Active Separation Control on Thick Wind Turbine Airfoils by Means of Steady and Unsteady Blowing

IET Renewable Power Gen

Parkinson

Lutz

2022

Self Cite

Wind turbines often have lower performance and experience higher loading in real operation compared to the original design performance. The reasons stem from the influences of complex atmospheric turbulence, blade contamination, surface imperfection and airfoil‐shape changes. Engineering models used for designing wind turbines are limited to information derived from blade sectional datasets, while details on the three‐dimensional blade characteristics are not captured. In these studies, a dedicated strategy to improve the prediction accuracy of engineering model calculations will be presented. The main aim is to present an elaborated effort to obtain a better estimate of the turbine loads in realistic operating conditions. The present studies are carried out by carefully utilizing data from high fidelity Computational Fluid Dynamics (CFD) computations into Blade Element Momentum (BEM) and Vortexline methods. The results are in a good agreement with detailed field measurement data of a 2.3 MW turbine. The studies are further extended to a large turbine having a rated power of 10 MW to provide an overview of its suitability for large turbines. Finally, calculations of the wind turbine under a realistic IEC design load case are demonstrated. The studies highlight important considerations for engineering modeling using BEM and Vortexline methods.

Section: Flowermentioning

confidence: 99%

Utilizing high fidelity data into engineering model calculations for accurate wind turbine performance and load assessments under design load cases

IET Renewable Power Gen

Parkinson

Lutz

2022

Self Cite

“…This has been reported for instance in ref. [4][5][6][7][8][9][10][11][12][13]. The shape of these airfoils have stronger adverse pressure gradient than thin airfoils, and hence promotes stronger flow separation.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic and Acoustic Simulations of Thick Flatback Airfoils Employing High Order DES Methods

Seel

Lutz

et al. 2022

Advcd Theory and Sims

Self Cite

The results of high fidelity aerodynamic and acoustic computations of thick flatback airfoils are reported in the present paper. The studies are conducted on a flatback airfoil having a relative thickness of 30% with the blunt trailing edge thickness of 10% relative to chord. Delayed Detached‐Eddy Simulation (DDES) approaches in combination with high order (5th) flux discretization WENO (Weighted Essentially Non‐Oscillatory) and l2Roe$l^{2}Roe$ Riemann solver are employed. Two variants of the DES length scale calculation methods are compared. The results are validated against experimental data with good accuracy. The studies provide guideline on the mesh and turbulence modeling selection for flatback airfoil simulations. The results indicate that the wake breakdown is strongly influenced by the spanwise resolution of the mesh, which directly contributes to the prediction accuracy especially for drag force and noise emission. The Reynolds normal stress u′u′¯$\overline{u^{\prime }u^{\prime }}$ and the u′v′¯$\overline{u^{\prime }v^{\prime }}$ Reynolds stress component have the largest contributions on the mixing process, while the contribution of the u′w′¯$\overline{u^{\prime }w^{\prime }}$ component is minimal. Proper orthogonal decomposition is further performed to gain deeper insights into the wake characteristics.

Investigations of active boundary layer control using DDES

Rumpf

2020

J. Phys.: Conf. Ser.

The root area of a wind turbine rotor is usually constructed by very thick airfoils with a relative thickness of more than 35%. An airfoil at that thickness is characterized with strong flow separation. To solve this issue, vortex generators can be used as an active control in order to stabilize the airflow and improve the aerodynamic performance, consequently. Boundary layer control however, investigated employing numerical techniques, strongly depend on the employed method as well as the mesh especially due to a weak vortex conservation in the RANS model. Using the method of Delayed detached eddy simulation (DDES) the solution can benefit from effort-efficient boundary layer modeling as well as LES vortex resolving apart from the surface. The present studies aims to investigate suitable numerical approach mesh dependencies in comparison to experimental data, for application to thick airfoil in future studies.