In view of the current development process of ski jumping in China, it is imperative to find out the technical differences and deficiencies between Chinese athletes and the world 's top athletes. Therefore, this study focuses on the stable flight posture that directly affects the jump distance. Based on the performance of elite athletes in the 2022 Beijing Winter Olympics ski jumping and Nordic Combined competitions, the performance and technical characteristics of athletes are compared from the perspective of kinematics. At the same time, a refined model of athlete/ski system with the characteristics of ski jumping is established, and CFD technology is used to compare the aerodynamic characteristics of athletes in stable flight posture from the perspective of aerodynamics. It aims to provide a theoretical basis for the technical improvement of Chinese athletes, the training guidance of coaches and the preparation for the 2026 Milan Winter Olympics.
Performance and related kinematic parameters of 8 Chinese athletes, 8 Japanese athletes and 10 European athletes were recorded, including take-off speed (m/s), AT 30M speed (speed at 30 m flight distance, m/s), ski V-shaped angle ski angles at 30 m flight distance, (°), landing speed (m/s), and jump distance (m). Stable flight athlete/ski posture angles parameters were obtained through Simi Motion video analysis. Then through the UG NX 11.0 modeling software, the athlete/ski system was finely modeled, and the solid model with the characteristics of the ski jumping (goggles, skis, holders) and the body shape characteristics (face, fingers, muscles). Simcenter STAR-CCM + 2019.3 simulation software was used to calculate the CFD simulation of the athlete/ski system model. The Reynolds time-averaged method was used to simulate and compare the aerodynamic characteristics of the stable flight athlete/ski system.
The results proved that: (1) the speed of Chinese athletes to form a stable flight posture in early phase and maintain a stable flight posture in later phase was significantly slower than that of European and Japanese athletes, so that there was a large level gap in jumping distance (P<0.01); (2) Chinese athletes did not have enough hip extension and ankle dorsiflexion activities in stable flight, and the angle between the body and the ski was large, the posture was not forward enough; (3) the back-flow vortex behind the Chinese athletes was strong, the streamline was disordered and dense in stable flight, the total lift obtained was small, especially the body lift, and the total drag was large, so that the lift-drag ratio was small, and the overall aerodynamic characteristics effect was relatively poor.
The study found that the large level gap in the performance of Chinese athletes was mainly caused by unreasonable athlete/ski flight posture, which directly affected the aerodynamic characteristics in stable flight. It was suggested that Chinese ski jumping coaches and athletes should pay attention to the existing technical differences and deficiencies, and strengthen the muscle strength of the main V-shaped flight techniques such as the trunk extensors and ankle dorsiflexion muscle group in daily training. When flying in the air, the hip angle was increased by 4°~8°, the ankle angle was reduced by 7°~11°, the distance between the athlete and ski was reduced as much as possible, and a stable flight posture with more stretch and forward inclination was formed to obtain better aerodynamic characteristics and improve the performance of Chinese athletes.
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