Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 44-122 Applied Fluid Mechanics 2 nd Week Vehicle Aerodynamics.

Presentation on theme: "Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 44-122 Applied Fluid Mechanics 2 nd Week Vehicle Aerodynamics."— Presentation transcript:

1 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 44-122 Applied Fluid Mechanics 2 nd Week Vehicle Aerodynamics

2 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 자동차 공기역학의 중요성 - 주행안정성 - 항력감소로 인한 연비향상 비행기와의 차이점 - 유동의 박리를 수반 - 지면과 가까움

3 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 항력계수 측정방법 - 도로상의 주행 : Coast-Down Test 설계단계에서는 측정 불가능 - 풍동에 의한 측정 자동차용 대형 아음속 풍동 필요 - CFD Simulation 실험 대체 가능 격자생성, 해의 정확성 등 문제

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26 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory -Rear wing with gurney(1) -Underbody almost completely covered(2) -Diffuser channels separated by strakes(3) -Wooden bars at each side of the vehicle to reduce the underbody flow leakage(4) -Wheel-house ventilation(5) -Variable device using a set of flaps to shut the inlet of the engine cooling duct(6)\ -Brake cooling duct(7) -front splitter(8)

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41 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 트럭 공기 역학 - 대형 수송 차량 (HGVs, Heavy goods vehicles) 은 대형 화물의 장거리 수송을 위하여 설계 - 화물 수송 과정 중 상당량의 에너지 소비  항력은 연비에 직결 HGVs(Heavy Goods Vehicles)

42 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory - 항력계수를 줄이기 위하여 대형 수송 차량에 다양한 종류의 항력저감장치 개발 항력 저감 장치의 종류 Examples of truck aerodynamic fairings and example of devices

43 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory Cap deflector - Cab deflector 는 트럭 운전석 상단에 설치하여 운전석과 화물간 높이 차이로 인한 항력 발생 최 소화 Correlation for Cd and the cap deflector height(left) and simulation result of velocity magnitude(right)

44 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory - Tear-drop 형상으로 전체적인 트럭 형상을 유선형으로 만들어 항력 감소 Tear-drop shape Teardrop shape to optimize air-flow and minimize turbulence and truck model in wind tunnel

45 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory - Boat-tail plate 는 트럭 뒤쪽에서 형성되는 후류를 저감시켜 항력 감소 Boat-tail plate Basic data for anti-mud adhesion and simulation result of vortex strake device (VSD)

46 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory - 후류를 감소시키기 시키기 위하여 트럭 후미 형상 최적화에 대한 연구 수행 The influence of backlight angle

47 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 차량 간 상호작용 - 차량 교차 운행 시 상호 작용에 의하여 차량 주변에 형성된 유동장 간섭 Pressure iso-surfaces from top view 차량 교차 운행

48 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory - 차량 간 상호작용에 의하여 간섭된 유동장은 차량 운행에 영향 Velocity magnitude iso-surface of preceding automobile

49 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory - 앞차의 바로 뒤를 달리는 (Tailgating) 운행에 의하여 후미 차량의 공기 저항이 감소 - 앞차가 후미 차량의 차폐물 역할을 함으로써 항력 저감 효과 꼬리 물기 (Tailgating) 운행 Sketch of the flow over two cars, separated by a distance dx

50 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory - 자동차 사이의 간격이 차 하나의 길이 보다 작을 때 차의 항력계수가 크게 감소하며 특히 앞서 가는 차의 항력계수가 더 크게 감소 Lift and drag coefficients for two cars separated by a distance dx

51 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory - 꼬리물기 (Tailgating) 현상에 대하여 실 차량 실험 수행을 통한 항력계수 저감 효과 확인 Drag coefficient ratios for a full-scale two car platoon

52 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory - 상용 트럭에 적용 시 장거리 운행으로 인한 연료 저감 효과 기대 Two truck platoon maneuver(left) and drag reducing effect with various body combinations

53 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 군집 운행 - 철새의 편대 비행 현상  항력을 줄여 에너지 소비 최소화 Formation of the migratory birds

54 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory - 항력을 최소화 할 수 있는 간격을 유지하여 차량 운행 - 도로의 효율적인 이용, 항력 저감 및 안성성 증대 군집 운행의 개념 Illustration of vehicle platooning concept(left) and air streamlines for platooned vehicles(right)

55 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 군집 운행 형태 - 효율적인 항력 감소를 위하여 다양한 타입의 군집 운행 형태에 대한 연구 수행 Types of the vehicle platooning

56 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 군집 운행 연구 (1) – 풍동 실험 - 차량 간격에 따른 항력 감소 효과에 대한 연구 Transient aerodynamics of vehicle platoons during in-line oscillations

57 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 군집 운행 연구 (2) – 풍동 실험 - 모형 실험을 통하여 군집 운행으로 인한 차량의 항력 저감 효과 및 운행 안정성 파악 Aerodynamic Forces Experienced By a 3-Vehicle Platoon in a Crosswind

58 Sogang University Dept. of Mechanical Engineering Computational Fluid Dynamics Laboratory 군집 운행 연구 (3) – 실차 실험 - 실제 차량 실험을 통하여 군집 운행으로 인한 차량의 항력 저감에 대한 연구 Quantifying Platoon Fuel Savings: 1999 Field Experiments