Exhaust Blown Floor - Forward Exhaust Exit

[strad]

No there is no ambient air flying pass the car. The car is dragging still air allong with it self. The car gives speed to the air.

You mean like when I drive by and the litter along side the road gets sucked along by the vacuum created when the car goes by and drags air with it?
Malcolm..IF what you think is true, why does no dust come out the diffuser?
Why then doesn't it suck up the dust rather than disperse it?

[strad]

My revised exhaust trajectory is the thick black line.

Which flows roughly along the side of the car,,,not under it.
I firmly believe the exhaust gases do flow along the side simular to your black line and create a seal/aero skirt. BUT that the diffuser doesn't suck anything that's not under the car.
I think that IF the diffuser was that strong, it would be spitting out gravel and clag off the track back at the following drivers.

[malcolm]

I never said all the exhaust would end up going through the diffuser (just some of it), and I just said why some of the exhaust might go through even if the dust does not (dust particles have more inertia than the exhaust).

Ringo and I only differ by a small amount in our theories (if at all), and to be totally fair I guess I am nitpicking a bit here and there whenever I think he's wrong about something (but he's doing the same with me, so fair game?).

It's not like Ringo is saying that the exhaust does not deflect at all and it blows off the marshals' hats as the car races by... and it's not like I am saying the diffuser sucks everything around it, including sucking the marshals' hats as the car races by.

[shelly]

No there is no ambient air flying pass the car. The car is dragging still air allong with it self. The car gives speed to the air.

Now this explains a lot about why you have so strange ideas.

[shelly]

My revised exhaust trajectory is the thick black line.

Which flows roughly along the side of the car,,,not under it.
I firmly believe the exhaust gases do flow along the side simular to your black line and create a seal/aero skirt. BUT that the diffuser doesn't suck anything that's not under the car.
I think that IF the diffuser was that strong, it would be spitting out gravel and clag off the track back at the following drivers.

What about the diffuser being strong enough to suck air, but not enough to drag heavy objects?

[Pierce89]

My revised exhaust trajectory is the thick black line.

Which flows roughly along the side of the car,,,not under it.
I firmly believe the exhaust gases do flow along the side simular to your black line and create a seal/aero skirt. BUT that the diffuser doesn't suck anything that's not under the car.
I think that IF the diffuser was that strong, it would be spitting out gravel and clag off the track back at the following drivers.

Diffusers do suck up the dirt and dust and throw it in the air

[ringo]

No there is no ambient air flying pass the car. The car is dragging still air allong with it self. The car gives speed to the air.

Now this explains a lot about why you have so strange ideas.

Ha ha. the feelings are mutual.

Let this be clear:

The car drags still air along, imparting speed to it. That is what CFD is representing.

The car displaces air.

That is indisputable, it can be no other way

example:
[youtube]http://www.youtube.com/watch?v=sFaRAXa9bM0[/youtube]
look on the wind hitting the woman behind the fence. That is air that is being pulled along and displaced by the car; pressure waves passing through and all that good stuff.

better yey, watch at 43s
[youtube]http://www.youtube.com/watch?v=z7Kg4oR87e4[/youtube]

and here,
[youtube]http://www.youtube.com/watch?v=6M-lXM1D ... re=related[/youtube]
what colides into the camera man? something moving forward or backward?

This is why the F1 car loses downforce when following another car. The speed of the air behind the leading car is higher than still air. This means that the following car will pass through the air at a slower rate. It's all relative.

An F1 car makes more downforce in still air or a head wind. In the case of still air, it's the friction between the car and the shapes that causes displacement and "dragging along" of the air, the disturbance the propagates to surrounding air molecules.

Saying that, re evaluate how the dust lying on the ground comes into this.
Chime in after thinking about it.

[shelly]

ringo, it is obvious that a object moving into air induces a perturbation.

But there is plenty of relative velocity between the car and the air around it.

So: on the side of the car between the wheels in the reference frame of the car there is a strong fluid flow, which is the one deflecting exhausts and dust backwards in that reference.

While looking for videos, have you found some references on PIV tracers?

[shelly]

My revised exhaust trajectory is the thick black line.

