Aerodynamic implications of nose inlets

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Post Sat Feb 11, 2012 10:40 pm

marcush. wrote:hm ...I always thought everything counts .sure with those four wheels and barndoorlike wings a little hump will not alter drag very much but then where do you stop saying it does not matter?


"Compared to clean air flow between the front tires: Top nose drag does not matter..."

It's all about making compromises and picking your shots.

Do you want...

...a large front air dam that will give you a tiny bit less drag for a tiny amount of time on an unimportant part of an already very draggy car...

...at the expense of pushing a bubble of low-energy air into an area where it is most critical to have clean, smooth flowing air, resulting in decreased downforce over the entire length of the undertray?

I would say no, but most people on this board disagree.

To each, his own...
Adrian Newby
 
Joined: 7 Feb 2012

Post Sat Feb 11, 2012 11:09 pm

If you work with the theory this is ducted rather than a dead end dam, I think the exit would the important bit.

As a few people have mooted, it might not be great for cooling as the speed of flow may be impeded in the duct . if however it were aiming for a variant of the fluidic valve trick (using a low energy flow to switch flow of a higher energy flow) they all learned from the f-duct dev, they could utilise the flow to "switch" flow direction over some of the bodywork at high speed (assuming the duct doesnt choke) .

So a passively activated flow switching device. I'm imagining a duct splitting in 2, either side of the driver to some area of the rear bodywork. If working on free flow, it might be a no. starter, but if there's a more powerful ducted flow to work with ( as per f-duct) might it have a usable effect...

Sound plausible?

If so, any useful areas that might benefit from an altered flow at high speed?
avatar
 
Joined: 13 Mar 2009

Post Sat Feb 11, 2012 11:14 pm

Adrian Newby wrote:
I would say no, but most people on this board disagree.

To each, his own...


I don't disagree. I might not like your Bernoulli description earlier, but I don't subscribe to the concept of an air dam. Of course , I've been proven wrong before,so we'll have wait and see the nose off to find out.
volarchico
 
Joined: 26 Feb 2010

Post Sat Feb 11, 2012 11:20 pm

Adrian Newby wrote:

Even if it did work as an air dam, which it won't - especially not to the wildly exaggerated extent shown in that MS paint drawing earlier in this thread - it would spill lots of air over the sides, exactly where you don't want it, doing more harm than good.

Compared to clean air flow between the front tires:

Top nose drag does not matter. Top nose drag does not matter. Top nose drag does not matter.

I can't say it any plainer than that, so I can only repeat it.


I wonder if the aero designers at the various teams share the same opinion as you do? If they believed that top nose drag did not matter, then they could just a easily have disregarded any form of streamlining. And McLarn would not have made sure that they had a smooth upper surface.

I believe that ANY air passing over, under or alongside the car, is critical.

If you look at the RBR8 'intake', you will see that Newey brought fences forward of the opening. This would be to prevent overspill and would contain the air that is creating the airdam.

You are, of course, entitled to your opinion, but hopefully you will allow me to continue to differ.
gilgen
 
Joined: 3 Apr 2010

Post Sat Feb 11, 2012 11:36 pm

avatar wrote:If you work with the theory this is ducted rather than a dead end dam, I think the exit would the important bit.

As a few people have mooted, it might not be great for cooling as the speed of flow may be impeded in the duct . if however it were aiming for a variant of the fluidic valve trick (using a low energy flow to switch flow of a higher energy flow) they all learned from the f-duct dev, they could utilise the flow to "switch" flow direction over some of the bodywork at high speed (assuming the duct doesnt choke) .

So a passively activated flow switching device. I'm imagining a duct splitting in 2, either side of the driver to some area of the rear bodywork. If working on free flow, it might be a no. starter, but if there's a more powerful ducted flow to work with ( as per f-duct) might it have a usable effect...

Sound plausible?

If so, any useful areas that might benefit from an altered flow at high speed?


Any decrease in downforce at a speed greater than that of the fastest corner on the track would result in less drag down the faster straights...
Adrian Newby
 
Joined: 7 Feb 2012

Post Sun Feb 12, 2012 12:02 am

gilgen wrote:
Adrian Newby wrote:

Even if it did work as an air dam, which it won't - especially not to the wildly exaggerated extent shown in that MS paint drawing earlier in this thread - it would spill lots of air over the sides, exactly where you don't want it, doing more harm than good.

Compared to clean air flow between the front tires:

Top nose drag does not matter. Top nose drag does not matter. Top nose drag does not matter.

I can't say it any plainer than that, so I can only repeat it.


I wonder if the aero designers at the various teams share the same opinion as you do? If they believed that top nose drag did not matter, then they could just a easily have disregarded any form of streamlining. And McLarn would not have made sure that they had a smooth upper surface.

