著者

姜 東赫 佐藤 光太郎 横田 和彦

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.850, pp.17-00038-17-00038, 2017 (Released:2017-06-25)

参考文献数

15

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The present study investigates a swirl flow instability induced by a rotating cylinder between coaxial two disks as a model of a vaneless diffuser at zero flow rate. To begin with, the experiment and three-dimensional finite volume simulation were performed. The rotating cylinder was used to produce the swirl flow. Small vortices were generated from the cylinder surface. They were combing and forming one croissant-shaped toroidal vortex (CTV), which was rotating around the cylinder. Small vortices were separating from the CTV and flowing away from the cylinder. In order to investigate the cause of the swirl flow instability, a 2D stability analysis for an annular vortex street was performed. The annular vortex street became less unstable for the larger radial location and the fewer number of vortices. This implies that the vortices could be forming into one vortex as their radial locations increased. In order to validate the stability analysis, the vortex simulations were carried out. The vortices generated from the cylinder surface were forming into one cell as their radial locations increased. In order to validate the stability analysis and vortex simulation, the 2D finite volume simulation was performed. The vortices were generated from the cylinder surface. They were combining and forming one cell, which was rotating around the cylinder. The vortices were separating from one cell and flowing away from the cylinder. The frequencies of vortex rotation agreed in the experiment, the two and three-dimensional simulations. Therefore, it is considered that the 2D vortex transforms to the 3D CTV, similarly the Tayler vortex. Furthermore, all the results indicate that the 2D swirl flow instability causes the CTV, and the vortices combining to and separating from the CTV.