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5DLQ HURVLRQ QXPHULFDO PRGHOLQJ DSSOLHG WR PXOWL±0: RII±VKRUH ZLQG WXUELQH VI International Conference on Computational Methods in Marine Engineering MARINE 2015 F. Salvatore, R. Broglia and R. Muscari (Eds) RAIN EROSION NUMERICAL MODELING APPLIED TO MULTI-MW OFF-SHORE WIND TURBINE A. CORSINI*†, A. CAS TORRINI*, P. VENTURINI* AND F. RISPOLI * Sapienza University of Rome, Dept. of Mechanical and Aerospace Engineering, Via Eudossiana 18, 00184 Roma, Italy. Tel: +39 0644585231 SED Soluzioni Energia e Diagnostica Srl, Via Asi Consortile 7, 03013 Ferentino, Italy Key words: Wind turbine, rain erosion, particles cloud tracking Abstract. In this work, the authors present a numerical prediction of erosion on two different blade geometry of a 6 MW HAWT designed for different aerodynamic loading, with the aim of studying their sensitiveness to erosion. First, the fully 3D simulations are performed using an Euler-Lagrangian approach. Flow field simulations are carried out with the open-source code OpenFOAM, based on a finite volume approach, using Multiple Reference Frame methodology. Reynolds Averaged Navier- Stokes equations for incompressible flow were solved with a k- İ WXUEXOHQFH PRGHO± An in-house code (P-Track) is used to compute the rain drops transport and dispersion, adopting the Particle Cloud Tracking approach (PCT). The PCT was used by some of the authors in previous works (Corsini et al., 2012; Corsini et al., 2014) to predict erosion on both axial and centrifugal fans, obtaining satisfactory results. The PCT allows to simulate a huge number of transported phase tracking just few cloud trajectories, thus resulting in reduction of computational time comparing with single particle tracking approach. Erosion is modelled accounting for the main quantities affecting the phenomenon, which is impact velocity and angle, and material properties of the target surface. Results provide the regions of the two blades more sensitive to erosion, and the effect of the blade geometry on erosion attitude. 1 INTRODUCTION A consequence related to the increasing of offshore wind turbine size is that the wind velocity at the blade tip region reaches very high values. In normal operating conditions the tip velocity is typically between 90 and 110 m/s and in this range of velocity, the rain erosion phenomenon can have a relevant effect on the overall turbine performance. Works like [7] and [17] state that the power in case of deeply eroded leading edge can reach the 20%. Woods [2] and 3M [17] report that, in particular conditions, a serious damage on the blade leading edge can be observed after only two years of operation. Therefore, erosion related issues should be accounted for in the scheduling of the wind turbine maintenance. This aspect becomes even more relevant in off-shore applications where, seen that the maintenance and monitoring operations must be reduced to the minimum, the rain erosion should be challenged mainly in the design phase. The use of computational tools allowing to study the erosion phenomenon in wind turbines may be of great help for 139