I believe that ANY air passing over, under or alongside the car, is critical.

If you look at the RBR8 'intake', you will see that Newey brought fences forward of the opening. This would be to prevent overspill and would contain the air that is creating the airdam.

You are, of course, entitled to your opinion, but hopefully you will allow me to continue to differ.


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!
Adrian Newby
 
Joined: 7 Feb 2012

Post Sun Feb 12, 2012 2:06 am

Your state the goal is drag reduction and clean flow..so do you guess this nose has cleaner flow and less drag than the Caterham nose?
"You can't change what happened. But you can still change what will happen.
Sebastian Vettel"
n smikle
 
Joined: 12 Jun 2008

Post Sun Feb 12, 2012 3:43 am

n smikle wrote:Your state the goal is drag reduction and clean flow..so do you guess this nose has cleaner flow and less drag than the Caterham nose?


The main goal of the RB8's upper intake is to allow as much clean, high energy flow in between the front tires as possible. There is likely to be a secondary goal of routing the internal flow somewhere specific (or it may just exit through the cockpit). The tertiary goal would be to cool the driver. All of these will be accomplished with as little drag penalty as possible.

As far as the Caterham goes, it has quite a nice nose, functionally speaking, compared to the Ferrari, for instance. But I think the RB8 will have cleaner flow between the front tires while also accomplishing one or two other objectives, but at a slightly higher drag penalty.

You would also have to take into account any drag acquired by the Caterham as it cooled the driver, and accomplished the other goals, if you wanted a more complete comparison.

The Lotus solution, much like Caterham's, is quite nice too (for a step-nose, that is), and it did very well in Jerez.
Adrian Newby
 
Joined: 7 Feb 2012

Post Sun Feb 12, 2012 4:16 am

Another thought I have had is that...

At faster speeds, air going up the ramp and hitting the underside of the upper intake could tend to lift the nose of the RB8 just enough to break the suction of the front wing and undertray, thereby reducing downforce and therefor drag.

At slower speeds, the nose comes back down, regains downforce and rockets through the turns.
Adrian Newby
 
Joined: 7 Feb 2012

Post Sun Feb 12, 2012 4:26 am

I've somewhat had that idea before: putting proper wings on a car configured in such a way as to reduce downforce - drag - at a certain speed when such downforce is unnecessary. Then I realized that would just be countering Drag A with Drag B.

(Looking through this thread, I do find it more than a little amusing that regarding the Red Bull, drag occurring over the top of the nose is, generally speaking, insignificant. Regarding the Ferrari, however, it's critical, and their design is crude. It's always the little things that crack me up.)
bhall
 
Joined: 28 Feb 2006

Post Sun Feb 12, 2012 4:44 am

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 beleive it is for other reasons. Like maybe an F-duct.

I hope someone who is an aero expert investigates it.
"You can't change what happened. But you can still change what will happen.
Sebastian Vettel"
n smikle
 
Joined: 12 Jun 2008

Post Sun Feb 12, 2012 5:12 am

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.)
bhall
 
Joined: 28 Feb 2006

Post Sun Feb 12, 2012 5:17 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'm not talking about very much movement at all - about the same as the "flexible" front wing and tea tray, but in the opposite direction - just enough to "break the seal" - and it would have to be tuned to only be effective at speeds higher than the fastest corner of a given circuit. I don't think it would be any more dangerous or shocking to the driver than DRS.
Adrian Newby
 
Joined: 7 Feb 2012

Post Sun Feb 12, 2012 5:18 am

bhallg2k wrote:(Looking through this thread, I do find it more than a little amusing that regarding the Red Bull, drag occurring over the top of the nose is, generally speaking, insignificant. Regarding the Ferrari, however, it's critical, and their design is crude. It's always the little things that crack me up.)


Not confronting you...

What is the basis for this opinion? How do you know that the drag over the RB nose is insignificant and that Ferrari's is critical? Do you have CFD to demonstrate this or any source of data?

Brian
hardingfv32
 
Joined: 3 Apr 2011

Post Sun Feb 12, 2012 5:24 am

hardingfv32 wrote:Not confronting you...

That's not what I meant. When talking about potential purposes for the upper slot on the RB8 nose, it's been asserted more than a few times that drag associated with air passing over the top of the nose is insignificant. And that's fair enough.

However, the crude shape of the Ferrari nose has also been mentioned more than a few times as a (subtle) knock on F2012's overall design quality. Well, if drag in that area is insignificant, why does it matter, you know?

It's only in good humor that I point any of this out.
bhall
 
Joined: 28 Feb 2006

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