2012 Exhaust Blowing & Coanda

[strad]

I think the point is that between the pressurised airbox and the cam timing it is possible.

[PhillipM]

I've never heard of that without forced induction.

Tip velocity increases proportionally with volumetric efficiency. VE is increased this year due to less back pressure, and this is per Renault advising the new exhaust regs have afforded them slightly more power. So more VE = more air which means more volume being pushed through the same sized port as last year which means more velocity.

Hell, there's plenty of road cars with over 100% VE at peak torque, it's pretty common, why do you think exhaust and intake lengths are tuned so carefully?

[Caito]

viewtopic.php?f=1&t=9877

There it goes, so according to mercedes gp, they have 125% volumetric efficiency. Let's say they have less, I'd bet it's still more than 115%.

[Joie de vivre]

okay it's no secret everybody wants to redirect exhaust gases somewhere else ... and it's legal because exhaust exits are at the legal angel

but what about redirecting the gases directly to rear like last year?



let's say the exhaust angle is legal, the gap between exhaust exit and redirection tube is minimal (1mm)

is it legal? the exhaust is at the angle that FIA perscribes (let's not forget ferrari's cooling solutions with their gills (http://www.formula1.com/news/technical/ ... 9/580.html), where they cut thin line between them and make them legal saying it's only one gill like FIA decleared!)

so exhaust exit is legal and gases are redirected to the rear (just like last year)

[kilcoo316]

Well, if you assume the overfill (VE) is 125% and the exhaust temp is 200 degC:

18000 rpm => 84 m/s => 187 mph
16000 rpm => 74 m/s => 166 mph
14000 rpm => 65 m/s => 145 mph
12000 rpm => 56 m/s => 125 mph

[hardingfv32]

Well, if you assume the overfill (VE) is 125% and the exhaust temp is 200 degC:

18000 rpm => 84 m/s => 187 mph

Which is much lower than the 170-210 m/s that the exhaust simulation shows. IF we apply this new data to the velocity gradient shown in the simulation, how fast do you think the exhaust gas is going to be when it gets to the diffuser? The average flow over the body is in the range of 50-70 m/s.

Brian

[hardingfv32]

Coanda Effect:

Before I attempt a test of the Coanda Effect I wish to evaluate the validity of the test apparatus.

I wish to use a oxy-acetylene flame for the test. Neither the temp or velocity of the flame match the exhaust actual exhaust flow. The flame is 5-7 times hotter and not sure what the velocity might be at the nozzle outlet, maybe 5-10 m/s. To much difference with actual to make for a valid experiment?

Brian

[PlatinumZealot]

No. Getting to 95% is quite an achievement.

Up to 115-130% normally aspirated is possible with a good intake and exhaust system.

Brian

I've never heard of that without forced induction.

Tip velocity increases proportionally with volumetric efficiency. VE is increased this year due to less back pressure, and this is per Renault advising the new exhaust regs have afforded them slightly more power. So more VE = more air which means more volume being pushed through the same sized port as last year which means more velocity.

It is possible with pulse tuning the intake. Over 100% Volumetric efficiency just means on the intake stroke the cylinder is filled at a pressure higher than the pressure higher than atmospheric pressure (or the pressure in the airbox if the intake is not very efficient). This can be achieved using the air momentum, car speed (ram air intake) and acoustic effects.

A large air box with straight runners help this a lot.. I know F1 engines would have very high VE's.. Even 120% might be a good guess. Though it might be for a narrow rev range.

[bhall]

[My comments made much more sense within the context - and thread - in which they were posted. In the future, please delete my comments outright if they're summarily deemed immaterial to their respective discussions rather than move them and render the thoughts completely neutered. Thank you.]

[Adrian Newby]

I have looked at the exhaust, in many pictures, and it points 10 degrees outward and 10 degrees upward, to the letter of the law.

It's actually +/- 10 degrees when viewed from above and +10 to +30 degrees when viewed from the reference plane.

I think we're beat on this, man. Look at the last picture I posted.

Yes, you are right that that is the allowable range.

It still looks like it is actually aimed "out 10" to me, but I will say that it is hard to tell with such a short stub of a tailpipe to look at, and all the different camera angles.

It is always important to compare side-photos to above-photos. The outside of the bridge seems like it would go straight back from a side view, but it really "waists" back in quite a lot immediately after the exhaust, if looked at from above (I know you know this. I'm just saying it in general/for the record).

[hardingfv32]

How does this exhaust flow seal the diffuser? Air screen, vortex, etc?

How narrow do you think the exhaust plume is by the time it reaches diffuser edge?

I say the plume would be highly dispersed and you have nothing in the area of the diffuser edge to gather it up into a useful flow.

It is my claim that even if the flow is routed to the diffuser edge it is of no value.

Brian

[hardingfv32]

I guess I needed to be a little more explicit.
I think the "inboarders" have won the day.

Please restrict comments to the car.

Brian

[bhall]

[My comments made much more sense within the context - and thread - in which they were posted. In the future, please delete my comments outright if they're summarily deemed immaterial to their respective discussions rather than move them and render the thoughts completely neutered. Thank you.]

[Adrian Newby]

Are you kidding me? Is that a joke?

Or are you really that dense?

You forgot to throw some calculations at him!


Edit: It's not worth a new post, but this is still cracking me up!

[Pup]

Hey everybody, I'm new here and was wondering if you guys have any idea what Red Bull are trying to accomplish with their exhaust?



Just kidding. Oh, how I kid.

Personally, I think y'alls problem is that you're thinking too much about the tunnel and not enough about what makes it. That is, the tunnel has always been there - it's just that they hadn't pointed it out for you.