Aerodynamic implications of nose inlets

[Adrian Newby]

Once my initial impression of the slot's purpose was justifiably marginalized, I went along with the idea that it likely combines with the lower slot under the nose to sufficiently cool Red Bull's problematic KERS.

But, now I'm wondering what part of KERS is even in the nose to be cooled. I was under the impression that KERS components are (generally) placed in the sidepond(s), under the fuel tank and just ahead of the engine. (And something is making me think Red Bull reportedly placed one of those at the very rear of the car. But I might be making that up.)

You are right about KERS placement not being in the nose. There would have to be ducting routing air from the intake to the back of the seat/under the fuel tank area. Much of this would have already been there if the lower intake from the RB7 was for KERS cooling (although it would have to be enlarged for more flow if it were joined with the upper intake).

It seems like someone would know what that lower duct was for, after a year's worth of running...

[Adrian Newby]

I keep trying to move on and get back to the topic at hand

Let's go then. Like many others here I think that the main aim of the slot over the nose is about external aero effciency. I do not knowhre tha air in the inlet goes, what it cools etc, I think, like others, that the vent is there mainly not to make air go elsewhere.

Two most important points in my view:
-making the boundary layer start new from the leading edge above the slot
-avoiding air spill form the sides in the form of vortices, badly interacting with the push rod pin point. I think ferrari can afford a vanilla ramp because they have no pushrod. Because of this, I think that the advantage of such a solution is 3dimensional.

The convex shape before the slot is for forcing a bit of pressure recovey and guide the flow inside the slot better.

Excellent point on the Ferrari's pull-rod system possibly not requiring a more intricate hump design. I have always liked pull-rods better than pushrods for aero, as well as a couple of non-aero ones, so you think I would have come up with it! Front pull rods are harder to tune, and a bit more unexplored territory than push rods. I thought that was part of what Ferrari were running into on the first days at Jerez. Then Alonso cracked of his fast time, so... who knows what goes on in testing.

[Adrian Newby]

It seems to me that the air thru the slot, above a certain speed, stalls and spills around the sides. What air does make it thru probably does cool something. Most probably the KERS unit.
Don't one of you guys have one of them fancy flow programs?

One thing we can be sure of is that Adrian Newey has tuned that intake - its size, flow, exit, etc. - to be exactly what he wants.

We just don't know what that is!

I don't know if this is true, but I read that the RB7 was only designed to use something like 60% of the KERS allowed by the FIA, so it could be packaged better for aero reasons and not overheat. And at only 60% it still overheated. So I could definitely see the need for much more cooling, which would allow them to bump KERS up to 100% and keep it cool.

[hardingfv32]

-avoiding air spill form the sides in the form of vortices, badly interacting with the push rod pin point.

The spillage thesis seems very weak and inconsistent with what we can observe along the body.

Why do we not see an effort to control spillage on to the front mounting point of the upper control arm?

While I appreciate that there are some constraints under the latest rule set, why in the past was there not an 'universal' effort to control spillage along to upper surface of the front body? Observation of past designs would indicate spillage is not an issue.

Brian

[strad]

At least part...(the battery?)..is under the drivers seat. Remember when Webber I think it was scalded his balls?

[hardingfv32]

There would have to be ducting routing air from the intake to the back of the seat/under the fuel tank area. Much of this would have already been there if the lower intake from the RB7 was for KERS cooling (although it would have to be enlarged for more flow if it were joined with the upper intake).

It seems like someone would know what that lower duct was for, after a year's worth of running...

Well, it is not to provide cooling air to the KERS under the fuel cell. Do you guys have any practical experience on race cars? There are issues with different forms of drag in the duct that is this long and contorted. The duct would need to expand in ID size to maintain pressure levels. Is there space for this expanded duct in the chassis? Do you want to raise the fuel CG to provide room for all this ducting under the fuel cell? The heat exchange form/system would take up more volume. Finally, how do you exhaust the flow into a preferable low pressure zone.

Does not sound plausible to me.

Brian

[bhall]

You are right about KERS placement not being in the nose. There would have to be ducting routing air from the intake to the back of the seat/under the fuel tank area. Much of this would have already been there if the lower intake from the RB7 was for KERS cooling (although it would have to be enlarged for more flow if it were joined with the upper intake).

It seems like someone would know what that lower duct was for, after a year's worth of running...

Of course, that's always a possibility. But, really, there must be easier and better ways to cool KERS components that don't involve air intake at the nose that then has to be routed through a veritable obstacle course to reach the objective area.

[shelly]

-avoiding air spill form the sides in the form of vortices, badly interacting with the push rod pin point.

The spillage thesis seems very weak and inconsistent with what we can observe along the body.

Why do we not see an effort to control spillage on to the front mounting point of the upper control arm?