Which flows roughly along the side of the car,,,not under it.
I firmly believe the exhaust gases do flow along the side simular to your black line and create a seal/aero skirt. BUT that the diffuser doesn't suck anything that's not under the car.
I think that IF the diffuser was that strong, it would be spitting out gravel and clag off the track back at the following drivers.

Diffusers do suck up the dirt and dust and throw it in the air

He thinks they can not suck in air form the sides.

[ringo]

Ok shelly draw you diagram with the full lenght of the car and the diffuser and exhuast gases.

You must do this!!

[ringo]

ringo, it is obvious that a object moving into air induces a perturbation.

But there is plenty of relative velocity between the car and the air around it.

So: on the side of the car between the wheels in the reference frame of the car there is a strong fluid flow, which is the one deflecting exhausts and dust backwards in that reference.

While looking for videos, have you found some references on PIV tracers?

That's why a discussion like this is best done with diagrams.
Nothing you said here is true.

Sounds correct but it isn't.

The exhuast is the only thing that pushes backwards.It is doing the pushing, nothing is pushing it. If the dust is pushed back it's by the exhuasts, but you will skirt around that issue, to avoid admitting that the dust is going where the exhuast is, as from the video the dust is clear to the side of the rear wheels.

I posted exampls of air craft and nascar demonstrating that the air is pushed back and that it doesn't push inward. The car pushes it outward from the center, and after the car passes the air fills the low pressure in the wake.

Enough talk, let's see a diagram of this specific case. No unrelated pictures. A diagram from you.

and while you're at it, say what the difference is between this and the video.
[youtube]http://www.youtube.com/watch?v=8CtLB7g5s9s[/youtube]

[strad]

Nice work Ringo...This last shows just what I mean..the exhaust flows along the sidepod forming a kind of seal...Thank You.

[DumHed]

having read this thread from the beginning, after hearing people talking about how the FEE works, I've finally signed up on F1Technical - because it's getting a bit stupid!

Why is everyone arguing in absolutes?

Obviously in at least some conditions, some of the exhaust will go under the floor and through the diffuser. (High yaw, low exhaust flow, crosswinds?)
Will the small amount of exhaust, after travelling the distance to the diffuser, add any meaningful mass flow or drop of temperature and therefore volume / pressure through the diffuser?

I see no possibility of the majority of the exhaust being sucked under the floor and into the diffuser, as there would be no benefit. Normally the floor is designed to keep low pressure high velocity air underneath - sucking minimal air in from the sides.
To get the diffuser to suck exhaust in from the sides would mean a massive amount of ambient air coming in with it, greatly reducing the effectiveness of the floor and diffuser.

In my opinion, the FEE is creating downforce directly on the front corner of the floor, by blowing very high velocity gas under the small aerofoil section there, and is also creating a virtual skirt by pushing air away from the side of the floor - to prevent it from being sucked in and harming floor / diffuser efficiency.


The exhaust volume and velocity, especially with the extra "blowing" engine mapping techniques carries a lot of energy, and with the near 90° exits, will blow quite wide until high car speeds.

Have a look at the exhaust of a car running on a dyno. Even with a 300-400hp turbo engine and a 75-100mm diameter exhaust exit, quite a strong jet can be seen and felt - usually very visible due to the light fuel smoke caused by rich air fuel ratios.

[shelly]

ringo, you forgot to put in bold the important part of my post, which is "in that reference". So read the post completely before flaming and declaring it wrong.

Also you will be surprise to see that the car pushes backward a certain amount of air, alla that amount that in your cfd has a velocity grater than the the far field velocity.

But we can discuss this later. First we have to close the point on the dust not being a good tracer, then we can go on discussing where the exhausts go.

But as I wrote before,and as others also advised you, discussing is pointless if you do not read my and other's post.

[ringo]

If you keep putting all kinds of loop holes and semantic gymnastics in your posts, you can't expect people to get your intentions every time. And even so "in that reference" is still ambiguous.
And this is why i said just post a diagram. And i'm not flaming; it's all in your mind.

@DumHed, well said about the intention of the design.