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Investigation and Optimization of Structural Parameters of an Elastic Flapping Wing

Badri Kouhi, Ehsan | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44892 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Dehghani Firouzabadi, Roohollah
  7. Abstract:
  8. In this thesis, effects of bending and torsional elasticity of a flapping wing on its average lift and input power are studied, using a semi-analytic method. Bending stiffness and torsional rigidity of wing spar, wing mass ratio and chordwise and spanwise center of gravity, also spar location are considered as variables for controlling elastic behavior of the wing.Governing integral equation is derived using Hamilton principle via modified quasi aerodynamic and linear Green-Lagrange strain tensor. Also an idealized flapping pattern is used to maximize average acceleration during each cycle. Next, integral equation is converted to a set of ordinary differential equations by means of Galerkin method. Further it is formed into a matrix equation, using state space parameters.Optimality is defined as the ratio of average lift coefficient to average input power coefficient. Based on the results, if wing spar is located on the leading edge, increasing torsional elasticity, decreases average lift and optimality factor while input power approximately remain constant. Increasing bending elasticity although lower required power, but also lower the average lift and results in the lower optimality factor. Optimality can be increased by decreasing mass ratio or bringing center of gravity to the wing root and spar location. Also it is shown that if spar is located at trailing edge, optimality will increase but this can lead to wing divergence or lowering trust
  9. Keywords:
  10. Flapping Wing ; Flexible Wing ; Aeroelasticity ; Input Power ; Optimality Condition ; Lift Coefficient

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