Alistair Duff, for technical assistance Mr. Andrew Crockett, for strain gauge assistance
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- 14. DESIGN PERFORMANCE ASSESMENT
- 14.1 PRESSURE DRAG
9.3 VALIDATIONWith the possible errors recognised and taken account of, it is apparent that the results from the two methods of testing correlate well. This provides the evidence that the use of CFD can provide an accurate representation of fluid flow in the application of testing such things as wing mirrors. With this CFD validation accomplished, it was then possible to assess the performance of the wing mirror in greater detail in Fluent, with the aim of performing design optimization. 14. DESIGN PERFORMANCE ASSESMENTOne of the many advantages of using a CFD package such as Fluent is that with the analysis solved, various plots and graphs of the fluid behaviour and properties can be produced. These features can then be utilised to assess the performance of the model and identify any strengths or weaknesses. Using this method, it was possible to assess the strengths and weakness of the L319 wing mirror in Fluent. 14.1 PRESSURE DRAGBy producing a contour plot of the static pressure levels on the wing mirror surfaces, it was possible to identify the areas of high pressure and low pressure as can be seen in Figure 13; with blue representing the lowest pressure and red representing the highest. 
Figure 13 - Contours of Static Pressure (Pascal) at 60mph From this plot, it can be seen that on the leading surfaces of the wing mirror there are high levels of static pressure. It can also be observed that on the trailing faces the static pressure is comparatively low, and thus this pressure difference is a major contributor to the wing mirror’s pressure drag and therefore its overall drag. The high static pressure on the leading faces can be attributed to the fact that a sizeable amount of flow stagnation takes place on this area resulting in low velocity air flow and thus a high static pressure. This flow behaviour is especially evident on the wing mirror mount. Download 3.93 Mb. Share with your friends:
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