Aerodynamic design and optimization of a swept horizontal axis wind turbine blade

Wind energy is one of the most applied renewable energy sources and it has a crucial importance for our country since Turkey has a very hight energy import ratio. One of the most important elements of wind turbines are wind turbine blades which convert the wind energy to mechanical energy. Aerodynamic designs of blades are still an important topic and various blade designs are available in order to increase the produced energy. In this study, design and optimization of a swept horizontal axis wind turbine blade performed in order to increase the power production by using Computational Fluid Dynamics (CFD) method. A rotor with 0.94 m is used as a baseline, and optimum design parameters, sweep begin section (rss/R), tip displacement (d/R) and sweep strength (M), additionally the pitch angle, were investigated in order to find optimum parameters to maximise the power coefficient at the design tip speed ratio. Firstly, effect of sweep direction, tip displacement and sweep begin section on power was investigated using two horizontal axis wind turbines, NREL Phase II wind turbine that has a rotor diameter of 10 m and NTNU model wind turbine that has a rotor diameter of 0.9 m, which have experimental data available. At this time, an equation that allows to change sweep begin section, tip displacement and sweep strength independently is developed in order to desing new swept blades. According to the results of the parametric study, an important outcome was obtained: increase in power coefficient can be obtained using forward swept blades while backward swept blades have negative effect on power production. After that optimizaton was performed using a meta model based method, response surface method. Face Centered Central Composite Design method was used as the design of experiments method. After that response surfaces are created using the Kriging method which showed best accuracy among various methods. As the final step of the optimization, optimum parameters were found using genetik algorithms. A significant boost in power coefficient, namely 4.28% is obtained at the design tip speed ratio using optimal baldes After that the performance of the designed optimal blade is tested with various pitch angles to find the optimum pitch angle. In the final stage of this study, the optimal swept blade was produced and experimentally tested at two pitch angles, 0° and 5° (up), using an open jet wind tunnel and a model wind turbine test system, and the results were compared with CFD simulation results. According to the comparison, it is observed that experimental results are in a good agreement with CFD results. In the study, ANSYS Fluent 17.2 was used for CFD simulations.