Numerical and Experimental Investigations of an Elasto-Flexible Membrane Wing at a Reynolds Number of 280,000

Abstract

This work presents numerical and experimental investigations of an elasto-flexible membrane wing at a Reynolds number of 280,000. Such a concept has the capacity to adapt itself to the incoming flow offering a wider range of the flight envelope. This adaptation is clearly observed in the numerical study: the camber of the airfoil changes with the dynamic pressure and the angle of attack, which permits a smoother and delayed stall. The numerical results, obtained from Fluid Structure Interaction (FSI) simulations, also show that the laminar-turbulent transition influences the aerodynamic characteristics of the wing, as it directly affects the pressure distribution on the membrane and the geometry of the airfoil. Two different turbulence models were therefore tested. Furthermore, experimental investigations are considered in this paper to estimate the precision of the FSI simulations. It appears that the FSI study overestimates the lift coefficient, and the drag coefficient is undervalued, which can be explained by dynamic calibration of the model. Nevertheless, the velocity field obtained with the hot-wire anemometry system shows good agreement on the upper side of the model. The membrane deflection measurements also appear to be consistent with the expected geometry of the deformed airfoil from the FSI simulations.

The effect of static deformation on the lift loss phenomenon of an ABS downforce producing wing in ground effect

“…A numerical investigation was executed to analyse the impact of aeroelasticity on the aerodynamic performance of an inverted downforce producing wing in ground effect. This study was performed with the static loosely-coupled FSI strategy at two Reynolds numbers, Re = 4.64Á10 5 and Re = 6.96Á10 5 , and at ground clearances ranging from 0:053c to 0:313c. The T026 wing had angle of attack of 3.45°and was modelled with ABS material.…”

“…Due to wing deflection, the loss in downforce occurred at higher ground clearances. At Re = 4.64Á10 5 , the critical height increased from h = 0:080c to 0:091c, while it increased to 0:101c at Re = 6.96Á10 5 . II.…”

“…Aerodynamic solver validation. The aerodynamic solver is validated across 10 different ground clearances ranging from h/c = 0.053 to h/c = 0.313 at the Reynolds number of 4.64Á10 5 . Results are compared to experimental values of the wing with tripped transition at 0.1 c since the boundary layer is modelled as fully turbulent.…”

“…Variations in camber due to an aeroelastic response have also shown a significant impact on aerodynamic performance. Flexible flapping wings in Micro Air Vehicles (MAV) 4 and morphing wings 5 presented an increase in lift peak by up to 12.5% 4 and stall angle from 13°to 15°5 due to the self-adapting camber behaviour that delayed flow separation.…”

Aerodynamic analysis of a generic wing featuring an elasto-flexible lifting surface

“…Before presenting the results obtained during this analysis, a brief introduction is given on the effects of the membrane as lifting surface of a wing. Previous investigations [25,26] show that the membrane flexibility and adaptivity allow a passive flow control. The membrane enables a change of the surface contour under a varying dynamic pressure permitting a change in the airfoil's camber.…”