Acetone planar laser-induced fluorescence for supersonic flow visualization in air and nitrogen jet

Abstract

Background: Laser based flow visualization techniques are indispensable tools for flow visualization in fluid dynamics and combustion diagnostics. Among these, PLIF is very popular because of its capability to give quantitative information about the flow. This paper reports the acetone tracer-based PLIF imaging of supersonic jet with air and nitrogen as bath gases. Methods: The tracer was seeded in the flow by purging bath gas through the liquid acetone at ambient temperature. Planar laser sheet from frequency quadrupled, Q-switched, Nd:YAG laser (266 nm) was used as an excitation source. Emitted PLIF images of a jet flow field were recorded on ICCD camera. Results: In this study, the dependence of PLIF images intensity on oxygen by comparing nitrogen jet with air in supersonic regime was presented. A lower temperature at the exit of the supersonic jet condenses the tracer which in turn forms droplets. Conclusions: There was a significant decrease in the PLIF image intensity in the case of air. This may be attributed to the oxygen present in the air. It is shown that image adding and Gaussian image processing of PLIF images for steadystate jet improve the quality of images.