Fundamental studies in hypersonic aeroelasticity using computational methods

This dissertation describes the aeroelastic analysis of a generic hypersonic vehicle using methods in computational aeroelasticity. This objective is achieved by first considering the behavior of a representative configuration, namely a two degree-of-freedom typical cross-section, followed by that of a three-dimensional model of the generic vehicle, operating at very high Mach numbers.; The typical cross-section of a hypersonic vehicle is represented by a double-wedge cross-section, having pitch and plunge degrees of freedom. The flutter boundaries of the typical cross-section are first generated using third-order piston theory, to serve as a basis for comparison with the refined calculations. Prior to the refined calculations, the time-step requirements for the reliable computation of the unsteady airloads using Euler and Navier-Stokes aerodynamics are identified. Computational aeroelastic response results are used to obtain frequency and damping characteristics, and compared with those from piston theory solutions for a variety of flight conditions. A parametric study of offsets, wedge angles; and static angle of attack is conducted. All the solutions are fairly close below the flutter boundary, and differences between the various models increase when the flutter boundary is approached. For this geometry, differences between viscous and inviscid aeroelastic behavior are not substantial.; The effects of aerodynamic heating on the aeroelastic behavior of the typical cross-section are incorporated in an approximate manner, by considering the response of a heated wing. Results indicate that aerodynamic heating reduces aeroelastic stability.; This analysis was extended to a generic hypersonic vehicle, restrained such that the rigid-body degrees of freedom are absent. The aeroelastic stability boundaries of the canted fin alone were calculated using third-order piston theory. The stability boundaries for the generic vehicle were calculated at different altitudes using piston theory for comparison. The flutter boundaries using first-order piston theory were found to be much higher than those calculated using third-order piston theory. Computational aeroelastic response of the complete vehicle using Euler aerodynamics was found to predict a significantly higher flutter boundary as compared to third-order piston theory, due to substantial three-dimensional flow effects. Also, both methods predicted an increase in the flutter boundary with increasing altitude.