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시험모델 정밀도가 공력성능 예측에 미치는 영향에 관한 연구
김무상(Moo-Sang Kim),기정도(Jung-Do Kee),오민수(Min-Su Oh) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Vehicle aerodynamic performance is developed using both full-scale wind tunnel as well as quarter scale model at Hyundai-Kia Nam_yang R&D Center. The model wind tunnel is a relatively useful tool compared to the full-scale wind tunnel especially when the aerodynamic performance of a new vehicle is being predicted during the styling stage for a new vehicle. Model scale test can provide valuable aerodynamic data well before the prototype or pilot vehicle construction stage if the geometry and Reynolds similarities are considered properly for the scale model. The prediction accuracy of vehicle aerodynamic performance depends on the detailing of the test model such as underbody and engine room geometry.
An Experimental Study on the Aerodynamic Characteristics around Moving Bodies near the Ground
Moo-Sang Kim(김무상),Tae-Yoon Kim(김태윤),Jung-Do Kee(기정도),Dong-Ho Lee(이동호) 한국자동차공학회 2006 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
The objective of present study is to compare the flow characteristics around moving bodies near the ground. The influence of the gap height and ground conditions, the moving and fixed grounds, on the aerodynamic forces as well as the dynamic behavior of the wake flow around the square cylinder near a ground is investigated. The model wind tunnel experiments were carried out in an open circuit low turbulence subsonic wind tunnel. The wind tunnel is equipped with moving belt system to simulate the ground effect. The mean velocity and the turbulent field around a square cylinder were measured using a two-component Particle Image Velocimetry (PlV). From the velocity profiles in wake region, the pressure recovery on a moving ground decreases due to the high momentum supply, finally causing the drag to increase from the fixed ground, while the lift has opposite pattern. Through the full scale wind tunnel testing, aerodynamic force difference occurs under ground conditions and increases as yaw angle increases. Therefore the adequate ground simulation is necessary to enhance the control stability under the transient crosswind.
승용차의 공기저항 감소를 위한 외부유동 시뮬레이션 분석
송기선(Ki-Sun Song),강승온(Seung-On Kang),박훈일(Hoon-Il Park),기정도(Jung-Do Kee),김규홍(Kyu-Hong Kim),이동호(Dong-Ho Lee) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11
When a passenger car cruises, the characteristics of external fluid flows which pass near the car body vary depending on the aerodynamic shape of the car so that many kinds of aerodynamic drags occur as the results of this phenomenon. According to previous researches, it is well known that the aerodynamic drag affects the fuel efficiency of a car directly. Although this factor has played a powerful motivation for many researchers to conduct many cases of studies on reducing the aerodynamic drag of cars by using CFD simulations, it is true that the quality of the reliability of the CFD results was not reasonable because of the excessive simplifications of the car body shapes. For this reason, in order to overcome and reduce these kinds of limits, a feasibly meshed car body shape of YF SONATA of Hyundai Motors Company for CFD analysis was suggested and the aerodynamic characteristics were studied comprehensively by CFD analysis so that it was analyzed how the external fluid flows around the car body affect the aerodynamic characteristics of the car.
Vehicle Modeling Function 으로 구현한 3차원 자동차 모델 주위의 유동 시뮬레이션 및 공력성능예측
강승온(Seung-On Kang),전상욱(Sang-Ook Jun),박훈일(Hoon-Il Park),구요천(Yo-Cheon Ku),기정도(Jung-Do Kee),김규홍(Kyu-Hong Kim),이동호(Dong-Ho Lee) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
The objective of this study is Computational Fluid Dynamics (CFD) flow simulation and aerodynamic performance prediction around three dimensional automobile configuration represented by Vehicle Modeling Function (VMF). For performing CFD analysis of three-dimensional automotive vehicle configuration, 3D virtual automobile shape is needed in the initial stage . In this study, VMF is mathematically defined in the form of an exponential function to smoothly express the complex 3D curved shapes of an automotive vehicle. Then CFD analysis is performed to simulate and analyze the characteristics of the flow field over the external configuration of the 3D virtual automobile model. Finally, aerodynamic performance is predicted and discussed considering the external configuration, wheel arch, rotating wheel and moving ground effects.
Vehicle Modeling Function으로 구현한 3차원 승용차의 후면 형상 변형이 공력성능에 미치는 영향에 관한 Parametric Study
송기선(Ki-Sun Song),강승온(Seung-On Kang),박훈일(Hoon-Il Park),이준호(Jun-Ho Lee),기정도(Jung-Do Kee),김규홍(Kyu-Hong Kim),이동호(Dong-Ho Lee) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
This paper conducts a parametric study on the overall tendencies of changes of aerodynamic characteristics of a sedan depending on the rear body shape modifications through CFD simulation. In these research, the shapes of YF SONATA are represented by vehicle modeling function(VMF) which can generate and change the shapes of YF SONATA very quickly, compared with the realistic complicated model. The vehicle modeling functions are improved; several section functions and variables are added in order to generate the rear body shapes in detail. And the tendency of changes of the aerodynamic characteristics is analyzed. Finally, this paper suggests that the 3D shape of YF SONATA represented by VMF can reduce the overall time cost in designing a car because it takes so less time to know the ultimate car’s aerodynamic performance through proving the overall tendencies of the shape represented by VMF and the rear shape are very similar.
Synthetic jet을 이용한 승용차의 공력저항 감소에 대한 실험적 연구
박훈일(Hoon-Il Park),이영빈(Youngbin Lee),강승온(Seung-On Kang),송기선(Ki-Sun Song),기정도(Jung-Do Kee),이준호(Jun-Ho Lee),정형석(Hyoung-Seog Chung),장영일(Young Il Jang),김규홍(Kyu-Hong Kim),이동호(Dong-Ho Lee) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5
This paper describes drag reduction of a passenger car by using synthetic jet in wind tunnel test. For the reduction of aerodynamic drag, 11 synthetic jets are installed at the edge of the trunk on a 1/4 scale passenger car model to control the separation of the flow. Aerodynamic drag reduction is observed according to the jet location, jet direction and jet driving frequency. However, in case of the trunk sideward jet, aerodynamic drag is increased. As a result, drag reducing jet location, jet direction and jet driving frequency are revealed and it shows the possibility of aerodynamic drag reduction of a passenger car can be achieved by the synthetic jet.
승용차의 공기저항 감소를 위한 후면 형상의 공력 최적설계
송기선(Ki-sun Song),강승은(Seung-on Kang),전상욱(Sang-ook Jun),박훈일(Hoon-il Park),기정도(Jung-do Kee),김규홍(Kyu-hong Kim),이동호(Dong-ho Lee) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11
This study proposed an aerodynamically optimized outer shape of a sedan using Artificial Neural Network (ANN) and focused its attention on modifying the rear body shapes of the sedan. To determine the optimization variables, the unsteady flow field around the sedan cruising very fast was scrutinized by CFD simulation, and thereby, the fluctuations of the drag coefficient (CD) and pressure around were confirmed. Regarding the baseline result for CFD, 6 local parts of the end from the sedan were chosen as the design variables for the optimization. Moreover, the ANN approximation model was established with 64 experimental points generated by the D-optimal methodology. As a result, an aerodynamically optimized shape for the rear end of the sedan in which the drag was minimal was proposed with its aerodynamic performance improving by about 5.517%, compared with that of the baseline. Finally, it is expected that in the proper range of shape modifications for a rear body, the aerodynamic performance of a sedan can be enhanced, and thereby, the fuel efficiency of the sedan can be improved. The YF SONATA, a sedan manufactured by Hyundai Motors Company, played a major role in this research as the baseline vehicle.