• Search Research Projects
  • Search Researchers
  • How to Use
  1. Back to previous page

Study on the effect of the boundary layer on the generation of aerodynamic noise and its control method.

Research Project

Project/Area Number 09450084
Research Category

Grant-in-Aid for Scientific Research (B)

Allocation TypeSingle-year Grants
Section一般
Research Field Fluid engineering
Research InstitutionNIHON UNIVERSITY

Principal Investigator

FUJITA Hajime  College of Science and Technology, NIHON UNIVERSITY, Professor, 理工学部, 教授 (40251673)

Co-Investigator(Kenkyū-buntansha) ZENDO Yasuo  Environmental Engineering Division, Railroad Technical Research Institute, Section Head, 環境工学研究部, 研究室長
SAGAWA Akio  Environmental Engineering Division, Railroad Technical Research Institute, Section Head, 環境工学研究部, 研究室長
佐川 明郎  鉄道総合技術研究所, 環境防災技術開発推進部, 主幹技師
Project Period (FY) 1997 – 1999
Project Status Completed (Fiscal Year 1999)
Budget Amount *help
¥13,500,000 (Direct Cost: ¥13,500,000)
Fiscal Year 1999: ¥2,800,000 (Direct Cost: ¥2,800,000)
Fiscal Year 1998: ¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 1997: ¥6,700,000 (Direct Cost: ¥6,700,000)
KeywordsAerodynamics Noise / Aeolian Tone / Flow around cylinders / pressure Fluctuation / Karman Vortex / 円柱回り流れ
Research Abstract

Experimental investigations were conducted in order to understand the characteristics of the Aeolian tone generated from two-dimensional square and circular cylinders with pressure transducers embedded on the surface. The following conclusions were obtainec.
1) Square Cylinder
The peak level of the Aeolian tone is maximum when the angle of attack is 0°, or, a flat surface is placed normal to the mean flow. The separated flow from the leading edge corner of the square cylinder reattaches to the side surface for the angle of attack between 10°to 13°. The surface pressure fluctuation becomes minimum at this angle of attack and consequently the Aeolian tone becomes minimum.
2) Circular Cylinder
The characteristics of the Aeolian tone radiated from a circular cylinder can be divided into three categories in the Reynolds number, Re, I.e. sub-critical (Re<3x10ィイD15ィエD1), super critical (3x10ィイD15ィエD1<Re<10ィイD16ィエD1) and trans-critical (Re>10ィイD16ィエD1) regions. In the sub-critical region, the surf … More ace pressure fluctuation is uniform spanwise and the coherence between the Aeolian tone is high and the Strouhal number is 0.2. In the super-critical region, the Strouhal number jumps up to 0.45 and the peak level of the Aeolian tone decreases sharply. The surface pressure fluctuation shows strong three-dimensionality and only a fractional part in spanwise shows high coherence with the Aeolian ire. In the trans-critical region, the Strouhal number returns to 0.2 and the spectra of the surface pressure fluctuation and the Aeolian tone show somewhat random nature with a blunt peak. The comparison between the measured and predicted Aeolian tone level from the surface pressure fluctuation shows good agreement for the sub- and super-critical regions but the predicted level is approximately 10 dB lower than the measured level for the trans-critical region.
3) Reduction of the Aeolian Tone
A half rounded square cylinder shows approximately 10 dB lower Aeolian tone level when the rounded part is faced to the mean flow, compared to the circular cylinder with the same diameter. When a wire of diameter d is wound in spiral with a pitch p,around a circular cylinder of diameter D, the Aeolian tone is considerably decreased when d/D>0.2 and p/D=3. Less

Report

(4 results)
  • 1999 Annual Research Report   Final Research Report Summary
  • 1998 Annual Research Report
  • 1997 Annual Research Report
  • Research Products

    (7 results)

All Other

All Publications (7 results)

  • [Publications] H.Fujita: "The Aeolian tone and the surface pressure fluctuation in high Re flow"Proceedings of 6^<th> AIAA/CEAS Aeroacoustics Conference. (CD-ROM). (2000)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Fujita: "The Aeolian tone characteristics of a circular cylinder in high Reynolds number flow"Proceedings of 5^<th> AIAA/CEAS Aeroacoustics Conference. 2. 305-310 (1999)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Fujita: "Experimental investigations and prediction of aerodynamic sound generated from square cylinders"Proceedings of 4^<th> AIAA/CEAS Aeroacoustics Conference. 2. 942-947 (1998)

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Hajime Fujita, Hideaki Suzuki, Akio Sagawa and Takehisa Takaishi: "The Aeolian tone and the surface pressure fluctuation in high Re flow"Proceedings of 6ィイD1thィエD1 AIAA/CEAS Aeroacoustics Conference, AIAA Paper 2000-2002. (2000)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Hajime Fujita, Hideaki Suzuki, Akio Sagawa and Takehisa Takaishi: "The Aeolian tone characteristics of a circular cylinder in high Reynolds number flow"Proceedings of 5ィイD1thィエD1 AIAA/CEAS Aeroacoustics Conference, AIAA Paper 99-1849. vol.1. 305-310 (1999)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] Hajime Fujita, Wei Sha, Hiroshi Furutani and Hideaki Suzuki: "Experimental investigations and prediction of aerodynamic sound generated from square cylinders"Proceedings of 4ィイD1thィエD1 AIAA/CEAS Aeroacoustics Conference, AIAA Paper 98-1849. vol.2. 942-947 (1998)

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      1999 Final Research Report Summary
  • [Publications] H.Fujita,A.Sagawa et al: "The Aeolian tone characteristics of a circular cylinder in high Reynolds Number flow"Proceedings of the 5th AIAA/CEAS Aeroacoustics Conference. vol1. 305-310 (1999)

    • Related Report
      1999 Annual Research Report

URL: 

Published: 1997-04-01   Modified: 2016-04-21  

Information User Guide FAQ News Terms of Use Attribution of KAKENHI

Powered by NII kakenhi