Wind Farm Wake Loss Factor Calculator

Quantify the fractional power loss a downstream turbine experiences because of the velocity deficit created by an upstream rotor. Provide free-stream wind speed, turbine spacing, thrust coefficient, and optionally a wake decay constant to apply the Jensen/Park wake model.

Mean hub-height wind speed upwind of the farm.
Centreline distance to the downstream turbine expressed in rotor diameters.
Dimensionless thrust coefficient from the turbine power curve.
Leave blank to apply a default 0.05 decay constant for offshore terrain.

Educational simplification of the Jensen/Park wake model; calibrate with site measurements for investment decisions.

Examples

  • 9.0 m/s free-stream, 10D spacing, C_T 0.76, k default ⇒ Wake loss factor: 33.59% power deficit | Rotor wind speed: 7.85 m/s | Net power retention: 66.41%
  • 10.5 m/s free-stream, 12D spacing, C_T 0.78, k 0.09 ⇒ Wake loss factor: 15.12% power deficit | Rotor wind speed: 9.94 m/s | Net power retention: 84.88%

FAQ

What range is reasonable for the wake decay constant?

Use 0.04–0.06 for offshore arrays, 0.07–0.10 for onshore projects with moderate surface roughness, and up to 0.15 in complex terrain or forested sites.

How do multiple upstream turbines affect the result?

This single-wake model captures the deficit from one rotor directly upstream. For multiple wakes, superpose deficits using root-sum-square or energy-balance methods in a layout tool.

Can I convert power retention into annual energy yield?

Multiply the net power retention percentage (expressed as a decimal) by the standalone turbine's expected energy to estimate wake-adjusted production before other losses.

Does the calculator account for turbulence intensity?

Not directly. Turbulence influences the decay constant. Increase k to reflect higher ambient turbulence that accelerates wake recovery.

Additional Information

  • The Jensen/Park wake model assumes a top-hat wake profile and linearly expanding wake radius characterised by the decay constant k.
  • Express spacing in rotor diameters so array layout studies can mix turbines of different sizes without re-scaling distances.
  • Power retention approximates how much of the upstream turbine's power output remains available downstream before electrical losses.
  • Leaving the decay constant blank defaults to 0.05, typical for smooth offshore conditions; rough onshore terrain may require 0.08–0.1.

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