Effects of asymmetric inflow on near-field propeller noise

AIAA Journal ◽  
1996 ◽  
Vol 34 (2) ◽  
pp. 251-258 ◽  
Author(s):  
Johan B. H. M. Schulten
Keyword(s):  
2022 ◽  
Vol 185 ◽  
pp. 108395
Author(s):  
Yan Wu ◽  
Michael J. Kingan ◽  
Ryan S. McKay ◽  
Sung Tyaek Go ◽  
Young-min Shim

Fluids ◽  
2021 ◽  
Vol 6 (8) ◽  
pp. 299
Author(s):  
Roberto Camussi ◽  
Stefano Meloni

Wavelet transform has become a common tool for processing non-stationary signals in many different fields. The present paper reports a review of some applications of wavelet in aeroacoustics with a special emphasis on the analysis of experimental data taken in compressible jets. The focus is on three classes of wavelet-based signal processing procedures: (i) conditional statistics; (ii) acoustic and hydrodynamic pressure separation; (iii) stochastic modeling. The three approaches are applied to an experimental database consisting of pressure time series measured in the near field of a turbulent jet. Future developments and possible generalization to other applications, e.g., airframe or propeller noise, are also discussed.


2013 ◽  
Vol 774-776 ◽  
pp. 82-85
Author(s):  
Chang Run Xiao ◽  
Rui Jie Liu ◽  
Jin Ming Ye

The blade frequency noise of non-cavitation propellers in an non-uniform flow is analyzed in time domain. The unsteady loading (dipole source) on the blade surface is calculated by a potential-based panel method. Through calculation and comparison, the noise attenuation trend of propeller is discussed. The noise decays more quickly in the near field than in the far field. The Attenuation Trend of the Propeller Noise


AIAA Journal ◽  
1985 ◽  
Vol 23 (4) ◽  
pp. 499-504 ◽  
Author(s):  
Donald B. Hanson

Author(s):  
E. Betzig ◽  
A. Harootunian ◽  
M. Isaacson ◽  
A. Lewis

In general, conventional methods of optical imaging are limited in spatial resolution by either the wavelength of the radiation used or by the aberrations of the optical elements. This is true whether one uses a scanning probe or a fixed beam method. The reason for the wavelength limit of resolution is due to the far field methods of producing or detecting the radiation. If one resorts to restricting our probes to the near field optical region, then the possibility exists of obtaining spatial resolutions more than an order of magnitude smaller than the optical wavelength of the radiation used. In this paper, we will describe the principles underlying such "near field" imaging and present some preliminary results from a near field scanning optical microscope (NS0M) that uses visible radiation and is capable of resolutions comparable to an SEM. The advantage of such a technique is the possibility of completely nondestructive imaging in air at spatial resolutions of about 50nm.


2007 ◽  
Author(s):  
Stuart Gregson ◽  
John McCormick ◽  
Clive Parini

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