气动扰流对飞机T型尾翼跨音速颤振影响的试验研究

Influence of flow disturb on transonic flutter characteristic of an aircraft T-Tail

跨音速颤振试验通常在稳定的理想流场中进行,不考虑实际非稳定流场的气动扰流对颤振特性的影响。在飞机T型尾翼跨音速颤振试验中,通过设置一种气动扰流装置对风洞流场实施干扰以研究气动扰流对飞机T型尾翼跨音速颤振特性的影响。试验结果表明,气动扰流可以将飞机T型尾翼的颤振耦合模态从平尾弯扭耦合型改变为垂尾弯扭耦合型;可显著降低飞机T型尾翼的颤振动压,翼面外气动扰流较翼面内气动扰流对飞机T尾颤振特性的影响作用大。其原因在于施加的气动扰流所诱导产生的跨音速激波作用在垂尾翼面上改变了垂尾的非定常气动力,引起气动刚度和气动阻尼发生改变,由于平尾的气动阻尼相对较大,可以预计,一旦气动扰流引起垂尾的气动阻尼迅速减小到其临界颤振阻尼,则会引起垂尾弯扭耦合颤振型先于平尾弯扭耦合颤振型发生,从而表现出T尾颤振动压的降低。在颤振模型风洞试验中,当风洞试验结果与期望不一致时,需要研究气动扰流的影响。

Here, the effect of flow disturb on transonic flutter characteristic of an aircraft T-tail was inveatigated. The traditional transonic wind tunnel flutter test was conducted in a non-flow disturb wind tunnel And the influence of flow disturb on flutter was not considered in a transonic flutter wind tunnel test. A body installation was used to simulate flow disturb in a transonic wind tunnel. Results obtairred from non-flow disturb and flow disturb were compared and discussed in detail. The flutter coupled mode was changed from H-tail bending/torsion mode of non-flow disturb to V-tail bending/torsion mode of flow disturb. In addition, the flutter dynamic pressures for the aircraft T-tail become much lower when the flow disturb was functioned. The out-wing flow disturb was more critical than the in-plane wing flow disturb. The analysis results showed that the shock wave from transonic flow disturb changes V-tail unsteady aerodynamic force; if the aerodynamic damping decreases into its critical flutter damping, the V-tail flutter occurs earlier than H-tail flutter does; meanwhile, if H-tail flutter damping is high enough, then the flutter coupled mode is changed and the flutter dynamic pressures decrease for T-tail; the effect of flow disturb should be studied in a flutter model wind tunnel test if the test results are different from the predicted ones.