# Collaborative Optimization of Aerodynamics and Wind Turbine Blades
## 5 Conclusions  
Designing a wind turbine blade is a complicated system engineering procedure, in which many disciplines should be considered to achieve a blade that can maximize wind energy extraction while reducing the manufacturing cost and the effect of internal and external disturbances. In this study, the aerodynamic and structural performance of a horizontal-axis wind turbine blade are studied in a collaborative optimization framework. Through design optimization, the torque provided by the blade improves while the mass of the blade decreases under the stress and deflection constraints. Based on the results, the following conclusions can be made.  
1. Collaborative optimization provides an effective optimization strategy for the design of wind turbine blades. In the strategy, multiple disciplines can be optimized simultaneously. Unlike direct optimization, the consistency between disciplines is considered, which helps in obtaining an overall globally optimal solution.
2. In MDO and multiobjective optimization, design variables might be different for different disciplines. Parameter sensitivity analysis emphasizes the important design variables in a specific discipline. As can be seen from the results of the parameter analysis, the chord length and twist angle exert an important influence on the torque while spar ply thickness greatly affects the mass of the blade.
3. Surrogate models in an MDO framework can effectively replace the time-consuming use of numerical simulation modules, with high accuracy and high efficiency. In the study, an optimal Latin hypercube design-based Kriging surrogate model is established.
4. Parameterized modeling can effectively improve the modeling accuracy of an airfoil and help the subsequent optimization of the wind turbine blade. In the study, class function/shape function transformation is shown to be feasible for representing the airfoil of the wind turbine blade.  
In this study, only the aerodynamic and structural performance criteria of the wind turbine blade are considered. Other important performance criteria such as noise and aeroelastics are not considered. Similarly, fatigue and instability are not considered in the structural discipline analysis. In future work, these aspects will be studied. Moreover, the fluid-structure interaction (FSI) issue will be addressed in the next work. In the paper, the optimization work is based on numerical simulation; in future work, experiments will be performed to validate the numerical simulation.  
Figure 24: Change in aerodynamic shape of the wind turbine blade by optimization. (**a**) Change in chord length by optimization; (**b**) change in twist angle by optimization.  
**Author Contributions:** Conceptualization, F.H., X.Z. and W.L.; methodology, F.H., X.Z. and W.L.; software, F.H., X.Z., J.Z., Y.H., A.Y. and R.Q.; validation, W.L. and H.M.; writing--original draft preparation, F.H. and W.L.; writing--review and editing, W.L.; visualization, F.H., X.Z. and J.Z.; supervision, W.L. and H.M; project administration, W.L.; funding acquisition, W.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the Natural Science Foundation of Fujian Province of China, Grant Number 2023J011572, the Fujian Science and Technology Major Special Project, Grant Number 2022 NZ033023, and the Open Fund of Fujian Additive Manufacturing Innovation Center, Grant Number ZCZZ202-09.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** All data are contained within the article.  
**Conflicts of Interest:** The authors declare no conflicts of interest.