Overview of Jet Noise Measurement at JAXA

Experiments and numerical analyses were conducted to investigate the reflection and shielding effects of jet noise by a horizontal tail and an aft-mounted engine. An acoustic test using a cold jet at a Mach number of 0.98 was carried out with a 28.8-mm-diameter exhaust nozzle and a T-tail model. The effects of the position and angle of the horizontal tail were investigated using the boundary element method and a fitted jet noise source model. The experimental results showed that the sound pressure level increased by 1.5 dB in the downward direction of the aircraft at a Strouhal number of 0.94. The numerical analysis results showed that the reflection effect was highly dependent on the relative position and size of the horizontal tail, the location of the source, and the angle of the horizontal tail. In addition, the effect of the reflected direction was ascertained to find an appropriate horizontal tail and engine arrangement that reduces noise. It was found that the greatest influence in terms of the effective perceived noise level occurred when the reflected direction was 60°from the jet axis.

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“…Acoustic tests were conducted at the JAXA noise test facility, 11) a schematic of which is shown in Fig. 2.…”

Section: Methodsmentioning

confidence: 99%

Experimental and Numerical Study of Jet Noise Reflection and Shielding Effects by a Horizontal Tail

Akatsuka

Wada

Ishii

2019

Trans. Japan Soc. Aero. S Sci.

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“…Acoustic tests were conducted in the JAXA noise test facility, 14) as shown by the schematic in Fig. 2.…”

Section: Test Methodsmentioning

confidence: 99%

“…Noise test facility at JAXA. 14) the anechoic room is 400 Hz. Acoustic data were sampled at 200 kHz for 10 s through an 80 kHz low-pass filter using a TEAC DS160R data logger.…”

Section: Test Methodsmentioning

confidence: 99%

Comparison of Prediction Methods on Jet Noise Shielding and Reflection Effects

Akatsuka

2019

AEROSPACE TECHNOLOGY JAPAN

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Jet noise is one of the major sources of takeoff and landing noise at airports. The noise is also known to sometimes cause more complicated jet noise-airframe interference problems. Several prediction methods have been proposed to assess this issue in the past. However, the advantages and disadvantages of these methods have not been investigated sufficiently. In this study, three different approaches (i.e., an empirical method, a theoretical method, and an analytical method using the boundary element method) are utilized to predict the effects of a single jet with a horizontal tail. These results are compared with experimental data to clarify the difference. Whereas the results show that none of the three methods can predict noise effects perfectly, we extracted information that can be used as a guideline to choose an appropriate method in the future.

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