Transitional Characteristics of Three-Dimensional Vortices Issued from an Axisymmetric Body. Three-dimensional flow visualization with ligh-sheet scanning method

Autor: Hiroshi Sakamoto, Hiroyuki Haniu, Shinichi Hirata, Yoshihiro Obata
Rok vydání: 1994
Předmět:
Zdroj: TRANSACTIONS OF THE JAPAN SOCIETY OF MECHANICAL ENGINEERS Series B. 60:1125-1132
ISSN: 1884-8346
0387-5016
DOI: 10.1299/kikaib.60.1125
Popis: Three-dimensional flow visualization of a vortex-generating region behind a conical axisymmetric body was conducted in a hydraulic flume using computer image-processing techniques. In order to obtain three-dimensional images, a light sheet set normal to the free-stream direction is swept mechanically in the longitudinal direction with periodic motion, and a series of cross-sectional images at very short time intervals of 1/30 second for each sweep were digitized by a video digitizer and input into the computer data storage. Then the time coordinate of each cross-sectional image is converted to a spatial coordinate obtained from the phase information of the sweep to create quasi-instantaneous three-dimensional image data. From the time variation of the three-dimensional images, transitional characteristics of flow behind the body were clarified. In particular, the switching mechanism of issuing direction of spoon-type vortex at Reynolds number of 300 was clarified.
Databáze: OpenAIRE