S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Mechanical Aerospace Engineering (기계항공공학부) Theses (Master's Degree_기계항공공학부)
활강/활공 단계의 스키점프 선수 주위 유동의 큰 에디 모사
Large eddy simulations of flows over a ski jumper during flight and in-run phases
- 공과대학 기계항공공학부
- Issue Date
- 서울대학교 대학원
- 학위논문 (석사)-- 서울대학교 대학원 : 기계항공공학부, 2016. 2. 최해천.
- Investigation of flows over ski jumper is important to control their posture, which is essential to achieve a longer flight distance. For this purpose, we conduct a large eddy simulation (LES) of turbulent flow past a model of a ski jumper which is obtained by 3D scanning the ski jumpers body (Mr. Chil-Ku Kang, a member of the Korean national ski jump team). In flight posture, the angle of attack of the jump ski is 30° and the Reynolds number based on the length of jump ski ( ) and the flight velocity ( ) is 5.4 × 105, and in-run posture the Reynolds number based on the height of posture ( ) and the sliding velocity ( ) is 1.8 × 105. The flow statistics including the drag and lift coefficients during the flight and in-run phases are in good agreements with our own experimental data in each posture. We investigate the flow characteristics such as the stagnation region, flow separation, and three-dimensional vortical structures and their effects on the drag, lift, and lift/drag. To find the optimal flight posture of the ski jumper, we build a simple geometric model of a ski jumper based on the result of LES where each part of the ski jumpers body is modeled as a canonical bluff body such as a sphere, cylinder and flat plate. The drag and lift obtained from this approach are in good agreements with those from LES. Also, using this approach, the optimal flight posture for the best aerodynamic performance is to be found.