A single camera volumetric particle image velocimetry and its application

Volumetric particle image velocimetry (VPIV) refers to a PIV-based technique which can obtain full velocity components in a three-dimensional measurement volume. A new VPIV method with a single lens was developed. A three-vision prism was used to make viewing from different angles using one camera. The technique was tested and successfully applied to a three-dimensional three-component (3D3C) measurement of a zero-net-mass-flux jet flow. The accuracy of the measurement was investigated, specifically in steps of calibration, self-calibration and particle triangulation. Time sequence of a vortex ring development was presented. It was shown that the measurement has high accuracy with validation rate of velocity vector reaching about 95%. The flow with vortex ring passing the measurement volume was studied using both swirl strength and vorticity magnitude criteria. Through comparison, the swirl criterion was found to be superior to the criterion of vorticity in differentiating the rotation motion and the free shear.