טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
M.Sc Thesis
M.Sc StudentPustilnik Mark
SubjectDynamic Loads Alleviation Using Floating Flaps and
Tip Sections
DepartmentDepartment of Aerospace Engineering
Supervisor Professor Emeritus Mordechay Karpel
Full Thesis textFull thesis text - English Version


Abstract

The use of active free-floating flaps (FFFs) to reduce the dynamic response levels of aeroelastic systems and the associated loads is investigated in this work. The FFFs are investigated in two main configurations: (a) FFFs that are parts of trailing-edge control surfaces such as ailerons or flaps; and (b) An FFF that is a whole wing tip section that is connected to the rest of the wing through a shaft and a clutch that can be released in midflight. The FFFs are driven by trailing-edge tabs driven by piezoelectric actuators.

A numerical model based on wind tunnel tests conducted at the Technical University of Delft (TUDelft) is examined. The structural model is adapted to agree with the measured vibration data of the wind tunnel model. The flaps are free to rotate about their hinges within a free-play zone, which produces limit-cycle oscillations (LCO) similar to those measured in the wind tunnel tests. Flutter-suppression and load-alleviation controllers for the tabs that drive the FFFs are developed, and the interaction between the two control loops is examined. The potential dynamic load alleviation for gust excitations of the wing with the actively controlled FFFs is examined. A control law for obtaining a controlled LCO of the wing with which energy can be harvested is developed. The advantages and disadvantages of both configurations are examined.

The behavior of the tip-section FFF when its clutch is released in midflight is investigated. The dynamic response of the wing to gust excitation is analyzed and the tip section FFF effectiveness in reducing the dynamic load is evaluated.