@inproceedings{oai:jaxa.repo.nii.ac.jp:00036775,
 author = {青木, 誠 and 近藤, 夏樹 and 齊藤, 茂 and 青山, 剛史 and Aoki, Makoto and Kondo, Natsuki and Saito, Shigeru and Aoyama, Takashi},
 book = {航空宇宙技術研究所特別資料, Special Publication of National Aerospace Laboratory},
 month = {Jan},
 note = {航空宇宙技術研究所 7-9 Jun. 1995 東京 日本, National Aerospace Laboratory 7-9 Jun. 1995 Tokyo Japan, ヘリコプタロータの高速衝撃騒音への翼端平面、翼形、2面および単面の影響を調べた。拡張Kirchhoff方程式組込みCFD手法を用いてロータの騒音圧を推定した。本手法ではEuler方程式を解いてロータ翼周りの流れ場を求める。移動面への適用拡張Kirchhoff方程式を用いて、全音源を包含するKirchhoff表面上でEuler方程式を解くことにより、1観測点での騒音圧を推定する。第1段階での計算は定高度ホバリングの飛行条件で実行した。計算の結果、翼端平面の修正はロータ騒音のピーク音圧レベルを顕著に引き下げること、それは40度の後退角、ロータ半径90%でのテーパ比が0.333のロータ翼でピーク値の70%カットを示した。また、翼端厚みの修正もピーク音圧レベルを引き下げること、それはロータ外径10%での厚みを12%から6%へ直線方向に変えることで、45%のピーク値カットを示した。結論として、ロータ翼端の平面形状と厚みの最適な組合せは低騒音ロータの設計を可能にすることを示唆した。, The effect of blade tip platform, airfoil, dihedral and anhedral on High-Speed Impulsive (HSI) noise of a helicopter rotor are investigated. A combined method of CFD (Computational Fluid Dynamics) with an extended Kirchhoff's equation is used to estimate the acoustic pressure of the rotor noise. The method solves Euler equations to obtain the flow field around a rotor blade. The Kirchhoff's equation extended to a moving surface is then used to estimate the acoustic pressure at an observer position by using the Euler solutions on the Kirchhoff surface in which all the acoustic sources are enclosed. Calculations are performed under the condition of non-lifting hover as the first stage of the study. The calculated results show that the modification of blade tip platform remarkably reduces the absolute value of the negative peak pressure of the rotor noise. It is indicated that the blade with the sweepback angle of 40 degree and the taper ratio of 0.333 from 90 percent rotor radius leads to the reduction of the peak pressure by about 70 percent. The calculated results also show that the modification of blade tip thickness reduces the absolute value of the negative peak pressure of the rotor noise. It is indicated that the blade with the thickness varying linearly from 12 percent to 6 percent in the outer 10 percent radial region leads to the reduction of the peak pressure by about 45 percent. As a result, it is suggested that the optimal combination of platform and thickness makes it possible to design a quiet rotor., 資料番号: AA0000294007, レポート番号: NAL SP-30},
 pages = {35--40},
 publisher = {航空宇宙技術研究所, National Aerospace Laboratory (NAL)},
 title = {ヘリコプタの高速衝撃騒音を低減するブレード形状の設計に関する考察},
 volume = {30},
 year = {1996}
}