field Noise For Three Significantly Different Model Turbofans

Comparison of Far-Field Noise for Three Significantly Different Model Turbofans

Author : National Aeronautics and Space Adm Nasa

Publisher : Independently Published

Page : 26 pages

File Size : 43,50 MB

Release : 2019-01-19

Category : Science

ISBN : 9781794259386

Get eBook

Book Description

Far-field noise sound power level (PWL) spectra and overall sound pressure level (OASPL) directivities were compared for three significantly different model fan stages which were tested in the NASA Glenn 9 15 Low Speed Wind Tunnel. The test fans included the Advanced Ducted Propulsor (ADP) Fan1, the baseline Source Diagnostic Test (SDT) fan, and the Quiet High Speed Fan2 (QHSF2). These fans had design rotor tangential tip speeds from 840 to 1474 ft/s and stage pressure ratios from 1.29 to 1.82. Additional parameters included rotor-stator spacing, stator sweep, and downstream support struts. Acoustic comparison points were selected on the basis of stage thrust. Acoustic results for the low tip speed/low pressure ratio fan (ADP Fan1) were thrust-adjusted to show how a geometrically-scaled version of this fan might compare at the higher design thrust levels of the other two fans. Lowest noise levels were typically observed for ADP Fan1 (which had a radial stator) and for the intermediate tip speed fan (Source Diagnostics Test, SDT, R4 rotor) with a swept stator. Projected noise levels for the ADP fan to the SDT swept stator configuration at design point conditions showed the fans to have similar noise levels. However, it is possible that the ADP fan could be 2 to 3 dB quieter with incorporation of a swept stator. Benefits of a scaled ADP fan include avoidance of multiple pure tones associated with transonic and higher blade tip speeds. Penalties of a larger size ADP fan would include increased nacelle size and drag. Woodward, Richard P. Glenn Research Center NASA/TM--2008-215136, AIAA-2008-0049, E-16299-1



NASA Technical Note

Author :

Publisher :

Page : 688 pages

File Size : 38,60 MB

Release : 1972

Category :

ISBN :

Get eBook

Book Description





Aeroacoustics of Low Mach Number Flows

Author : Stewart Glegg

Publisher : Academic Press

Page : 554 pages

File Size : 31,78 MB

Release : 2017-02-15

Category : Science

ISBN : 0128097930

Get eBook

Book Description

Aeroacoustics of Low Mach Number Flows: Fundamentals, Analysis, and Measurement provides a comprehensive treatment of sound radiation from subsonic flow over moving surfaces, which is the most widespread cause of flow noise in engineering systems. This includes fan noise, rotor noise, wind turbine noise, boundary layer noise, and aircraft noise. Beginning with fluid dynamics, the fundamental equations of aeroacoustics are derived and the key methods of solution are explained, focusing both on the necessary mathematics and physics. Fundamentals of turbulence and turbulent flows, experimental methods and numerous applications are also covered. The book is an ideal source of information on aeroacoustics for researchers and graduate students in engineering, physics, or applied math, as well as for engineers working in this field. Supplementary material for this book is provided by the authors on the website www.aeroacoustics.net. The website provides educational content designed to help students and researchers in understanding some of the principles and applications of aeroacoustics, and includes example problems, data, sample codes, course plans and errata. The website is continuously being reviewed and added to. Explains the key theoretical tools of aeroacoustics, from Lighthill’s analogy to the Ffowcs Williams and Hawkings equation Provides detailed coverage of sound from lifting surfaces, boundary layers, rotating blades, ducted fans and more Presents the fundamentals of sound measurement and aeroacoustic wind tunnel testing



NASA Technical Paper

Author :

Publisher :

Page : 368 pages

File Size : 26,32 MB

Release : 1986

Category : Astronautics

ISBN :

Get eBook

Book Description





Computation of Noise Radiation from Turbofans

Author : National Aeronautics and Space Administration (NASA)

Publisher : Createspace Independent Publishing Platform

Page : 48 pages

File Size : 16,63 MB

Release : 2018-06-30

Category :

ISBN : 9781722116682

Get eBook

Book Description

This report presents the results of a parametric study of the turbofan far-field noise radiation using a finite element technique. Several turbofan noise radiation characteristics of both the inlet and the aft ducts have been examined through the finite element solutions. The predicted far-field principal lobe angle variations with duct Mach number and cut-off ratio compare very well with the available analytical results. The solutions also show that the far-field lobe angle is only a function of cut-off ratio, and nearly independent of the mode number. These results indicate that the finite element codes are well suited for the prediction of noise radiation characteristics of a turbofan. The effects of variations in the aft duct geometry are examined. The ability of the codes to handle ducts with acoustic treatments is also demonstrated. Nallasamy, M. Unspecified Center NAS3-27186; RTOP 538-03-11...



Bibliography of Lewis Research Center Technical Publications Announced in 1977

Author : Lewis Research Center

Publisher :

Page : 356 pages

File Size : 36,31 MB

Release : 1978

Category : Technology

ISBN :

Get eBook

Book Description

This compilation of abstracts describes and indexes over 780 technical reports resulting from the scientific and engineering work performed and managed by the Lewis Research Center in 1977. All the publications were announced in the 1977 issues of STAR (Scientific and Technical Aerospace Reports) and/or IAA (International Aerospace Abstracts). Documents cited include research reports, journal articles, conference presentations, patents and patent applications, and theses.