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Parallelized Coupled Solver (PCS) Model Refinements & Extensions. Sven Schmitz University of California, Davis. GE Wind November 29 th , 2007 Greenville, SC. Outline. 2007 Parallelized Coupled Navier-Stokes/Vortex-Panel Solver - PCS

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parallelized coupled solver pcs model refinements extensions
Parallelized Coupled Solver (PCS)Model Refinements & Extensions

Sven Schmitz

University of California, Davis

GE Wind

November 29th, 2007

Greenville, SC

GE Wind - PCS

slide2

Outline

2007

Parallelized Coupled Navier-Stokes/Vortex-Panel Solver - PCS

Nacelle Model, Latest version.

2008

Extension of Lifting-Line (LL) to Lifting-Surface (LS) - PCS

Vortex-Lattice type method on the blade surface.

‘Quasi-Steady’ PCS - PCS-Q

Quasi-Steady RANS/Vortex Model, Solution methodology for N blades.

‘Unsteady’ PCS - PCS-U

Time-accurate RANS/Vortex Model, Solution methodology for N blades.

GE Wind - PCS

slide3

Navier-Stokes

Biot-Savart Law (discrete)

Boundary of

Navier-Stokes Zone

Vortex Method

Bound Vortex

Converged for …

Vortex Filament

Coupling of NS Solver with Vortex Method

2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U

GE Wind - PCS

slide4

2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U

  • Nacelle Model : GEWIND-PCS_2_0.tar (avail. to GE)
    • Nacelle is approximated as a non-rotating ‘Rankine Body’.
    • User Input : Height, Width, Axial Location (dimens. by R)
    • Model finds position/strength of Source/Sink pair.
    • Influence coefficients are added to each point in RANS boundary.
    • => … acts as a perturbation to the incoming wind speed Uwind.
    • May reduce need for complex blade/nacelle grid topology.
    • No feedback from GE so far.
  • Latest Version : GEWIND-PCS_2_1.tar (avail. to GE)
    • New version of asymptotics for influence coefficients [Chattot, 2007].

GE Wind - PCS

slide5

2007 - PCS2008 - PCS 2008 - PCS-Q 2008 - PCS-U

Extension of Lifting-Line (LL) to Lifting-Surface (LS) - PCS

  • Motivation :
    • Current PCS limited to LL at blade ¼ chord, vortex filaments emanating from trailing edge (TE).
    • Bound Vorticity GjB concentrated at LL. => Effect of LL position unclear.
    • Spread LL (respect. GjB ) along sectional chord to receive …
      • Gi,jB with

GE Wind - PCS

slide6

2007 - PCS2008 - PCS 2008 - PCS-Q 2008 - PCS-U

Extension of Lifting-Line (LL) to Lifting-Surface (LS) - PCS

  • Implementation :
    • Obtain Gi,jB from GjB using …
      • ‘Parabolic Plate’ vorticity distribution on RANS mesh.
    • Treat each blade surface element in RANS zone as an ‘Elemental Horseshoe Vortex’ located on the blade’s sectional camber line.
    • Determine influence coefficients for the Lifting-Surface (LS).
      • (… at small computational expense)
    • Satisfy the following conditions …

Trailing Vortex

Bound Vortex

GE Wind - PCS

slide7

2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U

‘Quasi-Steady’ PCS - PCS-Q

  • Motivation :
    • Current (steady) PCS limited to zero-yaw condition.
    • Extension of PCS as an efficient hybrid method for wind turbine blade analysis under yawed flow conditions.
  • Implementation :
    • Extend vortex model to account for yaw in vortex structure. Neglect ‘shed’ vorticity.
    • Solution methodology of a N-bladed wind turbine in yawed flow.
    • Converge to steady-state at each azimuth angle.

PCS-Q is suitable for small yaw angles (<15deg), yet not capable of handling ‘dynamic stall’ and/or ‘blunt trailing edge airfoils’.

GE Wind - PCS

slide8

y=0deg

CFX

Solve N blades

Vortex Model

Converged to steady-state

BC – u,v,w

y=y+Dy

1/N Revolutions completed.

2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U

‘Quasi-Steady’ PCS - PCS-Q

GE Wind - PCS

slide9

2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U

‘Unsteady’ PCS - PCS-U

  • Motivation :
    • PCS-Q limited to small yaw angles.
    • Extension of PCS-Q to a fully ‘unsteady’ hybrid method.
  • Implementation :
    • Extend vortex model of PCS-Q to account for ‘shed’ vorticity in vortex structure. (Perform subiterations on convection equation along helicoidal sheet)
    • Solution methodology of a N-bladed wind turbine in yawed flow.
    • Time-accurate solution of RANS/Vortex Model.

PCS-U is capable of handling ‘dynamic stall’ and/or ‘blunt trailing edge airfoils’ through a fully unsteady solution methodology.

GE Wind - PCS

slide10

y=0deg

CFX

Solve N blades

Vortex Model

Converged or # subiterations

Converged

BC – u,v,w

y=y+Dy

# Revolutions until solution is periodic.

2007 - PCS 2008 - PCS 2008 - PCS-Q 2008 - PCS-U

‘Unsteady’ PCS - PCS-U

GE Wind - PCS

slide11

Research Proposal 2008

Extension of Lifting-Line (LL) to Lifting-Surface (LS) - PCS

Useful extension of steady PCS.

‘Quasi-Steady’ PCS - PCS-Q

1st Step towards fully unsteady PCS, yet limited in capability.

‘Unsteady’ PCS - PCS-U

Time-accurate extension of PCS-Q.

PCS-Q/PCS-U require extended implementation/validation time. Detailed model specifications are to be discussed.

GE Wind - PCS

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