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基于后缘小翼的翼型反流动态失速主动控制试验研究

TEST RESEARCH FOR ACTIVE CONTROL OF AIRFOIL REVERSE FLOW DYNAMIC STALL BASED ON TRAILING EDGE FLAP

  • 摘要: 针对直升机旋翼反流区因反流动态失速导致的非定常载荷、阻力激增以及负升力等问题, 开展了基于后缘小翼的翼型反流动态失速主动控制试验研究. 采用动态压力测量结合翼型表面压力积分的方法, 重点分析了后缘小翼不同的振荡相位差、幅值和减缩频率对反流动态失速控制的影响规律, 对比了后缘小翼动态偏转和固定偏转的差异, 试验雷诺数Re = 3.5 × 105. 结果表明, 当后缘小翼与翼型以相同的频率正弦振荡运动, 且二者的相位差为0°时, 能改善反流动态失速过程中钝几何前缘的流动分离, 并在反流状态下实现了翼型负升力系数下降21.2%, 阻力系数下降37.5%, 俯仰力矩系数迟滞环面积下降44.6%的控制效果; 动态偏转的后缘小翼对翼型反流动态失速的控制效果随后缘小翼振荡幅值的增加而增加, 但进一步增加振荡幅值对于控制效果的提升有限; 当减缩频率增加时, 动态偏转的后缘小翼对反流状态下翼型阻力的控制效果会更加明显; 后缘小翼的动态偏转与固定偏转都能有效改善翼型在反流中的动态气动性能, 但是动态偏转对于不同翼型迎角的适应能力优于固定偏转, 并取得了更好的非定常载荷控制以及更好的阻力和负升力改善效果.

     

    Abstract: In order to solve the issues such as unsteady load, increased drag and negative lift caused by reverse flow dynamic stall in reverse flow regime of helicopters, a test research which focused on the control of airfoil reverse flow dynamic stall was carried out using an airfoil test model with trailing edge flap. Dynamic pressure measurement was combined with integral of airfoil surface pressure to analyze the influence of different oscillating phase offset, amplitude and reduced frequency of trailing edge flap on reverse flow dynamic stall control, and the difference between dynamic pitching and fixed deflection of the trailing edge flap was compared. The test Reynolds number was Re = 3.5 × 105. The results show that the flow separation at the blunt geometric leading edge during reverse flow dynamic stall can be improved when dynamic pitching trailing edge flap oscillating in the same frequency with airfoil model and the phase offset between dynamic pitching trailing edge flap and airfoil model is set to 0°, negative lift coefficient can be reduced by 21.2%, drag coefficient can be reduced by 37.5%, hysteresis area of pitching moment coefficient can be reduced by 44.6% under typical test condition. The control effect of dynamic pitching trailing edge flap on reverse flow dynamic stall raises with the increase of oscillation amplitude, but further increasing the oscillation amplitude has limited impact on the improvement of control effectiveness. When reduced frequency was increased, the control effect of dynamic pitching trailing edge flap on the drag in the reverse flow regime will be more obvious. Both dynamic pitching and fixed deflection of trailing edge flap can improve the unsteady aerodynamic performance in reverse flow, but dynamic pitching trailing edge flap has better adaptability than fixed deflection trailing edge flap during different angle of attack. Better unsteady load control and better drag and negative lift improvement was also observed when trailing edge flap was dynamic pitching.

     

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