Aerodynamic implications of nose inlets

Here are our CFD links and discussions about aerodynamics, suspension, driver safety and tyres. Please stick to F1 on this forum.

Post Sun Feb 12, 2012 5:26 am

n smikle wrote: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.
Adrian Newby
 
Joined: 7 Feb 2012

Post Sun Feb 12, 2012 5:26 am

Adrian Newby wrote: just enough to "break the seal


Do you have any data showing the relationship of ground clearance to down-force showing that it could be non-linear at some point called 'breaking the seal'?

Brian
hardingfv32
 
Joined: 3 Apr 2011

Post Sun Feb 12, 2012 5:43 am

bhallg2k wrote:I suppose that does make sense. My idea came from the "delta" wings Ferrari ran on the nose of the 248F1 at Monza.

But, I must say, if the forces exerted on RB8's upper slot are enough to lift the nose and lessen its production of downforce, you can't then discount the notion that it's used as a sort of air dam(n).

Like n smikle, I do wonder if lifting the nose like that is even safe, though.

(For what it's worth, I think the philosophy behind the Ferrari nose is simple: max air underneath. That goal, combined with the regulations, has dictated its design. Then again, I also feel like we've not seen anything all that close to the definitive F2012.)



I still don't see it as any more effective as an air dam(n!), if the ramp is guiding the flow to hit the inside of the top of the intake/chassis and then exits through the cockpit from there. No blockage to flow, just taking the hit at a different angle that has a lift component.

As I said, this was just a thought, and probably the most ambitious (wildest) use of this intake that anyone has even postulated, so... not very likely, but fun to think about.

I agree that Ferrari has maximized their nose to get the most flow underneath. Job well done on that mark. And they have the entire season to refine the nose and the hump. The chassis, however is set, and I do think they could have better refined its contours. That said, I do think they have more room for change/improvement than McLaren, who, in my opinion, have kind of boxed themselves in.
Adrian Newby
 
Joined: 7 Feb 2012

Post Sun Feb 12, 2012 5:49 am

hardingfv32 wrote:
Adrian Newby wrote: just enough to "break the seal


Do you have any data showing the relationship of ground clearance to down-force showing that it could be non-linear at some point called 'breaking the seal'?

Brian

actually that relationship is never linear. you gain up exponentially until the choke point.
"The question isn't who is going to let me; it's who is going to stop me."
flynfrog
 
Joined: 23 Mar 2006

Post Sun Feb 12, 2012 6:16 am

flynfrog wrote:
hardingfv32 wrote:
Adrian Newby wrote: just enough to "break the seal


Do you have any data showing the relationship of ground clearance to down-force showing that it could be non-linear at some point called 'breaking the seal'?

Brian

actually that relationship is never linear. you gain up exponentially until the choke point.


Can you imagine what the engineers/wind tunnels/computers they have these days could do with those rubber seals, side skirts, and HUGE tunnels from the 1980's?!

The drivers would have to wear g-suits!
Adrian Newby
 
Joined: 7 Feb 2012

Post Sun Feb 12, 2012 12:02 pm

n smikle wrote: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 beleive it is for other reasons. Like maybe an F-duct.

I hope someone who is an aero expert investigates it.


Fantastic work, one of the best posts in this thread. Perhaps now this will be enough to stop people thinking that the "stepped" nose designs will make some revolutionary impact on the cars this year.

There's no doubt in my mind that all the teams investigated the effect of this on the car's aero package. There's clearly an advantage to be gained by using these noses if only for the airflow under the car.

As mentioned previously the cockpit / driver's helmet would no doubt cause more a negative effect on the car than one of these stepped noses.
lombers
 
Joined: 5 Feb 2012

Post Sun Feb 12, 2012 12:15 pm

@smikle: was it a 2d model or a 3d model?
twitter: @armchair_aero
shelly
 
Joined: 5 May 2009

Post Sun Feb 12, 2012 12:20 pm

Well, in either case, the air before the step would go into the the cocpit. This would avoid the formation of a recirculation bubble on top of the step. CFD experts may find this equivalent to a forward facing step problem.

The boundary layer is "broken" with the slot and a new BL will start from the top..
n_anirudh
 
Joined: 25 Jul 2008

Post Sun Feb 12, 2012 5:35 pm

lombers wrote:
n smikle wrote: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 beleive it is for other reasons. Like maybe an F-duct.

I hope someone who is an aero expert investigates it.


Fantastic work, one of the best posts in this thread. Perhaps now this will be enough to stop people thinking that the "stepped" nose designs will make some revolutionary impact on the cars this year.

There's no doubt in my mind that all the teams investigated the effect of this on the car's aero package. There's clearly an advantage to be gained by using these noses if only for the airflow under the car.

As mentioned previously the cockpit / driver's helmet would no doubt cause more a negative effect on the car than one of these stepped noses.


I agree the stepped noses are a necessary evil caused by the rule change and the desire to keep the noses as high as possible.

However, I do think the new rules present opportunities for those bright enough to do the most with the cars within the new confines. Adrian Newey is particularly good at this. I do appreciate n smikle's work, above (and was the first to say so), but I don't think what he has done so far has ruled anything out.
Adrian Newby
 
Joined: 7 Feb 2012

Post Sun Feb 12, 2012 5:57 pm

flynfrog wrote:actually that relationship is never linear. you gain up exponentially until the choke point.


But, is there some big change along the curve that one might label 'breaking the seal'?

Brian
hardingfv32
 
Joined: 3 Apr 2011

Post Sun Feb 12, 2012 6:12 pm

hardingfv32 wrote:
flynfrog wrote:actually that relationship is never linear. you gain up exponentially until the choke point.


