Wind tunnel experiments on a NACA 63₃‐418 airfoil with different types of leading edge roughness

Abstract

The NACA 633‐418 airfoil has been tested in the new Poul la Cour Wind Tunnel at the Technical University of Denmark, Risø campus, to expand the publicly available data of airfoils with leading edge roughness. The airfoil was constructed with an exchangeable leading edge. The clean airfoil showed good agreement with results from other high‐quality wind tunnels. The airfoil was equipped with three heights of zigzag tape, a trip strip, three sandpaper types, and leading edge cavities with different modifications. In general, increasing zigzag tape heights reduce the maximum lift, whereas the increase in drag is less affected by the zigzag tape height. Almost the same reduction in maximum lift is seen for the different sandpaper types. However, the drag increases with the coarseness of the sandpaper. The highest zigzag tape and coarsest sandpaper resulted in the highest penalty on the aerodynamics. A combination of sandpaper and cavities showed the largest reduction in maximum lift and the highest increase in drag.

On the extension of k−ω−SST corrections to predict flow separation on thick airfoils with leading‐edge roughness

“…The roughness height was chosen in relation to that used for wind‐energy purposes in the literature. Kruse et al 11 stated that the surface texture of the first stages of LE erosion has geometrical similarity with sandpapers. They used sandpapers with grit numbers of 40, 120, and 400 for the wind tunnel campaign of a NACA 63 3 − 418 airfoil with a of 1 m. Pires et al 32 used sandpapers of P40, P80, and P240 on the same NACA airfoil for a of 0.6 m. Recently, Nikolov et al 33 have scanned an eroded blade and classified its surface damages with grit numbers ranging from P40 to P180.…”

“…Recently, Olsen et al 9 attempted to include the effects of LE roughness in a panel method, which was, however, only validated for the LE‐roughness conditions of a 18% thick airfoil. Although several RANS studies focused on predicting LE‐roughness effects for thin airfoils, 10,11 also the numerical prediction of flow separation on thick airfoils remains inaccurate, even for smooth surfaces. Sezer‐Uzol et al 12 extensively reviewed CFD studies from 2001 to 2020 for wind‐turbine airfoils at a Reynolds number of .…”

Wind tunnel study on natural instability of the normal force on a full‐scale wind turbine blade section at Reynolds number 4.7 · 106

“…In recent collaborative wind tunnel experiments presented by Olsen et al, 15 the high sensitivity of the lift curve close to the maximum lift to small differences in the experimental execution has been demonstrated. In this study and in Krog Kruse et al, 6 lift curves were measured in four different wind tunnels (Poul La Cour tunnel at DTU's Risø campus, Delft University of Technologie, LM Wind Power, and University of Stuttgart) under similar conditions (low‐turbulent inflow (<0.1 % ), ) using 2d blade sections of type NACA63‐418. Despite these similarities, results exhibit a large dispersion of the lift curve around its maximum value.…”

“…This complicates both aerodynamic investigations and finding optimal positions when equipping the rotor blades of a turbine with aerodynamic sensors. One possibility to obtain the profile shape is by scanning the rotor blade of a wind turbine, which was for example done in Balaresque et al 5 for an investigation of “the potential of possible enhancement of energy yield by improving the aerodynamic performance” and Krog Kruse et al 6 to include leading edge damage and errosion altering the rotor blade over time.…”

Wind tunnel test of airfoil with erosion and leading edge protection

“…In this way the power losses can be predicted by summing up the influence section by section along the blade. Investigations have been carried out to predict the power losses ( [1], [2], [3], [4], [5]), but also to measure the losses in wind tunnels ( [6], [7], [8], [9], [10],). Different overviews of the problem are given and solutions are proposed ( [11], [12], [13]).…”