Low-level jets (LLJs) are the wind maxima in the lowest 50 to 1000 m of atmospheric boundary layers. Due to their significant influence on the power production of wind farms, it is crucial to understand the interaction between LLJs and wind farms. In the presence of a LLJ, there are positive and negative shear regions in the velocity profile. The positive shear regions of LLJs are continuously turbulent, while the negative shear regions have limited turbulence. We present large eddy simulations of wind farms in which the LLJ is above, below, or in the middle of the turbine rotor swept area. We find that the wakes recover relatively quickly when the LLJ is above the turbines. This is due to the high turbulence below the LLJ and the downward vertical entrainment created by the momentum deficit due to the wind farm power production. This harvests the jet's energy and aids wake recovery. However, when the LLJ is below the turbine rotor swept area, the wake recovery is very slow due to the low atmospheric turbulence above the LLJ. The energy budget analysis reveals that the entrainment fluxes are maximum and minimum when the LLJ is above and in the middle of the turbine rotor swept area, respectively. Surprisingly, we find that the negative shear creates a significant entrainment flux upward when the LLJ is below the turbine rotor swept area. This facilitates energy extraction from the jet, which is beneficial for the performance of downwind turbines.
Skip Nav Destination
Effect of low-level jet height on wind farm performance
Article navigation
January 2021
Research Article|
February 23 2021
Effect of low-level jet height on wind farm performance
Srinidhi N. Gadde
;
Srinidhi N. Gadde
a)
Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics, J. M. Burgers Center for Fluid Dynamics and MESA+ Research Institute, University of Twente
, P. O. Box 217, 7500 AE Enschede, The Netherlands
a)Author to whom correspondence should be addressed: s.nagaradagadde@utwente.nl
Search for other works by this author on:
Richard J. A. M. Stevens
Richard J. A. M. Stevens
Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics, J. M. Burgers Center for Fluid Dynamics and MESA+ Research Institute, University of Twente
, P. O. Box 217, 7500 AE Enschede, The Netherlands
Search for other works by this author on:
a)Author to whom correspondence should be addressed: s.nagaradagadde@utwente.nl
J. Renewable Sustainable Energy 13, 013305 (2021)
Article history
Received:
August 22 2020
Accepted:
January 13 2021
Citation
Srinidhi N. Gadde, Richard J. A. M. Stevens; Effect of low-level jet height on wind farm performance. J. Renewable Sustainable Energy 1 January 2021; 13 (1): 013305. https://doi.org/10.1063/5.0026232
Download citation file:
Sign in
Don't already have an account? Register
Sign In
You could not be signed in. Please check your credentials and make sure you have an active account and try again.
Sign in via your Institution
Sign in via your InstitutionPay-Per-View Access
$40.00