# Performance Optimization Design of Diagonal Flow Fan Based on Ensemble of Surrogates Model
## 6 Conclusions  
An Ensemble of surrogates model was established for the design parameters and response results of a small diagonal flow fan. The Pareto front of the Ensemble of surrogates model was solved by a fast non-dominated sorting algorithm to obtain the structural parameters of the wind turbine blades. Combined with numerical and experimental, the internal flow characteristics of the diagonal flow fan before and after modification were explored and studied. The following conclusions were obtained:  
1. Based on the combination concept, a new Ensemble of surrogates model was generated by combining an RBF model and Kriging model, and the error was analyzed. It was verified that the prediction accuracy of the five test sets of the Ensemble of surrogates model is higher than that of the traditional model in terms of efficiency prediction  
Figure 19: Comparison diagram of impeller before and after optimization. (**a**) Original. (**b**) Optimized.  
Figure 20: Comparison of fan performance curves before and after optimization.  
and flow prediction, and its linear regression coefficient \(R^{2}\) is close to 1, which further verifies that the Ensemble of surrogates model has higher prediction accuracy.
2. In this paper, the fast non-dominated sorting algorithm was used to optimize the flow rate and total pressure efficiency of the diagonal flow fan, which can greatly reduce the complexity of the calculation and has the characteristics of high accuracy in solving the Pareto solution set. The optimization work should not only focus on the flow rate of the diagonal flow fan, but also needs to pay attention to the efficiency (i.e., energy consumption). Therefore, this paper states that the weight relationship between the two optimization objectives should be considered comprehensively, and proposes a solution that uses the weighted objective function \(0.5\eta_{B}+0.5\eta_{v}\) to reach the maximum value.
3. Through the numerical simulation method, the flow characteristics of the diagonal flow fan before and after the modification are studied in depth. It is found that the optimized fan blade has stronger work performance, less energy loss, and significantly improved fan efficiency.
4. In order to further confirm the accuracy of the prediction method and optimization design, the optimized impeller was proofed and tested. The test results show that the optimized blade increased by 1.7 m\({}^{3}\)/min and the total pressure efficiency increased by 3.2% under the design condition of the fan.  
Data curation, S.Z.; Formal analysis, B.X.; Funding acquisition, S.Z.; Investigation, B.X., J.H. and D.X.; Methodology, L.L.; Project administration, S.Z.; Software, J.H. and D.X.; Supervision, S.Z.; Writing--original draft, L.L.; Writing--review & editing, L.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by National Natural Science Foundation of China grant number 51706203 and Natural Science Foundation of Zhejiang Province grant number LY20E090004.  
The authors declared no potential conflict of interest with respect to the research, authorship, and/or publication of this article.