Blowing in the Diffuser in 2012 - is it possible?

[PlatinumZealot]

I came across a stimulating post in the Mclaren thread about blowing the diffuser with 2012 regulations and I decided to start this thread so that we can explore the possibilities.

I will put forward the "passive Naturally aspirated blown diffuser." This concept is expressed as two upturned cowlings resembling cones, where air is "nozzled" along the outer edges of the diffuser throat,complete with strakes at their exists similar to the 2011 blown diffusers.

I will get a drawing up.

[italian]

Read here: http://scarbsf1.wordpress.com/2011/10/2 ... n-effects/

[shelly]

I think it has already been discussed in this forum also, in a specific thread, to some extent.
IIRC the discussion went on to include he meredith effect as a tool to accelerate flow.

The point is that a converging nozzle alone is not enough to accelerate flow.

I agree with you that we could see something fancy in this area; I expect for example evolved versions of the r31 sidepod cooling exits.

All the rumors about a floor conceived by byrne and implemented by tombazis for the f2012 seem to point in this direction also.

The genie of vortex stretching is out of the bottle anyway - we will see what the teams will come up with

[scarbs]

It wont be possible to exhaust blow the diffuser.

However the floor and diffuser can be treated to counteract some of the problems of tyre squirt and also to create fluid skirt. But this solution isn't new and was widely used before the EBD saga. If you look at the tyre deck area, you will see teams (particularly Red Bulls) used a raised coved section of floor (see pic). This added some energy to the flow passing under the floor between the tyre and diffuser. I suspect these solutions will return next year as a means to regain some of the lost flow in this area.



Although, I do have a one concept which uses the coanda effect to legally direct the exhaust flow downwards. The rules demand a minimum of 10-degree upturn to the exhaust and no bodywork inline or above the exhaust axis. It would be possible to create curved section of bodywork (sidepod) that sat behind and below the exhaust that catches and curves the flow downwards using the coanda effect, then direct this flow to the diffuser (or beam wing). A bit like a ski ramp from the exhaust outlet the diffuser trailing edge. Of course the exhaust will lose some energy along the way, but it is a legal way to redirect exhaust flow downwards.

[shelly]

@scarbs: wouldn't that application of coanda effect create lift on the curved ramp? Do you think it would be outweighted by the extra downforce gained with the jet elsewhere?

[scarbs]

@scarbs: wouldn't that application of coanda effect create lift on the curved ramp? Do you think it would be outweighted by the extra downforce gained with the jet elsewhere?

The coke bottle area creates lift anyway, but I'm not sure if it will provide more downforce at the diffuser than more lift at the sidepod. Only a wind tunnel can prove that. I'd love to try it out!

[Spankyham]

Is there any possibility that, instead of using the blowing from the exhausts for exclusively aero effects, that it could also be developed to create significant thrust? I guess it would be more relevant to hot blowing.

[raymondu999]

Well KITT could do it

[hardingfv32]

Although, I do have a one concept which uses the coanda effect to legally direct the exhaust flow downwards. The rules demand a minimum of 10-degree upturn to the exhaust and no bodywork inline or above the exhaust axis. It would be possible to create curved section of bodywork (sidepod) that sat behind and below the exhaust that catches and curves the flow downwards using the coanda effect, then direct this flow to the diffuser (or beam wing). A bit like a ski ramp from the exhaust outlet the diffuser trailing edge. Of course the exhaust will lose some energy along the way, but it is a legal way to redirect exhaust flow downwards.

I do not see how this is going to be possible. With a normal car body it is usually not possible to keep flow attached over an angle change of 15 deg. We are starting 10 deg above horizontal so that means we end up with a net downward flow of 5 deg. It is also likely that all of the exhaust flow is not going to make the transition.

Not sure if it is on point, but It is said that the Coanda Effect does not naturally occur on an aircraft wing. The Coanda Effect must be applied.

Brian

[PlatinumZealot]

It wont be possible to exhaust blow the diffuser.

However the floor and diffuser can be treated to counteract some of the problems of tyre squirt and also to create fluid skirt. But this solution isn't new and was widely used before the EBD saga. If you look at the tyre deck area, you will see teams (particularly Red Bulls) used a raised coved section of floor (see pic). This added some energy to the flow passing under the floor between the tyre and diffuser. I suspect these solutions will return next year as a means to regain some of the lost flow in this area.



Although, I do have a one concept which uses the coanda effect to legally direct the exhaust flow downwards. The rules demand a minimum of 10-degree upturn to the exhaust and no bodywork inline or above the exhaust axis. It would be possible to create curved section of bodywork (sidepod) that sat behind and below the exhaust that catches and curves the flow downwards using the coanda effect, then direct this flow to the diffuser (or beam wing). A bit like a ski ramp from the exhaust outlet the diffuser trailing edge. Of course the exhaust will lose some energy along the way, but it is a legal way to redirect exhaust flow downwards.

Your idea is interesting, but you will need a full pipe to redirect the exhuast down to the diffuser without interference and that may contravene the rules.

In addition to the bumps in the area of the floor in front of the rear wheels, do you remember this?



I suspect that this "cut out" shape in the floor will be revisited by some teams. There will be a balance in getting downforce from the diffuser Vs reducing the area of the floor (Less force for a given pressure difference above and below the floor).

[PlatinumZealot]

Is there any possibility that, instead of using the blowing from the exhausts for exclusively aero effects, that it could also be developed to create significant thrust? I guess it would be more relevant to hot blowing.

Yes. Although, the rules restrict the exhaust shape to uniform cylinders, so no nozzle effects. The thrust will be only from the natural expansion of the gases exiting the pipes.

[PlatinumZealot]

Guys, I hope you did not get the wrong idea, I see a lot of posts about the exhaust.. I really intended to have the discussion open to ANY kind of blowing.. doesn't have to be exhaust, It could even be redirection of free stream air as in my first post or even redirected farts through a tube coming out the back of the driver seat!

So.. keep the ideas flowing but don't restrict yourselves..

[MIKEY_!]

Here's one option!
The exhaust (red arrow) will be drawn downward along the upper side pod as it curves down to the floor. To help it along, hot air from the radiators is being blown downward though the cone where the exhaust would normally flow. This helps lower the exhaust flow (height not mass) towards the diffuser. There would also have to be a side wall to prevent air coming in from the side and disrupting this process.

Of course there will be some serious flow separation to overcome and for that reason I doubt it could succeed. The beam wing might be a less ambitious target.

smikle: farts are a no go sadly! The driver's not allowed to influence the aero

Blowing the diffuser with air from the radiators! Renault and Williams did it this year (there may have been others, I don't know). Possibly could be blown through the area the exhaust blew this year for a lesser vortex side-sealing thing like the EBD.

[MIKEY_!]

Another idea!





Using the mclaren slots and the little fins on the MGP (and lots of others) air could be forced under the floor to feed the diffuser. Not sure that it would be very effective however. It might create a vortex under the floor and that would certainly be beneficial.

[NonNewtonic]

Another idea!





Using the mclaren slots and the little fins on the MGP (and lots of others) air could be forced under the floor to feed the diffuser. Not sure that it would be very effective however. It might create a vortex under the floor and that would certainly be beneficial.

Its almost impossible to do that Mikey as it will require a low exhaust position and it was banned by the FIA as the rules has a 'box' area that the exhaust should be positioned in and the exhaust need to have a 10 degree angle from the horizontal even though engineers managed to work that out the solution will be ineffective as the exhaust will loose too much energy in the course of travelling to the diffuser