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<p><?tk 2?>To clarify the coupling mechanism between the aeroelastic responses and flow fields of helicopter blades experiencing subharmonic resonance, the experimental and numerical investigations are performed on a three-dimensional (3D) aeroelastic system that incorporates the tip vortex effect. The experimental results reveal subharmonic resonance phenomena occurring when the natural frequency is 1.45 times the driving frequency. For obtaining the 3D global flow fields, the high-fidelity numerical simulations are conducted under the conditions of subharmonic resonance. The dominant modes of flow fields and their spatio-temporal evolution are identified by proper orthogonal decomposition. It is shown that the subharmonic components in aeroelastic responses and aerodynamic loads result from the evolution of the flow fields. The decrease in reduced frequency leads to attenuation of the dynamic stall vortex, simultaneously enhancing flow stability and suppressing subharmonic components, which explains the saddle-node bifurcation of limit cycles during dynamical evolution. The formation of counter-rotating vortex pairs further enhances this stabilization mechanism.</p>

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Flow mechanism of subharmonic resonance for a finite-span wing

  • 期刊论文

  • 发表日期：

    2025年7月21日

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  • Lei Chen,
  • Jie Wu,
  • Dechuan Ma,
  • Bo Zeng,
  • Gaohua Li,
  • Junjie Peng,
  • Fuxin Wang

摘要

To clarify the coupling mechanism between the aeroelastic responses and flow fields of helicopter blades experiencing subharmonic resonance, the experimental and numerical investigations are performed on a three-dimensional (3D) aeroelastic system that incorporates the tip vortex effect. The experimental results reveal subharmonic resonance phenomena occurring when the natural frequency is 1.45 times the driving frequency. For obtaining the 3D global flow fields, the high-fidelity numerical simulations are conducted under the conditions of subharmonic resonance. The dominant modes of flow fields and their spatio-temporal evolution are identified by proper orthogonal decomposition. It is shown that the subharmonic components in aeroelastic responses and aerodynamic loads result from the evolution of the flow fields. The decrease in reduced frequency leads to attenuation of the dynamic stall vortex, simultaneously enhancing flow stability and suppressing subharmonic components, which explains the saddle-node bifurcation of limit cycles during dynamical evolution. The formation of counter-rotating vortex pairs further enhances this stabilization mechanism.