Predicting far-field broadband noise levels from in-duct phased array measurements

2014 ◽  
Author(s):  
Brian J. Tester ◽  
Yusuf Özyörük
Keyword(s):  
Phased Array ◽  
Broadband Noise ◽  
Far Field ◽  
Noise Levels ◽  
Array Measurements

scholarly journals Digital Predistortion of Phased-Array Transmitter With Shared Feedback and Far-Field Calibration

2021 ◽  
Vol 69 (1) ◽  
pp. 1000-1015
Author(s):  
Nuutti Tervo ◽  
Bilal Khan ◽  
Olli Kursu ◽  
Janne P. Aikio ◽  
Markku Jokinen ◽  
...  
Keyword(s):  
Phased Array ◽  
Far Field ◽  
Digital Predistortion ◽  
Field Calibration

Wake-Airfoil Interaction as Broadband Noise Source: A Large-Eddy Simulation Study

2005 ◽  
Vol 4 (1-2) ◽  
pp. 93-115 ◽  
Author(s):  
Jérôme Boudet ◽  
Nathalie Grosjean ◽  
Marc C. Jacob
Keyword(s):  
Large Eddy Simulation ◽  
Particle Image ◽  
Broadband Noise ◽  
Far Field ◽  
Acoustic Analogy ◽  
Eddy Simulation ◽  
Naca0012 Airfoil ◽  
Image Velocimetry ◽  
Large Eddy ◽  
Proper Orthogonal

A large-eddy simulation is carried out on a rod-airfoil configuration and compared to an accompanying experiment as well as to a RANS computation. A NACA0012 airfoil (chord c = 0.1 m) is located one chord downstream of a circular rod (diameter d = c/10, Red = 48 000). The computed interaction of the resulting sub-critical vortex street with the airfoil is assessed using averaged quantities, aerodynamic spectra and proper orthogonal decomposition (POD) of the instantaneous flow fields. Snapshots of the flow field are compared to particle image velocimetry (PIV) data. The acoustic far field is predicted using the Ffowcs Williams & Hawkings acoustic analogy, and compared to the experimental far field spectra. The large-eddy simulation is shown to accurately represent the deterministic pattern of the vortex shedding that is described by POD modes 1 & 2 and the resulting tonal noise also compares favourably to measurements. Furthermore higher order POD modes that are found in the PIV data are well predicted by the computation. The broadband content of the aerodynamic and the acoustic fields is consequently well predicted over a large range of frequencies ([0 kHz; 10 kHz]).

scholarly journals Jet-Surface Interaction Test: Phased Array Noise Source Localization Results

2012 ◽  
Author(s):  
Gary G. Podboy
Keyword(s):  
Source Localization ◽  
Phased Array ◽  
Noise Source ◽  
Jet Noise ◽  
Companion Paper ◽  
Far Field ◽  
Sound Waves ◽  
Axial Distribution ◽  
Noise Sources ◽  
Interaction Test

An experiment was conducted to investigate the effect that a planar surface located near a jet flow has on the noise radiated to the far-field. Two different configurations were tested: 1) a shielding configuration in which the surface was located between the jet and the far-field microphones, and 2) a reflecting configuration in which the surface was mounted on the opposite side of the jet, and thus the jet noise was free to reflect off the surface toward the microphones. Both conventional far-field microphone and phased array noise source localization measurements were obtained. This paper discusses phased array results, while a companion paper discusses far-field results. The phased array data show that the axial distribution of noise sources in a jet can vary greatly depending on the jet operating condition and suggests that it would first be necessary to know or be able to predict this distribution in order to be able to predict the amount of noise reduction to expect from a given shielding configuration. The data obtained on both subsonic and supersonic jets show that the noise sources associated with a given frequency of noise tend to move downstream, and therefore, would become more difficult to shield, as jet Mach number increases. The noise source localization data obtained on cold, shock-containing jets suggests that the constructive interference of sound waves that produces noise at a given frequency within a broadband shock noise hump comes primarily from a small number of shocks, rather than from all the shocks at the same time. The reflecting configuration data illustrates that the law of reflection must be satisfied in order for jet noise to reflect off of a surface to an observer, and depending on the relative locations of the jet, the surface, and the observer, only some of the jet noise sources may satisfy this requirement.

Aerofoil Surface Pressure Reconstruction from Far-Field Array Measurements

2018 ◽  
Author(s):  
Fabio Casagrande Hirono ◽  
Phillip Joseph ◽  
Filippo Maria Fazi
Keyword(s):  
Surface Pressure ◽  
Far Field ◽  
Array Measurements

Aeroacoustic Analysis of an Unmanned Aerial Vehicle

2007 ◽  
Author(s):  
Peter D. Lysak ◽  
James J. Dreyer ◽  
John B. Fahnline ◽  
Dean E. Capone ◽  
John E. Poremba
Keyword(s):  
Unmanned Aerial Vehicle ◽  
Acoustic Analysis ◽  
Three Dimensional ◽  
Broadband Noise ◽  
Frequency Noise ◽  
Noise Levels ◽  
Boundary Layer Turbulence ◽  
Ducted Fan ◽  
Inflow Turbulence ◽  
Aerial Vehicle

An acoustic analysis of a ducted fan unmanned aerial vehicle (UAV) was conducted to identify the primary aeroacoustic sources and to determine the potential for reducing the radiated noise levels. Computational fluid dynamics was used to determine the three-dimensional flow field through the ducted fan in hover and maneuvering configurations. The flow solutions provided information about the blade relative velocities, spatially non-uniform inflow, inflow turbulence, boundary layer turbulence, and blade wake velocity deficits for use in acoustical models of broadband and blade passing frequency noise. The computational results were in good agreement with experimentally measured noise levels, and showed that the tonal noise was produced primarily by unsteady forces resulting from the non-uniform inflow, while the broadband noise resulted from the inflow turbulence. Based on these findings, design modifications were recommended which offer the potential to reduce the noise by more than 10 dB.

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