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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.
신경망 학습알고리즘의 비교와 2차원 익형의 비정상 공력하중 예측기법에 관한 연구
강승온(Seung-On Kang),전상욱(Sang-Ook Jun),박경현(Kyung-Hyun Park),전용희(Yong-Hee Jeon),이동호(Dong-Ho Lee) 한국항공우주학회 2009 韓國航空宇宙學會誌 Vol.37 No.5
본 연구에서는 오일러 CFD코드에서 얻은 데이터를 이용하여 2차원 익형의 비정상 공력하중을 모델링하고 예측할 수 있는 신경망의 능력을 확인하였다. 신경망 모델은 감독자관리 학습을 기반으로 하여 르벤버그-마쿼트 알고리즘, 그리고 여기에 유전알고리즘을 결합시킨 혼합형 유전알고리즘을 사용하여 구성하고 각 경우에 대하여 그 효율성을 비교분석하였다. 복잡한 시스템을 모사하는 신경망을 학습시키는 데는 혼합형유전알고리즘이 더 효율적이라는 것을 보였으며 신경망모델에 의한 2차원 익형의 비정상공력하중 예측결과 실제 수치결과와 비교적 정확하게 일치하여 신경망 모델이 축소모델로서의 기능을 발휘하는 것을 입증하였다. In this study, the ability of neural network in modeling and predicting of the unsteady aerodynamic force coefficients of 2D airfoil with the data obtained from Euler CFD code has been confirmed. Neural network models are constructed based on supervised training process using Levenberg-Marquardt algorithm, combining this into genetic algorithm, hybrid genetic algorithm and the efficiency of the two cases are analyzed and compared. It is shown that hybrid-genetic algorithm is more efficient for neural network of complex system and the predicted properties of the unsteady aerodynamic force coefficients of 2D airfoil by the neural network models are confirmed to be similar to that of the numerical results and verified as suitable representing reduced models.
능동형 리어 디퓨져 장치의 형상이 자동차 공기저항 감소 효과에 미치는 영향에 대한 연구
조준호(Jun-Ho Cho),강승온(Seung-On Kang),박훈일(Hoon-Il Park),송기선(Ki-Sun Song),기정도(Jung-Do Ki),이준호(Jun-Ho Lee),김규홍(Kyu-Hong Kim),이동호(Dong-Ho Lee) 한국자동차공학회 2012 한국자동차공학회 부문종합 학술대회 Vol.2012 No.5
The main purpose of this paper is to examine the Influence of active translating rear diffuser configuration to aerodynamic drag reduction of automotive vehicle. Actively translating rear diffuser reduces aerodynamic drag of a fast cruising car. Actively translating rear diffuser is hidden under the trunk when a car is parked and is driven slowly. And it slides out from under rear car body only at high speed driving condition not to ruin the external design of the car. 10 types of rear diffuser devices whose configuration is different were installed under the car body and Computational Fluid Dynamics (CFD) analyses were performed under moving ground and rotating wheel conditions. Finding a configuration which shows the best aerodynamic drag reduction performance is to explain the aerodynamic drag reduction mechanism of a car cruising at a high speed via an actively translating rear diffuser device. The diffuser device blocks low pressure underbody flow and raises pressure of it with diffusing process and then underbody flow and upperbody flow mix strongly, bringing about an aerodynamic drag reduction. Finally, aerodynamic drag of the car is reduced by an average of more than 7% with plate arc type diffuser, which helps to improve the fuel efficiency.
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 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.