Experimental Investigations on the Flow Past a Circular Cylinder Just before a Backward-Facing Step

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基本資料

Project title

Code/計畫編號

MOST105-2221-E019-036

Translated Name/計畫中文名

圓柱臨背階流場之實驗研究

Project Coordinator/計畫主持人

Yi-Chih Chow

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Systems Engineering and Naval Architecture

Website

https://www.grb.gov.tw/search/planDetail?id=11876296

Year

2016

Start date/計畫起

01-08-2016

Expected Completion/計畫迄

01-07-2017

Bugetid/研究經費

592千元

ResearchField/研究領域

機械工程

"在實際的工程與力學應用中，流體流過結構物並在其周圍與後方形成渦漩流場乃是一極為常見的流場現象，而渦漩流在許多實際的工程問題上所帶來的效應往往是負面的，所以如何減少渦漩強度成為許多研究的焦點所在。本研究計畫遵循著這樣的宗旨，擬用實驗的方法，探討均勻入流通過一直立於壁面之圓柱，且此圓柱的後方馬上是一背階(backward-facing step)的低雷諾數基礎流場。背階為外部流(external flow)中產生剪切流效應(shear-flow effect)之最簡易的非平面幾何，圓柱流場乃是一經典的流體力學問題，代表了入流流過結構物這種類型的流場，所以本研究計畫嘗試觀測到背階流場所產生的剪切流效應能夠減弱圓柱周圍與後方的渦漩流強度。我們將運用流場可視化(flow visualization)與質點影像測速法(Particle Image Velocimetry, PIV)技術進行定性與定量的流場研究，探討在不同的背階高度與圓柱直徑比值下之剪切流效應變化的趨勢，並嘗試找出有效減弱渦漩流場之該幾何比例的範圍。" "In practical engineering and mechanical applications, it is an extremely common flow phenomenon that a fluid flows past a structure and forms a vortical flow field around and behind it. However, the effects of these vortices on many practical engineering problems are usually detrimental. As a result, many researchers have been focusing on how to reduce the strength of vortices. This project follows the aforementioned objective and proposes to experimentally investigate a low-Reynolds-number, fundamental flow field of a circular cylinder upright to a plane surface just before a backward-facing step with a uniform inflow. Backward-facing step is the simplest form among all the non-plane geometries that generate shear-flow effects in the type of external flow. A flow past a circular cylinder is a classical problem of fluid mechanics, representing the type of flow past a structure. Therefore, we attempt in this project to observe that the shear-flow effects generated by a backward-facing step reduce the strength of vortices around and behind a circular cylinder. We will use flow visualization and Particle Image Velocimetry (PIV) techniques to qualitatively and quantitatively investigate the flow field, study the variation trends of shear-flow effects under different ratios of the step height to the cylinder diameter, and attempt to find the range of the geometrical ratio in which the vortical flow field is effectively weakened."

Keyword(s)

圓柱流場
背階
剪切流效應
渦漩流場
流場可視化
質點影像測速法
flow past a circular cylinder
backward-facing step
shear-flow effect
vortical flow field
flow visualization
Particle Image Velocimetry

DSpace CRIS

Experimental Investigations on the Flow Past a Circular Cylinder Just before a Backward-Facing Step

基本資料

Description