Red Bull RB8 Renault

[Adrian Newby]

Here is my theory... Could it be that this tunnel works like a chimney?

The exhaust gases flow down the sidepod just over the rear end of the tunnel creating an area of low pressure and thus sucking more air through the tunnel. This could lead to more air on top of the floor plate which could be used to create downforce on e.g. the lower rear wing.

Without the tunnel, I think the exhaust gases would create some sort of barrier and this would lead to less air that could get routet in the direction of the rear wing.

Some shitty picture to "proof" my theory. XD

[img]http://www.abload.de/img/testyijsp.jpg[img]

I like everything about this idea except for two things: If you can seal the diffuser, the effect of the downforce is multiplied by the amount of the seal - resulting in much more bang for your buck. And, Adrian Newey installed a channel in the sidepod to direct as much of the exhaust flow as he could to outside of the sidepod. I believe he did this for a reason.

[Adrian Newby]

Yep. Well done. That's basically it.

There would also be some air joining the exhaust from the outside (between the sidepod/bridge and the tire). And the part of that air that is not parallel to the flow of the exhaust will get directed over the top of the exhaust by that vertical plate in front of the rear tire (the air will be hitting that plate at a sideways angle due to the tire).

[Crucial_Xtreme]

Yep. Well done. That's basically it.

There would also be some air joining the exhaust from the outside (between the sidepod/bridge and the tire). And the part of that air that is not parallel to the flow of the exhaust will get directed over the top of the exhaust by that vertical plate in front of the rear tire (the air will be hitting that plate at a sideways angle due to the tire).

Don't forget there is a vertical plate/strake on the inside of the tyre too.

ignore the red circle

[gandharva]

I like everything about this idea except for two things: If you can seal the diffuser, the effect of the downforce is multiplied by the amount of the seal - resulting in much more bang for your buck. And, Adrian Newey installed a channel in the sidepod to direct as much of the exhaust flow as he could to outside of the sidepod. I believe he did this for a reason.

Don't get me wrong. My picture and explanation refers only to the purpose of the tunnel as I see it. There's much more happening.

The channel imho is there to create a vortex of exhaust gases when the gases interacts with the air that flows from above the sidepods. See Leons picture.

[Adrian Newby]

I like everything about this idea except for two things: If you can seal the diffuser, the effect of the downforce is multiplied by the amount of the seal - resulting in much more bang for your buck. And, Adrian Newey installed a channel in the sidepod to direct as much of the exhaust flow as he could to outside of the sidepod. I believe he did this for a reason.

Don't get me wrong. My picture and explanation refers only to the purpose of the tunnel as I see it. There's much more happening.

The channel imho is there to create a vortex of exhaust gases when the gases interacts with the air that flows from above the sidepods. See Leons picture.

I think what you say is basically correct. And all of it is happening to certain degree all of the time but, in general, according to my theory, your picture would basically show what is happening at higher (straight) speeds and Leon's picture is basically showing what is happening at cornering speeds.

[eurocentric]

The vertical board at the start of the side pod at its side (not sure of the tech term sorry), was it connected to the side pod with that horizontal surface last year?

If it's new, that could have an effect downstream to encourage the air to follow the curve down more to where the exhaust outlet is.

[Pup]

I got some paisley socks for christmas that look like that airflow.

[beelsebob]

So... I engaged my adian newey style air flow visualisation mode ... Here's a more detailed diagram of what I'd expect than before... Can anyone suggest any of the flow lines that they think don't meat their theory of what's going on?

Why would the yellow and light green air be drawn into the tunnel?

Doesn't seem to be the the path of least resistance?

Because it's attached to the surface of the side pod. That's what laminar flow does.

[beelsebob]

This is clearly not what's going on – if this was all that was happening, there would be no reason to have the tunnel, nor would there be any reason to have tight side pods, because your air is detaching, rather than filling the void behind them by staying attached. If you wanted this effect, you'd do what Mercedes is doing, you wouldn't --- about with a tunnel under the ramp, and you wouldn't --- about with a channel after the exhaust going round a corner.

[beelsebob]

Yep, that's pretty much exactly what I see happening too.

[shelly]

So... I engaged my adian newey style air flow visualisation mode ... Here's a more detailed diagram of what I'd expect than before... Can anyone suggest any of the flow lines that they think don't meat their theory of what's going on?

Why would the yellow and light green air be drawn into the tunnel?

Doesn't seem to be the the path of least resistance?

Because it's attached to the surface of the side pod. That's what laminar flow does.

Attached flow is one thing, laminar flow another. I do not think there is laminar floor above the sidepod, it is turbulent and attached. Turbulent boundary layer on the sidepod.

[Shakeman]

OK, so I fully understand gandharva's explanation but what I don't see is how this arrangement can be more effective than the bridge/tunnel/duct not being there in the first place.

[gandharva]

As I already explained, imho it's a very clever way to get more air into the end of the red area as this would be the case without the tunnel.

[Ferraripilot]

They are losing too much laminar flow with this exhaust position. I believe the Mercedes arrangement is the best compromise as they are the only ones to really maintain a large undercut yet actually have the exhaust blowing something useful.

[Twaddle]

OK, so I fully understand gandharva's explanation but what I don't see is how this arrangement can be more effective than the bridge/tunnel/duct not being there in the first place.

If it's doing what is depicted in that image (and I don't think it is) then I'm sure it's not working as intended. Leon's sketch is much closer to how I see it working. The potential advantage I see in the bridge structure is in preventing the exhaust being pulled back inside with air moving in from the outside (not shown on any of the sketches so far).