Transonic flutter characteristics of an airfoil with morphing devices

Abstract

An investigation into transonic flutter characteristic of an airfoil conceived with the morphing leading and trailing edges has been carried out. Computational fluid dynamics (CFD) is used to calculate the unsteady aerodynamic force in transonic flow. An aerodynamic reduced order model (ROM) based on autoregressive model with exogenous input (ARX) is used in the numerical simulation. The flutter solution is determined by eigenvalue analysis at specific Mach number. The approach is validated by comparing the transonic flutter characteristics of the Isogai wing with relevant literatures before applied to a morphing airfoil. The study reveals that by employing the morphing trailing edge, the shock wave forms and shifts to the trailing edge at a lower Mach number, and aerodynamic force stabilization happens earlier. Meanwhile, the minimum flutter speed increases and transonic dip occurs at a lower Mach number. It is also noted that leading edge morphing has negligible effect on the appearance of the shock wave and transonic flutter. The mechanism of improving the transonic flutter characteristics by morphing technology is discussed by correlating shock wave location on airfoil surface, unsteady aerodynamics with flutter solution.

Computational analysis and design of an aerofoil with morphing tail for improved aerodynamic performance in transonic regime

“…Although, the authors of this research acknowledge that this is an aspect to focus on in the future as aeroelastic phenomena such as flutter and buffet may result in negative effects for the structural integrity of the wing. As regarded in the investigation of He et al [45] in which the author found that this technology can be of use to control the flutter generated by manipulating the harmful eddies and enhancing the beneficial ones by means of a vibrating TE (locking effect). Tô et al [46] focused their research on the effects of flutter when morphing technology is used in the TE concluding that the implementation of a morphing part can increase the transonic flutter speed up to 74.5%, as the shock wave can change of location and formation due to the change in the deflection of the morphing region.…”