Red Bull RB8 Renault

[Adrian Newby]

This happens at cornering speeds:

The bridge allows the red air (exhaust) and the green air to trade places, and also guides the exhaust to where it is needed to help seal the sides of the diffuser so the RB8 can run at greater rake angles and generate more downforce.







This happens at straightaway speeds:

The exhaust is blown more straight aft (aided by the naca duct), reducing the sealing of the diffuser, therefore the downforce, and therefore the drag.

[n smikle]

I think that happens as well..

Mainly due to increased pressure in front of the tyre.

[Ferraripilot]

This happens at cornering speeds:

The bridge allows the red air (exhaust) and the green air to trade places, and also guides the exhaust to where it is needed to help seal the sides of the diffuser so the RB8 can run at greater rake angles and generate more downforce.


This happens at straightaway speeds:

The exhaust is blown more straight aft (aided by the naca duct), reducing the sealing of the diffuser, therefore the downforce, and therefore the drag.

Yes, this is all true but it should be noted that this is at the expense of sidepod laminar flow. Merc have kept the tight sidepods yet blow in such a way that it does not make the diffuser larger, but rather helps it operate more efficiently by supercharging the area receiving normal flow. RB and Mclaren remain obsessed with making the diffuser larger by sealing it. I do not believe this sealing of the diff business is the way to go this year but we will find out.

[Maynard G. Krebs]

That's a great shot. There is clearly a "ridge" extending from the "bridge" that goes back under the suspension somewhere, that is miolded into the floor. There is no obvious reason to have that bridge or that ridge unless there were something inside of them, that something most likely being air. So where would that air exit?
I know on the Ferrari we have good enough pictures of the diffuser to see that what looks like a double diffuser is actually just a little Gurney flap, but the pictures I have seen of the RB are not definitive on that. The "gurney flap" on the RB could extend back far enough to accept this airflow. And I think the main reason would be just to keep it from exiting under the car or anywhere else that would disrupt airflow.

Either that or it's a James Bond oil spray device.

[raymondu999]

reducing the sealing of the diffuser, therefore the downforce, and therefore the drag.

I'm lost here - why would stalling the diffuser (which would probably happen with loss of said sealing) decrease drag? Wouldn't you be stopping the diffuser from filling up the low pressure zone behind the car? I'd think that would create quite a bit of drag - no?

On the bridge/duct speculation - I think the question on most people's minds is - if there weren't anything to the fact it's connected to the floor; why did it connect at all? Why couldn't they terminate it like the Ferrari exhausts or the McLaren exhausts? Why did they specifically have to terminate it at the floor?

[hardingfv32]

How would a double diffuser generate down-force? You are channeling air between two surfaces. Any pressure gradient that develops inside acts equally on both the top and bottom surface. Is this not correct?

Brian

[Crucial_Xtreme]

Closer look. Right click>view image

[Rikhart]

reducing the sealing of the diffuser, therefore the downforce, and therefore the drag.

I'm lost here - why would stalling the diffuser (which would probably happen with loss of said sealing) decrease drag? Wouldn't you be stopping the diffuser from filling up the low pressure zone behind the car? I'd think that would create quite a bit of drag - no?

On the bridge/duct speculation - I think the question on most people's minds is - if there weren't anything to the fact it's connected to the floor; why did it connect at all? Why couldn't they terminate it like the Ferrari exhausts or the McLaren exhausts? Why did they specifically have to terminate it at the floor?

Exactly, and i´m extremely dissapointed almost everyone just ignored that very interesting theory Holm put forward.

[Rikhart]

Ok another try at discussing what holm said, some pages back. Basically that the bridge over the tunnel is in fact hollow, and a duct that escapes somewhere in the back. I then put forward the idea that the fact its slap bang on the exhaust´s path, is heating the air in the duct, for extra benefit. This is the key factor in understanding this layout (in my humble oppinion), but no one is really even discussing it.

[Dragonfly]

Just tried to "enhance" the picture of the diffuser.

[myurr]

How would a double diffuser generate down-force? You are channeling air between two surfaces. Any pressure gradient that develops inside acts equally on both the top and bottom surface. Is this not correct?

Brian

A true double deck diffuser would work by increasing the effective volume of the diffuser. These diffusers with holes in them are more likely about helping to extract a greater volume of air by putting energy into the system. I'm not an aero guy but I'd imagine that this is achieved either by blowing the exhaust through this section or by using a high pressure zone above the car to blow through the diffuser helping to in turn to draw more air through the diffuser more than offsetting the loss of downforce from that small section.

If there wasn't a benefit the teams wouldn't do it, so clearly there is a beneficial effect there. Would be interesting to know the exact nature of that effect and how much it affects overall performance.

[Crucial_Xtreme]

reducing the sealing of the diffuser, therefore the downforce, and therefore the drag.

I'm lost here - why would stalling the diffuser (which would probably happen with loss of said sealing) decrease drag? Wouldn't you be stopping the diffuser from filling up the low pressure zone behind the car? I'd think that would create quite a bit of drag - no?

On the bridge/duct speculation - I think the question on most people's minds is - if there weren't anything to the fact it's connected to the floor; why did it connect at all? Why couldn't they terminate it like the Ferrari exhausts or the McLaren exhausts? Why did they specifically have to terminate it at the floor?

Exactly, and i´m extremely dissapointed almost everyone just ignored that very interesting theory Holm put forward.

The teams attempt to "seal the diffuser" with exhaust gas, to prevent other airflow entering the diffuser, hence maintaining DF. I think the said goal has the opposite effect Holm put forth, but I'm not expert either.

[Adrian Newby]

reducing the sealing of the diffuser, therefore the downforce, and therefore the drag.

I'm lost here - why would stalling the diffuser (which would probably happen with loss of said sealing) decrease drag? Wouldn't you be stopping the diffuser from filling up the low pressure zone behind the car? I'd think that would create quite a bit of drag - no?

On the bridge/duct speculation - I think the question on most people's minds is - if there weren't anything to the fact it's connected to the floor; why did it connect at all? Why couldn't they terminate it like the Ferrari exhausts or the McLaren exhausts? Why did they specifically have to terminate it at the floor?

Decreased sealing wouldn't stall the diffuser, it would allow more air in from the sides, decreasing the low pressure zone.

The bridge connects to the floor to keep the two over/under flows separate the whole way, and to guide the exhaust flow all the way down, and to the outside.

[richard_leeds]

[img]http://i42.tinypic.com/zxm9up.jpg[img]

Ok another try at discussing what holm said, some pages back. Basically that the bridge over the tunnel is in fact hollow, and a duct that escapes somewhere in the back. I then put forward the idea that the fact its slap bang on the exhaust´s path, is heating the air in the duct, for extra benefit. This is the key factor in understanding this layout (in my humble oppinion), but no one is really even discussing it.

I just don't see much reason for, or benefit to this. The air would be lower energy than what is already there (even with "heating"), and it doesn't seem to be directed anywhere particularly important.

[Blaze1]

Ok another try at discussing what holm said, some pages back. Basically that the bridge over the tunnel is in fact hollow, and a duct that escapes somewhere in the back. I then put forward the idea that the fact its slap bang on the exhaust´s path, is heating the air in the duct, for extra benefit. This is the key factor in understanding this layout (in my humble oppinion), but no one is really even discussing it.

There needs to be an exit and from the pictures of the updated RB8 I've seen, there are no exits for the 'duct' you have depicted.