Aerodynamic optimization of micro horizontal axis wind turbine via response surface method

Abstract

This study focuses on the redesign and optimization of the three- dimensional geometry of a micro horizontal-axis wind turbine (HAWT) blade

using Response Surface Methodology (RSM). The geometric variation of two key design parameters, chord length and twist angle, is mathematically modeled using a fourth-degree and second-degree polynomial, respectively. The optimization framework is based on eight input parameters that define the initial blade configuration. To evaluate aerodynamic performance and structural integrity, a comprehensive comparative analysis is conducted between the initial and optimized blade designs using Computational Fluid Dynamics (CFD) and Blade

Element Momentum (BEM) methods. The CFD simulations utilize the Reynolds- Averaged Navier-Stokes (RANS) equations with the k-ω SST turbulence model to

capture complex flow phenomena and predict aerodynamic efficiency. The optimization process is implemented using a Multi-Objective Genetic Algorithm (MOGA) coupled with a non-parametric regression (NPR) metamodel, enabling the automated selection of the most efficient blade design. Performance assessments of the turbine rotor are carried out using the open-source software QBlade, with results compared against CFD predictions across various Tip Speed Ratio (TSR) values. The optimized blade demonstrates significant improvements, yielding a 15% and 12.53% increase in power coefficient for CFD and QBlade analyses, respectively, at a design TSR of 3. Compared to the baseline blade, the optimized design exhibits superior aerodynamic characteristics, including enhanced lift generation, reduced flow separation, and improved efficiency across all TSR values. Furthermore, a detailed three-dimensional flow analysis, incorporating pressure distribution and limiting streamlines on both blade surfaces, confirms the optimization objectives. The results highlight a notable reduction in flow separation zones and a subsequent increase in rotor torque. Additionally, structural safety considerations reveal a 37% improvement in starting operability at lower wind speeds, contributing to enhanced overall performance and operational reliability.