But, is there some big change along the curve that one might label 'breaking the seal'?

Brian


Slightly different things going on here. The inverted airfoil (the "wing" portion) will gain exponentially as it gets closer to the ground, and go to zero when it touches the ground. The seals on the endplates only "seal" if they are very close to the ground, and are most effective when actually touching the ground. There is a big change along the curve for the seals.
Adrian Newby
 
Joined: 7 Feb 2012

Post Sun Feb 12, 2012 6:18 pm

Adrian Newby wrote: I do appreciate n smikle's work, above (and was the first to say so), but I don't think what he has done so far has ruled anything out.


Your opinions sound like you have ruled out all but the slot/vent design. So, smikle has actual data and you tour opinion is unswayed. How about McLaren or Ferrari with vast CFD and wind tunnel research efforts, they have not evaluated the slot/vent design and decide to go with different designs? Wouldn't it be more logical to think that the top of the nose is not that influential to the aero design and that there is no design that stands out above all others?

Brian
hardingfv32
 
Joined: 3 Apr 2011

Post Sun Feb 12, 2012 6:50 pm

hardingfv32 wrote:
Adrian Newby wrote: I do appreciate n smikle's work, above (and was the first to say so), but I don't think what he has done so far has ruled anything out.


Your opinions sound like you have ruled out all but the slot/vent design. So, smikle has actual data and you tour opinion is unswayed. How about McLaren or Ferrari with vast CFD and wind tunnel research efforts, they have not evaluated the slot/vent design and decide to go with different designs? Wouldn't it be more logical to think that the top of the nose is not that influential to the aero design and that there is no design that stands out above all others?

Brian


I was the first to applaud n smikle for his efforts, but I don't think anyone, including n smikle himself would say they are definitive or actually prove anything in particular. You could take them as "proving" there is no air dam if you like, but I didn't go there because he told us it was a "rough and dirty" exercise and I appreciated it for what it was. Also he did not model the "fences" on the sides of the RB8's hump, a major component. This is not a criticism of him or what he has done. He told us what he did and what the results were. I think it was great, for what it was.

McLaren has a completely different aero concept for their cars, so they didn't have a "hump" to have to mitigate.

I have pleaded with people, time after time after time, to understand that the top of the nose is (relatively) unimportant.

What IS important is that the top of the nose be designed in such a way that it not mess up parts of the car which ARE important.

In comes this "hump" necessitated by the new rules and the desire to keep the nose as high as possible. No one would have it there if they had a choice. But since it is, and since it is right in the middle of the critical area between the front tires (messing up parts of the car which ARE important), how are you going to mitigate its negative effects as much as possible? Newey made a slot. Lotus and Caterham made a big dip. All excellent solutions. I am not impressed with Ferrari's "worry about it later" hump. But I am sure they will change it at some point.

As far as McLaren and Ferrari not choosing the same solutions as Adrian Newey, in general? That hasn't worked out too well for them in recent years, has it?
Adrian Newby
 
Joined: 7 Feb 2012

Post Mon Feb 13, 2012 2:51 pm

Adrian Newby wrote:I'm sure all of the designers are far too clever to agree with me.

It's all a matter of trade-offs, so what are you willing to give up to get a little less drag on the nose of your car?

All air is critical, but some is far more critical than others.

The fences only extend as far as the hump, at which point an air dam is going to spill off to the sides as it builds forward (a goodly portion of the oncoming air running into the air dam would have already spilled off to the sides). And if that is as large as your air dam is going to be, I don't see the point, especially for the cost to the flow on the sides. I believe the fences are there to keep the air that is going up the ramp from being pushed over the sides.

Continue to differ with me all you like. It will put you in far better company!


I'm going to have to agree that it seems more likely for the top slot to be a vent than a dam.

You have a rule that would generally lead to a stepped nose if you want to maximise the underbody airflow. Other than being ugly, one of the main disadvantages of the step would be air spilling around the sides causing disruption in an area where you gain considerable benefit from keeping the flow as clean as possible.

Inserting a vent into the area where the step would be reduces this disruption while also scavenging some additional cooling air at virtually no cost; win/win. (Obviously we can't tell if they've managed to duct some of this air to provide additinoal KERS cooling, or if it's just servicing the driver and electronics.)

If you have an air dam that creates a large enough effect to be significantly better in terms of aero efficiency than a simple step, for air flowing over the nose, I don't see how it could do anything other than create increased "side-spill"; win/lose. I know which one sounds like the better option to me.

It would be good if someone could run some CFD with a detailed reproduction of the RB front end modelled as both a dam and a vent at some point to see how things look. Either way it looks like those side slop "fences" would be important in keeping the flow clean on either side. Apologies if n_smikle's work included these(I can't see it for some reason), but it sounds like it didn't from the discussion.
Last edited by Steven on Thu Feb 16, 2012 12:32 am, edited 1 time in total.
Reason: Removed personal comments
Twaddle
 
Joined: 17 May 2010

Post Mon Feb 13, 2012 4:08 pm

The discourse in this thread is actually quite gentle. But, if this is a bit much, I urge you to stay away from the Mercedes thread at all costs. Those people are savages.

Adrian Newby wrote:As far as McLaren and Ferrari not choosing the same solutions as Adrian Newey, in general? That hasn't worked out too well for them in recent years, has it?

And it never hurts to have four testbeds at your disposal when you inaugurate a brand new formula and enter a vacuous testing environment, ya know? ;)
bhall
 
Joined: 28 Feb 2006

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