Two and three component velocity measurements in a wind tunnel using PIV

Abstract

AbstractThis paper describes the development of particle image velocimetry (PIV) to measure instantaneous spatial distributions of velocity in flows generated around models in a low speed wind tunnel with a test section 3m wide by 1·5m high. The difficulties associated with using PIV in air at this scale, and how they can be overcome, are discussed. Stereoscopic PIV is used to correct errors due to parallax that are present in velocity components measured in the plane of a light sheet when there is an accompanying flow through the sheet. This technique is also used to measure all three components of velocity in planes across a flow. It is found that apparently good estimates of a mean flow field can be obtained by averaging as few as ten instantaneous measurements of the flow field. The flows studied are generated by a 1/8 scale model of an aircraft for which the wing sweep can be varied. Measurements of velocities associated with the main vortex structures generated over the wing are presented for a sweep angle of 70°. Measurements of velocities recorded in the wake of a large fuel tank mounted below the wing, for a wing sweep of 45°, are also shown.