異重流衝擊水平圓柱之實驗流場及受力分析

Density current impact on a horizontal cylinder: Experimental flow field and force analysis

葉祈賢(Chi-Shian Yeh)

指導教授 ： 卡艾瑋

國立臺灣大學/工學院/土木工程學研究所/碩士(2012年)

https://doi.org/10.6342/NTU.2012.01993

摘要

本篇論文主要在探討異重流衝擊水平圓柱時，其流場結構以及圓柱的受力情形。橫跨海峽的海底纜線和管線受到最大的威脅就來自於濁流的破壞，在這篇文章中，我們將以簡化的實驗，即異重流衝擊水平圓柱，去模擬這樣的風險情境。實驗的目的在於同時測量圓柱受力以及流場結構，並且將兩者連結起來。在實驗中，我們利用雷射照射產生的影像去量測非穩態的速度流場和密度流場；另外一方面，我們也利用應變計去測量圓柱的受力情形。之後，我們利用Poisson方程式，代入從雷射影像得到的速度流場和密度流場，去計算出壓力流場，進而推估出圓柱受力，最後在和應變規所測量到的結果兩者相互比較。

關鍵字

異重流 ； 圓柱 ； 海底纜線 ； 應變計 ； Poisson方程式 ； 壓力場

並列摘要

The aim of this thesis is to analysis the flow field and the force as the density current passing a horizontal cylinder. Where submarine cables and pipelines across submarine canyons, there is a danger that they will be damaged or destroyed by turbidity currents. To model this risk, the present thesis reports simplified experiments in which density currents impact a horizontal cylinder. The aim of the experiments is to simultaneously measure the force and flow field, and to relate one to the other. Laser-illuminated imaging is used to measure the unsteady velocity and density fields. On the other hand, a strain gauge is used to measure the associated force exerted on the cylinder. Inverse modeling is preformed to evaluate the pressure field and force from the velocity and density measurements, using the pressure Poisson equation. The modeled force was then compared to data retrieved from the strain gauge to evaluate the accuracy.

並列關鍵字

density current ； cylinder ； submarine cable ； strain gauge ； Poisson equation ； pressure field

參考文獻

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