Optimization of Horizontal-Axis Turbine Blades under Drivetrain Resistance

The classic design of the horizontal axis turbine blade optimizes aerodynamic or hydrodynamic aspects but often neglects drivetrain effects. However, at low rotational speeds, the torque generated by the blades must overcome the resistive forces from the bearings and the electrical generator. Considering these effects can improve turbine performance at low wind or water speeds. This study introduces an optimization model for turbine blades that incorporates drivetrain resistive forces into Glauert's optimization framework. Using Blade Element Momentum Theory, the model maximizes the power coefficient while accounting for drivetrain resistance. The resistive force coefficient is integrated into the velocity diagram of each blade section, where distributed loads are determined based on the resistive forces on the shaft. The results reveal significant variations in chord distribution, leading to improved blade geometry for torque generation - critical when a generator is coupled. A comparative analysis with Glauert's model shows enhanced energy extraction due to geometric adjustments. Notably, the starting torque increases by 16.39% when applying the new model to a system with.