Effect of ambient wind on the performance of alpine downhill skier.

Alpine skiing, especially alpine downhill, is one of the most extreme winter sports in terms of high-speed and narrow winning margin, and its tracks are always located in mountainous areas with high altitudes and complex ambient wind fields, resulting in a significant impact of ambient wind on the performance and the final ranking of alpine downhill skiers. In the present study, a method based upon the combination of field measurements, wind tunnel tests and kinematic simulations was used to evaluate the effect of ambient wind on the performance of an alpine downhill skier. Considering the effect of ambient wind, a kinematic model of the alpine skier-ski system was established, and the equations of motion for straight gliding and turning were deduced. Then, the Chinese National Alpine Ski Center (CNASC) downhill track was taken as a case study to investigate the effect of ambient wind on the gliding time using the proposed combined evaluation method. Field measurements and wind tunnel tests were performed to identify five critical ambient wind directions of 270°, 292.5°, 315°, 337.5° and 360°. Moreover, the wind speeds and the wind directions for 16 different measurement points of the downhill track were also obtained. The results of the modelling analysis showed that the finish time increased by 19.75% for the ambient wind direction of 270°, whereas the finish time decreased by 1.29% for the ambient wind direction of 360°.