Construction of a PIV System That Fully Resolves Velocity Vector and Gradient Tensor and Its Application on Measurements of Complex, Turbulent Flows Associated with Marine Propellers

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基本資料

Project title

Code/計畫編號

NSC98-2221-E019-062

Translated Name/計畫中文名

建立具有三維速度和完整的速度梯度之解析能力的質點影像測速系統並運用於測量船用螺槳之複雜紊流場

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=1917106

Year

2009

Start date/計畫起

01-08-2009

Expected Completion/計畫迄

01-07-2010

Bugetid/研究經費

1370千元

ResearchField/研究領域

機械工程

"為了能夠完整地測量複雜紊流場以及研究紊流模式種種的相關議題，必須採用雙光面立體式質點影像測速系統(Dual-Plane SPIV，DP-SPIV)或更高階的PIV 系統，例如 Tomographic PIV。然而傳統的DP-SPIV 系統需要用到兩台脈衝雷射以及四台PIV 相機，使得其造價昂貴，非一般流力實驗室能夠負擔。本計畫提出一替代方案，運用「雙折射晶體」(birefringent crystal)的特性和連續方程式(continuity equation)的應用，即可將設備需求大幅降低至一台脈衝雷射和三台PIV 相機。這樣簡化後的PIV 系統，仍可以解析出一平面上速度向量的三個分量和速度梯度張量的九個分量，因此非常適合於紊流的研究。我們為了要驗證此系統的精確性，提出使用有精確解(exact solution)的旋轉圓盤層流流場來作PIV 系統的評估校正之用，以強化此系統的可信度。我們將應用這個改良過的 DP-SPIV 系統來測量船用螺槳的複雜紊流場。當建立了一個完整的紊流場數據庫之後，我們會使用之前發展的紊流頻譜分析、紊流黏滯性之先驗測試和雙重平均分解法等等以紊流模式的角度來分析此數據庫，最後獲得的成果可用來改善現有的紊流模式或開發新的模式。" "In order to measure complex turbulent flows and investigate issues of turbulence modeling, it is necessary to use Dual-Plane Stereoscopic Particle Image Velocimetry (DP-SPIV) or higher-level PIV systems such as Tomographic PIV. However, the traditional DP-SPIV system requires two pulsed lasers and four PIV cameras, making it too expensive for a regular fluids lab to afford. We propose an alternative configuration of DP-SPIV consisting of applications of birefringent optics and the continuity equation, which only requires one pulsed laser and three cameras, i.e., much lower cost with the same capability of resolving full velocity vector and velocity gradient tensor on a plane. To validate the results obtained using this PIV system, the laminar flow of a rotating disk with exact solution is proposed to be used to evaluate and calibrate the PIV system. We will use this altered DP-SPIV system to measure complex turbulent flows generated by marine propellers. After this comprehensive database of turbulent flow is established, some analysis methodologies which had been developed before will be used to analyze the data in perspective of turbulence modeling. These analysis tools include turbulence spectral analysis, eddy-viscosity a-priori test, and dual-averaging decomposition. The final results can be expected to help improve the present popular turbulence models and even develop new models."

Keyword(s)

雙光面立體式質點影像測速系統
雙折射晶體
連續方程式
旋轉圓盤流場
船用螺槳
紊流
複雜流
紊流模式
紊流頻譜
Dual-Plane Stereoscopic Particle Image Velocimetry
birefringent optics
continuity equation
rotating disk flow
marine propeller
turbulent flow
complex flow
turbulence modeling
turbulence spectra

DSpace CRIS

Construction of a PIV System That Fully Resolves Velocity Vector and Gradient Tensor and Its Application on Measurements of Complex, Turbulent Flows Associated with Marine Propellers

基本資料

Description