Application of Particle Image Velocimetry - Theory and Partice

Abstract

The main interest of todays research in fluid mechanics is more and more directed to problems where unsteady and separated flows are predominant. For investigations of flow fields with pronounced spatial structures and/or rapid temporal or spatial changes (transition from laminar to turbulent flow, coherent structures, pitching airfoils in transonic flows with shocks, rotors, test facilities with short run time, etc.) new experimental techniques, such as Particle Image Velocimetry (PIV) are required which allow to capture the flow velocity of large flow fields instantaneously. An important feature of PN is that for the first time, a reliable basis of experimental flow field data is provided for direct comparison with numerical ca1culations and hence, for validation of computer codes. During the last years an increasing number of scientists have started to utilize the PIV technique to investigate the instantaneous structure of velocity fields in various areas of fluid mechanics. A number of different approaches for the recording and evaluation of PIV images have been described in literature. This course will mainly concentrate on those aspects of the theory of PIV relevant to applications. Besides giving lectures on the fundamental aspects, special emphasis is placed on the presentation of practica1 and reliable solutions of problems which are faced during the implementation of this technique in wind tunnels and other test facilities. During practice the participants will have the opportunity to carry out the recording and the evaluation of PIV images by themselves in small groups. Recent developments of the PIV technique such as 3C-PIV (stereo PIV, multi plane stereo PIV, dual plane PIV etc.) and 3D-PIV (holographic PIV) will be discussed and demonstrated.