Renault brake ducts

[manchild]

Just noticed this small additional duct (close to lower wishbone)

[Mikey_s]

ooooh yes, very well spotted Manchild - note to self; must check what the regs say about brake ducts...

[Mikey_s]

Here we are; anyone got a ruler?

11.4 Air ducts :
Air ducts around the front and rear brakes will be considered part of the braking system and shall not
protrude beyond :
- a plane parallel to the ground situated at a distance of 160mm above the horizontal centre line of the
wheel ;
- a plane parallel to the ground situated at a distance of 160mm below the horizontal centre line of the
wheel ;
- a vertical plane parallel to the inner face of the wheel rim and displaced from it by 120mm toward the
centre line of the car.
Furthermore, when viewed from the side the ducts must not protrude forwards beyond the periphery of the
tyre or backwards beyond the wheel rim.

[joseff]

- a vertical plane parallel to the inner face of the wheel rim and displaced from it by 120mm toward the
centre line of the car.

Another grey area. How is the inner face of the wheel rim = vertical? A plane can be parralel to the rim face (which then displaces with wheel travel) or stationary and vertical, and thus not affected by camber or steering (front wheel) or toe changes.

Of course, according to my 2nd interpretation, front wheel steering is also illegal

[mx_tifoso]

What are the aero or cooling differences between round, squarish, and vertical rectangular brake ducts??

Using common sense it's known that with either shape you can get the same dimensions/area but why is the geometrical design important?

Renault have been using the vertical rectangular design:


Ferrari squarish version:


HRT semi-circular:

[raymondu999]

I think to a certain extent it's used as a flow conditioner nowadays, to condition and direct the flow to the diffuser in a way that suits their aero package...

[riff_raff]

The cooling flow through the "brake" duct is very important. Besides cooling the brake rotor, that airflow must also provide cooling for the caliper and brake fluid within, cooling for the wheel bearings, and prevent excessive heat transfer into the wheel and tire. Since the duct must turn sharply 90 degrees and direct the airflow in many different directions, it is usually rather inefficient by nature. So the actual inlet geometry profile is likely not too critical, as long as it achieves the necessary mass airflow. The sharp turn will kill the duct flow efficiency, so having a super efficient inlet shape probably doesn't help much. The best choice for brake duct inlet shape then becomes the one that produces the least wake flow disturbances.