Jet Noise Reduction by Fluidic Injection on a Separate Flow Exhaust System

2007 ◽  
Author(s):  
Seth Harrison ◽  
Ephraim Gutmark ◽  
Steven Martens
Keyword(s):  
Noise Reduction ◽  
Jet Noise ◽  
Exhaust System ◽  
Separate Flow

Study of Jet Noise Reduction on Separated Exhaust System Using Chevron Nozzles

2014 ◽  
Vol 1078 ◽  
pp. 228-234
Author(s):  
Wan Ren Shao ◽  
Xi Hai Xu ◽  
Jing Yu He ◽  
Fei Wu
Keyword(s):  
Noise Reduction ◽  
Jet Noise ◽  
Exhaust System ◽  
Scale Model ◽  
Low Frequencies ◽  
Chevron Nozzles ◽  
Field Noise ◽  
Bypass Ratio ◽  
Computational Predictions ◽  
Noise Spectra

The jet noise reduction of chevron nozzles was investigated on high bypass ratio turbofan engine separated exhaust system using both computational predictions and scale model experiments. Six different exhaust nozzles are designed including one baseline nozzle and five different chevron nozzles. The jet noise experiments were carried out in the anechoic chamber. Tam and Auriault’s jet noise prediction theory and MGBK theory were used to predict the noise spectra of different exhaust nozzles. The results show that the far-field noise spectra as well as the noise reduction benefits of chevrons are predicted correctly by the two theories although some discrepancies occur at the high frequency range, and Tam and Auriault’s jet noise theory can give relatively more accurate prediction results. chevron nozzles reduce jet noise at the low frequencies, but increase it at high frequencies.

Experimental Analysis for Jet Noise Reduction of Chevron Pylon-Based Nozzles

2014 ◽  
Vol 1078 ◽  
pp. 183-186 ◽  
Author(s):  
Jing Yu He ◽  
Ying Bo Xu
Keyword(s):  
Noise Reduction ◽  
Experimental Analysis ◽  
High Frequency ◽  
Sound Pressure ◽  
Low Frequency ◽  
Jet Noise ◽  
Separate Flow ◽  
Frequency Noise ◽  
Chevron Nozzle ◽  
Chevron Nozzles

The experimental analysis is conducted for jet noise reduction of separate flow chevron pylon-based nozzles at takeoff condition. The experimental results indicate that the pylon makes a noise reduction at low-frequency but produces an increase at high-frequency, together with an overall sound pressure reduction below the pylon. Compared to chevron nozzle without pylon, the adding of a pylon reduces noise benefit of chevron nozzles found in the isolated nozzle without a pylon. The best low-frequency noise reduction is located below the pylon where peak noise reduction is as high as about 1.3dB on frequency spectrum.

Effect of Axial Location of Micro Vortex Generators on Supersonic Jet Noise Reduction

2022 ◽  
Author(s):  
Junhui Liu ◽  
Yu Yu Khine ◽  
Mohammad Saleem ◽  
Omar Lopez Rodriguez ◽  
Ephraim J. Gutmark
Keyword(s):  
Noise Reduction ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Vortex Generators ◽  
Supersonic Jet Noise ◽  
Axial Location

Supersonic Jet Noise Reduction Using Micro Vortex Generators

2021 ◽  
Author(s):  
Junhui Liu ◽  
Yu Yu Khine ◽  
Mohammad Saleem ◽  
Omar Lopez Rodriguez ◽  
Ephraim Gutmark
Keyword(s):  
Noise Reduction ◽  
Supersonic Jet ◽  
Jet Noise ◽  
Vortex Generators ◽  
Supersonic Jet Noise

scholarly journals Experimental Study of Pipes Shape Effect on Noise Reduction

2017 ◽  
Vol 5 (1) ◽  
pp. 71-86
Author(s):  
Muna S. Kassim ◽  
Ammar Fadhil Hussein Al-Maliki
Keyword(s):  
Experimental Study ◽  
High Pressure ◽  
Noise Reduction ◽  
Power Plants ◽  
Combustion Engine ◽  
Exhaust System ◽  
Noise Pollution ◽  
Shape Effect ◽  
Pipe Length ◽  
Exhaust Noise

Internal combustion engine is a major source of noise pollution. These engines are used for various purposes such as, in power plants, automobiles, locomotives, and in various manufacturing machineries. The noise is caused by two reasons; the first reason is the pulses which created when the burst of high pressure gas suddenly enters the exhaust system, while the second reason is the friction of various parts of the engine where the exhaust noise is the most dominant. The limitation of the noise caused by the exhaust system is accomplished by the use of silencers and mufflers. The aim of this study is the reduction of the noise by changing its inlet and outlet pipe length and shape. Also the losses in noise for different length and shapes have been investigated experimentally. The results show that the corrugated pipe is preferable for noise reduction.

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