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Experimental Aerodynamic Modeling of a Rigid Flapping Wing

Bighshdel, Ariyan | 2017

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 51122 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Pourtakdoust, Hossein
  7. Abstract:
  8. Flapping Aerial Vehicles (FAVs) are those kinds of aerial vehicles in which the wings are responsible for simultaneous producing of lift and thrust forces. To provide necessary aerodynamic loads, flapping wings employ various unsteady mechanisms. They often fly at relatively high Angle of Attacks (AoA), respective to the relative flow. The aerodynamic modelling of flapping wing has always been a challenging task. The unspecified assumptions in the existing models, make them almost insufficient in flight simulation applications. Therefore, this paper aims to develop a generalized aerodynamic model. To this aim, a comprehensive investigation has been conducted on some of previous aerodynamic models, and their deficiencies are discussed. Some of the main drawbacks in the existing models are the assumptions of low flapping amplitude and relative AoA, as well as constant flight speed and body AoA. These restricting assumptions have been thoroughly studied and largely overcome. The strip theory has been employed in the developed model and the unsteady shedding vortices have been modeled via Theodorsen function. The leading edge vortex has been also modelled using Plohamus analogy. Another aim of this study was set to experimental investigation of the validity range of strip theory and its key no-spanwise-flow assumption. In this regard, an experimental 3DOF flapping mechanism was designed and constructed that allows for plunging, root flapping and pitching motions of an FAV with independently adjustable amplitudes and frequencies. The results demonstrate that despite the flow complexities, strip theory assumptions are not restricting for acceptable aerodynamic load prediction of a rigid wing undergoing pure plunging and/or combined pitching-plunging motions. However, in case of a root-flapping wing it was shown that analytical STB models significantly underestimate aerodynamic loads for large flapping angles
  9. Keywords:
  10. Flapping Wing ; Aerodynamic Modeling ; Experimental Studies ; Rigid Wing

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