# Evaluation of Tip Loss Corrections to AD/NS Simulations of Wind Turbine Aerodynamic Performance
## 7 Conclusions  
This work presented AD/NS simulations for the _NREL Phase VI_ and the _NREL 5 MW_ rotors, which represent the typical small size and modern size rotors. The primary purpose of the numerical study is to evaluate the performance of tip loss corrections employed in the AD/NS simulations. Three different implementations of the widely used Glauert tip loss factor \(F\), denoted as Glauert-A/B/C, are discussed and evaluated in the study. In addition, a newly developed tip loss correction is also evaluated. As an extension, the influence of employing different tip loss corrections to the velocity field is studied as well. The following conclusions are drawn from the present study:  
* The three different implementations of the Glauert tip loss factor showed a certain degree of difference to each other, although the relative difference in blade loads is generally no more than 4%. The Glauert-C correction, in which the tip loss factor \(F\) is directly used to be divided by the interference factors, is recommended for AD/NS simulations, since it gives results closest to the reference data in all the studied cases.
* The performance of the Glauert-C correction in AD/NS was found to be almost equal to that of the standard Glauert correction in BEMT. That provides evidence for the reasonableness of the transplantation of the tip loss correction from BEMT into AD/NS.
* The Glauert-type corrections tend to make an over-prediction of the blade tip loads. In contrast, the new correction showed superior performance in various conditions of the present study.
* A difference in tip loss correction leads to the influence of not only on the blade tip loads, but also on the velocity field around and after the rotor. The range of this influence is observed expanding in the rotor wake. In addition, the magnitude of this influence is found to be increased after the _NREL 5 MW_ rotor.  
The above observations help to understand the performance of different tip loss corrections employed in AD/NS simulations. It is indicated that the blade loads, as well as the wake velocity, can be simulated better by choosing the best implementation of the Glauert tip loss factor or employing the new tip loss correction. That is the major contribution of this study.  
Conceptualization, W.Z.; Formal analysis, W.Z. and W.J.Z.; Funding acquisition, T.G.W.; Investigation, W.Z. and W.J.Z.; Methodology, W.Z.; Supervision, T.G.W. and W.Z.S.; Writing--Original draft, W.Z.; Writing--Review and editing, W.J.Z. and W.Z.S.  
This work was funded jointly by the National Natural Science Foundation of China (No. 51506088 and No. 11672261), the National Basic Research Program of China (\"973\" Program) under Grant No. 2014 CB046200,  
Figure 9: Contours of the axial velocity difference between the results of the new and the Glauert-C tip loss corrections.  
the Priority Academic Program Development of Jiangsu Higher Education Institutions, and the Key Laboratory of Wind Energy Utilization, Chinese Academy of Sciences (No. KLWEU- 2016-0102).  
The authors declare no conflict of interest.