tailieunhanh - Advanced Vehicle Technology Episode 3 Part 12

Tham khảo tài liệu 'advanced vehicle technology episode 3 part 12', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | High speed low pressure Reduced speed increase in pressure Lip spoiler 0 20 40 60 80 100 Fig. a-c Turbulent wake Lip height mm Effect of rear end spoiler on both lift and drag coefficients Negative lift tendency High speed low pressure Reduced speed increase in pressure Aerofoil spoiler Turbulent wake and therefore there is virtually no variation in the afterbody drag see Fig. . With a parallel sided squareback rear end configuration the whole rear surface area base area becomes an almost constant low negative pressure wake region. Tapering the rear quarter side and roof of the body and rounding the rear end tends to lower the base pressure. In addition to the base drag the afterbody drag will also include the negative drag due to the surrounding inclined surfaces. Fastback drag Figs and When the rear slope angle is reduced to 25 or less the body profile style is known as a fastback see Fig. . Within this much reduced rear end inclination the airstream flows over the roof and rear downward sloping surface the airstream remain ing attached to the body from the rear of the roof to the rear vertical light-plate and at the same time the condition which helps to generate attached and trailing vortices with the large sloping rear end is no longer there. Consequently the only rearward suction comes from the vertical rear end projected base area wake thus as the rear end inclined angle diminishes the drag coefficient decreases see Fig. . However as the angle approaches zero there is a slight rise in the drag coefficient again as the rear body profile virtually reverts to a squareback style car. Hatchback drag Figs and Cars with a rear sloping surface angle ranging from 50 to 25 are normally referred to as hatchback 612 b Lift and drag components on an inclined negative lift wing a Air streamlining for an inclined negative lift aerofoil wing Rear negative down- thrust c Racing car .