Experimental and Numerical Icing Penalties of an S826 Airfoil at Low Reynolds Numbers

Abstract

Most icing research focuses on the high Reynolds number regime and manned aviation. Information on icing at low Reynolds numbers, as it is encountered by wind turbines and unmanned aerial vehicles, is less available, and few experimental datasets exist that can be used for validation of numerical tools. This study investigated the aerodynamic performance degradation on an S826 airfoil with 3D-printed ice shapes at Reynolds numbers Re = 2 × 105, 4 × 105, and 6 × 105. Three ice geometries were obtained from icing wind tunnel experiments, and an additional three geometries were generated with LEWICE. Experimental measurements of lift, drag, and pressure on the clean and iced airfoils have been conducted in the low-speed wind tunnel at the Norwegian University of Science and Technology. The results showed that the icing performance penalty correlated to the complexity of the ice geometry. The experimental data were compared to computational fluid dynamics (CFD) simulations with the RANS solver FENSAP. Simulations were performed with two turbulence models (Spalart Allmaras and Menter’s k-ω SST). The simulation data showed good fidelity for the clean and streamlined icing cases but had limitations for complex ice shapes and stall.

Aerodynamics of an airfoil with leading‐edge icing

“…According to Etemaddar et al, 16 the increase in drag is higher than the reduction in lift for streamlined ice accretions, so the reduced performance of wind turbines is mostly due to increased drag on the airfoil. This agrees with the results from Hann et al 20 The relative difference is smaller for high α, where the reduction in lift is more prominent. 16 Some studies report increased lift of the airfoil for some icing geometries at high α.…”

“…38 The lift and drag, as well as the surface pressure distribution of the airfoil, have been characterised experimentally for Re c on the order of 10 5 . 18,20,39,40 The parameters have been shown to be Re-independent for Re c > 4.0 × 10 5 . 41 The closed-loop low-speed wind tunnel at the Norwegian University of Science and Technology (NTNU) was employed for this experimental campaign.…”

“…[12][13][14] Several experiments have been performed to measure the forces acting on an airfoil subjected to icing. 10,[15][16][17][18][19][20] The pressure distribution of the flow has also been evaluated for various icing geometries. 18,20,21 Increased drag and reduced lift are observed in most studies.…”

“…10,[15][16][17][18][19][20] The pressure distribution of the flow has also been evaluated for various icing geometries. 18,20,21 Increased drag and reduced lift are observed in most studies. The magnitude of these parameters is dependent on the geometry of the icing profile, the airfoil, the Reynolds number (Re), α, and icing conditions.…”

“…Simulating the flow around a contaminated airfoil is notoriously difficult given the multiscale effects on the developing boundary layer; the flow immediately adjacent to the airfoil is itself modelled in all computational fluid dynamics except for direct numerical simulations, which are too expensive for such problems. 20,23…”