Beijing City International School Jiayi Ling
Aerodynamic is a branch of fluid mechanics (hydrodynamics), and its prior purpose is to find characters the motion of air when it's in interaction with solid. It is heavily used in aerospace industry and automation industry, and the field of Formula One Racing car is no doubt one of them. Traces of the use of aerodynamics in the design of F1 cars is obvious: for years, F1 cars are known for its peculiar appearance which differs from other commercially produced cars. Not hard to imagine, this appearance is carefully calculated by mechanical engineers to help the F1 cars to achieve the best aerodynamics, and this carefulness on these trivial details is the reason why F1 cars are being referred to the most high-tech products on this planet other than rockets and space station.
In the field of Formula One, the aim of aerodynamics consists two aspects: the first is to reduce air resistance, and the second is to increase downward force. The need to reduce air resistance is apparent, since the amount of air resistance is in quadratic proportion to the speed of the moving object, the waste of speed for fast moving racing car is unimaginable. Therefore, design that could reduce air resistance would very useful in the design of F1 cars. The second aspect, however, is a bit tricky to understand. The logic for this need is that since there are lots of turns in a F1 race, it would save much time if drivers don't need so slow down too much at every turns. To achieve this aim, designers need to increase the grip (friction force) between the tire and the track so that it wouldn't slip even at a high speed. Since friction force is proportionate to the downforce, the increase of downforce can pushes the car to stay in the track and prevent the car from slipping in high speed turns, thus increases the speed limitation boundary for drivers. For this reason, the increase of downforce is also an aspect of aerodynamics. In the following chapter, I will introduce some basic principles in aerodynamics for us to understand the logic behind different aerodynamic devices on a F1 racing car.
Principles of Aerodynamics
Production of downward force
To understand the production of downward force, we might want to investigate on a similar concept: the production of uplifting force. To get an idea of how strong this force can be, consider this as the power source for planes to stay on the sky. Swiss physicist Nicolaus Bernoulli raised in 1738 the Bernoulli Equation that can be very usefully in explaining the production of downward or uplifting force. The Bernoulli equation is as follows:
In this function, P represents the pressure energy of the fluid, represents the gravitational potential energy, and represents the kinetic energy; the sum of all of which is always the same for represents a constant. Therefore, according to this equation, when gravitational potential energy and the density of the fluid ( ) is constant, as in the case of a running F1 car, the pressure is inversely proportionate to the speed of the object. That is, the faster an object moves, the less pressure it will receive.
Now if we look at the figure 1 bellow, the air flow from bellow the object covers longer distance in the same time comparing to the air flow from above the object. This means that they travel in faster speed and thus less pressure. Because all objects tend to move from high-pressure area to low-pressure area, the difference in pressure will create a force on the object, and in this case a downward pressure L.