Qihui Hu
China University of Petroleum, China
Title: Investigation on the internal two-phase flow induced vibration characteristics of the marine riser system
Biography
Biography: Qihui Hu
Abstract
Statement of the Problem: With the exploitation of offshore oil and gas moving to deep water, the safety and stability of offshore equipment has drawn increasing attention. Marine riser system is the key structure connecting the offshore platform and the subsea production system, which suffer both external vortex excitation and internal two-phase flow, making the riser system under complicated dynamic loadings. Researches on the vibration of marine riser were mainly focused on the external vortex induced vibration. However, the influence of internal flow on the vibration of marine riser has not been previously studied. In this study, the vibration characteristics of the marine riser system induced by the internal flow and its influence on the vortex induced vibration were investigated by experimental and numerical method in detail.
Methodology & Theoretical Orientation: A testing apparatus for simulating the marine riser was built to measure the pressure fluctuations in the riser and the internal flow induced vibration of the riser. The numerical model of the two-phase flow in riser system was also established. The measured data and the simulation results will be compared to verify the numerical model.
Findings: The vibration of riser system could be evaluated according to the good corresponding relationship between the vibration signal at the bottom of the riser and the bottom pressure signal. The influence of the different flow patterns on the impact force of the elbow, and the effect of the geometry size on the severe slug flow parameters were both obtained.
Conclusion & Significance: The modal analysis of the riser system with different support modes showed that the possibility of resonance caused by the internal flow was very small. The vortex induced vibration of the riser considering two-way coupling effects simulation results showed that risers with different mass ratios would be motivated by the different forms of vibration.
Figure 1: Pressure fluctuation characteristic of the severe slug flow
Recent Publications
1.Xing L C and Yeung H (2013) Numerical study on mitigating severe slugging in pipeline/riser system with wavy pipe. International Journal of Multiphase Flow 53:1-10.
2. Kuiper G L, Metrikine A V, Battjes J A (2007) A new time-domain drag description and its influence on the dynamic behavior of a cantilever pipe conveying fluid. Journal of Fluids and Structures 23(3):429–445.
3. Zhang T, Cao B, Fan Y, et al. (2011) Gas-liquid flow in circular microchannel. Part I: Influence of liquid physical properties and channel diameter on flow patterns. Chemical Engineering Science 66(23):5791-5803.
4.Tay B L and Thorpe R B (2004) Effects of liquid physical properties on the forces acting on a pipe bend in gas-liquid slug flow. Chemical Engineering Research and Design 82(3):344-356.
5.Morse T L, Govardhan R N and Williamson C H K (2008) The effect of end conditions on the vortex-induced vibration of cylinders. Journal of Fluids and Structures 4(8):1227-1239.