Inviscid Unsteady Aerodynamic Model of Airfoils Moving Near Boundaries

Open Access
Author:
Sen, Nilanjan
Graduate Program:
Mechanical Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Christopher Rahn, Thesis Advisor
Keywords:
  • Aerodynamic model
  • Conformal mapping
  • Potential Method
  • Clap-and-fling
Abstract:
There is considerable interest in the development of flapping wing Nano Air Vehicles (NAVs) for military applications. These NAVs operate in the Reynolds number regime 10^2-10^4 which is similar to the Reynolds regime of small insects. It is important to understand the aerodynamics of flapping wing flight in this regime in order to build high performance NAVs. Aerodynamic models that can predict the flow and associated forces are a useful tool to understand flapping wing mechanisms. The Weis-Fogh clap-and-fling mechanism, is used by certain insects operating in the low Reynolds number range (10^2). The Weis-Fogh mechanism generates additional lift compared to conventional flapping wing mechanisms and is therefore advantageous to use in NAVs. This thesis presents a two-dimensional, non-linear, unsteady aerodynamic model of an airfoil in a bounded domain. Key concepts of flapping wings such as leading edge vortices and wing-wake interaction are included in the model to provide a better prediction of the flow and aerodynamic forces. The model predicts the flow field and the lift and drag forces on the airfoil. The non-linear governing equations for the flow are solved using numerical methods. The Weis-Fogh clap-and-fling mechanism is studied and compared with previous CFD results.