Design optimization of a blunt trailing-edge airfoil for wind turbines under rime ice conditions

Abstract

A new optimization method is developed for the design of a blunt trailing-edge airfoil for wind turbines under rime ice conditions. The parametric representation of the airfoil is given using the profile integration theory and B-spline function. The rime ice shape from wind tunnel tests is fitted using a linear interpolation algorithm with equidistant and equiangular steps to preserve the same number of ice shape feature points. The blunt trailing-edge thickness and distribution ratio on the upper side of the middle arc are included in the design variables. The optimizer, based on the Bare-Bones Multi-Objective Particle Swarm Optimization (BB-MOPSO) algorithm integrated with ICEM-CFD and FLUENT software, seeks the solutions maximizing the lift coefficient and lift-drag ratio. A new airfoil NACA0012BT (with BT denoting the blunt trailing-edge) with the trailing-edge thickness of 2.2004 %c (with c denoting the chord length) and distribution ratio of 1:55.8482 is obtained, and the lift and drag coefficients, lift-drag ratios, pressure distributions, and flow characteristics are investigated using the Computational Fluid Dynamics (CFD) method. Significant improvements of the NACA0012 airfoil design are achieved in this process, confirming that the developed method constitutes a valuable tool for designing and optimizing the wind turbine airfoil operating in icing conditions.