Vortex flows of downwind sails - PIV data

Three different spinnaker twist prototypes were manufactured (“Geometries” dataset) and their near wake was studied with Particle Image Velocimetry (PIV). The reference sail (high twist geometry) was recorded in uniform flow in a water flume (“Near Wake” dataset). This geometry provided the highest maximum driving force, assuming an apparent wind angle of 55 deg. The data set contains 5 particle image velocimetry measurement planes along the span of the sail. The planes are labelled A, B, C, D and E and are located at 7/8th, 5/6th, 3/4th, 1/2th and 1/4th the distance from the bottom of the sail to the tip. A total of 500 images are recorded per plane. The reference geometry can be found in Arredondo-Galeana and Viola, in OE, 2018. The top planes of the three different twist geometries (“NearWake_TopPlanes” dataset) were subsequently studied to assess the influence of a twisted inflow. Twist influences secondary vorticity production on the surface of the sail and can be used to enhance the driving force of downwind sails. Further details can be found in the PhD thesis from Abel Arredondo-Galeana, “A study of the vortex flows of downwind sails”, available at the Edinburgh Research Archive repository. A manuscript describing the findings of this research is in preparation.