Experimental and Numerical Fluid-Structure Analysis of Rigid and Flexible Flapping Airfoils

Abstract

A combined experimental and computational study is presented for an airfoil undergoing a combined pitching and plunging motion at Reynolds number 100,000, where transition takes place along laminar separation bubbles. The numerical simulation approach addresses unsteady Reynolds-averaged Navier―Stokes solutions and covers transition prediction for unsteady mean flows. To study the effect of wing flexibility, the aerodynamic computational method is coupled with a structural solver using a Galerkin method. The numerical simulations are validated using high-resolution, phase-locked stereoscopic particle image velocimetry for one flapping case with a reduced frequency of k = 0.2. Hereby both a rigid and a flexible birdlike airfoil are investigated. The flow reveals strong unsteadiness resulting in moving laminar separation bubbles, both well captured by the numerical simulations performed in this study.