3-DIMENSIONAL PARTICLE IMAGE VELOCIMETRY - EXPERIMENTAL ERROR ANALYSIS OF A DIGITAL ANGULAR STEREOSCOPIC SYSTEM

Experimental error analysis of a digital angular stereoscopic PIV syst em is presented, The paper firstly describes an experimental rig which includes the design of a novel PIV test block for in situ calibration . This allowed the user to set up a static seeded flow volume which wa s translated in and out of plane to record PIV images using two megapi xel CCD cameras positioned for angular stereoscopic viewing. PIV data were collected for a range of camera angles up to 45 degrees and for a range of flow displacements and processed by cross correlation into a set of two-dimensional calibration and flow displacement vectors. The se 2D data were then processed into three-dimensional data by the use of geometric and bicubic spline interpolation algorithms and an error analysis performed on the predicted displacements. Results from this a nalysis have shown optimum system performance will be obtained by usin g camera angles of between 20 and 30 degrees and f numbers of f16 and higher. The results have also shown a theoretical prediction of system performance derived in previous work, which considers the ratio of ou t of plane to in plane errors, matches to within 8 and 18% of the expe rimental system performance.