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타이어가 존재하는 단순 차량모델의 boat tail형상에 따른 항력변화
박희경(Heekyoung Park) 한국자동차공학회 2014 한국자동차공학회 학술대회 및 전시회 Vol.2014 No.11
The simple model without tire have tendency that the drag coefficient is smaller at separation bubble decreased. But real vehicle have not that tendency. Drag coefficient is increased with more slant angle of roof and side. Generally separation bubble at upper tire is shown at all vehicles with Tire. The Separation bubble and vortex is larger at case of shot tail with high slant angle. If the tail length is long, drag is decreased by reattaching separation flow form tire on the tail of body and small separation bubble. And drag coefficient is smaller when the simple body have boat tail with 10~11° slant angle. Tail shape is very important to decreased drag coefficient.
Hatch back type의 단순한 형태의 테일 형상변화에 따른 항력 변화
박희경(Heekyoung Park) 한국자동차공학회 2012 한국자동차공학회 학술대회 및 전시회 Vol.2012 No.11
A CFD simulation has been carried out for hatch back type simple model to reduce vehicle drag coefficient. The commercial CFD code for Ahmed body gives reliable drag coefficient with in 5% error on the body with plane and slant angle 12.5˚. Virtual trailing edge is established to decrease the vortex on the body with momentum imbalance. Tail length and length of virtual trailing edge have large effect on drag for hatch back type simple model as decreasing not only area of rear body but vortex strength. Drag is minimized at 3˚ of flow angle after rear body and others flow angles increase high drag coefficient. Distance between virtual tailing edge with body and angle of back area of body has minor effect.
박희경(Heekyoung Park),안재일(Jae-il Ahn),오문석(Munsuk Oh),이오희(Oh-hee Lee),배종호(Jongho Bae) 대한기계학회 2005 대한기계학회 춘추학술대회 Vol.2005 No.11
Some SUV vehicle have a problem that water droplet is attached in wind shield at lower speed 40㎞/h-60㎞/h when the vehicle run on load with a swallow rain puddle. Why the problem is happened? Various test and theorical approach is adopted for solving the problem. Finally we find the mechanism where water droplet is generated, how they escape from the tire and bumper, at last how they are attached on wind shield. The approach angle at front of tire is the major factor tor preventing the problem. The next car that we make will obviously adapt lower approach angle at the front tire to prevent this phenomena.
박희경(Heekyoung Park),안재일(Jae-il Ahn),오문석(Munsuk Oh),이오희(Oh-hee Lee),배종호(Jongho Bae) 한국자동차공학회 2005 한국자동차공학회 춘 추계 학술대회 논문집 Vol.2005 No.11_1
Some SUV vehicle have a problem that water droplet is attached in wind shield at lower speed 40㎞/h-60㎞/h when the vehicle run on load with a swallow rain puddle. Why the problem is happened? Various test and theorical approach is adopted for solving the problem. Finally we find the mechanism where water droplet is generated. how they escape from the tire and bumper, at last how they are attached on wind shield. The approach angle at front of tire is the major factor for preventing the problem. The next car that we make will obviously adapt lower approach angle at the front tire to prevent this phenomena.