Turbulence Parameter for a tidal turbine

Turbulence Parameters

Field Data



Novo P Kyozuka Y 2017   Field measurement and numerical study of tidal current turbulence intensity in the Kobe Strait of the Goto Islands, Nagasaki Prefecture ‎

1 Turbulence Parameters   Turbulence_intensity

keywords: turbulence intensity, turbulence length scale, tidal turbine, flume

1.1 Turbulence Intensity:

  • 1-3% 1
1.75 % 2
  • 10-20% (James Mcnaughton, 2013)
Field Data: 10%-25.5%3 TI_novo2017_Goto_Islands_japan.png

1.2 Turbulent Length scale:

  • 5% of tunnel diameter1
  • 1/3 channel depth 4
  • 0.5m in water flume (turbine D=0.5m) 2
numerical DES modelling of the effect on turbulence length scale on wake recovery rate of a 1/20th scale model (0.5m) of HWTT 2 comparing ℓ =0.5m and 1m, the results shows that

1.3 Turbulence Parameters for e387 turbine

U=0.6m/s, Turbulent length scale:
  • based on BL thickness (user guide, fluent)
    • in a turbulent BL, ℓ is the order of δ99, ℓ~δ99
ℓ = 0.4 δ99 =0.4 * 0.35mm=1.4e-4m where BL thickness is based on post -processing of RANS
  • based on channel depth 4
ℓ= 1/3 channel depth = 1/3*1.6=0.53m
  • Based on Turbulent viscosity ratio, (user guide, fluent)
for external flow, 1< μt/μ <10 if I=1%, and μt /μ =5, then ℓ = 1.25e-2m
ℓ= μt /(ρ Cμ1/4 k1/2)

1.4 Turbulence Parameter in Numerical Modelling

Footnotes:

1
Luis Eca 2009 Report, Best Practice Guidelines for the application of Computational Fluid Dynamics in Marine Hydrodynamics
2
Ebdon, T., et al. "Modelling the Effect of Turbulence Length Scale on Tidal Turbine Wakes using Advanced Turbulence Models."
3
Novo P Kyozuka Y 2017 Field measurement and numerical study of tidal current turbulence intensity in the Kobe Strait of the Goto Islands, Nagasaki Prefecture
4
Blackmore, T., et al. "The sensitivity of actuator-disc rans simulations to turbulence length scale assumptions." (2011).
Created: 2018-07-22 Sun 21:11
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