A parametric study on flutter characteristics of a folding wing

Abstract

Conventional aircrafts with fixed wings can fly efficiently only for select flight profile or conditions. For example low aspect ratio wings are preferred for better maneuverability, high aspect ratio wings are aerodynamically efficient, straight wings are fit for low-speed operations, swept wings are desired for drag reduction, etc. Operating aircrafts as efficiently as possible is the key to keeping the operating costs as low as possible. Hence, morphing aircrafts capable of varying their wing form corresponding to desired efficiency can address the limitations faced by the conventional wings.

However, morphing wing concept poses several engineering challenges which need to be solved before their potentials can be fully realized. Radical morphing of the aircraft leads to increased structural complexities resulting in occurrence of dynamic instabilities such as flutter. Flutter of wing surfaces can end in catastrophic accidents. Thus, flutter instability of the wing surfaces are one of the key obstacles which needs to be addressed. Therefore, it is of utmost importance to investigate and understand the changes in flutter characteristics of morphing wings to ensure maximum reliability and uncompromised safety.

In this thesis, a study on flutter characteristics of folding wing type morphing concept is conducted to examine the effect of changes in folding angles on the flutter speed and frequency of the folding wing aircraft. Folding wing geometry model is developed using MSC. Patran FlightLoads. The subsonic aerodynamic theory Doublet Lattice Method (DLM) is used for aeroelastic analysis. Additionally, for a better understanding of the folding wing’s aerodynamic characteristics, a simple aerodynamic analysis is executed using a thin airfoil NACA 4412. Aerodynamic mesh generation is done through GAMBIT and Computation Fluid Dynamics simulation is performed on ANSYS/FLUENT. Then the flutter analysis of the folding wing is performed using MSC. NASTRAN solutio...