{"title":"带同心圆孔护套的浮力容器的VIM抑制:网格方向和直径比的影响","authors":"J. Crosswell, Cheslav Balash","doi":"10.1115/OMAE2018-77251","DOIUrl":null,"url":null,"abstract":"Here, we experimentally studied the vortex-induced motion (VIM) of a free-standing riser (FSR; 1:65 scale model) with and without a porous metal screen (‘sheath’) placed co-centrically around the buoyancy can (BC). Specifically, we investigated the effects of mesh orientation (square and square rotated 45° in its own plane) and screen-BC diameter ratio (1.1 and 1.2) over a range of flow velocities. BC motions were recorded with a submersible camera; and inline (IL) and cross-flow (CF) amplitudes were then estimated with a motion tracking software. As expected, the installation of the screen changed the natural frequency of the models. Furthermore, the screen increased the reduced velocity at which the lock-in occurred, delaying it by a factor of ∼1.2 and ∼1.4 for the CF and IL respectively. All sheathed models had a prominent reduction in IL amplitudes compared to the bare/unsheathed BC; and at smaller flow velocities, the sheathed models also exhibited significantly lower CF motions, particularly those with a greater screen-BC diameter ratio.","PeriodicalId":345141,"journal":{"name":"Volume 2: CFD and FSI","volume":"1 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"2018-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"VIM Suppression for a FSR With a Co-Centric Porous Sheath Around the Buoyancy Can: Effects of Mesh Orientation and Diameter Ratio\",\"authors\":\"J. Crosswell, Cheslav Balash\",\"doi\":\"10.1115/OMAE2018-77251\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Here, we experimentally studied the vortex-induced motion (VIM) of a free-standing riser (FSR; 1:65 scale model) with and without a porous metal screen (‘sheath’) placed co-centrically around the buoyancy can (BC). Specifically, we investigated the effects of mesh orientation (square and square rotated 45° in its own plane) and screen-BC diameter ratio (1.1 and 1.2) over a range of flow velocities. BC motions were recorded with a submersible camera; and inline (IL) and cross-flow (CF) amplitudes were then estimated with a motion tracking software. As expected, the installation of the screen changed the natural frequency of the models. Furthermore, the screen increased the reduced velocity at which the lock-in occurred, delaying it by a factor of ∼1.2 and ∼1.4 for the CF and IL respectively. All sheathed models had a prominent reduction in IL amplitudes compared to the bare/unsheathed BC; and at smaller flow velocities, the sheathed models also exhibited significantly lower CF motions, particularly those with a greater screen-BC diameter ratio.\",\"PeriodicalId\":345141,\"journal\":{\"name\":\"Volume 2: CFD and FSI\",\"volume\":\"1 1\",\"pages\":\"0\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2018-06-17\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Volume 2: CFD and FSI\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1115/OMAE2018-77251\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Volume 2: CFD and FSI","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1115/OMAE2018-77251","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
VIM Suppression for a FSR With a Co-Centric Porous Sheath Around the Buoyancy Can: Effects of Mesh Orientation and Diameter Ratio
Here, we experimentally studied the vortex-induced motion (VIM) of a free-standing riser (FSR; 1:65 scale model) with and without a porous metal screen (‘sheath’) placed co-centrically around the buoyancy can (BC). Specifically, we investigated the effects of mesh orientation (square and square rotated 45° in its own plane) and screen-BC diameter ratio (1.1 and 1.2) over a range of flow velocities. BC motions were recorded with a submersible camera; and inline (IL) and cross-flow (CF) amplitudes were then estimated with a motion tracking software. As expected, the installation of the screen changed the natural frequency of the models. Furthermore, the screen increased the reduced velocity at which the lock-in occurred, delaying it by a factor of ∼1.2 and ∼1.4 for the CF and IL respectively. All sheathed models had a prominent reduction in IL amplitudes compared to the bare/unsheathed BC; and at smaller flow velocities, the sheathed models also exhibited significantly lower CF motions, particularly those with a greater screen-BC diameter ratio.