| タイトル | Helicopter rotor noise due to ingestion of atmospheric turbulence |
| 本文（外部サイト） | http://hdl.handle.net/2060/19860015745 |
| 著者（英） | Simonich, J. C.; Schlinker, R. H.; Greitzer, E. M.; Amiet, R. K. |
| 著者所属（英） | United Technologies Research Center |
| 発行日 | 1986-05-01 |
| 言語 | eng |
| 内容記述 | A theoretical study was conducted to develop an analytical prediction method for helicopter main rotor noise due to the ingestion of atmospheric turbulence. This study incorporates an atmospheric turbulence model, a rotor mean flow contraction model and a rapid distortion turbulence model which together determine the statistics of the non-isotropic turbulence at the rotor plane. Inputs to the combined mean inflow and turbulence models are controlled by atmospheric wind characteristics and helicopter operating conditions. A generalized acoustic source model was used to predict the far field noise generated by the non-isotropic flow incident on the rotor. Absolute levels for acoustic spectra and directivity patterns were calculated for full scale helicopters, without the use of empirical or adjustable constants. Comparisons between isotropic and non-isotropic turbulence at the rotor face demonstrated pronounced differences in acoustic spectra. Turning and contraction of the flow for hover and low speed vertical ascent cases result in a 3 dB increase in the acoustic spectrum energy and a 10 dB increase in tone levels. Compared to trailing edge noise, turbulence ingestion noise is the dominant noise mechanism below approximately 30 rotor harmonics, while above 100 harmonics, trailing edge noise levels exceed turbulence ingestion noise by 25 dB. |
| NASA分類 | ACOUSTICS |
| レポートNO | 86N25216
NAS 1.26:3973
NASA-CR-3973 |
| 権利 | No Copyright |
| URI | https://repository.exst.jaxa.jp/dspace/handle/a-is/154137 |
