Open AccessImpact of wall roughness and turbulence level on the performance of a horizontal axis wind turbine with the U‐RANS solver THETA
Author(s) -
LängerMöller Annika
Publication year - 2019
Publication title -
wind energy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.743
H-Index - 92
eISSN - 1099-1824
pISSN - 1095-4244
DOI - 10.1002/we.2304
Subject(s) - mechanics , turbulence , reynolds averaged navier–stokes equations , turbulence kinetic energy , turbine , wake , physics , boundary layer , roughness length , log wind profile , wind profile power law , turbulence modeling , planetary boundary layer , classical mechanics , geometry , wind gradient , mathematics , thermodynamics
The presented work investigates the impact of different sheared velocity profiles in the atmospheric boundary layer on the characteristics of a wind turbine by modifying the wall roughness coefficients in the logarithmic velocity profile. Moreover, the rotor and wake characteristics in dependence of the turbulence boundary conditions are investigated. In variant I, the turbulence boundary conditions are defined in accordance to the logarithmic velocity profile with different wall roughness lengths. In variant II, the turbulent kinetic energy and turbulent viscosity remain independent of the velocity profile and represent the free‐stream turbulence level. With an increase of the shear in the velocity profile, the amplitudes in the 3/ r e v characteristics of rotor thrust and rotor torque, induction factors, and effective angles of attack are increased. In variant I, the overall levels of thrust coefficient are hardly affected by the velocity profiles resulting from different wall roughness length values. The power coefficient is reduced about 1 % . Conversely, compared with variant II, a difference of 2 % in the power coefficient has been detected. Moreover, the wake recovery process strongly depends on the turbulence boundary condition. Simulations are carried out on an industrial 900‐kW wind turbine with the incompressible U‐RANS solver THETA.