Two-phase flow induced vibrations in a marine riser conveying a fluid with rectangular pulse train mass

Abstract

A riser conveys fluids from a subsea system to a host floater; however, oil and gas phases may alternate, increasing pipe's stress and damaging downstream facilities. This paper studies the nonlinear planar vibrations of a steel lazy wave riser excited by slug flow. The employed formulations comprise the Euler-Bernoulli beam model and the steady plug-flow model with a time-space-varying mass per unit length in the form of a rectangular pulse train. The equations are solved by a Runge-Kutta finite difference scheme and frequency-response curves are constructed for effective tension, curvature, usage factor and fatigue damage. The results offer a useful insight of the slugging frequencies and slug lengths that may receive attention during the design of risers.

Fatigue reliability assessment of offshore catenary risers conveying internal slug flow

“…An experiment performed by Zhu et al is utilized to evaluate the efficacy of the ALE-ANCF simulation program. 22 Table 1 presents the main parameters of the flexible riser model. It should be noted that the values of superficial velocity and slug flow length in Table 1 are estimated approximations, derived from the volumetric flow rates of the liquid and gas.…”

“…An experiment performed by Zhu et al. is utilized to evaluate the efficacy of the ALE‐ANCF simulation program 22 . Table 1 presents the main parameters of the flexible riser model.…”

“…Consequently, the nonuniform density and volume of the two-phase flow in slug flow can result in increased vibration amplitudes and higher stresses, leading to elevated fatigue of risers. Cabrera-Miranda and Paik 22 conducted a numerical study of a steel lazy wave riser (LWR) convey slug flow case and showed that the slug flow may yield a significant diminishing of the fatigue life or attain the ultimate limit state. To investigate the fatigue contributions of slug flow, Jeong et al 23 estimated fatigue of an LWR with and without slug flow by using the global dynamic analysis, it was concluded that the slug flow has a significant influence on the sag bend position of the LWR.…”

Influence of Pulsating Internal Fluid Flow on the Nonlinear Dynamics of Marine Risers

“…The results showed that the increased internal flow speed can increase the amplitude, but the vibration frequency can decrease. Cabrera-Miranda and Paik [18] used the Euler-Bernoulli beam model and the plug-flow model for the pipe structure and the internal fluid of the riser, respectively. The study utilized the finitedifference method, to solve for the spatial domain, and the Rung-Kutta for the temporal part to reveal the dynamics of the internal flow.…”

Boundary vibration suppression for a flexible three‐dimensional marine riser against unknown sensor and actuator faults

“…In offshore engineering, more and more research results have emerged 1‐3 . A marine riser is one of the most typical systems and can be used as a curved pipe to convey fluid oil to the seabed 4 . Driven by engineering application, flexible material has the advantage of light weight, low energy consumption and fast speed, which are widely used in modern offshore engineering.…”