**5. Conclusions**

In this study, the aerodynamic performance of a wind turbine blade was examined according to the chord and twist linearization parameters, which are required in blade geometry design. In addition, an optimization algorithm for the linearization and an objective function that considers multiple TSRs to satisfy the optimal aerodynamic efficiency at various wind speeds were proposed. The main conclusions drawn by analysing the effects of the blade linearization parameters (chord length, chord profile slope, and twist profile) can be summarized as follows:


By applying the linearization parameter design ranges and multiple TSRs, a blade geometry that improved the power coefficient at all wind speeds below the rated wind speed compared to the NREL baseline wind turbine was derived. Therefore, it is necessary to consider multiple TSRs during blade design to satisfy the optimal aerodynamic performance at various wind speeds. As the structural performance of the blade was not addressed in this study, there is a limit to the practical blade design. In the future, based on the results of this study, further research on blade geometry optimization considering blade structural stability for more practical blade design will be conducted.

**Funding:** This work was supported by the Korea Institute of Energy Technology Evaluation and Planning (KETEP) gran<sup>t</sup> funded by the South Korean governmen<sup>t</sup> (MOTIE) (NO. 20173010025010 and NO. 20184030202200).

**Conflicts of Interest:** The author has no conflict of interest.
