Red Bull RB8 Renault

[Adrian Newby]

Could airflow over the sidepods push exhaust gases down the channel at certain speeds?

I think at higher speeds, increased airflow through the naca duct will blow the exhaust more straight back so it won't follow the channel when the channel turns. At lower speeds, more of the exhaust will follow the channel over the side of the sidepod.

[Adrian Newby]

Is there any reason to generated a vortex starting at the location of the exhaust tip?

Brian

No, but there will probably be rotation induced to the flow at/along the splitter. Varying with speed, a certain portion of the air will go on either side of the splitter, causing the flow to spiral. Newey used this same trick to help seal the diffuser last year with the EBD. This year's version won't be nearly as efficient, of course, but just as clever.

[GrizzleBoy]

. The black, heat-resistant portion of the sidepod is probably changeable, in order to tune the splitter to the speed of the fastest corner on each particular circuit.

That's brilliant. That sounds like something Newey would do. That's a friggin genius idea.

The air around the outer edge of the exhaust channel will most likely push the gases along with the green line.

Imagine there's another blue line higher up the side pod, just below the exhaust channel.

That would represent the air flowing round the side of the sidepod.

The exhaust gases would be pushed downwards into the channel after emerging at an upward angle by the air coming over the side pod (green line), then be pushed along the side towards the rear of the car (blue line I asked you to imagine).

The green, red and imaginary blue would all converge at some point along the top edge of the side pod towards its rear end.

/theory

[bhall]

I think that rule-induced lack of efficiency is also why Red Bull ran with far less rake the last two days of the test.

[Adrian Newby]

I think that rule-induced lack of efficiency is also why Red Bull ran with far less rake the last two days of the test.

Yes, there are definitely diminishing/negative returns on the rake with a less efficient seal. We should be able to roughly calculate how much less effective their seal is this year by comparing this year's rake (in race trim) to last year's rake.

[Pierce89]

Is there any reason to generated a vortex starting at the location of the exhaust tip?

Brian

No, but there will probably be rotation induced to the flow at/along the splitter. Varying with speed, a certain portion of the air will go on either side of the splitter, causing the flow to spiral. Newey used this same trick to help seal the diffuser last year with the EBD. This year's version won't be nearly as efficient, of course, but just as clever.

The vortex that sealed the diffuser was created by a metal strake(vortex generator) at the exhaust tip. Go back and look.

[Pierce89]

I think the red exhaust line is correct for cornering speeds. And at speeds greater than the fastest cornering speeds, the exhaust gets blown more straight aft (more along the green line. This is most likely the reason for the naca duct too), reducing the sealing effect, and therefore downforce and drag. You could think of the "bridge" piece of sidepod between these two lines as a speed sensitive/controlled "splitter" for the exhaust flow. The black, heat-resistant portion of the sidepod is probably changeable, in order to tune the splitter to the speed of the fastest corner on each particular circuit.

I just don't see it. The exhaust gas isn't an inseparable slug fluid. If you've ever fired an old black powder rifle,you'll know what I mean. Exiting exhaust gas diffuses into free stream air VERY quickly coming out.That's why last year's exhaust had to be so close to the diffuser to work properly. With the current regulations, I believe the exhaust will only be able to increase mass flow over much less specific and less concentrated area area than your idea implies. I also highly doubt the exhaust could increase DF at low speeds and then hit a switch over point and start reducing the DF and drag.

[GrizzleBoy]

...

Agreed.

The gases will have already been blown upwards immediately after exiting, downwards after being influenced by air going over the sidepod/exhaust channel and sideways/inwards towards the car from the air around the side of the sidepods before it even gets a chance to do anything that requires a focused stream of exhaust gases.

A "slow" corner can be taken at 60mph in a Formula 1 car and even at that speed, the exhaust gasses would have to fight against fast moving air moving directly backwards across the sidepods (underneath the exhaust flow) to be able to dip down in the manner people are proposing. As well as the flow over the pods pulling it inwards towards the tail of the car.

This is all without even taking into account the amount of force pushing the gases outwards from the car in the first place.

[Jamie]

I think the red exhaust line is correct for cornering speeds. And at speeds greater than the fastest cornering speeds, the exhaust gets blown more straight aft (more along the green line. This is most likely the reason for the naca duct too), reducing the sealing effect, and therefore downforce and drag. You could think of the "bridge" piece of sidepod between these two lines as a speed sensitive/controlled "splitter" for the exhaust flow. The black, heat-resistant portion of the sidepod is probably changeable, in order to tune the splitter to the speed of the fastest corner on each particular circuit.

G'day all. Been reading for a long time and enjoy the technical aspects of F1.

Would the duct from the outside of the sidepod create a low pressure area that the exhaust plume would look to fill, thereby moving the plume towards the same areas on the diffuser sides as last year.

The increased pressure next to the gearbox would also drive the plume in the same direction wouldn't it?

Hence the increased rake that has been evident once the update was installed.

What do you think?

[beelsebob]

G'day all. Been reading for a long time and enjoy the technical aspects of F1.

Would the duct from the outside of the sidepod create a low pressure area that the exhaust plume would look to fill, thereby moving the plume towards the same areas on the diffuser sides as last year.

The increased pressure next to the gearbox would also drive the plume in the same direction wouldn't it?

Hence the increased rake that has been evident once the update was installed.

What do you think?

Yep, I'm quite sure that's what's going to happen personally – I think the one bit that's lacking is that as it curves round and tumbles off the side of the side pod, it's going to start spinning, and that vortex is going to hold it in a reasonably tight line until it hits its target at the back.

[kalinka]

What bothers me with this solution, is that the pullrod is not quite at a good place for that blue stream. Actually wouldn't it work better with a pushrod this year ? For me that pullrod just doesn't fall into the puzzle. Just asking.

[raymondu999]

To an extent I guess the position of the arms would be more favorable in the pushrod arrangement for this sidepod-exhaust config. But doing so would compromise the packaging too - which could lead to a net loss anyways.

[Robbobnob]

The push rods benefits are more in terms of getting the suspension mass (the springs dampers roll bars etc..) low down for COG reasons, secondary benefits being ultra tight packaging at the rear.

In terms of disturbance caused by the pull rod itself, it will be quite minimal and will have little to no effect on the behaviour of the airflow through that region

[kebab]

The push rods benefits are more in terms of getting the suspension mass (the springs dampers roll bars etc..) low down for COG reasons, secondary benefits being ultra tight packaging at the rear.

I guess you mean pull

[beelsebob]

What bothers me with this solution, is that the pullrod is not quite at a good place for that blue stream. Actually wouldn't it work better with a pushrod this year ? For me that pullrod just doesn't fall into the puzzle. Just asking.

Huh? The pull rod was there last year and the year before, as was the blue stream... It certainly worked for them then.