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김상재(Sangjae Kim),권재성(Jaesung Kwon),허강열(Kang Y. Huh) 한국연소학회 2013 KOSCOSYMPOSIUM논문집 Vol.2013 No.12
It is crucial to understand the flame characteristics and their influence on turbulent burning velocity at the leading edge in turbulent premixed combustion. Statistics are checked for curvature and tangential strain rate and their relationships with displacement speed and flamelet thickness at the leading edge in incompressible Direct Numerical Simulation (DNS). Parametric study is performed on the statistics of six test cases with different turbulent intensities, integral length scales and laminar flame thicknesses.
Sine파 형상의 선단부가 적용된 Serrated Flap의 공력 특성
김용승(Yongseung Kim),김상재(Sangjae Kim) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
Recently, many studies have shown that airfoils of which the leading edge had a shape with Humpback Whale flipper or sine wave had a increased lift coefficient and a decreased drag coefficient. In this research, wind tunnel experiments are performed to analyze the aerodynamic characteristics of the NACA4412 airfoil which has serrated Fowler flap and slotted flap with the sinusoidal leading edge. Results show that two serrated flaps with a specific sine wave shape have a larger lift-to-drag ratio and a smaller magnitude of pitching moment coefficient than the reference flaps. Therefore, the leading edge using a sine wave with the optimal amplitude and wavelength can improve aerodynamic behaviors of flaps.
NACA0012 익형에서 윙렛의 공력 특성에 대한 매개변수적 연구
조재범(Jaebeom Cho),김상재(Sangjae Kim) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
In this research, the winglet attached to the NACA0012 airfoil is studied through wind tunnel experiments to analyze its aerodynamic characteristics with respect to the cant angle and incidence angle which are key design factors of the winglet. Additionally, split scimitar winglets characteristics are verified. Results show that the winglet model with a larger cant angle has a larger lift-to-drag ratio and a smaller size of pitching moment coefficient. The model with an incidence angle of 0° shows improvements of aerodynamic characteristics at the range of low angle of attack and one with an incidence angle of -4° does at the range of high angle of attack. The split scimitar winglet model has a larger lift-to-drag ratio and a smaller size of pitching moment coefficient than the reference of winglet model.
Automatic Moving Deflector를 이용한 NACA4412 익형의 공력 특성
우수한(Suhan Woo),김상재(Sangjae Kim) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
Recent researches show that an automatic moving deflector(AMD) attached to the airfoil and 3D vehicle model can enhance the delay of boundary layer separation and a decrease in drag. In this research, a parametric study is performed with length and tilting angle, which are the main parameters of AMD, through wind tunnel experiments to analyze the aerodynamic characteristics of AMD attached to the NACA4412 airfoil. Results show that the airfoil model with smaller length or tilting angle of AMD has a higher lift-to-drag ratio and a smaller magnitude of pitching moment coefficient. The delay of stall is also verified. However, if the length of AMD is less than a critical value, AMD has no significant effects on the delay of stall.
풍동 실험을 통한 초고층 건물 형상에 따른 내풍성능 분석
황민호(Minho Hwang),김상재(Sangjae Kim) 대한기계학회 2017 대한기계학회 춘추학술대회 Vol.2017 No.11
In this research, wind tunnel experiments are performed to measure the drag and pitching moment of various skyscraper models at various yaw angles, that are motivated by Lotte World Tower, World Trade Center, Shanghai Tower, Shanghai Financial Center and Torch Tower, to analyze the influence of building shapes on wind-resistant performance. In addition, the effects of concave and convex dimples in a rectangular building model are checked. Results show that the Torch Tower model has the best wind-resistant performance in terms of drag and pitching moment and the Shanghai Financial Center has the worst one, which means that curved shapes can help improve the performance. This is consistent with the previous results of studies. Both concave and convex dimples make the model have a decreased drag and the model with convex dimples has better wind-resistant performance than one with concave dimples.