CT Visualization of High-Speed Unsteady Flow Field by using High-Speed-Background-Oriented Schlieren

摘要

This paper describes quantitative flow visualization of large-scale shock waves generated by open-air experiment such as safetyrnexamination of explosives. Overpressure prediction, density distribution behind shock front, and the x-t diagram of shock wavesrngenerated by explosion are shown. The visualization method used here was background-oriented Schlieren method combined withrna high-speed camera (Hi-BOS). The experiment was piggyback one on the explosive safety examination held by Japanrngovernment. A high-speed video camera, Phantom V730, with 100,000 frames per second, 480 pixels by 680.pixels of imagesrnsize, and 33 microseconds of exposure time, was used as an image-recording device. The cross-correlation function was used torndetermine background image shift with eight by eight of interrogation window. Numerical analysis using hydro-code, AUTODYN,rnwas made to theoretically estimate both overpressure history and profile of density behind the shock front. Our experimentalrnresults showed that overpressure profile and density profile behind shock wave, was successfully extracted from the imagesrnobtained with Hi-BOS. The comparison of those values with numerically obtained ones showed good agreement except the densityrnprofile behind shock wave. Based on these findings, we proposed three-dimensional shock wave visualization in open-airrnexperiment.