Universal Journal of Mechanical Engineering Vol. 5(2), pp. 35 - 46
DOI: 10.13189/ujme.2017.050202
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Vortex Induced Vibration of Subsea Umbilicals: A Case Study of Deep Offshore Nigeria

Ugochukwu Kenneth Udeze , ChinwubaVictor Ossia ^*
Offshore Technology Institute, School of Graduate Studies, University of Port Harcourt, Nigeria

ABSTRACT

This study involved using typical Joint North Sea Wave Project (JONSWAP) based Umbilical design of lengths 3044m, 3215m, 4481m and 2873m clamped to Floating Production Storage and Offloading (FPSO) unit in Deep Offshore Nigeria at water depth of 2000m. Relevant metOcean data was used to simulate the environmental conditions. The process was simulated using different wave spectra on OrcaFlex software. JONSWAP spectra results for Umbilical-1 to Umbilical-4 at near-surface current (End A: 850m) showed a Transverse Vortex Force (TVF) range of 0.0115 – 0.018kN/m; 0.009 – 0.0149kN/m; 0.006-0.014kN/m; 0.0048 -0.009kN/m, respectively. For Ochi-Hubble spectra, the corresponding TVF range obtained include: 0.004 - 0.0305kN/m; 0.004 - 0.028kN/m; 0.003 - 0.027kN/m; 0.003 - 0.0232kN/m, respectively. JONSWAP spectra showed maxima (t, TVF) values of (0.013, 0.018); (0.012, 0.0149); (0.008, 0.014); (0.0074, 0.009) from Umbilical-1 to Umbilical-4, respectively. With the Ochi-Hubble spectra, maxima (t, TVF) values were (0.018, 0.0305); (0.016, 0.028); (0.013, 0.027); (0.0141, 0.0232) for Umbilical-1 to Umbilical-4, respectively. Hence, maxima (t, TVF) values were greater for Ochi-Hubble than JONSWAP. Simulation plots indicate that adjusting the peakedness parameter (γ) of the JONSWAP spectra does not give the required accuracy for this region. Therefore, using a JONSWAP based Umbilical design in Ochi-Hubble environment like Offshore Nigeria shows higher vortex induced vibration (VIV) at near surfaces leading to higher TVF, and higher fatigue damage tendency.

KEYWORDS
Transverse Vortex Force, Ochi-Hubble Spectra, JONSWAP Spectra

Cite This Paper in IEEE or APA Citation Styles
(a). IEEE Format:
[1] Ugochukwu Kenneth Udeze , ChinwubaVictor Ossia , "Vortex Induced Vibration of Subsea Umbilicals: A Case Study of Deep Offshore Nigeria," Universal Journal of Mechanical Engineering, Vol. 5, No. 2, pp. 35 - 46, 2017. DOI: 10.13189/ujme.2017.050202.

(b). APA Format:
Ugochukwu Kenneth Udeze , ChinwubaVictor Ossia (2017). Vortex Induced Vibration of Subsea Umbilicals: A Case Study of Deep Offshore Nigeria. Universal Journal of Mechanical Engineering, 5(2), 35 - 46. DOI: 10.13189/ujme.2017.050202.