Unsteady Fluid-Structure-Jet Interactions of Agile High-Speed Vehicles

This paper considers the nonlinear and unsteady loads environment of an agile high-speed vehicle with reaction control jets and structural degrees of freedom to account for the flexibility of the slender vehicle. At supersonic flow conditions, the jet flow interacts with the external flow and induces a complex pressure distribution on the vehicle surface. This interaction has been well documented in the literature for jets mounted on rigid structures and considering steady-state flow. However, the fluid-structure interaction must be considered for a slender vehicle due to increased flexibility. Static and dynamic aeroelastic analyses using direct and reduced-order modeling based on the aeroelastic capability of the FUN3D computational fluid dynamics code are presented. The results show that dynamic rigid-body motion, structural deformation, and pulsating jets lead to variations in the applied loads up to 50% compared to the equivalent conditions with a rigid vehicle without jet interaction. A modeling approach for the unsteady loads is compared against the dynamic aeroelastic solution. The model-predicted results capture some of the unsteady effects, and the results show good correlation with the computational fluid dynamics solution for low-frequency inputs.