Estructura del Flujo y Dinámica de los Vórtices en el Borde de Ataque de Semillas Autorrotantes (Swietenia macrophylla)

Abstract

An experimental investigation of near and far field aerodynamics of wind dispersed seeds has been performed using digital stereoscopic particle image velocimetry (DSPIV). As they fall, the spinning seeds generate a prominent leading-edge vortex (LEV) which is responsible for augmenting lift forces. In this work, the three-dimensional (3D) flow structures around free falling autorotating Mahogany seeds in a vertical wind tunnel are revealed for the first time. The results show that the LEV system is comprised of two vortical elements: one primary vortex at the leading edge and one minor vortex at the trailing edge. Thrust coefficients of the seeds were obtained using the measured lift and drag coefficients, and terminal velocities were calculated as a function of the Reynolds number and wing loading. Our experimental findings indicate that the size of the LEV is larger than predicted in previous two-dimensional (2D) studies. It is pointed out that studying pronounced 3D flow using 2D approximations is prone to errors.