Do certain rims act as brake coolers, engine coolers, or air intakes?

[KevRC4130]

Hi guys,
I've noticed that some rims, like the ones on the Mercedes SLR prototype for example, have spokes that are directed in, and seem like they create a fan kind of thing. It seems like this could be a self powered fan to cool the brakes, give air to the engine, remove air from the engine (like an exhaust fan), etc. I'm just wondering if these kinds of rims are designed for this purpose, or its just cosmetic. Maybe the rims don't blow air at all? Maybe the sucking in/blowing air causes more air resistance to the car? These are all hypothetical, but maybe somebody actually has facts about what directional rims do?

Like these:

 

[epj3]

Simple answer - NO. There's a reason an airplane's propellar's aren't that close together - it's not efficient at all. Allows almost no air through when spinning fast.

 

[Nataku]

Simple answer - NO. There's a reason an airplane's propellar's aren't that close together - it's not efficient at all. Allows almost no air through when spinning fast.

I disagree, there is movement of air. But, perhaps not very efficiently. That's the idea of the brake dust cover. To force air inward toward the hub to prevent dust from getting to your wheels.

 

[epj3]

I disagree, there is movement of air. But, perhaps not very efficiently. That's the idea of the brake dust cover. To force air inward toward the hub to prevent dust from getting to your wheels.

No - a brake dust cover simply keeps the brake dust from going from the brakes to the outside of the wheel. I'll take pictures of my dad's old brake covers (he had on his olllld pontiac), you'll see that by the way it spins, it will actually draw air from inside the wheel well out of the wheel.

My wheels get COATED in brake dust, and you're telling me these things push air? I HIGHLY doubt it.

Also; Explain why this Ferrari, which has the most advanced brakes IN THE WORLD (which get RED HOT...) does not have wheels designed to 'push air' by the brakes? If the wheel design helped the car.... I'm pretty sure they'd be the first one to use it.

 

[Kirby]

Probably not as it would have minimal effect compared to the other dynamics of the air around the car. I'm thinking that there will be a higher pressure zone under the car as it displaces the air it is moving through. The air on the outside of the wheels will be at a lower pressure (Bernoulli effect - think airplane wing). So the net result is that air will flow OUT of the wheels. And I guess our brake dust problem on our wheels would help to confirm my idea?

 

[MrElussive]

Yeah, I really don't think the rims have the power of doing that. I think it's just the brakes' job to keep things cool, not the wheels'.

 

[epj3]

Probably not as it would have minimal effect compared to the other dynamics of the air around the car. I'm thinking that there will be a higher pressure zone under the car as it displaces the air it is moving through. The air on the outside of the wheels will be at a lower pressure (Bernoulli effect - think airplane wing). So the net result is that air will flow OUT of the wheels. And I guess our brake dust problem on our wheels would help to confirm my idea?

I agree that air WILL flow out of the wheel - but I don't think the design of the wheel will help it at all. If it did -- we wouldn't be getting ANY dust on the inside of our wheels, since it would all be blown out (though, if the rotor is spinning, obviously the brake dust will come out of the side of the rotor that is leaving the pad, which would cause the dust to collect direcly under (from the force of it being 'thrown' for lack of better words.)

Almost all cars (or atleast mine...) are designed as to push air past the brake system. Mine has two channels next to the fog lights on the lower body that have tubes that direct air onto the brakes.

I still don't think the wheel design does anything for the performance -- becuase like i said, if it did, Formula 1 would have a very intricately designed wheel to push air out of it. F1 is the cutting edge of technology - I'm pretty sure they would NOT have overlooked something like that.

 

[tool fan]

That is funny...legitamate question,,,but NO. That is like asking if a spoiler on the top of a ford focus actually improves performance (no not the GTR model, standard everyday 25 hp focus) and SURVEEEEEEEEEEEEEEEEEEY SAYS NO!!!!!!

 

[theBMWenthusiast]

they're cosmetic

 

[gizzy]

Simple answer - NO. There's a reason an airplane's propellar's aren't that close together - it's not efficient at all. Allows almost no air through when spinning fast.

Using this logic then the turbo fans on the cessna citations jet engines would also be useless. Two options exist in the majority of small aircraft propellers - two and three blade propellers, four is available when you get into turbo props. Some of the reasons include sight (you have to look through the propeller in single engine airplanes which would be difficult to do if you had a fan their), drag (more blades more drag requiring more power to spin the props), and cost (three blade props cost more to purchase and maintain than their two blade counterparts).

As far as the rims making much of any difference in air movement in the wheel well, I doubt it. Air will be forced around the wheel well by the front fender actually sucking air out of the wheel well (Bernoulli's principle).

 

[Nataku]

No - a brake dust cover simply keeps the brake dust from going from the brakes to the outside of the wheel. I'll take pictures of my dad's old brake covers (he had on his olllld pontiac), you'll see that by the way it spins, it will actually draw air from inside the wheel well out of the wheel.

My wheels get COATED in brake dust, and you're telling me these things push air? I HIGHLY doubt it.

Also; Explain why this Ferrari, which has the most advanced brakes IN THE WORLD (which get RED HOT...) does not have wheels designed to 'push air' by the brakes? If the wheel design helped the car.... I'm pretty sure they'd be the first one to use it.

All i'm saying is that there is air movement.

As for the brake dust cover have a set ( not on my BMW ). The type of cover I have has radial slit. The slit are oriented such that the rotation of the wheel draws air inward in towards the hub. The brake dust cover are designated left and right. Put the right on the left would make the cover useless, drawing air out and get the brake dust on the wheels. The design allows for air to get to the brake yet not allow dust to get to the wheel.

By the way, I have a BS in Aerospace Engineering.

 

[epj3]

All i'm saying is that there is air movement.

As for the brake dust cover have a set ( not on my BMW ). The type of cover I have has radial slit. The slit are oriented such that the rotation of the wheel draws air inward in towards the hub. The brake dust cover are designated left and right. Put the right on the left would make the cover useless, drawing air out and get the brake dust on the wheels. The design allows for air to get to the brake yet not allow dust to get to the wheel.

By the way, I have a BS in Aerospace Engineering.

I know what you're saying - I just misunderstood your original post.


What I said about the size/number of the propellers is that on an aircraft still holds - a prop-engine is built the way it is for the reasons gizzy gave - but I didn't say anything about a turbo-prop where there are actually turbines - not a propellar (At least, not the part being discussed.) I understand that smaller turbines like that can have a larger number of 'blades'. IE - a turbocharger.

 

[Ghost]

I think that the direction of the spokes makes minimal difference in the amount of air that goes through the wheel as opposed to the surface area that is covered by the wheel. I think that the more the wheel is “open” the better the air movement through it, which is why Ferrari and other car manufacturers have seemed to go with a more “open wheel” approach to the design of their wheels.