Slug Flow and Waves Induced Motions in Flexible Riser

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Arturo Ortega ◽  
Ausberto Rivera ◽  
Carl M. Larsen
Keyword(s):  
Dynamic Analysis ◽  
Slug Flow ◽  
Distributed Simulation ◽  
Coupled Analysis ◽  
Induced Response ◽  
Element Formulation ◽  
Wave Loads ◽  
Flexible Riser ◽  
Two Phase ◽  
Slender Structure

Flexible risers provide optimum solutions for deep water offshore fields. Reliable dynamic analysis of this kind of slender structure is crucial to ensure safety against long time fatigue failure. Beyond the effects from wave loads, the influence from transient internal slug flow on the slender structure dynamics should also be taken into account. In this study, two coupled in-house codes were used in order to identify and quantify the effects of an internal slug flow and wave loads on the flexible riser dynamics. One code carries out a global dynamic analysis of the slender structure displacements using a finite element formulation. The other program simulates the behavior of the internal slug flow using a finite volume method. The slug flow is influenced by the dynamic shape of the riser, while the time varying forces from internal slug flow plus external waves will influence the shape. Hence, a fully coupled analysis is needed in order to solve the coupled problem. By means of the distributed simulation, these two programs run synchronously and exchange information during the time integration process. A test case using hydrodynamic forces according to the linear Airy wave theory coupled with an internal unstable slug flow was analyzed and the results shown amplification of the dynamic response due to the interaction between the two load types, effects on the effective tension caused by the internal two-phase flow, and influence on the internal slug flow caused by the wave-induced response.

Flexible Riser Response Induced by Combined Slug Flow and Wave Loads

2013 ◽  
Author(s):  
Arturo Ortega ◽  
Ausberto Rivera ◽  
Carl M. Larsen
Keyword(s):  
Dynamic Analysis ◽  
Slug Flow ◽  
Distributed Simulation ◽  
Coupled Analysis ◽  
Induced Response ◽  
Element Formulation ◽  
Wave Loads ◽  
Flexible Riser ◽  
Two Phase ◽  
Slender Structure

Flexible risers provide optimum solutions for deep water offshore fields. Reliable dynamic analysis of this kind of slender structure is crucial to ensure safety against long time fatigue failure. Beyond the effects from wave loads, the influence from transient internal slug flow on the slender structure dynamics should also be taken into account. In this study two coupled in-house codes were used in order to identify and quantify the effects of an internal slug flow and wave loads on the flexible riser dynamics. One code carries out a global dynamic analysis of the slender structure displacements using a finite element formulation. The other program simulates the behaviour of the internal slug flow using a finite volume method. The slug flow is influenced by the dynamic shape of the riser, while the time varying forces from internal slug flow plus external waves will influence the shape. Hence, a fully coupled analysis is needed in order to solve the coupled problem. By means of the distributed simulation these two programs run synchronously and exchange information during the time integration process. A test case using hydrodynamic forces according to the linear Airy wave theory, coupled with an internal unstable slug flow was analysed and the results show: amplification of the dynamic response due to the interaction between the two load types, effects on the effective tension caused by the internal two-phase flow, and influence on the internal slug flow caused by the wave induced response.

On Instabilities in Horizontal Two-Phase Flow

1994 ◽  
Vol 59 (12) ◽  
pp. 2595-2603
Author(s):  
Lothar Ebner ◽  
Marie Fialová
Keyword(s):  
Differential Equation ◽  
Flow Regime ◽  
Slug Flow ◽  
Annular Flow ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Annular Flows ◽  
Flow Regime Maps

Two regions of instabilities in horizontal two-phase flow were detected. The first was found in the transition from slug to annular flow, the second between stratified and slug flow. The existence of oscillations between the slug and annular flows can explain the differences in the limitation of the slug flow in flow regime maps proposed by different authors. Coexistence of these two regimes is similar to bistable behaviour of some differential equation solutions.

Pressure drop and drag reduction in two-phase non-newtonian slug flow

1976 ◽  
Vol 54 (1-2) ◽  
pp. 111-114 ◽  
Author(s):  
Lambert Otten ◽  
Abdelrahman S. Fayed
Keyword(s):  
Pressure Drop ◽  
Drag Reduction ◽  
Slug Flow ◽  
Two Phase

scholarly journals Research on the Dynamic Responses of Simply Supported Horizontal Pipes Conveying Gas-Liquid Two-Phase Slug Flow

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 83
Author(s):  
Gang Liu ◽  
Zongrui Hao ◽  
Yueshe Wang ◽  
Wanlong Ren
Keyword(s):  
Slug Flow ◽  
Peak Frequency ◽  
Dynamic Responses ◽  
Piping System ◽  
Transverse Displacement ◽  
Vibration Acceleration ◽  
Two Phase ◽  
Horizontal Pipes ◽  
Simply Supported ◽  
Superficial Gas Velocity

The dynamic responses of simply supported horizontal pipes conveying gas-liquid two-phase slug flow are explored. The intermittent characteristics of slug flow parameters are mainly considered to analyze the dynamic model of the piping system. The results show that the variations of the midpoint transverse displacement could vary from periodic-like motion to a kind of motion whose amplitude increases as time goes on if increasing the superficial gas velocity. Meanwhile, the dynamic responses have certain relations with the vibration acceleration. By analyzing the parameters in the power spectrum densities of vibration acceleration such as the number of predominant frequencies and the amplitude of each peak frequency, the dynamic behaviors of the piping system like periodicity could be calculated expediently.

An Investigation of Two-Phase Slug Flow in Inclined Pipelines

2004 ◽  
Vol 26 (7) ◽  
pp. 627-638 ◽  
Author(s):  
SUAT BAGCI
Keyword(s):  
Slug Flow ◽  
Two Phase

Experimental Characterization of Slug Flow Velocity Distribution in Two Phase Pipe Flow

2009 ◽  
Author(s):  
Afshin Goharzadeh ◽  
Peter Rodgers
Keyword(s):  
Velocity Distribution ◽  
Slug Flow ◽  
Two Phase ◽  
Significant Drop ◽  
Horizontal Pipe ◽  
Measured Velocity ◽  
Air Bubble ◽  
Velocity Magnitude ◽  
Index Matching ◽  
Refractive Index Matching

This paper presents an experimental study of gas-liquid slug flow inside a horizontal pipe. The influence of air bubble passage on liquid flow is characterized using Particle Image Velocimetry (PIV) combined with Refractive Index Matching (RIM) and fluorescent tracers. A physical insight into the velocity distribution within slug flow is presented. It was observed that the slug flow significantly influences the velocity profile in the liquid film. Measured velocity distributions also revealed a significant drop in the velocity magnitude immediately upstream of the slug nose. These findings aim to aid an understanding of the mechanism of solid transportation in slug flows.

scholarly journals STUDY ON FLUIDITY CHARACTERISTICS OF LIQUID-GAS TWO-PHASE SLUG FLOW CAUSED BY COMPRESSED AIR IN HORIZONTAL PIPELINE

2002 ◽  
Vol 18 ◽  
pp. 617-622
Author(s):  
Hajime OGAWA ◽  
Michihiro TAZAKI ◽  
Minoru OCHIAI ◽  
Shigekatsu ENDO
Keyword(s):  
Slug Flow ◽  
Compressed Air ◽  
Two Phase
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