Particle image velocimetry

Abstract

This document describes the development of a new flow visualization and measurement facility that incorporates a sheet of laser light and digital image enhancement and processing techniques. A simple bench test that was used to demonstrate the feasibility of such techniques is also described. This technique offers the advantages of real time visualization of flow and the ability to freeze the flow pattern at any instant in time. In this sense, the technique plays a role similar to that of large scale direct numerical simulation of flows on supercomputers. Therefore it will provide a better basis for code qualification than we have today. In addition, quantitative information about the flow field (e.g., the velocity vectors), both instantaneous and time-averaged, can easily be extracted from the still or video image with a high level of accuracy and in considerably shorter testing time. This is considered to be a very powerful tool for use in future computer model qualification. Because of the capabilities of the cameras in magnifying the image, this technique is far superior to previous techniques when the test geometry is very small.