Journal of KSNVE (소음진동)

The Korean Society for Noise and Vibration Engineering (한국소음진동공학회)
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Au Experimental Study on the Aerodynamic Noise by a Circular Jet Impinging on a Plate

평판에 충돌하는 원형분류의 공력소음에 관한 실험적 연구

  • 이동훈 (서울산업대학교, 기계공학과) ;
  • 권영필 (숭실대학교공과대학기계공학과) ;
  • 한희갑 (숭실대학교 대학원, 기계공학과)
  • Published : 1997.02.01
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Abstract

The objective of this study is to investigate experimentally the effect of surface conditions of the plate on the impinging jet noise. The experimental results about the spectrum, the sound pressure level and the directivity are pressented and discussed in relation with the surface conditions. Regardless of the surface conditions, the pure tones of high level are generated at the same frequency band and the overall sound power level of impinging jets is much higher than that of the free jet. However, the velocity dependence of the sound pressure level and the directivity are different between smooth surfaces and rough surfaces. The dependence of sound pressure level on the jet velocity shows that the smooth surface generates quadrupole-type sound like free jets. However, the perforated or the rough surface radiates sound power exactly proportional to the sixth power of the jet velocity, indicating that the source is fixed dipole type. The directivities of 1/3 octave band sound pressure level for both the free and impinging jet show the peak directivity at 115$^\circ$ upstream, probably due to the refraction associated with velocity gradient.

Keywords

References

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