Red Bull RB8 Renault

[bhall]

If I may interject with a little deductive reasoning. (Forgive me if someone's previously taken this route.)

I think the intention of the RB8 exhaust is what Newby and I have suggested - I was on board many, many pages ago - otherwise it would work. I can't imagine there are too many things in F1 that are easier to accomplish than having the car's exhaust flow straight back. In fact, that seems like it would be the default setting, if you will.

Trying to coax the exhaust flow to the outside, on the other hand...

[shelly]

This exhaust flow is supposed to hit that vane infront of the wheel in some sort of coherent stream-tube, roll up and continue as a longitudinal vortex along the side of the diffuser?!?!

The coherent stream tube is already there: it is the footplate vortex. The more you get to accelerate it along its axis with some momentum (i.e. the momentum of the exhausts) the more downforce you can get from it.

[marekk]

You don't want those tubulent, hot, (relatively) low kinetic energy exhaust gases near your brake ducts, beam and main rear wings.

You don't want them to cross with your carefully maintained flows around the sidepods and engine cover either. Can't see this one adding to footplate vortex.

If you manage to place them just over the diffuser center without interfering to much with other flows, you can at least fill the gap behind the car, reducing drag and maybe gain a little stability inside diff blowing through starter hole.

From this point of view, the route through the tunnel is optimal.

And can someone please explain, why it's harder to route the gases this way at higher speeds ?

[hardingfv32]

But seriously if you look at Neweby's post, there's clear markings as to where the exhaust is exiting and which way it is initially flowing. Which it directly towards the inside of the rear tyre.
McLaren are obviously doing this, why are we to think RB doesn't have the same intentions?

His whole discussion disregards the actual information we have about flow velocity in that area. The flow leaving the exhaust is very low about 200 mm for the tip. The air flow over the body has high amount of control over the flow direction at that point and by the time you reach the floor the body air flow has complete control.

We have nothing that clearly indicates what the teams intentions are. You get one picture if you exclude air flow realities and another picture in you include actual flows.

Brian

[shelly]

This is the picture. Instead of the supposed slots (too similar to suspension arms in shape and colour), what I find interesting is the small rectangle inside the cannon exit. End of a pipe? Seems the cousin of the pipe towards the beam wing on the f2012

[hardingfv32]

[The coherent stream tube is already there: it is the footplate vortex. The more you get to accelerate it along its axis with some momentum (i.e. the momentum of the exhausts) the more downforce you can get from it.

The exhaust flow will never make it to the surfaces forming the vortex. If a little flow does reach the side of the tire, will it in fact help the vortex? I do not thing so.

Brian

[Froggolo]

Any idea what is this?

Hello

probably this is an outlet for the boundary layer air that enters in the sidepods.
It is something very common in jet engine intakes.

[hardingfv32]

And can someone please explain, why it's harder to route the gases this way at higher speeds ?

Because the exhaust leaves the the tip at 84 m/s. 200 mm from the tip it is at less than 40-30 m/s. It is hit by a body flow of 40-70 m/s. ASSUMING the exhaust flowing 90 deg to the body air flow, it would change direction by 45 deg. You are never going to make it to the opening down below.

Brian

[shelly]

@brian: Conservation of momentum in longitudinal direction holds. Whatever decreases (in this case the flow of the car) the longitudinal velocity of the exhausts plume, gets accelerated by the same amount (bar external forces, pressures).

[hardingfv32]

@brian: Conservation of momentum in longitudinal direction holds. Whatever decreases (in this case the flow of the car) the longitudinal velocity of the exhausts plume, gets accelerated by the same amount (bar external forces, pressures).

Expand... What does this mean for the exhaust flow leaving at 90 deg to the body flow....

1) Shortly after the leaving the exhaust pipe?

2) 100-200 mm after leaving the exhaust pipe?

Brian

[marekk]

This is the picture. Instead of the supposed slots (too similar to suspension arms in shape and colour), what I find interesting is the small rectangle inside the cannon exit. End of a pipe? Seems the cousin of the pipe towards the beam wing on the f2012

Perfect place for a low-pressure driven fluidic switch or something like this. Not very sensitive to wind and yaw.

[PhillipM]

@brian: Conservation of momentum in longitudinal direction holds. Whatever decreases (in this case the flow of the car) the longitudinal velocity of the exhausts plume, gets accelerated by the same amount (bar external forces, pressures).

Expand... What does this mean for the exhaust flow leaving at 90 deg to the body flow....

1) Shortly after the leaving the exhaust pipe?

2) 100-200 mm after leaving the exhaust pipe?

Brian

It means that exhaust flow has accelerated the flow around it. So what does it matter about the flow 100-200mm after the pipe?

[Adrian Newby]

The nozzle is not pointed down because it is illegal to point it down, or even straight back: "From the side the exhaust must exit tailpipe-up and between 10 to 30 degrees from the reference plane."

Adrian Newey takes it from the minimum of 10 degrees up and channels it downward as much as possible.

I didn't even bother to read the technical regs.

So what happens when the cross-flow around the side-pod hits it*? No way will it emerge in any coherent form, it'll be swept inboard in the cross-flow.

*I know it doesn't work in whatever way RBR intended (as you've previously mentioned).

I noticed that too - that you didn't read the regs. You obviously still have no clue what that tunnel is for either.

I'll give you a hint... bhallg2k said it a long time ago.

[Adrian Newby]

You don't want those tubulent, hot, (relatively) low kinetic energy exhaust gases near your brake ducts, beam and main rear wings.

You don't want them to cross with your carefully maintained flows around the sidepods and engine cover either. Can't see this one adding to footplate vortex.

If you manage to place them just over the diffuser center without interfering to much with other flows, you can at least fill the gap behind the car, reducing drag and maybe gain a little stability inside diff blowing through starter hole.

From this point of view, the route through the tunnel is optimal.

And can someone please explain, why it's harder to route the gases this way at higher speeds ?

The faster the car goes, the more it is going to blow the exhaust farther back, away from the entrance to the tunnel.

[kilcoo316]

I noticed that too - that you didn't read the regs.

Yeah - point being - exhaust points up, sidepod curves in. Exhaust plume is caught in cross-flow around sidepod and does not go anywhere near the wheel.

My point regarding the regs is simple - I'm surprised you knew the exhaust pointed up and still came up with that hair brained idea!

You obviously still have no clue what that tunnel is for either.

The tunnel is for directing cleaner air to the diffuser deck along the centre section - where interaction with the beam wing* is much more important - having dirty exhaust gas there is non-desirable.

*And from there, interaction with the main wing to increase overall diffuser effectiveness.




Its like a pack of undergrads in here at times.