טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentBuchnik Shlomi
SubjectAeroelastic Optimization of Varying Sweep Angle Wing
DepartmentDepartment of Aerospace Engineering
Supervisor Professor Emeritus Mordechay Karpel
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

It is common in modern aerodynamic platform design to have multiple design conditions in which the platform is expected to function properly.  A way to have high performance levels at very different flight conditions can be the use of a morphing wing with variable sweep angle. Multidisciplinary design of the structure and the control system for the platform at different flight conditions and different wing sweep angles poses an engineering challenge. The different design goals such as low wing inertia, sufficient platform performance, adequate control system gain and phase margins and sufficient flutter margins, form an elaborate optimization problem with contradictory requirements and constraints. This work proposes a novel automated approach for solving the aeroservoelastic optimization problem by using the modal approach with modal coupling techniques. 

Aeroservoelastic optimization has been studied in a large number of studies. Usually the solution approach is based on the modal approach. According to the modal approach, which is well suited for aeroelastic problem, a limited low frequency set of structural vibration modes are taken into account. By doing so the number of problem's dof is reduced significantly. Reducing problem's dof enables rapid optimization sessions even on ordinary of the shelf personal computers. The optimization sessions includes derivatives calculations and design updates, which demands extensive CPU time.  The optimization sessions includes control system's gains change and structure design parameters change.

This research goal is to develop a method for interdisciplinary optimization which optimizes the control system's gains and structure design parameters for varying sweep angle wing. The work is focused at optimizing predefined aerodynamic platform while changing its control gains and wing's structure. As stated the optimization is performed using the modal assumption, while larger number of structure modes is used than normal aeroelastic analysis. The aerodynamic model of the configuration is calculated using panel method with appropriate compression correction, the aerodynamic matrices are approximated using minimum states method. The control system is formalized with state space representation. Combining the different models creates a full state space model of the configuration. The cost function and the design constraints for the optimization process are derived from roll-performance requirements, control stability margins, closed-loop flutter velocities, aileron aeroelastic effectiveness and the wing moment of inertia about its rotation axis that affects the sweep-angle rate.