굽은 형상을 가지는 라이저 주위 유동 특성에 관한 연구

• Published in: Han-guk haeyang gonghak hoeji (Online) Vol. 33; no. 2; pp. 123 - 130
• Main Authors: 정재환(Jae-Hwan Jung), 오승훈(Seunghoon Oh), 남보우(Bo-Woo Nam), 박병원(Byeongwon Park), 권용주(Yong-Ju Kwon), 정동호(Dongho Jung)
• Format: Journal Article
• Language: Korean
• Published: 한국해양공학회 2019
• Subjects: 해양공학; Flow incident angle 유동 입사각; Sectional force coefficients 단면별 유체력 계수; Curved riser 굽은 라이저
• ISSN: 1225-0767; 2287-6715
• DOI: 10.26748/KSOE.2018.079

The flow around a curved riser exposed to the current in various directions was investigated at a Reynolds number of 100 using a numerical simulation. The present study found that the flow features of the curved riser were distinct from those of a straight riser as a result of its large radius of curvature. Namely, there were various wake patterns according to the flow's incident angle. As the incident angle increased from $0^{\circ}$ to $90^{\circ}$, a two-row street of vortices that developed along the centerline of the curved riser became more apparent. However, when the incident angle approached $180^{\circ}$ from $90^{\circ}$, these vortices were completely suppressed by the interaction between the wake and an axial flow induced by the curvature of the riser. To identify this feature, the sectional force coefficients were also considered, and it was found that the force coefficients could be different from those found in a sectional analysis based on the strip theory when investigating vortex-induced vibration. As a result, this kind of study would be important to realistically estimate the riser VIV (vortex-induced vibration) and fatigue life, and a new force coefficient database that includes the three-dimensional effect should be established.