| To raise the awareness of the sailing athletes’ understanding of the flow filed around theNeil Pryde RS: X sail and to improve the performance in Yacht race, the Olympics Neil PrydeRS: X (NP) wing was studied. The software of Pro/ENGINEER Wildfire5.0was applied inmodeling the shape of the sail, using the data we measured. Then, we take advantage of theANSYS software, especially the software FLUENT13.0, modeling, in simulation andanalysis of the wing.In order to choose an appropriate turbulence model, NACA0012sail wing at5°attackangle was numerical simulated, and the influences of different turbulence models werediscussed. Comparing to experiment data, we found that the Realizable model was proper.Then, we computed the NP sail in18kinds of working conditions by using this turbulencemodel. Three typical conditions at10°,50°,90°angles attack were analyzed as follows:Common points in three conditions: pressure was large on the windward side, while theleeward side was the negative pressure zone; the velocity was lower than windward side.Pressure distribution near the mast under three conditions was more complex. Generally, therewas a zone which pressure was a little higher at the rear of the windward side of the mast,with various swirls.The main differences between the three conditions:The differences in pressures distribution: on the windward side, the pressure of10°anglesof attack was larger in the upper region; there was a higher pressure zone at mast rear at50°inthe windward side while this region at90°is very small. On the leeward surface, the higherpressure region was located at trailing edge at10°angle, middle and rear at50°angle whilecentral at90°angle. There was a small high-pressure area at the mast rear, but the impactionwas not significant, especially in larger angle of attack. In other words, the impaction waslager at10°angle than50°and90°.The differences between velocity magnitude: the flow field, the velocity magnitude at 10°angle sail was basically the flow close to the inlet, with no obvious flow separation; at50°angle leeward side of the rear, there was a low velocity zone, with the phenomenon of flowseparation; the three planes of the flow fields at90°was complex: the downstream had a lowvelocity zone, resulting in separations. The middle plane was more complex and the swirlsaffected lager zone.The differences between velocity vectors and streamlines: the flow in the upper zone ofwindward side at10°angle was relatively smooth, passing along the sail surface from thefront to the downside. At the upper and the lower edge of the sail, the streamlines from thewindward and leeward of the sail intertwined together; on the leeward side of main sail, it wassimilar to the windward side, finding no obvious swirl. Similar to the10°situation, the flowon the windward side of the sail was relatively smooth. However, in the upper and lower areasof the sail, the streamlines were more distortions. Passing the mast of90°angle condition, thestreamlines flowed towards the leeward direction and the streamlines around were relativelysmooth. But the streamlines in the leeward side were more complex, with a pair of largeeddies.In the range of0-180°angles, the lift and drag coefficients of the NP sail showed: the NPsail, NACA0012and the jib had the tendency in common. Compared to the other sails, NPsail had a relative higher lift coefficient. Compared with the spinnaker, NP sail dragcoefficient is larger. On the other hand, the drag coefficients of the NP sail is higher than thejib.This study helps the athletes recognize aerodynamic characteristics of NP sail, providingtechnical supports in preparing for the Olympics. |
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