Jumper Analysis with Interacting Internal Two-phase Flow Leonardo - - PowerPoint PPT Presentation
Jumper Analysis with Interacting Internal Two-phase Flow Leonardo - - PowerPoint PPT Presentation
Jumper Analysis with Interacting Internal Two-phase Flow Leonardo Chica University of Houston College of Technology Mechanical Engineering Technology March 20, 2012 Overview Problem Definition Jumper Purpose Physics
Overview
- Problem Definition
- Jumper
- Purpose
- Physics
- Multiphase Flow
- Flow Induced Turbulence
- Two-way Coupling
- Conclusions
- Future Research
- Q & A
Problem Definition
A fluid structure interaction (FSI) problem in which the internal two-phase flow in a jumper interacts with the structure creating stresses and pressures that deforms the pipe, and consequently alters the flow of the fluid. This phenomenon is important when designing a piping system since this might induce significant vibrations (Flow Induced Vibration) that has effects
- n fatigue life of the jumper.
Jumper
Types:
- Rigid jumpers: U-shaped, M-shaped, L or Z shaped
- Flexible Jumpers
www.oceaneering.com
Manifold Tree
Purpose
- Couple FEA and CFD to analyze flow induced vibration in
jumper.
- Assess jumper for Flow Induced Turbulence to avoid fatigue
failure.
- Study the internal two-phase flow effects on the stress
distribution of a rigid M-shaped jumper.
- Find a relationship between the fluid frequency, structural
natural frequency, and response frequency.
Fluid Dynamics
- Conservation of mass:
- Conservation of momentum:
X Component: Y Component: Z Component:
ππ ππ’ + πΌ ΟV = 0 π(ππ£) ππ’ + πΌ ππ£π = β ππ ππ¦ + πππ¦π¦ ππ¦ + πππ¦π§ ππ§ + πππ¨π¦ ππ¨ + ππ
π¦
π(ππ) ππ’ + πΌ πππ = β ππ ππ§ + πππ¦π§ ππ¦ + πππ§π§ ππ§ + πππ¨π§ ππ¨ + ππ
π§
π(ππ₯) ππ’ + πΌ ππ₯π = β ππ ππ¨ + πππ¦π¨ ππ¦ + πππ§π¨ ππ§ + πππ¨π¨ ππ¨ + ππ
π¨
Fluid Dynamics
- Conservation of Energy:
π ππ’ π π + π2 2 + πΌ π π + π2 2 π = ππ + π ππ¦ π ππ ππ¦ + π ππ§ π ππ ππ§ + π ππ¨ π ππ ππ¨ β π π£π ππ¦ β π ππ ππ§ β π π₯π ππ¨ + π π£ππ¦π¦ ππ¦ + π π£ππ§π¦ ππ§ + π π£ππ¨π¦ ππ¨ + π πππ¦π§ ππ¦ + π πππ§π§ ππ§ + π πππ¨π§ ππ¨ + π π₯ππ¦π¨ ππ¦ + π π₯ππ§π¨ ππ§ + π π₯ππ¨π¨ ππ¨ + πππ
Solid Mechanics
- Elasticity equations
πππ¦ ππ¦ + πππ¦π§ ππ§ + πππ¦π¨ ππ¨ + ππ = 0 πππ¦π§ ππ¦ + πππ§ ππ§ + πππ§π¨ ππ¨ + π
π = 0
πππ¦π¨ ππ¦ + πππ§π¨ ππ§ + πππ¨ ππ¨ + ππ = 0
http://en.wikiversity.org
Multiphase Flow
- Horizontal pipes
Dispersed bubble flow Annular flow Plug flow Slug flow Stratified flow Wavy flow ππππ£ππ ππ πππ’πππ ππ π₯ππ’ππ (π½) = π€πππ£ππ ππ π ππππ π‘ππππππ’ ππππ£ππππ ππ§ π₯ππ’ππ π€πππ£ππ ππ π’βπ ππππ π‘ππππππ’
Bratland, O. Pipe Flow 2: Multi-phase Flow Assurance
- Vertical Pipes
Multiphase Flow
Dispersed bubble flow Slug flow Churn flow Annular flow
Bratland, O. Pipe Flow 2: Multi-phase Flow Assurance
Slug Flow
- Terrain generated slugs
- Operationally induced surges
- Hydrodynamic slugs
β Instability in stratified flow β Gas blocking by liquid β Gas entrainment
http://www.feesa.net/flowassurance