While I appreciate that there are some constraints under the latest rule set, why in the past was there not an 'universal' effort to control spillage along to upper surface of the front body? Observation of past designs would indicate spillage is not an issue.

Brian

There were no steps on the noses in the past, hence no big spillage to manage

[hardingfv32]

There were no steps on the noses in the past, hence no big spillage to manage

1) There is always spillage off the top surface of the front of the car. I can agree that the step causes more, but why allow ANY if spillage is truly a negative? Is this not logical?

2) Why does Ferrari not have fences at their step? Would it not be simple to CFD or test in the wind tunnel? If you guys can dream up such thesis, would not paid professional also be able to see the possibilities?

Brian

[volarchico]

If your posts keeping getting "policed", maybe you should look to what you are posting and stop taking offense. Your feelings seem to be getting bent out of shape for nothing. The rest of the posts are void of emotion. People just want the discussion to remain technical and accurate. Not sure why you feel the need to argue and roll your eyes instead of just answering a question.

[hardingfv32]

[...]
So then to the questions:

1) There is always spillage off the top surface of the front of the car. I can agree that the step causes more, but why allow ANY if spillage is truly a negative? Is this not logical?

2) Why does Ferrari not have fences at their step? Would it not be simple to in CFD or test in the wind tunnel? If you guys can dream up such a thesis, would paid professional not be able to see the possibilities as well as us?

Brian

[Adrian Newby]

At least part...(the battery?)..is under the drivers seat. Remember when Webber I think it was scalded his balls?

I'm sure part of the KERS is under the seat back, since it is lying down, but I can't imagine they put any of it under the "seat" portion, for center of gravity reasons.

[Adrian Newby]

You are right about KERS placement not being in the nose. There would have to be ducting routing air from the intake to the back of the seat/under the fuel tank area. Much of this would have already been there if the lower intake from the RB7 was for KERS cooling (although it would have to be enlarged for more flow if it were joined with the upper intake).

It seems like someone would know what that lower duct was for, after a year's worth of running...

Of course, that's always a possibility. But, really, there must be easier and better ways to cool KERS components that don't involve air intake at the nose that then has to be routed through a veritable obstacle course to reach the objective area.

Apparently it is quite a chore to cool the KERS and still achieve Adrian Newey's aero packaging concerns, since it over heated so much last year. The only potential problem I could see with the ducting, if getting cooling flow from the nose, is connecting the upper duct to the lower one. The most room for that would probably be on the sides, in the ankle area.

[PlatinumZealot]

That would be very dangerous if it did happen. you need 1000's of Netwons to lift the front up. That would be a real shock to the driver, not to mention an increase in drag as the wing starts to work.



I did a basic, rough and dirty CFD test. Air speed 100mph. A car with a slot in the step and a car without.
The air flow behave very similarly, almost identical. Maybe I need a supercomputer? lol.

Anyway. There was air backed up inside the cockpit in both models. I didn't have a driver in there just open cockpit. I will model a driver and try again later but for now this is what I saw:

The car with the slot in the step was had a few Newtons (880N Vs 890N) less of drag at 100mph. You can call it the same because with the driver it might be even closer.I do not know how accurate these values are of course, just a quick dirty model.

The slot modeled was actually very generous at about 3/4 inch tall. Flow went through it at a decent speed about 80mph then slows down.
The slot was still too restrictive to change the general quality of the air spilling over the sides (I just looked on the velocity component in the sideways direction).
It did not change the quality of the air going over the top edge of the step either. It still had that pressure "inflection" over the edge.

I Really don't know.. other than driver cooling- which Newey didn't need such a step, The air flow quality change was very miniscule.
I don't know what Newey is using it for, but my deduction leads me to believe it is for other reasons. Like maybe an F-duct.

I hope someone who is an aero expert investigates it.

Excellent rough and dirty effort with the CFD. I do think the Caterham/Lotus type nose will give the best drag numbers with that kind of analysis. Did you include the RB8's side fences on your CFD analysis? I think that would improve the spillage greatly, and increase the flow into the intake.

Yes I had the side fences. When I say Rough and dirty I mean:

I had rolling road
5 refinement levels (very good actually)
No spining wheels
Just ball park surface roughness and turbulence levels
I had gravity effects
No driver

There might be other effects that propagate backwards, but I am no expert.

[hardingfv32]

Apparently it is quite a chore to cool the KERS and still achieve Adrian Newey's aero packaging concerns, since it over heated so much last year. The only potential problem I could see with the ducting, if getting cooling flow from the nose, is connecting the upper duct to the lower one. The most room for that would probably be on the sides, in the ankle area.

Is the chassis's exterior dimensions pretty much controlled by the internal cross section specification or rule? If so, are they going widen the chassis to provide space for the very inefficient ducting being proposed? I think not. They want the chassis as narrow as possible.

Brian