15 th EAWE PhD Seminar on Wind Energy 29-31 October 2019 Ecole Centrale de Nantes, France Aerodynamics of Leading-Edge Protection Tapes for Wind Turbine Blades D Major, J Palacios, M Maughmer, S Schmitz The Pennsylvania State University, State College, PA, USA E-mail: dzm305@psu.edu Keywords: New concepts, rotor/aerodynamics, leading-edge erosion, annual energy production 1 Introduction One of the primary sources of blade damage is erosion of the blade surface at the leading edge from the impact of particles such as sand, rail, or hail over time [1]. High rotational speeds and a high impact count make the leading edge in the blade tip region the most susceptible to severe damage [2]. Beside posing structural concerns [1], leading-edge erosion notably increases sectional profile drag as much as 500%, which results in Annual Energy Production (AEP) losses of up to 25% for utility-scale wind turbines [3]. To avoid these losses and protect the blades, leading-edge protection (LEP) tapes have so far proven to be a reliable and affordable solution. Standard LEP tapes on the market today are made from a polyurethane-based material and are of constant 350 µm thickness for sufficient erosion protection [4]. There are still losses associated with standard LEP tape application due to the backward- facing step at the tape edge, which transitions the boundary layer. Depending on the tape, blade geometry, and wind turbine operating conditions, drag increases anywhere from 8% to 15%, resulting in a 0.45% AEP loss for standard LEP tapes [3]. The aerodynamics of the backward-facing step of an LEP tape is not a well-studied phenomenon on utility-scale wind turbines. To investigate and reduce the aerodynamic impact of LEP tape on wind turbine performance, numerical models are developed to estimate the effect of both standard and new tape designs on cl and cd of a NACA 64-618 airfoil – a representative wind turbine tip section airfoil – at Re = 3x10 6 . Down-selected designs are experimentally verified in a wind tunnel on a full-chord tip section of a utility-scale wind turbine blade. A wind turbine design and analysis code, XTurb [5], is used to predict the power output of a representative utility-scale 1.5 MW wind turbine for the tape designs of interest to verify whether the proposed tape design reduces AEP losses compared to standard tapes currently in production. 2 Numerical Analysis Combining boundary-layer theory and the need for erosion protection, the proposed new tape design is a tapered profile that is thick in the middle and thin at the edges, reducing the height of the backward- facing step, Tedge in Figure 1. Figure 1 Schematic of a proposed tapered LEP tape design (*not to scale) Performance of an airfoil with LEP tape applied is numerically estimated using Computational Fluid Dynamics. The flow field around a NACA 64-618 airfoil with LEP tape applied is computed in STAR- CCM+ using the 2-D, incompressible Reynolds-Averaged Navier Stokes equations. The two-equation