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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By analyzing the distribution of pressures on the surfaces of the elements and in the plane of symmetry as in Figure 8, the supposition of a low-pressure system generated behind the nacelle was confirmed. The low air pressure in the area behind the nacelle effectively increases the aerodynamic drag generated by the structure. Looking at the airflow comparison in Figure 9, it was noted that when the nacelle is close to the wing significant air turbulence and turbulence behind the nacelle is generated.

Fig. 8. - comparison of pressure distribution on the elements and in the plane of symmetry. (from top: optimal, suboptimal)

Fig. 9. - Comparison of visualization of air streams colored depending on their speed (from the top: optimal, suboptimal)

This leads to the conclusion that in order not to create air turbulence behind the object, the nacelle should be moved away from the wing in order to separate the air currents.

8. Summary

• Optimization by the DoE method is relatively simple to perform and provides an answer to the question of what input parameters have the greatest impact on the outcome of the experiment. • Optimization of the shape by the DoE method resulted in a reduction of aerodynamic drag by 9.39% relative to the input geometry.The geometry due to optimization was significantly slenderized, which reduced the generated aerodynamic drag.The biggest impact on the reduction of drag is the parameter describing the position of the second node in the Y axis. Thanks to this parameter, the element gains slenderness. Increasing the slenderness also had a positive effect on turbulent flows and air turbulence • Optimization of the height of the connecting element revealed that seating the nacelle as close to the wing as possible does not yield the best results. As the length of the connecting element increases, the drag value decreases to 2.96N at 100 mm of connecting element length, which corresponds to a distance of 33 mm between the surface of the nacelle and the surface of the wing. Further lengthening of the connecting element does not bring a decrease in aerodynamic drag. This is due to the generated turbulence, turbulence and backflow behind the nacelle at small distances between the wing and the nacelle. By the above-mentioned factors, at small distances between the nacelle and the wing, there is a low pressure area behind the nacelle. • The gradient optimization method resulted in a 12.27% reduction in generated aerodynamic drag relative to the input geometry. the gradient algorithm slimmed the profile of the connecting element to an even greater extent than the DoE method. Which resulted in an additional 2.88% decrease in aerodynamic drag relative to DoE.