M.Sc Thesis


M.Sc StudentEvgeny Selitrennik
SubjectComputational Aeroelastic Simulation of Wing Unfolding
Process
DepartmentDepartment of Aerospace Engineering
Supervisors Professor Emeritus Karpel Mordechay
Dr. Levy Yuval
Full Thesis textFull thesis text - English Version


Abstract

A new approach for time-domain CFD-based simulation of morphing flight vehicles, taking into account multi-body dynamics and aeroelastic effects due to structural flexibility, is presented. The vehicle consists of a number of components interconnected by actuators and contact constraints. Due to aerodynamic, inertial and actuation loads the overall structure undergoes large-displacement morphing. The simulation assumes that each component experiences large rigid-body displacements and small elastic deformations.  The small displacements are defined for each component as a linear combination of its own free-free vibration modes generated with fictitious masses loading the interface degrees of freedom. Modal coupling of the component modes with compatibility constraints at the interface points yields generalized-coordinate nonlinear matrix equations of motion that is embedded into the time-accurate CFD code. The vector of generalized forces includes aerodynamic forces from the CFD solution, inertial forces due to modal accelerations and relative component rotations, and actuation forces. The time derivations of the constraint equations are taken into account to allow large and fast relative rotations of the components. These derivatives yield non-symmetric structural damping and stiffness matrices that affect the numerical integration process. The computational process is demonstrated for two models: the first model is a two-wings-and-body configuration, where the wings are rotated rapidly from parallel position along a fuselage to perpendicular position. The second model is a wing-body configuration where the wing is rotating about a hinge attached to a slender body from a parallel position to a perpendicular one. The morphing simulation demonstrates a robust and stable computational process that exhibits significant aeroelastic effects.