2026-03-10T06:20:14Z https://jaxa.repo.nii.ac.jp/oai

oai:jaxa.repo.nii.ac.jp:00044780 2023-06-20T21:51:00Z 1887:1893 1896:1898:1913:1917

Acoustics and Performance of High-Speed, Unequally Spaced Fan Rotors 不等ピッチで高速回転するファンの音響特性と空力性能 藤井, 昭一 西脇, 英夫 武田, 克巳 FUJII, Shoichi NISHIWAKI, Hideo TAKEDA, Katsumi This paper describes an experimental measurement of the effects of uneven blade spacing on the acoustic and aero-thermodynamic characteristics of high-speed, high-pressure-ratio fan rotors at two selected spacing configurations. A test rig, consisting of inlet guide vanes and transonic rotor blades, was employed to explore the redistribution of harmonic sound energy into a series of multiple tones of lower sound pressure level. The measured data indicated that a 10％ modulated rotor exhibited a six to eight decibel decrease in the sound pressure level as compared with the original first blade passage frequency harmonic. Disadvantages in aerodynamic performance resulting from spacing modulation were not so unfavourable for 10％ modulated blades. However, with 5％ modulated blades, serious deterioration in aerodynamic performance was observed particularly near the blade tip section, which produced an unfavourable acoustic signature. A calculation method, assuming a pulse event for each blade sound pressure, provided agreeable results with the measured data. 資料番号: NALTR0526000 レポート番号: NAL TR-526 technical report 航空宇宙技術研究所 National Aerospace Laboratory(NAL) 1977-02 application/pdf 航空宇宙技術研究所報告 526 19 Technical Report of National Aerospace Laboratory TR-526 0389-4010 https://jaxa.repo.nii.ac.jp/record/44780/files/naltr00526.pdf https://jaxa.repo.nii.ac.jp/records/44780 jpn