Jumper Model
Feature Value Cross section Outer Diameter (in) 10.75 Wall thickness (in) 1.25 Carbon Steel Properties Density (lb/in3) 0.284 Young Modulus (psi) 3x107 Poisson Ratio 0.303
Flow Selected Parameters
- Velocity: 10 ft/s
- 50% water β 50 % air
Volk, M., Delle-Case E., and Coletta A. Investigations of Flow Behavior Formation in Well-Head Jumpers during Restart with Gas and Liquid
Geometry Models
- Two-bend model: Two-way coupling simulation
- Jumper model: CFD simulation
Flow Induced Turbulence
- Formation of vortices (eddies) at the boundary layer of the wall.
- Dominant sources:
β High flow rates β Flow discontinuities (bends)
- High levels of vibrations at the first modes
- f vibration.
- Assessment for avoidance induced fatigue
failure.
Flow Induced Turbulence Assessment
- Likelihood of failure (LOF):
πππΊ = ππ€2 πΊ
π€
πΊππΊ
- 0.5 β€ LOF < 1 : main line should be redesigned, further analyzed, or
vibration monitored. Special techniques recommended (FEA and CFD).
Flow Section Value Multiphase Οv2 (kg/(mβs2)) 4,649.5 FVF (Fluid Viscosity Factor) 1 Fv (Flow Induced Vibration Factor) 8,251.76 LOF 0.5634
Engineering Packages
- Computational Fluid Dynamics (CFD)
β STAR-CCM+ 6.04
- Finite Element Analysis (FEA)
β Abaqus 6.11-2
Two-way Coupling
- CFD and FEM codes run simultaneously.
- Exchange information while iterating.
- Work for one-way coupled or loosely-coupled problems.
CFD flow solution Exporting Fluctuating Pressures FEA structural solution Exporting displacements and stresses
Finite Element Analysis (FEA)
Two-bend case parameters Element type Linear elastic stress hexahedral
- No. of elements
9,618 Time step 0.003 s Minimum Time step: 1.0x10e-9 s
Modal Analysis: Two-bend Model
Determine the structural natural frequencies
Top view (1st mode) Isometric view (1st mode)
Mode No. Frequency (Hz) Period (s) 1 1.079 0.927 2 2.320 0.431 3 3.289 0.304 4 5.366 0.186
Modal Analysis: Jumper Model
Mode No. Frequency (Hz) Period (s) 1 0.20485 4.882 2 0.34836 2.871 3 0.46962 2.129 4 0.52721 1.897
Top view (1st mode) Isometric view (1st mode)
Computational Fluid Dynamics (CFD)
Two-bend case parameters Element type Polyhedral + Generalized Cylinder
- No. of elements
295,000 Time step (s) 0.003 Total physical time (s) 20 Physics Models Time Implicit Unsteady Turbulence Reynolds-Averaged Navier-Stokes (RANS) RANS Turbulence SST K-Omega Multiphase Flow Volume of Fluid (VOF)
Two-bend Case: Volume Fraction
Volume fraction of water after 7.4 s
Two-bend Case: Slug Frequency
Two-bend case Slug Period (s) 0.96 Slug Frequency (Hz) 1.0417 Natural Frequency 1st mode (Hz) 1.079
Jumper Simulation
- Similar flow patterns in first half of jumper as one-bend and two-bend
cases
- Mesh: 640159 cells
- Time step: 0.01 s
- Total Physical time: 30 s
Jumper Simulation: Volume Fraction
0.1 0.2 0.3 0.4 0.5 0.6 0.7 5 10 15 20 25 30 Volume Fraction Time (s)
Volume Fraction of Water
Plane A Plane B
Plane A Plane B
Volume fraction of water after 22.5 s
