ESTRATEGIAS PARA LA CONSERVACION DEL ADOBE
FACTORES EXTERNOS
Before the optimisation study was carried out, the impact that adding a fuselage to the wing would have on the wing tip was investigated. A fuselage was added to the wing model and is shown together with the mesh in Fig. 87.
Fig. 87: Fuselage plus wing and mesh
The mesh type and configuration used in section 3.4.2 was adopted as well as the physics models in section 3.4.3. To analyse this effect, the following were considered: the lift-to-drag ratio, the wing per unit span, the drag per unit span, pressure and skin friction of the wing were studied. The lift-to-drag ratio of the wing only configuration was 12.4543 and 10.7928 for the fuselage plus wing configuration. This shows a drop-in value due to an increase in drag and a subsequent decrease in lift by adding the fuselage, this is shown in Table 15 and in Fig.88–Fig. 89. Fig. 88 shows the wing per unit span for both cases, the lift distribution at the wing tip region was shown to remain unchanged although the in-board wing section did show some modification due to the presence of the fuselage. Fig. 89 shows the drag per unit span in the span-wise direction, showing the comparison of both set-ups. The wing-tip regions once again seem to have not been affected by the addition of the fuselage. On the contrary, the in-board section of the wing shows higher CD values on the plot. Fig. 90 gives a better clue as to the reason for
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this occurrence; from analysis the pressure contours of the wing’s top and bottom surface for both configurations, the pressure around the wing tip sections are identical but in-board of the wing. A higher-pressure region is observed near the wing’s leading edge with fuselage top surface which causes the sudden drop in lift and increase in skin friction drag that is observed in Fig. 91. Based on these findings, it was concluded that the addition of the fuselage had no significant effect on the flow characteristics in the wing-tip region, therefore, it could be omitted during the optimisation process and for subsequent simulations. It was also helpful to do this as it saved computational time.Table 15: Aerodynamic coefficients wing only and wing plus fuselage
Wing only Wing plus fuselage
CL 0.5572 0.5245
CD 0.0447 0.0486
CL/CD 12.4543 10.7928
Fig. 88: Lift per unit span
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09 2 4 6 8 10 12 14 16 18 20 CL Spanwise direction (m)
Clean wing only Fuselage plus wing
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Fig. 89: Drag per unit span
(i. ) wing top surface
(ii. ) Fuselage plus wing top surface
0 0.002 0.004 0.006 0.008 0.01 0.012 0.014 2 4 6 8 10 12 14 16 18 20 CD Spanwise direction (m)
Clean wing only Fuselage plus wing
Wing tip region
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(iii. )wing bottom surface(iv. ) Fuselage plus wing bottom surface
Fig. 90: Pressure contour (i,ii,iii,iv)
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(ii. ) Fuselage plus wing top surface(iii. ) wing bottom surface
(iv. ) Fuselage plus wing bottom surface
Fig. 91: Skin friction coefficient (i,ii,iii,iv)
The optimisation process adopted, final design models with results and analysis are presented in the next chapter of this thesis.
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4.5. Conclusion
Test cases to validate the numerical modelling approach has been performed in this chapter of this thesis with the results showing good correlation with the data reported in literature which was discussed in section 4.1. A new spiroid winglet design campaign was undertaken on a scaled wing and winglet models. This investigation was a prerequisite to the new set of proposed designs which was developed and used as a base design for further optimisation research presented in chapter 5. The qualitatively studied scaled wing and wing with winglet models had the following benefits and short comings:
• Improved generation of lift by increasing the lift coefficient (CL) significantly for the spiroid winglet technologies and the blended winglet with the spiroid winglet technologies achieving a CL improvement of up to 8 percent.
• Improved lift-to-drag ratio.
• Reduced induced drag by up to 18 percent for the spiroid winglets and the blended winglet technologies • Significant increased range by up to 5 percent.
• Slight reduction in cruise drag of up to 2 percent.
• Increased parasite drag for both spiroid wing-tip devices and the blended winglet due to increased wetted area.
Although results obtained are encouraging there is a lot of room for improvement in terms of increasing the drag reduction percentage of the spiroid devices by performing optimization studies which is addressed in chapter 5.
In addition to the spiroid trapezium technology, three new spiroid technologies (Designs 1-3) were introduced for optimisation due to the spiroid trapezium under performing at higher subsonic Mach numbers when the model was scaled up to a full size model and retrofitted.
Further, a comprehensive study on the effect of fuselage on wing aerodynamic forces with particular interest on the wing tip has been presented in this chapter of the thesis. Based on the findings, it is understood that the addition of the fuselage has no significant effect on the flow characteristics in the wing-tip region, therefore, it could be omitted during the optimisation process and for subsequent simulations. It was also helpful to do this as it saved computational time.