A study of the nonlinear aerodynamic characteristics of a slender double-delta wing in roll.

摘要

An experimental investigation of the dynamic behavior of an 80{dollar}spcirc/65spcirc{dollar} double-delta wing at high angles of incidence was conducted. It was found that depending upon the angle of incidence, different dynamic regimes were encountered as the wing was free to rotate about its longitudinal axis. These dynamic regimes included damped oscillations, quasi-limit-cycle wing-rock motion, and chaotic oscillations. The presence of vortex breakdown on the model was shown to influence the type of dynamic regime obtained and the location of the roll attractors. Results are presented that indicate how the individual physical features of the double-delta wing affected the overall dynamic behavior of the {dollar}80spcirc/65spcirc{dollar} double-delta wing. It is shown that the 65{dollar}spcirc{dollar} main wing had a strong influence on the location of the roll attractors, while the presence of the 80{dollar}spcirc{dollar} strake seemed to affect the amplitude of oscillation.; Force balance experiments and flow visualization tests were also conducted and the results show a relationship between vortex behavior and wing aerodynamics. The behavior of the leeward strake vortex at large roll angle was shown to have a strong influence on the roll moment acting on the wing. Flow visualization also helped explain the presence of critical states in the force and moment data. It also showed that different dynamic regimes were associated with different flow regimes. Moreover, a method was developed to predict the roll attractors and amplitude of oscillation from static roll moment coefficient results.; Finally, numerical simulation of the free-to-roll behavior of the wing led to a better understanding of the possible chaotic nature of the free-to-roll response of the wing at certain angles of incidence.