An experimental study on porous plug jet noise suppressor

1979 ◽  
Author(s):  
L. MAESTRELLO
Keyword(s):  
Experimental Study ◽  
Jet Noise ◽  
Porous Plug

Experimental Study of the Effects of Jet Noise on an Aircraft Structure

1957 ◽  
Vol 61 (554) ◽  
pp. 112-114
Author(s):  
K. W. Hetzel
Keyword(s):  
Experimental Study ◽  
Jet Noise ◽  
Aircraft Structure ◽  
Noise Effects ◽  
Noise Damage

Reports of noise effects on the rear fuselage structure of large British aircraft indicated that one might expect noise damage in this region on the Vickers Supermarine Type 544 aircraft. It will be seen from Fig. 1 that the jet efflux from each engine passes close to the fuselage side and under the tailplane. The fuselage structure proper is, however, protected from the heat and noise effects at the jet efflux by a fairing which is insulated at all attachments. This fairing, by virtue of its shape, is called the “ pen nib. ”

LETTER TO THE EDITOR: AN EXPERIMENTAL STUDY OF UNDEREXPANDED SQUARE JET NOISE

1996 ◽  
Vol 197 (2) ◽  
pp. 255-261 ◽  
Author(s):  
M. Brassard ◽  
R.-H. Chen ◽  
L. Chew
Keyword(s):  
Experimental Study ◽  
Jet Noise ◽  
Letter To The Editor

Experimental Study on a Notched Nozzle for Jet Noise Reduction

2011 ◽  
Author(s):  
T. Ishii ◽  
H. Oinuma ◽  
K. Nagai ◽  
N. Tanaka ◽  
Y. Oba ◽  
...  
Keyword(s):  
Experimental Study ◽  
Noise Reduction ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Mixing Layer ◽  
Jet Noise ◽  
Computational Prediction ◽  
Pressure Level ◽  
Far Field ◽  
Noise Sources

This paper describes an experimental study on a notched nozzle for jet noise reduction. The notch, a tiny tetrahedral dent formed at the edge of a nozzle, is expected to enhance mixing within a limited region downstream of the nozzle. The enhanced mixing leads to the suppression of broadband peak components of jet noise with little effect on the engine performance. To investigate the noise reduction performances of a six-notch nozzle, a series of experiments have been performed at an outdoor test site. Tests on the engine include acoustic measurement in the far field to evaluate the noise reduction level with and without the notched nozzle, and pressure measurement near the jet plume to obtain information on noise sources. The far-field measurement indicated the noise reduction by as much as 3 dB in terms of overall sound pressure level in the rear direction of the engine. The use of the six-notch nozzle though decreased the noise-benefit in the side direction. Experimental data indicate that the high-frequency components deteriorate the noise reduction performance at wider angles of radiation. Although the increase in noise is partly because of the increase in velocity, the penetration of the notches into the jet plume is attributed to the increase in sound pressure level in higher frequencies. The results of near-field measurement suggest that an additional sound source appears up to x/D = 4 due to the notches. In addition, the total pressure maps downstream of the nozzle edge, obtained using a pressure rake, show that the notched nozzle deforms the shape of the mixing layer, causing it to become wavy within a limited distance from the nozzle. This deformation of the mixing layer implies strong vortex shedding and thus additional noise sources. To improve the noise characteristics, we proposed a revised version of the nozzle on the basis of a computational prediction, which contained 18 notches that were smaller than those in the 6-notched nozzle. Ongoing tests indicate greater noise reduction in agreement with the computational prediction.

Experimental Study of the Properties of Near-Field and Far-Field Jet Noise

2006 ◽  
Author(s):  
Sébastien Barré ◽  
Vincent Fleury ◽  
Christophe Bogey ◽  
Christophe Bailly ◽  
Daniel Juve
Keyword(s):  
Experimental Study ◽  
Near Field ◽  
Jet Noise ◽  
Far Field

Experimental Study of Supersonic Jet Noise Reduction With Microjet Injection

2009 ◽  
Author(s):  
Toshinori Watanabe ◽  
Ryuichi Okada ◽  
Seiji Uzawa ◽  
Takehiro Himeno ◽  
Tsutomu Oishi
Keyword(s):  
Experimental Study ◽  
Turbulent Mixing ◽  
Sound Pressure ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Pressure Level ◽  
Broadband Noise ◽  
Screech Tone ◽  
Supersonic Jet Noise ◽  
Mixing Noise

Experimental study was conducted concerning active control of supersonic jet noise with a microjet injection technique. The microjets were injected into a rectangular main jet with Mach number up to 1.49. The nozzle lip of the main jet was equipped with 44 injection holes of the microjets, whose angles against the main jet were changed as 60 and 90 degrees. From far-field sound pressure data, a significant reduction of the jet noise by several dB was found in the cases with 60 and 90 degrees of injection angles. The microjet was found to affect all components of supersonic jet noise, namely, turbulent mixing noise, shock-associated broadband noise and screech tone noise. In the results of FFT analysis, the effect of the microjet was observed in the sound pressure level of the shock-associated broadband noise, the pressure level and frequency of the screech tone noise, and average level of the turbulent mixing noise. Schlieren visualization was also made for the jet flow, and the microjet was seen to change the shock structure and shear layer behavior of the supersonic jet.

scholarly journals Experimental Study of the Spectral Properties of Near-Field and Far-Field Jet Noise

2007 ◽  
Vol 6 (2) ◽  
pp. 73-92 ◽  
Author(s):  
Christophe Bogey ◽  
Sébastien Barré ◽  
Vincent Fleury ◽  
Christophe Bailly ◽  
Daniel Juvé
Keyword(s):  
Experimental Study ◽  
Spectral Properties ◽  
Near Field ◽  
Jet Noise ◽  
Far Field
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