本文的目的即探討當一直昇機的彈性葉片與非穩態空氣動力環境耦合在一起時, 彈性葉片上的空氣動力在不同的尾流振動頻率下之變化及分析。本文對於滯空及前飛時的情況也將一併探討之。本文的結果除了提供直昇機主旋翼彈性葉片於不同的尾流振動頻率下之響應外, 此研究較之以往的剛性葉片的假設更趨近於真實葉片。結果顯示我們可以瞭解升力由於誘導尾流頻率和葉片拍撲頻率、升力的激發頻率、及葉片結構頻率共振, 而造成升力減少。很明顯地, 尾流層的影響不會因前飛角的增加而減少。
The frequency response of a helicopter rotor aeroelastic system in vertical and forward flight will be studied by a three-dimensional unsteady wake model and coupled with a 4-elastic-bladed vibrating rotor. This three-dimensional wake model is extracted from a finite- state inflow theory in time domain. Fourier series are applied to the elastic blade vibrating motion and rotor inflow state coefficients to extend the coupled equations to frequency domain. Results from the frequency analysis show that the lift was dropped for each resonant area, includes wake to blade flapping, wake to lift spike, and wake to blade structure. Apparently, the effect of wake layering is not diminished in forward flight, and the wake spacing is small enough for typical rotors that the skew angle does not significantly shift the layers of resonant vorticity below the rotor. The frequency response of a helicopter rotor aeroelastic system in vertical and forward flight will be studied by a three-dimensional unsteady wake model and coupled with a 4-elastic-bladed vibrating rotor. This three-dimensional wake model is extracted from a finite- state inflow theory in time domain. Fourier series are applied to the elastic blade vibrating motion and rotor inflow state coefficients to extend the coupled equations to frequency domain. Results from the frequency analysis show that the lift was dropped for each resonant area, includes wake to blade flapping, wake to lift spike, and wake to blade structure. Apparently, the effect of wake layering is not diminished in forward flight, and the wake spacing is small enough for typical rotors that the skew angle does not significantly shift the layers of resonant vorticity below the rotor.
關聯:
中國航空太空學會八十六年年會暨第三十九屆學術研討會論文集=Proceedings of the 39th Conference on Aeronautics and Astronautics, R.O.C.，頁643-650
