Aeroelasticity, Aerothermoelasticity and Aeroelastic Scaling of Hypersonic Vehicles

摘要

This final report describes the work during the period of the grant. Three separate hypersonic aeroelastic stability problems were considered: (a) a typical cross section having a double wedge airfoil, (b) the stability of a low aspect ratio wing, also with a double wedge airfoil, and (c) the behavior of a complete generic hypersonic vehicle. For problems (a) the unsteady airloads were computed using third order piston theory, as well a CFD based Euler and Navier-Stokes loads. For case (b) piston theory, Euler and Navier-Stokes based airloads were used, and case (c) both piston theory and Euler airloads were used. For the three-dimensional wing the treatment of thermal effect was also considered by solving the heat transfer problem using the Navier Stokes equations to determine the temperature distribution over the vehicle and conducting an aeroelastic analysis that accounts for the effect of thermal stresses and material degradation on the mode shapes. These mode shapes were used in an aeroelastic analysis based on 3rd order piston theory. This comprehensive treatment of the aerothermoelastic problem, the first of its kind in the literature, produces large reductions in aeroelastic stability margins. The results indicate that the flutter boundaries for third order piston theory can differ by 35% from those based on Euler unsteady loads. Solutions based on the loads obtained from the solution of the Navier-Stokes equation indicate further changes in aeroelastic stability margins. Important conclusions for the design of such vehicles are summarized in the body of the report.