Direct measurements of velocity vectors by digital picture processing. (Part I).
Shigeru Aso, Atsuhiro SAKAMOTO, Masanori HAYASHI, Yasuo IDE · JOURNAL OF THE FLOW VISUALIZATION SOCIETY OF JAPAN · 1989
A new type of flow visualization method with helium bubbles has been developed. This method is based on the ordinary helium bubble method which uses soap bubbles filled with helium gas. The bubbles are injected into the flow in front of the body or injected into the separated region directly. The traces of bubbles are photographed twice in a proper interval. The velocity vectors are calculated by measuring the distance between two traces of each bubble.In the determination of the position of each bubble and distinction of starting point and ending point of traces as a velocity vector digital picture processing technique is used. In the process data are input from video camera and stored microcomputer. Determination of edge of each trace and combination of a pair of traces are processed automatically. The results show a good agreements with previous results. The separated flow fields around two-dimensional wing are visualized qualitatively by the method. The results have proved that the method is quite useful for qualitative flow visualization.