Fundamental Study on PIV Analysis of Flow Field Visualized by Focusing Schlieren Method

Abstract

In this study, a focusing schlieren PIV system of the LED light source was used to estimate the flow vector of free jets, as a first step toward the application of wind tunnel testing. The system was constructed by an extended light source, a Fresnel lens, source and cutoff grid, focusing lens and a camera. A source grid of the lattice configuration was prepared to visualize the vertical and horizontal density gradients at the same time. The light source was designed by consisting of 4 LEDs. The helium gas was used as the test gas to obtain large density gradient in low speed flows. As a result, the image of the flow pattern by the lattice grid was different from the image of the vertical and horizontal grids. By utilizing the lattice grid, the radial velocity distribution by PIV analysis of the jet showed good agreement with the empirical formula.