An advanced off-axis holographic particle image velocimetry (HPIV) system

Holographic PIV (HPIV) is the most promising candidate for the next generat ion full-field velocimetry that can measure high spatial resolution instant aneous three-dimensional (3D) velocity fields. To explore the maximum perfo rmance capabilities of HPIV including spatial resolution, off-axis holograp hy based HPIV has become a major direction of development. A fully automate d off-axis HPIV system based on an injection-seeded dual-pulsed YAG laser a nd 3D data processing software has been implemented in the laser flow diagn ostics lab (LFD). In our system, 90-degree particle scattering, dual refere nce beams, in situ reconstruction/data processing, and 3D velocity extracti on based on a fast "concise cross correlation" (CCC) algorithm are utilized . The off-axis HPIV system is tested for an acoustically excited air jet an d the wake of a surface-mounted tab in a water channel flow giving instanta neous 3D velocity fields for both flows. Experimental data of instantaneous ly measured 3D flow structures using this technique show great promise.