Estimation of roughness effects on wind turbine blades with vortex generators

Abstract

Surface degradation of the wind turbine blades lead to a reduction while on the other hand blade add-ons like, vortex generators, lead to an increase in the aerodynamic performance. Within this study, both the reduction due to leading edge roughness and the increase due to vortex generators in the aerodynamic performance are quantified individually first, and then it is investigated if the vortex generators would compensate for the losses due to roughness. Roughness models for the Spalart-Allamaras (SA) and k — ω SST turbulence models are implemented in the open source CFD suite SU2 and validated against theoretical predictions and experimental data. The roughness model is then applied to a commonly used airfoil section, DU97-W-300 and steady RANS simulations are carried out with SU2. Four different conditions are considered-no erosion (clean), eroded (rough), clean blade section with VGs and rough blade section with VGs. Numerical simulations are validated with experimental data for the clean airfoil section and airfoil section equipped with vortex generators. Finally, a preliminary analysis is presented for each of the cases considered on the effect of power production.

Ice Shape Convergence in Multi-Step Ice Accretion Simulations over Straight Wings

“…The surface roughness is estimated a-priori with the empirical formula of Shin [31], as a function of liquid water content (LWC), static air temperature, and freestream velocity. It provides an equivalent sand-grain roughness, 𝑘 𝑠 , which is needed by the Boeing extension for the SA turbulence model [32]. In this work, the heat transfer coefficient is computed by employing two simulations of the flow field with two different boundary conditions for the wall temperatures.…”

Assessing the impact of vortex generators on the dynamic stall behaviour of a thick airfoil

“…The effectiveness of VGs to delay flow separation and, subsequently, increase AEP has been widely studied [11][12][13]. VGs have also been shown to be effective in reducing the detrimental effects of leading edge roughness [14,15]. Conventionally designed as protruding vanes from the blade surface and placed angled with respect to the incoming flow, the primary effect of VGs is to generate streamwise vortices that enhance mixing in the boundary layer.…”

Performance improvement of a Vestas V52 850kW wind turbine by retrofitting passive flow control devices

“…In the case of wind turbines, both devices are used to improve the performance of the rotor, making them an inexpensive means of increasing energy yield. Vane VGs are used at the root region of the blade (inboard) to suppress flow separation and at the tip region to counteract the negative effects of roughness [5][6][7][8]. The expected gain is approximately 2-3% in Annual Energy Production (AEP) [1].…”