REFINED DYNAMIC STALL MODEL FOR THE S809 AEROFOIL

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NACA 0012
Legend 1 Beddoes original 3rd generation
dynamic stall model 2 Leishmans modification in
reattachment
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Comparison of unsteady airloads
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(a)
(b)

• Pitch rates (NACA 0015)
• Staring angles (NACA 23012C)
• Aerofoils (NACA series)

(c)
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Normal force reconstructions for ramp-down (Niven
et al)

Prediction with the Beddoes original model The
improved prediction
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Comparison of unsteady airloads
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(a)
(b)

• Pitch rates (NACA 0015)
• Staring angles (NACA 23012C)
• Aerofoils (NACA series)

(c)
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Pressure distributions for a ramp-down test of
the NACA 23012B (Green et al)
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Onset criterion
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Force reconstructions for NACA0012 ramp-up test
(r 0.0145)
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Force reconstructions for S809 ramp-up test (r
0.0169)
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NORMAL FORCE
PRESSURE COEFFICIENT AT 2.5 CHORD
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Non-dimensional time delay constants for
reattachment processby Green et al
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?min0 Tr ?
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Linear fits for ?min
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Reconstructions for normal force
(a) r -0.005 (b) r -0.0119
NACA 0015, ramp-down
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CN reconstruction with different gradients during
the down-stroke for NACA0012 (oscillation, ?
0.075)
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NACA 23012B
? 0.076 ?0.101 Legend 1 Beddoes original
3rd generation dynamic stall model 2 Beddoess
return and Sheng et als onset criterion
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criterion 4 New return and Sheng et als onset
criterion
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Force reconstructions for NACA0012 oscillatory
test (? 0.124 )
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Force reconstructions for S809 oscillatory test
(? 0.074 )
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Forced transition model
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Comparison clean vs. sanded
Ramp-up test
Static case
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continued
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clean vs. sanded (continued)
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Ramp-up cases (r0.0098)
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Ramp-up cases (r0.0253)
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Oscillatory cases (?0.01)
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Oscillatory cases (?0.05)
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Oscillatory cases (?0.15)
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Glasgow University Rotor Aeromechanics
Laboratory Wind Turbine Aerodynamic Modelling
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Vorticity Transport Model (VTM)

• High fidelity wake modelling
• Solves vorticity transport equation gt
• Accurate wake structure and evolution by explicit
  conservation of vorticity and control using flux
  limiters
• Efficient Weissinger-L lifting line blade
  aerodynamic model
• Rigid-blade dynamics modelled using a Lagrangian
  formulation
• Validated extensively for rotorcraft
  applications
• (Brown 2000, Brown et al. 2005 AIAA Journal)

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Turbine Wake Interaction using VTM
Contours of vorticity magnitude represent
wake Blue Rotor 1 Yellow Rotor 2 (downwind)

• Two 3-bladed turbines
• Operating in yawed crosswind conditions
• Tip speed ratio 4
• Constant pitch
• Constant rotor speed

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Turbine Lifting Performance Degradation
Wind direction
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CHRONoS

• Compressible High Resolution Overset Navier
  Stokes Solver
• Cell-vertex finite volume solver
• Structured overset meshes
• RANS turbulence modelling Spalart Allmaras
  model
• LES modelling Detached Eddy Simulation and wall
  modelled LES
• Steady / unsteady calculations, moving meshes,
  deforming meshes
• Extensively validated for rotor flows
  performance, vortex evolution, dynamic stall,
  blade vortex interaction etc.

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Flow Field in the Vicinity of a Blade Tip using
CHRONoS
Streamwise vorticity contours
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