The aerodynamic response of a pre-stressed elastically nonlinear aileron

TL;DR

This paper investigates a pre-stressed nonlinear aileron that exhibits bistability under aerodynamic loads, demonstrating a snap-through behavior that reduces drag, with potential applications in aerodynamic drag mitigation.

Contribution

It introduces a novel nonlinear aileron design with bistable behavior under aerodynamic loads and experimentally demonstrates its snap-through response and drag reduction.

Findings

Bistability occurs at certain airflow velocities.

Snap-through reduces drag significantly.

The structure recovers shape after flow reduction.

Abstract

We study the aerodynamic response of a pre-stressed curved aileron. Whilst the fluid flow is standard (high Reynolds air flow undisturbed at infinity), the structure is designed to have a peculiar nonlinear behavior. Specifically, the aileron has only one stable equilibrium when the external forces are vanishing, but it is bistable when relevant aerodynamic loads are applied. Hence, for sufficiently high fluid velocities, another equilibrium branch is possible. We test a prototype of such an aileron in a wind tunnel; a sudden change (snap) of the shell configuration is observed when the fluid velocity exceeds a critical threshold: the snapped configuration is characterized by sensibly lower drag. However, when the velocity is reduced to zero, the structure recovers its initial shape. A similar nonlinear behavior can have important applications for drag reduction strategies.