Jumper Simulation: Pressure Fluctuations
- 4
- 2
2 4 6 8 5 10 15 20 25 30 35 Pressure (psi) Time (s) 1st bend 3rd bend 4rd bend 2nd bend
3rd bend 4th bend
Section
- Max. Pressure (psi)
3rd bend 7.2 4th bend 7.1
Displacements
Maximum displacement: 0.0725 in after 8.28 s
Von Mises Stress
πππ = 2 2 π2 β π1 2 + π3 β π1 2 + π3 β π2 2
π1 , π2, and π3: principal stresses in the x, y, and z direction Maximum von mises stress: 404 psi < Yield strength: 65000 psi
Stress vs. Time
5 10 15 20 25 30 35 40 0.0 2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 Stress (psi) Time (s)
Von Mises Stress vs Time
Time History in 2nd bend Period between peaks (s) 6 Response frequency (Hz) 0.167
Conclusions
- For Flow Induced Turbulence assessment, modal analysis and CFD is
required to check stability and likelihood of failure.
- Slug frequency falls close by the structural natural frequency for the two-
bend model.
- A sinusoidal pattern was found for the response frequency.
- Two-way coupling is a feasible technique for fluid structure interaction
problems.
Future Research
- Further FSI analysis for the entire jumper.
- Apply a S-N approach to predict the fatigue life of the two-bend model
and the entire jumper.
- Include different Reynolds numbers, free stream turbulence intensity
levels, and volume fractions.
- Couple Flow-Induced Vibration (FIV) and Vortex-Induced Vibration (VIV).
Thank You
- University of Houston:
β Raresh Pascali: Associate Professor β Marcus Gamino: Graduate student
- CD-adapco:
β Rafael Izarra, Application Support Engineer β Tammy de Boer, Global Academic Program Coordinator
- MCS Kenny:
β Burak Ozturk, Component Design Lead
- SIMULIA:
β Support Engineers
References
- Banerjee. Element Stress. Wikiversity. 22 Aug. 2007. Web. 17 Jul. 2011.
<http://en.wikiversity.org/wiki/File:ElementStress.png>
- Bratland, O. Pipe Flow 2: Multi-phase Flow Assurance. 2010. Web. 14 Oct 2011.
<http://www.drbratland.com/index.html >
- Blevins, R. D. Flow Induced Vibration. Malabar, FL: Krieger Publishing Company, 2001.
- Energy Institute. Guidelines for the avoidance of vibration induced fatigue failure in
process pipework. London: Energy Institute, 2008. Electronic.
- Feesa Ltd, Hydrodynamic Slug Size in Multiphase Flowlines. 2003.
<http://www.feesa.net/flowassurance>
- Izarra, Rafael. Second Moment Modeling for the Numerical Simulation of Passive Scalar
Dispersion of Air Pollutants in Urban Environments. Diss. Siegen University, 2009. Print.
- Mott, Robert. Machine Elements in Mechanical Design. Upper Saddle River: Pearson
- --. Applied Fluid Mechanics. Prentice Hall 6th edition, 2006. Print.
- Timoshenko, S. and Goodie, J. Theory of Elasticity. New York: 3rd ed. McGraw-Hill, 1970.
Print.
- Volk, M., Delle-Case E., and Coletta A. βInvestigations of Flow Behavior Formation in
Well-Head Jumpers during Restart with Gas and Liquidβ. Office of Research and Sponsored Programs: The University of Tulsa. (2010): 10-41.