Experimental Investigation on Supersonic Jet Noise

A systematic study has been undertaken to quantify the effects of jet Mach number and nozzle size on the noise radiated by supersonic jets. All the tests were carried out at an experimental bench of the supersonic jet. Results indicate that the field distribution of supersonic jet screech tones is characterized with very strong directivity. Under the textual experimental conditions, if the jet Mach number remain unchanged, the diameter of nozzle throat increases gradually from 5mm to 8mm or 10mm, and the amplitude values of both the turbulent mixing noise and broadband shockwave correlated noise increase by 2-5dB, and the amplitude value change of the whistler type noise is not obvious, and the occurrence frequency of the whistler type noise decreases by more than 2000Hz; if the jet Mach number increases to 3.0 from 2.0, the amplitude value of the whistler type noise increases by more than 2dB, and the occurrence frequency of the whistler type noise decreases obviously. The experimental measurements of supersonic jet noise provide the sound production mechanism research on the supersonic jet noise with data supports and references and provide the numerical modeling of the supersonic jet noise with validation criteria.

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Experimental Investigation on Supersonic Jet Screech Tones

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.232.213 ◽

2012 ◽

Vol 232 ◽

pp. 213-217

Author(s):

Jia Ming Li ◽

Chun Bo Hu ◽

Jun Hua Bai

Keyword(s):

Mach Number ◽

Field Distribution ◽

Experimental Measurement ◽

Supersonic Jet ◽

Jet Noise ◽

Occurrence Frequency ◽

Supersonic Jet Noise ◽

Nozzle Size ◽

Screech Tones ◽

Peak Value

In order to investigate the characteristic of the supersonic jet screech tones, an experimental bench of the supersonic jet was designed and a free field noise signal acquisition system was established. Effects of the nozzle size and jet Mach number on jet noise sound field distribution was analyzed, through the result comparison of supersonic jet noise experimental measurement. Results indicate that the field distribution of supersonic jet screech tones is characterized with very strong directivity. Peak value of the screech tones decrease and occurrence frequency of the screech tones increase with the decreasing jet exit Mach number; occurrence frequency of the screech tones decrease with the increasing nozzle size, but the peak value change very less. The experimental measurement of supersonic jet noise provides mechanism research of sound production with data supports and references; and also provides the numerical modeling of supersonic jet noise with validation criteria.

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Physics and Prediction of Supersonic Jet Noise

Applied Mechanics Reviews ◽

10.1115/1.3124402 ◽

1994 ◽

Vol 47 (6S) ◽

pp. S184-S187

Author(s):

Christopher K. W. Tam

Keyword(s):

Supersonic Jet ◽

Jet Noise ◽

Supersonic Jets ◽

Wave Radiation ◽

Instability Wave ◽

Empirical Constant ◽

Supersonic Jet Noise ◽

Turbulence Structures ◽

Mixing Noise ◽

Dominant Part

Both the large turbulence structures and the fine scale turbulence of the flows of supersonic jets are sources of turbulent mixing noise. At moderately high supersonic Mach numbers especially for hot jets, the dominant part of the noise is generated directly by the large turbulence structures. The large turbulence structures propagate downstream at supersonic velocities relative to the ambient sound speed. They generate strong Mach wave radiation analogous to a supersonically travelling wavy wall. A stochastic instability wave model theory of the large turbulence structures and noise of supersonic jets has recently been developed. The theory can predict both the spectrum and directivity of the dominant part of supersonic jet noise up to a multiplicative empirical constant. Calculated results agree well with measurements.

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Experimental Study of Supersonic Jet Noise Reduction With Microjet Injection

Volume 7: Turbomachinery, Parts A and B ◽

10.1115/gt2009-59436 ◽

2009 ◽

Cited By ~ 2

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.

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