Preliminary Study of a Wing-Tip Vortex Using Laser Velocimetry

SUMMARY Measurements have been made in the wake of a semispan NACA 0015 airfoil with emphasis on the region of the wing tip vortex. The spanwise and streamwise velocity components were measured using a two-component laser Doppler velocimeter. The purpose of the study was to initiate the operation of a laser velocimeter system and to perform preliminary wake measurements in preparation for a more extensive study of the structure and near-field development of a tip vortex. j NOMENCLATURE I a0 vortex core radius I I I b full span length I CN normal force coefficient c airfoil chord length I Re, Reynolds number, cc/v i r axisymmetric vortex radial coordinate I t time I I V, streamwise velocity component i I V, spanwise velocity component I Ve vortex tangential velocity 1 - V time averaged velocity V, flow velocity in wind tunnel test section 1 - TI$ spanwise Reynolds stress component x streamwise coordinate , I y spanwise coordinate I z normal coordinate I z' normal coordinate with origin at the vortex center