Radiator angle and aero balance

[bhall]

A radiator generates lift/drag when air passes through it for the same reason why any angled surface generates lift/drag when air passes over it. The only difference is the quantity of that lift/drag.

As stated earlier, it's possible to exploit those forces by changing the angle and/or shape of the radiator to gently nudge the car's center of pressure one way or the other. The rules are so tight, you almost have to look into such solutions.

That said, I do wonder about how much can actually be gained.






(Click each to enlarge)

I've always assumed - could be wrong - that teams try to direct turbulent flow into the radiator inlets due to the fact that turbulent convection is better than laminar convection. That would seem to enable a measure of flexibility in terms of inlet size, shape and placement. In the photos above you can see how teams have placed various aerodynamic devices upstream to the inlets.

The white appendages between the upper and lower wishbones on the BMW appear to have sent an eddy to the radiators. The camera housings on each car seem to have been placed with similar intentions, and I think it's also the reason behind both the Ferrari's brake duct winglets and the front pull rod.

How does such turbulent flow affect the lift/drag of the radiators it impacts, and would those benefits, if any, outweigh the benefits granted by the relative freedom to optimize the size and shape of radiators/sidepods for overall efficiency?

[olefud]

Generally, the average velocity of the “turbulence” in turbulent flow is zero. Thus -lift would depend on the throughput flow the same as laminar flow. But even if –lift is generated at the radiator, there’s a good chance that offsetting +lift would result in the ductwork that is part of the same system.

I would expect the radiator fins to function as flow straighteners. The energy used to generate the turbulent flow would show up as drag. However, if the heat transfer is more efficient with turbulent flow, the radiator could be reduced in size with an offsetting reduction in drag.

Put more succinctly, I don’t know what the net effect would be.

[bhall]

[...]

However, if the heat transfer is more efficient with turbulent flow, the radiator could be reduced in size with an offsetting reduction in drag.

Put more succinctly, I don’t know what the net effect would be.

Heat transfer is indeed more efficient with turbulent flow as it results in a thinner boundary layer on the surface of whatever it is being cooled by convection. That's the basis for my assumptions about appendages upstream to side pod inlets.

Along those lines, I wonder if McLaren separated the steering arm from the control arm in 2009(?) for that same reason.

[riff_raff]

I don't know much about aerodynamics, but I'm a bit confused by the comments claiming that the angle of the heat exchanger core itself can influence downforce. If the core is positioned entirely within a duct, how can local airflow across it produce an aerodynamic force beyond the duct wall?

Basic physics dictate that the dynamic air pressure just ahead of the core should always be greater than that just behind it. Otherwise there would be no flow in the desired direction. As for any thrust force produced by the discharged airflow mass, that is a result of energy transfer to the airflow mass when it picks up heat/momentum passing thru the core. And the momentum force of the ejected air mass would probably not be normal to the aft core face.

Also, one of the prime considerations with any radiator exit duct design is ensuring that the discharged airflow velocity is equal to or greater than the ambient passing airflow

[bhall]

I don't think the idea is that the aerodynamic influence on the faces of the radiators is by any means large, just if it's enough worth considering that influence on the car's center of pressure. At least, that's how I read the original premise.

Personally, I think it's more beneficial to design cooling solutions according to cooling requirements and the overall efficiency of the side pods, especially if teams are using turbulent flow for cooling.

EDIT: Damn you, grammar!

[peanutaxis]

bgall2k..something brings up an in teresting point. What on earth ARE these:

[flynfrog]

bgall2k..something brings up an in teresting point. What on earth ARE these:

pretty sure those are cameras

[peanutaxis]

bgall2k..something brings up an in teresting point. What on earth ARE these:

pretty sure those are cameras

Don't think so. I've never seen such a camera angle (since the early 90's).

[bhall]

Those are unequivocally camera housings. However, they may or may not have cameras within them. The FIA requires two housings on the nose, one on the engine cover and, of course, the ubiquitous one on top of the roll hoop.

Teams often use them to their advantage. The F2008, as pictured earlier, had camera housing with end plates. These days, it's not at all uncommon to find them arrayed within the neutral section of the front wing to combat the lift caused by that section.

[mx_tifoso]

They're the mandatory front end cameras... moving on! I have more to learn besides differentiating what a camera is.

[joncho]

I don't know much about aerodynamics, but I'm a bit confused by the comments claiming that the angle of the heat exchanger core itself can influence downforce. If the core is positioned entirely within a duct, how can local airflow across it produce an aerodynamic force beyond the duct wall?

Basic physics dictate that the dynamic air pressure just ahead of the core should always be greater than that just behind it. Otherwise there would be no flow in the desired direction. As for any thrust force produced by the discharged airflow mass, that is a result of energy transfer to the airflow mass when it picks up heat/momentum passing thru the core. And the momentum force of the ejected air mass would probably not be normal to the aft core face.

Also, one of the prime considerations with any radiator exit duct design is ensuring that the discharged airflow velocity is equal to or greater than the ambient passing airflow

What you say make sense riff raff, but the engineer who help in the team changed the front radiator position and angle (the car similar to a radical) and he see a marginal downforce

maybe it is because it is not a duct and a frontal radiator?

[peanutaxis]

Those are unequivocally camera housings. However, they may or may not have cameras within them. The FIA requires two housings on the nose, one on the engine cover and, of course, the ubiquitous one on top of the roll hoop.

Teams often use them to their advantage. The F2008, as pictured earlier, had camera housing with end plates. These days, it's not at all uncommon to find them arrayed within the neutral section of the front wing to combat the lift caused by that section.

They don't seem to exist on the 2011 cars - I was just watching some.

[mx_tifoso]

Ok, I think we're going off topic with the camera chat...

Anyways, here is a recent thread about angled radiators that's related and very interesting.

[flynfrog]

Those are unequivocally camera housings. However, they may or may not have cameras within them. The FIA requires two housings on the nose, one on the engine cover and, of course, the ubiquitous one on top of the roll hoop.

Teams often use them to their advantage. The F2008, as pictured earlier, had camera housing with end plates. These days, it's not at all uncommon to find them arrayed within the neutral section of the front wing to combat the lift caused by that section.

They don't seem to exist on the 2011 cars - I was just watching some.

they are f-ing camera housing how many people need to tell you that?