State Key Laboratory of Tribology of Tsinghua University Helps Winter Olympic Ice and Snow Project: Aerodynamic Drag Reduction

On February 20, 2022, the 24th Beijing Winter Olympic Games successfully concluded, and Chinese athletes achieved the best record in history of 9 gold, 5 silver and 2 bronze medals. Since 2019, Wang Jiandao, Weng Ding, Ma Liran, Ma Yuan, etc. led the research and development team (Wang Yanqing, Wei Yuju, Pang Zuobo, Nie You, Zhang Chuanbin, Chen Yiqing, Liang Zhenwei, Li Xuan, Zhang Xuanhe, Xue Yu, Zhang Ji, etc.) in the State Key Laboratory of Tribology of Tsinghua University, and participated in the "Winter Sports and Training Competition" two key projects of the Ministry of Science and Technology "Science and Technology Winter Olympics", such as the key technology of high-performance clothing research and development, making full use of the research advantages of the State Key Laboratory of Tribology in fluid-solid interface drag reduction, the theoretical results of aerodynamic drag reduction of fluid-solid interface, wind tunnel experimental techniques, surface microstructure design and preparation techniques are closely combined to complete the optimization of athletes' posture drag reduction, wind tunnel auxiliary training, and aerodynamic drag reduction optimization tasks for key competition equipment such as competition clothing and helmets. At the same time, the team adheres to the combination of theory and practice, fully combines "production, learning, research and application", and realizes the practical application of independent intellectual property equipment. The research results have helped Chinese athletes win gold and silver in skating events at the Winter Olympic Games, the first medal breakthrough on steel frame snowmobile, and the first appearance of Nordic two events, It has become a typical demonstration of "science and technology Winter Olympics.
aerodynamic attitude drag reduction
In the typical winter Olympic racing, air resistance is the main resistance factor, and the pressure resistance is the main resistance term. Through the optimization of the athlete's posture, a significant reduction in differential pressure resistance can be achieved; through the technical and tactical optimization of the formation, the energy consumption can be reduced and the finish performance can be improved.
For winter sports such as road speed skating, short track speed skating, steel frame snowmobile and Nordic biathlon, the team collected athletes' body digital models through 3D scanning, carried out fluid mechanics simulation to analyze the sources and proportion of resistance, clarified the key parts of posture resistance reduction, and proved the influence law of athletes' posture on resistance through digital model deformation, combined with the attitude angle and resistance data of the athletes recorded synchronously by the attitude capture device and the six-component force balance in the wind tunnel experiment, the optimal drag reduction attitude of each tested athlete is determined, and the reasonable formation and following parameters are provided for the multi-player sports team as a reference for technical and tactical arrangement, and the relevant research also lays a foundation for the drag reduction design of athletes' clothing, helmets and other equipment.



 

   

 
Resistance Optimization of Short Track Speed Skating Formation 




Nordic two, steel frame snowmobile and other projects wind tunnel training and testing
 

　　In the two medium-high risk events of ski jumping and Nordic, the Wang Jiatao team and Shenyang Aerodynamics Research Institute constructed the air flight simulation calculation method through the athlete's digital model, obtained the sliding aid and drag reduction attitude and the air attitude angle that can obtain a larger lift-drag ratio, and cultivated the athlete's muscle memory through the lifting training of Laiyuan Wind Tunnel. The immersive training method carried out with the help of wind tunnel has solved the problems of training time and safety of team members, helped China's Nordic biathlon team members to improve their performance rapidly, and helped Zhao Jiawen to make his debut in the Nordic biathlon of the Winter Olympics on behalf of China. It has become a typical demonstration of China's science and technology to help the Winter Olympics and reflects the important supporting role of high technology in sports training.
Aerodynamic Drag Reduction Racing Suit
Racing clothing is an indispensable equipment in winter projects. In the past, my country's winter racing clothing was completely dependent on imports, which greatly restricted the healthy development of my country's winter sports, and it was impossible to customize it according to the characteristics of athletes, making my country's athletes "aggrieved" before the starting line ".
Weng Ding and other young teachers undertook the research task of aerodynamic drag reduction of the key special competition clothing "Key Technologies for Research and Development of High Performance Clothing in Winter Sports and Training Competition. In cooperation with Liu Li's team of Beijing Institute of Fashion Technology and in combination with the principles of fluid mechanics simulation and aerodynamic drag reduction, the design schemes of structural drag reduction and fabric drag reduction for winter racing clothing are proposed. The air resistance of self-developed competition clothing for short track speed skating, road speed skating, alpine skiing, steel frame snowmobiles and other projects has been reduced by 5-10%, which is better than imported clothing that can be obtained, and has been applied in actual combat in the 2022 Beijing Winter Olympics. The successful application of aerodynamic drag reduction technology in competitive sports is a new milestone in sports science and technology in China.



 

Self-developed short-track speed skating drag-reducing suit on the field to win gold
 

Short Track Speed Skating Drag Reduction Helmet
As a necessary equipment, short track speed skating helmet has an important influence on the wind resistance of athletes under the condition of ensuring the personal safety of athletes. With the strong support of the Winter Sports Management Center of the State General Administration of Sports and the National Short Track Speed Skating Team, Wang Jiadao's team has developed a drag reduction optimized helmet for the typical speed of Chinese athletes. Through computational fluid dynamics simulation and flexible imprinting technology, the aerodynamic drag reduction optimization design of the short-track helmet was obtained, the drag reduction helmet preparation was realized, and the wind resistance evaluation was completed using a 3D printed human model. Compared with the helmet used by the national team of the Pyeongchang Winter Olympics, the maximum drag reduction rate of the final shaped helmet reached 8%. Finally, after discussion between the Winter Games Center of the General Administration of Sports and the national short-track speed skating team, it was determined to use the drag-reducing helmet as the national team's equipment. The team mobilized all, rushed to work 24 hours a day, completed the surface treatment of 30 helmets with high quality in only 5 days, and sent special personnel to escort them to Suzhou for spray painting. On January 21, 2022, the national short track speed skating team was delivered as the equipment for the Beijing Winter Olympics, and the scientific and technological support work was successfully completed. At the Beijing Winter Olympics, the short track speed skating team was equipped with resistance reduction helmets and won 2 golds, 1 silver and 1 bronze.

 

   
Wind resistance test of short track speed skating helmet


The short track team is fully equipped with aerodynamic drag reduction helmets.
 

The achievements of the Beijing Winter Olympics preparations and competitions have made the pneumatic drag reduction technology highly valued in the sports world and even among sports enthusiasts. With the increasingly perfect experience in the construction and application of special wind tunnels for sports in China, the widespread popularization of pneumatic drag reduction knowledge, and the iterative update of domestic pneumatic drag reduction sports equipment, it is believed that pneumatic drag reduction technology will "fly into the homes of ordinary people" in the future. to contribute more to the overall improvement of our national life experience and physical quality.
 

Reprint... State Key Laboratory of Tribology, Tsinghua University.