Exhaust Blown Floor - Forward Exhaust Exit

[forty-two]

The Renault team have APPARENTLY shown their big innovation with exhausts which appear to exit at a point roughly level with the sidepod inlets, with sideways firing outlet ports.

The discussion in the Renault thread is becoming clogged with speculation about the system, with questions like How it might work, what the benefits/drawbacks are etc. I thought it might be sensible if we had a thread about "Exhaust Blown Floors" in general.

It's not yet known if anyone else will try to copy this idea, possibly because nobody knows yet if it will actually work. But of course as soon as another team does copy it, the discussion in the Renault car thread will no longer be in the right place.

[andrew]

I may be going into the realms of fantasy here but could it be possible that they have a version of the blown diffuser, only mid way along the car, which rather than sucking the rear of the car to the tack actually sucks nearly the entire car to the track?

I'm not an aerodynamisist so I may just have invented something that is imposible to create.

[forty-two]

On the contrary, I think that's kind of what they are TRYING to achieve, and anyway even if that wasn't the case, it's an idea well worth discussing IMO.

Most of the discussion has understandably taken place in the R30 thread so far as it initially appears that they are the only team who are working on this, but it's my belief that if this proves useful (or perhaps even if it doesn't) other teams will at least be looking at this concept, so I thought a dedicated thread in the Aero section would be a good idea.

[ubrben]

The photos I've seen show it blows outwards and slightly upwards towards the gap between the leading edge of the sidepod and the vertical turning vane. The floor extension below this channel in concave.



This channel creates a vortex down the side of the car the will act as a skirt discouraging air from migrating under the car. I believe that Renault are using the exaust flow to augment this vortex and enhance underwing sealing.

Ben

[forty-two]

I've been thinking about this some more and I reckon that Red Bull are possibly also heading toward a solution like this.

Here's some things I've noticed:

I know it's not uncommon for the floor of an F1 car to be unpainted CF, but I notice that the Renault has apparently the same type of surface all the way along the edge of the sidepod, widest near to the exhaust exit where the fumes are going to be hottest.

Well, I took a look at another team running a Renault engine and sure enough:

If anything, the Red Bull has it's heat sheilding (if indeed that's what this is) even higher up on the sidepod. Could it be that Red Bull are planning on sending more of their exhaust over the floor than Renault?

Second thing I noticed was that the Renault has these vertical fences placed in front of it's rear wheels.

Presumably, the idea behind this is to steer the hot gases inboard in order to ensure that they pass over the diffusor and are not sent in front of the rear tyres.

Well, shock horror, guess which other car has these too:


What do you guys think?

[WhiteBlue]

I think that Scarbs is spot on with his explanation. Scarb's Blog

For a diffuser to create downforce it needs as much flow to pass through the venturi as possible. Teams arrange bargeboards and other aero devices to build up a high pressure region ahead of the floor to ensure the greatest mass flow underneath. Its then down to the expansion ratio of the diffuser to pull that flow through. Last years blown diffusers improved the expansion ratio, but not the flow ahead of the floor. What Renault have done in to lead the exhausts forward through the sidepods (about 1 meter) in-between the chassis and the radiators, then turn the exhaust 90-degrees to point it down towards the leading edge of the floor. The exhausts gasses follow the curved leading edge and round underneath the floor. This accelerates the flow under the floor for more mass flow and hence more downforce.

[andrew]

What do you guys think?

The small fences certainly look like they would act as channels.

It looks like Renault have found something clever and have had to share it with Red Bull. It'll be interesting to see if Lotus have a similar system.

[humble sabot]

he's off by 90º and 4 inches.

[forty-two]

he's off by 90º and 4 inches.

Who?

[forty-two]

What do you guys think?

The small fences certainly look like they would act as channels.

It looks like Renault have found something clever and have had to share it with Red Bull. It'll be interesting to see if Lotus have a similar system.

Maybe, but maybe it was a Red Bull idea, they approached Renault Motorsport to discuss the "Q3" mapping required, and in order to "sweeten the deal" they agreed to share some intellectual property with the Renault F1 team. This would theoretically yield some advantages, not least letting Renault snag the problem first, and draw all the attention away from what they're up to in the first test session.

Just a theory!

[luca]

Wouldn't this exhaust system be more dangerous in case of side crashes?
Sidepods are far less solid than the rear-end, and side crashes also happen more often than rear crashes.

[forty-two]

Possibly true!

Actually, my biggest concerns are:
- Proximity of exhaust pipe to fuel cell.
- Danger for operatives during pitstops.

EDIT Thinking about it, most road cars route their exhaust under the fuel tank, but two important differences exist. Fuel tanks are metal, and exhaust doesn't run anything like as hot!

[donskar]

RE: whose idea -- Renault or Red Bull? I'll leap in and guess Red Bull. Just like Newey. IF this exhaust positioning does what it seems then =D> for whoEVER thought of it.

I do hope it was NOT a Newey idea -- otherwise it won't be long before FIA just rules that ANYthing he designs is a priori illegal.

Looks like Toro Rosso/Ascanelli also have a new aero twist. (The double floor is so old in F1 terms that it will appear new.) Good to see some different approaches this year.

[marcush.]

Possibly true!

Actually, my biggest concerns are:
- Proximity of exhaust pipe to fuel cell.
- Danger for operatives during pitstops.

EDIT Thinking about it, most road cars route their exhaust under the fuel tank, but two important differences exist. Fuel tanks are metal, and exhaust doesn't run anything like as hot!

it seems you have not looked under a contemporary car for quite a while forty two....fuel tanks are ,without exception now made of:plastics.

as for the exhausts run to the front...they need some air channelled around the pipes running in the sidepods to isolate...or a water jacket (which would cool the flow and lead to a loss of energy maybe?)....both will increase necessary airflow through the sidepods and look at the quite big inlets...
I doubt you could just coat with thermal barrier and add a bit of wrap and get away with it.

[mith]

I'm wondering about one thing. How directing exhaust gases under the sidepods, but over the floor would actually make downforce? There's suggestion in MP4/26 thread about that (in this post: viewtopic.php?p=221340#p221340)

As I understand, when exhaust is blowing over diffuser (or even better through it) it's speeding up air going through it and those creating areas of lower pressure prior to diffuser. But I imagine that blowing it over the floor all the way from the sidepods would rather speed up air passing over the floor those creating lift instead of downforce. Correct me, please, if I'm wrong - I'm here to learn