Jet Noise Characteristics of Unsuppressed Duct Burning Turbofan Exhaust System

1977 ◽  
Vol 14 (3) ◽  
pp. 227-232 ◽  
Author(s):  
A.B. Packman ◽  
H. Kozlowski ◽  
O. Gutierrez
Keyword(s):  
Jet Noise ◽  
Exhaust System ◽  
Noise Characteristics

Connecting high-power jet noise characteristics with human annoyance

2019 ◽  
Vol 146 (4) ◽  
pp. 3042-3042
Author(s):  
Micah Downing ◽  
Michael M. James ◽  
Matt Calton ◽  
Alexandria R. Salton ◽  
Kent L. Gee ◽  
...  
Keyword(s):  
High Power ◽  
Jet Noise ◽  
Noise Characteristics ◽  
Human Annoyance

Connecting high-power jet noise characteristics with human annoyance: Physical characterization

2019 ◽  
Vol 146 (4) ◽  
pp. 3042-3042
Author(s):  
Aaron Vaughn ◽  
Kent L. Gee ◽  
Micah Downing ◽  
Michael M. James ◽  
Matt Calton ◽  
...  
Keyword(s):  
High Power ◽  
Jet Noise ◽  
Physical Characterization ◽  
Noise Characteristics ◽  
Human Annoyance

Experimental Study of Jet Noise Characteristics of Series Connected Nozzles

2005 ◽  
Author(s):  
Qiang Xu
Keyword(s):  
Frequency Spectrum ◽  
Frequency Band ◽  
Low Frequency ◽  
Jet Noise ◽  
Steel Tube ◽  
The Other ◽  
Chamber Pressure ◽  
Band Frequency ◽  
Noise Characteristics ◽  
Frequency Peak

Put abstract text here. A serial of experiments were conducted to study the noise radiated from a series connected nozzle pair. The experiment results are presented in this paper. This nozzle pair consists of two nozzles, one is called source nozzle, and the other is a secondary nozzle. In these experiments, the structure of source nozzle was fixed while that of secondary nozzle was changeable. The source nozzle is mounted on a pressure chamber which is connected to an air compressor. A steel tube is fixed at the tail of source nozzle. The secondary nozzle is connected to the other end of the tube. Throat size of secondary nozzle is larger then that of source nozzle. 15 types of nozzles with different expansion ratio, length of expand segment, and throat structure were used as the secondary nozzle. Jet noise pressure of these nozzle pairs was measured by 40AF Free Field Microphone. The frequency spectrum of jet noise from source nozzle with steel tube under different chamber pressures was calculated. The pressure range is from 0.1 to 1.2 MPa. This result is compared with those spectrums of nozzle pair with different secondary nozzle under different chamber pressures. The trend of peak frequency shifts for different nozzle pair and different chamber pressure is presented in this paper. The secondary nozzles make frequency peak shift from the source nozzle, especially in low frequency band. Different structure of secondary nozzle has different influence on the frequency characteristics of jet noise. Length of expand segment has greater influence on low frequency peak than other two factors. Joint time-frequency analysis is also used in analyze the change of frequency spectrum during throat size decreased under fixed chamber pressure and various spectrograms are also presented. In low frequency band, frequency peak remains during the change of source nozzle throat size. But in higher frequency band, the frequency peak shifts from low frequency to higher ones as the throat size decreases.

scholarly journals Numerical Simulation and Experiment on Impulse Noise in a Small Caliber Rifle with Muzzle Brake

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Xin Yi Zhao ◽  
Ke Dong Zhou ◽  
Lei He ◽  
Ye Lu ◽  
Jia Wang ◽  
...  
Keyword(s):  
Flow Field ◽  
Impulse Noise ◽  
Jet Noise ◽  
Blast Waves ◽  
Jet Flows ◽  
Data Sets ◽  
Negative Effects ◽  
Aeroacoustic Noise ◽  
Noise Characteristics ◽  
Simulation And Experiment

Blast waves generated from the muzzles of weapons may exert negative effects, such as shock waves and impulse noise. If the weapon is fired with a muzzle brake, these effects are recognized to be more severe. This paper discusses the influence of the muzzle brake on certain aeroacoustic noise characteristics based on numerical simulations and a corresponding experiment. The impulse noise, which is induced by complex jet flows discharging from small caliber rifles with muzzle brakes, is focused in this study. Computational fluid dynamics (CFD) and computational aeroacoustics (CAA) are combined to calculate the muzzle flow field and jet noise for cases with and without a muzzle brake, and then the data sets are carefully compared. The simulations indicate that the muzzle brake alters the muzzle flow field and directional distribution of the jet noise compared to a rifle sans muzzle brake. Deviations less than 7.6% between experimental data and simulation results validate the simulation model. The results presented in this paper may provide a workable reference for the prediction of muzzle noise and the optimization of muzzle brake designs.

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.

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