Numerical and experimental study on noise shielding effect of eaves/louvers attached on building façade

2015 ◽  
Vol 94 ◽  
pp. 773-784 ◽  
Author(s):  
Shinichi Sakamoto ◽  
Ami Aoki
Keyword(s):  
Experimental Study ◽  
Shielding Effect ◽  
Building Facade ◽  
Noise Shielding

Sound radiation from a cylindrical duct. Part 2. Source modelling, nil-shielding directions, and the open-to-ducted transfer function

1996 ◽  
Vol 313 ◽  
pp. 367-380 ◽  
Author(s):  
C. J. Chapman
Keyword(s):  
Transfer Function ◽  
Good Accuracy ◽  
Shielding Effect ◽  
Front Face ◽  
Main Beam ◽  
Mean Flow ◽  
Sound Fields ◽  
Ducted Fan ◽  
Noise Shielding ◽  
Cylindrical Duct

This paper analyses the sound radiated from the front face of a hard-walled circular cylindrical duct in a subsonic mean flow when the duct contains acoustic sources typical of those in a ducted-fan aeroengine. Two main results are established for modes of any given frequency and circumferential order. The first result is that in certain easily calculated directions, called here the nil-shielding directions, the sound radiated by ducted sources is the same as the sound radiated by the corresponding open sources, i.e. by unducted sources of the same distribution and strength radiating into free space. Thus in these special directions the duct has no noise-shielding effect. The second result is that, in the Kirchhoff approximation, the sound radiated by the open sources in the nil-shielding directions determines the sound radiated by the ducted sources in all directions; i.e. the sound fields radiated by open and ducted sources are related by an open-to-ducted transfer function. This function is such that the sound radiated by the ducted sources is a linear combination of certain diffraction functions, in which the coefficients are given by the sound radiated by the open sources in the nil-shielding directions. The diffraction functions do not depend on the sources and are here calculated explicitly in terms of Bessel functions. The method used in the paper is Kirchhoff's approximation; within linear theory this gives the nil-shielding directions exactly, i.e. in agreement with the Wiener—Hopf solution, and gives the main beam of the radiated field, including the major side-lobes, to good accuracy. The results are relevant to the sound radiated into the forward arc by a ducted turbofan aeroengine.

scholarly journals Experimental Study of Noise Shielding by a NACA 0012 Airfoil

2018 ◽  
Author(s):  
Florence V. Hutcheson ◽  
Christopher J. Bahr ◽  
Russell H. Thomas ◽  
Daniel J. Stead
Keyword(s):  
Experimental Study ◽  
Noise Shielding ◽  
Naca 0012

Experimental study on shielding effect for shielding cable in metallic duct

1989 ◽  
Vol 72 (5) ◽  
pp. 48-57
Author(s):  
Hiroshi Yamane ◽  
Hisaaki Kanamori ◽  
Tsuyoshi Ideguchi ◽  
Tamio Motomitsu
Keyword(s):  
Experimental Study ◽  
Shielding Effect
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