# Automation of Winglet Wings Geometry Generation for Its Application in TORNADO
## 2 Methods
### Definition of the Wingtip Devices
#### 2.2.2 Open and Closed Spiroid Winglet
From the front view, the difference can be seen between not having the winglet and the changing

of the joints with the winglet type. The side and ISO views give the winglet details with the number of components. The parts that have an according radius have more components because the part of the wing-winglet joint that is more complicated needs to have more panels for its study. In the main wing and the winglets, the linear distribution can be seen more clearly and is spaced. About the computational cost of the developed algorithm, which was commented on before, the necessary time to compile the blended wing is 3.2 s, while the closed spiroid winglet is 22.1 s. It can be noticed that there is an increase in the time as the geometry gets more complex. With CFD (see Section 3.2), the time increases to 232 s, so for obtaining the optimal geometry, it is better to use the proposed algorithm. Figure 12: Cont. In Figure 13, the different 3D views of the complete wing are presented. In this view, the components, wing and winglets are observed. Figure 13b-d are the configurations with winglets, so when the curve part starts, the components of the joints between the wing and winglet can be seen. It can be noticed that for the open spiroid, the components are distributed in a more progressive way since the turn is smoother. The blended and the closed spiroid winglets have closer joints when the winglet starts since the turn is more aggressive. Figure 12: Depictions of different types of views from the types of winglets used. (**a**) No winglet. (**b**) Blended winglet. (**c**) Open spiroid winglet. (**d**) Closed spiroid winglet. Finally, TORNADO has also the option to represent an estimation of the vortex and the wake structure. Those results are collected in Figure 14, and they depend on the number of panels that are used for dividing the wing structure. The red lines show the structure that the wake will follow. The concentration of these red lines at the ends means the concentration of the vortex in those areas. A first early conclusion can be observed in Figure 14c,d; they both can change the vortex size, helping in reducing the induced drag. Figure 14: _Cont._

Figure 13: Details of the 3D view for the types of winglets studied. (**a**) No winglet. (**b**) Blended winglet. (**c**) Open spiroid winglet. (**d**) Closed spiroid winglet. ### CFD Comparisons

After the geometry was defined, Ansys-Fluent was used to perform a detailed study of the closed spiroid winglet. The results of the aerodynamic coefficients were calculated for the reference wing without winglets, the closed spiroid winglet for TORNADO and the closed spiroid winglet for Ansys-Fluent (see Table 1). Experimental study of the wing without the winglet and the closed spiroid winglet was also conducted because of the TORNADO limitations specified before; the coefficients for the first case are collected in the table. It can be seen from the table that TORNADO has problems with the coefficients. For the drag coefficient, as it was explained before, only the induced drag is obtained. The lift coefficient for the reference wing has a good approximation but for the closed spiroid winglet, it differs more, which happens because of the complexity of the geometry in the winglet. The results that are interesting are the closed spiroid winglet with Ansys-Fluent and the experimental results using the reference wing because they are obtained with reliable methods (the purpose of using TORNADO was only to obtain the final geometry). It can be seen that the closed spiroid winglet reduces the drag coefficient and increases the efficiency as wanted. ## 4 Conclusions

Although TORNADO encounters challenges in two specific cases (the study of the separation point and the overall calculation of the drag coefficient), it is a very useful tool, as evidenced in this article, and the winglet primarily affects induced drag (the studied one).