# Sinusoidal-gust generation with a pitching and plunging airfoil

## TL;DR

This paper demonstrates a simple method to generate uniform sinusoidal gusts using an oscillating airfoil, improving control and symmetry of gusts for experimental aerodynamics and vehicle design.

## Contribution

It introduces a pitching and plunging airfoil as an alternative gust-generation method, guided by Theodorsen theory, producing smooth, repeatable gusts with high amplitudes.

## Key findings

- Produces high-amplitude, smooth gusts
- Improves symmetry of vertical velocity fluctuations
- Reduces vorticity shed influence

## Abstract

The generation of uniform, periodic gust disturbances in an experimental context is demonstrated using a single oscillating airfoil. A pitching and heaving symmetric airfoil is suggested as a simpler alternative to existing gust-generation methods. The Theodorsen theory of unsteady aerodynamics is used as an analytical tool to dictate the kinematics necessary to produce well-defined sinusoidal gusts downstream of the airfoil. These analytic predictions improve the symmetry of fluctuations in the vertical velocity induced by the airfoil, as well as minimize the influence of vorticity shed by the oscillating airfoil. The apparatus is shown to produce smooth, repeatable gusts with high amplitudes and reduced frequencies compared to other gust-generation mechanisms in the literature. Furthermore, the control of downstream flow properties by airfoil motion kinematics has applications in experimental aerodynamics, the design of rotorcraft and light aerial vehicles, and biological propulsion.