2012 Exhaust Blowing & Coanda

[Crucial_Xtreme]

You dont need any of that stuff if you have a good enough general grasp of physics, especially in the general terms we are speaking.

The coanda effect is in play, but the majority of it is from downwash.

I don't disagree with that in the least. I posted earlier I think Coanda starts the plume off, then the downwash takes over. The other two are saying Coanda has no effect whatsoever. That I disagree with.

[GrizzleBoy]

I wouldn't really say it "starts it off" as really the effect is minimal until the downwash takes over.

I think that's what nando meant by "nullified".

Not that it isn't happening, but the effect that it has is so small it's not worth considering it an effect on the car at all.

[Nando]

I don't disagree with that in the least. I posted earlier I think Coanda starts the plume off, then the downwash takes over. The other two are saying Coanda has no effect whatsoever. That I disagree with.

Not true at all. We are not entirely convinced the coanda effect has any notable effect.

I personally think that this is the work of downwash. I could be wrong though.

Nobody is denying that the effect is there, the question is how much.

[Nando]

This is how i think the air would pass on an airplane wing as full take off mode.

If you compare that 90 degree angle to the mini-bend of the exhaust housing on the mclaren it´s hard to see how that little bend would be able to bend down exhaust gases all the way down to the floor.

[Crucial_Xtreme]

Not true at all. We are not entirely convinced the coanda effect has any notable effect.

I personally think that this is the work of downwash. I could be wrong though.

Nobody is denying that the effect is there, the question is how much.

Oh ok, I thought you two were saying it wasn't in play at all. My apologies. I would be great to have unfettered access to the teams engineer to find out.

[Nando]

Oh ok, I thought you two were saying it wasn't in play at all. My apologies. I would be great to have unfettered access to the teams engineer to find out.

No not at all I´m sure the effect is there, i just doubt the effect it has.

Updated the picture with what i think will happen to the exhaust flow.
And i added a darker line of what some people think the exhaust gases will do?

Just by thinking that these exhaust gases leaves the tip at 360km/h i just find it hard to believe that it can change direction like the darker yellow-ish. Or even a less extreme angle. 360km/h is an immense speed and not something you divert by not really interacting with it.

[Owen.C93]

I don't think that's how aeroplane wings work. I'm not really sure what we're discussing because it's not particularly important to know whether the coanda effect is pulling substantial exhaust gas down to the floor at idle when not moving.

[Nando]

I don't think that's how aeroplane wings work. I'm not really sure what we're discussing because it's not particularly important to know whether the coanda effect is pulling substantial exhaust gas down to the floor at idle when not moving.

You mean like this? Remember that i´m only discussing take off (or landing) angles of the wing. It will create the most lift because it pushes air right down to the ground as showed in the video someone posted a page back or so.

[Nando]

From NASA, I would say the one to the right is close to the exhaust housing of the Mclaren. Check out the airflow.

[amouzouris]

It doesn't nullify anything. To the best of my knowledge you nor Brian, nor myself has a degree in Aeronautical Engineering and we're not privy the the McLaren exhaust specification details. It's your opinion. Same as ours is our opinion. Neither opinion proves or disproves the other. Whats more is people (Scarbs- Mark Hughes- Gary Anderson) who have access to inside information from the teams and are more familiar with the particulars with the latter actually having worked in Formula One say the Coanda effect is in play here. I think I'll go with the opinion of someone who has worked in F1 & those that have direct access to the teams.

Do we agree on the angle of the exhaust housing?

Do we agree that you need to angle a wing 90 degrees in order to get air to the ground? As been proven by the video showed.

Do we agree that this gif from wikipedia is correct?

Do we also agree that the angle of that circle far and away exceeds the angle of the exhaust housing on the Mclaren?



Should also mention that i don´t think anyone denies the Coanda effect.

The part where we split sides is the effectiveness of it.

the reason i provided the video was not to show that you need to angle bodywork at 90 degrees to deflect the exhaust plume...i provided the video to show that the coanda effect indeed does help...and quite a lot to deflect the exhaust plume downwards...

[Nando]

the reason i provided the video was not to show that you need to angle bodywork at 90 degrees to deflect the exhaust plume...i provided the video to show that the coanda effect indeed does help...and quite a lot to deflect the exhaust plume downwards...

Ok fair enough. But do we agree that the air is hitting the ground?

And do we agree that with less angle on that wing, less air will hit the ground?

And do we agree that the Mclaren exhaust housing holds a much less extreme angle to divert (in this case) exhaust gases?

[Pup]

I see no problem with Brian's experiment. If it works, great, and if not then it would certainly add doubt.

But I do think that there would still be questions. How well does a torch flame model exhaust flow? How much does the texture of the surface affect the flow? How much effect does the surrounding airflow have? How much does the diameter or speed of the airflow matter? How much of the flow must be diverted to make a difference?

I'm sure there are other questions as well.

When I first did my experiment, it was just to show that it was possible to bend a stream of air. Beyond that, I think it's difficult if not impossible to prove that McLaren's exhaust is being bent, simply because without all their CFD data, we can't really come close to knowing what they're doing.

And if it were so easy enough to reproduce, then surely Red Bull and Ferrari wouldn't be having trouble, right?

But having said that, I'm all for taking the experiment further. I'm just as curious as anyone else, so go for it.

[amouzouris]

the reason i provided the video was not to show that you need to angle bodywork at 90 degrees to deflect the exhaust plume...i provided the video to show that the coanda effect indeed does help...and quite a lot to deflect the exhaust plume downwards...

Ok fair enough. But do we agree that the air is hitting the ground?

And do we agree that with less angle on that wing, less air will hit the ground?

And do we agree that the Mclaren exhaust housing holds a much less extreme angle to divert (in this case) exhaust gases?

well..first of all the angle of the wing is certainly not 90 degrees...it is much less....but the airflow continues to change its angle even after it passes the wing and flows almost directly below it...mclaren doesnt want the exhaust to hit the floor directly below the trailing edge if the sidepod channel...so even at the much lower angle the bodywork behind the exhaust is located probably does manage to deflect the exhaust quite a lot...and at low speeds where the downwash doesnt have a strong effect...they are relying almost solely on the coanda effect to point the exhaust plume where they want to....(I know what i'm saying involves a lot of armchair aerodynamics but that's where i would put my 2c)

[hardingfv32]

But having said that, I'm all for taking the experiment further. I'm just as curious as anyone else, so go for it.

1) I need some agreement on how wide to make the channel in relation to the 'visible' flame width.
2) If I use a flat bottom I could do multiple tests with different radiuses.
3) I should mount the channel floor at the bottom edge of the nozzle hole?

4) I might be able to through in some side-pod body flow in the form of a heat gun blower. I am not sure what the flame will accept before it gets upset. I would also need to know roughly what contour to use as a body surface simulator.

Brian

[n smikle]

This is how i think the air would pass on an airplane wing as full take off mode.

If you compare that 90 degree angle to the mini-bend of the exhaust housing on the mclaren it´s hard to see how that little bend would be able to bend down exhaust gases all the way down to the floor.

Because the bending is not a function of the angle of the bend alone. Your theory is not accurate you see. There is also gas speed, and the speed of the surrounding gasses.
The higher angle of the bend is more like to cause separation of the gas than a lower angle.

In the same CFD I did,you can see the 10 degree angle of the exhaust. It follows the curve very well.