民机操纵面极限环振荡特性试验研究

Experimental study on limit cycle oscillation characteristics of civil aircraft control surface

操纵面的极限环振荡是一种重要的气动弹性不稳定型态,其被诱发的速度可能远低于飞机的颤振稳定性包线速度。民用飞机设计中的质量平衡和非质量平衡操纵面,在服役过程中都曾出现过由于间隙导致的气动弹性稳定性降低以及结构损伤的情况。本文构建了带副翼操纵面的三维柔性机翼模型,开展了低速颤振风洞测试,试验中在副翼偏转自由度上引入可调大小的间隙。通过风洞试验观测到了机翼-副翼系统独特的极限环振荡现象,获得了不同测试工况下的结构气动弹性响应,并研究了线性连接及不同间隙对副翼振荡特性的影响。试验结果表明,在副翼弱弯曲刚度和弱偏转刚度组合情况下模型更容易发生极限环振荡;副翼极限环振荡与主翼面的颤振耦合型态不同,触发速度更低。本文最后提出了民机操纵面间隙控制的适航认证建议。

Limit cycle oscillation(LCO)of control surfaces is significant aeroelastic instability,which may be induced at a speed well below the flutter stability speed envelope.Both mass balanced and unbalanced control surfaces in the civil aircraft designs had experienced aeroelastic stability degradation,and thus structural damage induced by freeplay during aircraft service.This paper develops a three-dimensional flexible wing model with an aileron,to investigate the LCO characteristics in the low-speed flutter wind tunnel.Adjustable freeplay is introduced into the degree of freedom of aileron deflection.Through the testing,the unique limit cycle oscillation phenomenon of aileron system is observed,the aeroelastic responses of the model are recorded under different testing conditions.The effects of different freeplay and linear connection on aileron oscillation characteristics are also studied.The test results showed that the limit cycle oscillation is more likely to occur under the combination condition of weak aileron bending stiffness and weak deflection stiffness.The aileron limit cycle oscillations distinguish from the flutter coupled modes of main wing surface,with much lower on-set speed.Airworthiness practices for control surfaces of civil aircrafts with freeplay are proposed for the conclusion.