Aerodynamic drag is a large resistance force to vehicle motion,particularly at highway speeds.Conventional wheel deflectors were designed to reduce the wheel drag and,consequently,the overall vehicle drag;however,they...Aerodynamic drag is a large resistance force to vehicle motion,particularly at highway speeds.Conventional wheel deflectors were designed to reduce the wheel drag and,consequently,the overall vehicle drag;however,they may actually be detrimental to vehicle aerodynamics in modern designs.In the present study,computational fluid dynamics simulations were conducted on the notchback DrivAer model-a simplified,yet realistic,open-source vehicle model that incorporates features of a modern passenger vehicle.Conventional and air-jet wheel deflectors upstream of the front wheels were introduced to assess the effect of underbody-flow deflection on the vehicle drag.Conventional wheel-deflector designs with varying heights were observed and compared to 45◦and 90◦air-jet wheel deflectors.The conventional wheel deflectors reduced wheel drag but resulted in an overall drag increase of up to 10%.For the cases studied,the 90◦air jet did not reduce the overall drag compared to the baseline case;the 45◦air jet presented drag benefits of up to 1.5%at 35 m/s and above.Compared to conventional wheel deflectors,air-jet wheel deflectors have the potential to reduce vehicle drag to a greater extent and present the benefit of being turned off at lower speeds when flow deflection is undesirable,thus improving efficiency and reducing emissions.展开更多
文摘Aerodynamic drag is a large resistance force to vehicle motion,particularly at highway speeds.Conventional wheel deflectors were designed to reduce the wheel drag and,consequently,the overall vehicle drag;however,they may actually be detrimental to vehicle aerodynamics in modern designs.In the present study,computational fluid dynamics simulations were conducted on the notchback DrivAer model-a simplified,yet realistic,open-source vehicle model that incorporates features of a modern passenger vehicle.Conventional and air-jet wheel deflectors upstream of the front wheels were introduced to assess the effect of underbody-flow deflection on the vehicle drag.Conventional wheel-deflector designs with varying heights were observed and compared to 45◦and 90◦air-jet wheel deflectors.The conventional wheel deflectors reduced wheel drag but resulted in an overall drag increase of up to 10%.For the cases studied,the 90◦air jet did not reduce the overall drag compared to the baseline case;the 45◦air jet presented drag benefits of up to 1.5%at 35 m/s and above.Compared to conventional wheel deflectors,air-jet wheel deflectors have the potential to reduce vehicle drag to a greater extent and present the benefit of being turned off at lower speeds when flow deflection is undesirable,thus improving efficiency and reducing emissions.
