A model of the flow around bilge keels of FPSO hull sections subject to roll motions - PowerPoint PPT Presentation

Loading...

PPT – A model of the flow around bilge keels of FPSO hull sections subject to roll motions PowerPoint presentation | free to view - id: 216977-ZDc1Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

A model of the flow around bilge keels of FPSO hull sections subject to roll motions

Description:

A model of the flow around bilge keels of FPSO hull sections subject to roll motions ... of added mass and damping coefficients for various sizes of bilge keel ... – PowerPoint PPT presentation

Number of Views:205
Avg rating:3.0/5.0
Slides: 23
Provided by: jjw7
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: A model of the flow around bilge keels of FPSO hull sections subject to roll motions


1
A model of the flow around bilge keels of FPSO
hull sections subject to roll motions
  • The University of Texas at Austin
  • Ocean Engineering Group
  • S. A. Kinnas, Y.-H. Yu,
  • B. Kacham, and H. S. Lee
  • Supported by the Offshore Technology Research
    Center (OTRC)

2
Introduction
  • Motivation
  • - FPSO hulls have often been subject to
    amplitudes of roll motion which seem to be larger
    than the predicted using potential flow solvers.

3
Introduction
  • Objectives
  • - Develop efficient computational model to
    predict
  • the hydrodynamic coefficients of FPSO hulls
  • in roll motions.
  • - Investigate effectiveness of bilge keels on
    roll
  • mitigation

4
Numerical Formulation
  • 2D Continuity and Momentum Equations
  • Conservation form

v
q
y
u
x
5
  • Nis Lax Wendroff method for time

B
C
  • Artificial Viscosity

D
A
Node 1
  • SIMPLE method for Pressure Correction

to satisfy the continuity equation
6
Oscillating Flow past a Flat Plate
  • Fluid domain and Boundary Conditions

7
  • Definition of Keulegan-Carpenter Number
  • Horizontal force on Plate (Morisons equation)

8
  • Background
  • - Sarpkaya OKeefes Experiment (1995)

9
  • Comparison of results from Euler and
    Navier-Stokes solvers, and Sarpkayas
    measurements

Inertia Coefficients (Cm)
Drag Coefficients (Cd)
10
  • Vorticity Streamlines at t0xT (KC1)
  • Vorticity Streamlines at tT/4 (KC1)

Navier-Stokes Solver
Euler Solver
11
  • Vorticity Streamlines at tT/2 (KC1)
  • Vorticity Streamlines at t3T/4 (KC1)

Euler Solver
Navier-Stokes Solver
12
Movie (KC1)
13
Movie (KC10)
14
  • Comparison of force over one period (KC1)

15
FPSO Hull Section Motion
  • Fluid domain and Boundary Conditions

16
  • Boundary Condition on Free-surface
  • Body motion (Roll motion)
  • Added mass and damping coefficients

2b
17
  • Grid and geometry details

18
  • Comparison of Added mass and Damping coefficients
    for Heave motion (B/D2, No bilge Keel)

19
  • Vorticity contour and Streamlines for roll motion
    (6 bilge keel, roll angle0.05(rad), and Fn
    0.8)

t 0xT
t T/4
t T/2
t 3T/4
20
  • Comparison of added mass and damping coefficients
    for various sizes of bilge keel

Added mass Coefficients
Damping Coefficients
21
Conclusions
  • Developed CFD model to solve the Euler equations
    around a flat plate, and an FPSO hull section
    subject to roll motions.
  • Validated the present method
  • - Flat plate subject to an oscillating
    flow
  • Euler results comparable to those from
    Navier-Stokes
  • and experimental data
  • - Hull in Heave motion
  • Present method predicted hydrodynamic
    coefficients well.
  • - Hull in Roll motion
  • Euler solver is capable of capturing
    the separated flow
  • from bilge keels.
  • Present solver can predict expected
    increase in added mass,
  • and damping coefficients with
    increasing bilge keel size.

22
Future Work
  • Implement viscous flow terms in the case of FPSO
    hulls with and without bilge keels
  • Use the modified hydrodynamic coefficients at
    each FPSO hull section, to correct the results
    from potential flow solvers.
  • Validate the method with existing and future
    experiments on FPSO hulls to be carried out at
    OTRCs Wave Basin.
About PowerShow.com