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

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 obtained 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.