F1 physics – rear blown diffusers
Formula One’s 2010 season is fast approaching its climax, and this year, the championship title will be dependent upon every aspect of the race – the driver, the track, the team politics, and inevitably
the car set-up. Designing a winning vehicle with the technical brilliance of a Red Bull or the aerodynamic innovation of the McLaren is a complicated feat, and it is small wonder that mechanics work around the clock to perfect their craft while keeping within
regulation.
Because race cars need as much downforce as possible on the track to enable greater speed and acceleration, various tweaks and tricks have been implemented into F1 vehicles to keep the car on the ground
with as little effort as possible. One way this is done is to use a rear blown diffuser, which functions by channelling hot air expelled from the exhaust pipe at high speeds and blowing it over a curved surface, creating low pressure beneath the car.
Due to the extreme temperatures being reached – sometimes as high as 1000'C – finding materials capable of withstanding the heat can be highly challenging, as well as ensuring that the gases are directed
correctly to achieve the maximum suction rate, claims F1 Pulse’s expert, Prof. Schumster.
He goes on to discuss the delicate attributes of the device as well, which can be affected by how the driver opens and closes the throttle. This changes the amount of downforce additionally generated,
and is at its maximum when the driver hits the apex and begins to regain power. Because of this, the way a driver handles their vehicle is dependent upon very precise deliberation in order to achieve the best result.
One team which has been able to handle the rear blown diffuser system is this season’s current constructor’s title leader Red Bull, which has adopted a system to map the constant flow of exhaust which
passes through the diffusers. Its only flaw is the danger of overheating over a period of time, such as the duration of a race; it is better suited to being activated during qualifying sessions only – perhaps a part of Sebastian Vettel’s magical qualifying
ability.
As well as Red Bull, other F1 teams have utilized the rear blown diffuser system this season. Ferrari debuted their own temporary model this year at Valencia, and it has been a work in progress since.
Germany’s Auto Motor und Sport reported that “the new layout allows a steeper shape of the diffuser, but the downforce advantage will only come when the exhaust fumes are directed through the diffuser.” In order to effectively monitor the device, engineers
have applied small stripes of temperature-sensitive paint which changes colour, enabling the crew to prevent the device from overheating.
Renault, Mercedes, and McLaren have also jumped on the diffuser band wagon this season, satisfied with the increased efficiency of under-body aerodynamic movement, although at times dropping it in order
to try out other alternatives.
Either way, it is a big improvement from last year’s double diffuser, put into action by Brawn GP, Toyota, and Williams. The rear diffusers were positioned towards the rear to reduce downforce, increasing
drivers’ chances of overtaking. Yet the reduction in downforce was too great to be beneficial, causing the teams to seek new ways of increasing it.
Blown diffusers are not a completely new invention, having been pioneered by Renault in the early 80’s and more commonly used since 1985. But with each remarkable feature of the F1 car being constantly
redesigned and the boundaries of physics challenged, the 2010 model has come a long way and could have a powerful role to play in the remaining races this season as each driver strives to capitalize on every advantageous aspect of his car.
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