Secondary resonances in aeroelastic response of oscillating airfoil under dynamic stall

SAGE Publications - Tập 24 Số 23 - Trang 5665-5680 - 2018
Zhan Qiu1, Wenhao Xu1, Jiaxin Yuan1, Fuxin Wang2,1
1School of Aeronautics and Astronautics, Shanghai Jiao Tong University, Shanghai, China
2J.C. Wu Aerodynamic Center, Shanghai Jiao Tong University, Shanghai, China

Tóm tắt

To clarify the mechanism of the complex aeroelastic responses of flexible blades of helicopter rotors under dynamic stall, experiments on a 2D aeroelastic system are performed. In the spectra of the response from experiment results, special frequency components are found. Then, a numerical method based on the same aeroelastic model is introduced. Here, the flow field is solved using a zonal solver based on vorticity dynamics. When changing a system’s natural frequency, the same extra frequency components in the response spectra are found when particular ratios of natural and forcing frequencies are achieved. Secondary resonances are believed to then happen, which feature a larger response amplitude, multiple periodic motion and a subharmonic peak of driving frequency in the load spectra. With an analysis of the flow field, the 1/2 subharmonic in the airload spectra (i.e. the period doubling of the loads) is believed to be associated with the nonlinear variation of vortex structures. With a dynamic mode decomposition analysis, a counter-rotating vortex interaction instability is detected as the physical mechanism of period doubling. The coincidence of natural frequency with the odd times of the subharmonic leads to the secondary resonances.

Từ khóa


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Thông tin xuất bản

SAGE Publications

Tập 24 Số 23

5665-5680

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