정상흐름 하에서 스포일러 부착형 해저파이프라인의 자가매설 기구에 관한 수치해석
Numerical Analysis on Self-Burial Mechanism of Submarine Pipeline with Spoiler under Steady Flow
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초록
본 연구에서는 정상흐름 하에서 스포일러가 부착된 해저파이프라인의 자가매설 기구를 분석하기 위하여 유체역학적 특성을 고정도로 해석할 수 있는 Navier-Stokes Solver(LES-WASS-2D)를 이용하였다. 본 논문에서 적용하는 수치모형의 타당성 및 유효성을 확보하기 위하여 기존의 스포일러 유무에 따른 파이프라인 주변의 흐름특성을나타낸 수리모형실험결과와 비교·분석하였다. 그리고 입사유속, 스포일러의 제원 및 배치에 따른 파이프라인 주변의 수리특성(유동, 와동, 압력)과 작용력 특성을 수치적으로 분석하였다. 그 결과 1차적으로 해저파이프에 스포일러가 부착된 경우에 투영면적이 증가함으로 인하여 배후로 빠져나가는 유속이 커지고, 동시에 배후에서 발생하는 후류에 기인한 강한 와동이 발생한다. 그리고 2차적으로는 스포일러의 영향으로 상하 비대칭적인 유동 및 와동장이발생하고, 이로 인해 비대칭적인 압력장이 형성된다. 이것은 파이프에 작용하는 힘의 비대칭성을 증가시켜 하향의유체력을 크게 발달시킨다. 이와 같은 두 가지의 큰 원인으로 인하여 스포일러 부착형 해저파이프라인이 자가매설되는 것으로 이해된다.
Abstract
This study used Navier-Stokes Solver(LES-WASS-2D) for analyzing hydrodynamic characteristics with high order in order to analyze self-burial mechanism of pipeline with spoiler under steady flow. For the validity and effectiveness of numerical model used, it was compared and analyzed with the experiment to show flow characteristics around the pipeline with and without the spoiler. And the hydraulic(flow, vortex, and pressure) and force characteristics were numerically analyzed around the pipeline according to the incident velocity, and shape and arrangement of spoiler. Primarily, if the spoiler is attached to the pipeline, the projected area is increased resulting in higher flow velocity toward the back and strong vortex caused by wake stream in the back. Secondly, the spoiler causes vertically asymmetric flow and vorticity fields and thus asymmetric pressure field. It increases the asymmetry of force on the pipe and thus develops large downward fluid force. Both of them are the causes of selfburying of the pipeline with spoiler
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