9781422272862

Open-wheel racecars have large spoilers that disrupt airflow around the car to decrease drag.

Designers try to limit flow detachment by designing the car’s contours, tires, and items such as side mirrors to reduce it. For example, racecars have tails called spoilers that extend beyond the back wheels. The tail allows air to converge more smoothly into the vacuum at the back. When air is able to flow more smoothly, a smaller empty space is created and drag is reduced. The force of the rear vacuum is always greater than frontal pressure, so designers work very hard to minimize the size of the rear vacuum. A boundary layer is created when the air meets the surface of the car. Depending on the surface, there are two types of airflow and boundary layers: turbulent and laminar. Turbulence is created when air detaches from the car in a rough manner. At the rear of the vehicle, as air finally leaves the car for good, there is an unavoidable turbulent airflow. Turbulent air is chaotic air. Therefore, designers try to create smooth airflow called laminar airflow around the vehicle. Any object that protrudes from a car, like a side mirror or even a hood ornament, can affect laminar flow. If a side mirror were to be designed as a square-shaped object with sharply defined edges, the air coming off

10

AUTOMOBILES