PSI - Issue 54

Wojciech Skarka et al. / Procedia Structural Integrity 54 (2024) 498–505 Bartosz Rodak/ Structural Integrity Procedia 00 (2019) 000 – 000

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4 4 Edge round

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194,2mm 0 2,4mm

186,7mm 0 1,2mm

7. Element height optimization A full aerodynamic simulation of the entire system containing the wing, the nacelle and the optimized connecting element was carried out. The input parameter was the distance between the wing chord and the geometric center of the nacelle. The output parameter is the aerodynamic drag generated by the entire structure. The wing model was created on a standardized NACA 633-618 profile. The wing span for the simulation is 1m. The model of the measuring nacelle was created on the basis of a symmetrical NACA EPPLER 863 STRUT 9 profile. And the model of the connecting element is an optimized version of the connecting element from the previous chapter. The entire structure is shown in Figure 6. solver settings are identical to those for the simulation when optimizing the shape of the connecting element. The optimization was performed using the design of experiments method due to the fact that this method gives more information about the course of the optimization process.

Fig. 5. - The way to search for the optimal solution (top: DoE, bottom: Gradient)

The optimization process proved that, the highest drag is provided by a design with the nacelle very close to the wing. With distances of 1mm to 7mm between the surfaces of the nacelle and the wing, the aerodynamic drag was about 3.7N. A clear decrease in the generated aerodynamic drag can be observed at a distance of 8mm between the surfaces of the nacelle and the wing, that is, when the length of the connecting element counting from the wing chord to the structural plane of the nacelle was 75mm. The lowest resistance was shown by

Fig. 6. - Model used in optimizing the height of the connecting element

the geometry with the length of the connecting element from about 90mm, while the minimum resistance of 2.96N was obtained with the length of the connecting element of 100mm. This corresponds to distances between the nacelle surface and the wing surface of 23mm and 33mm, respectively. Below is presented a graph (Figure 7) showing how the length of the connecting element affects the generated aerodynamic drag

Fig. 7. - Effect of the height of the connecting element on aerodynamic drag.