2012 Exhaust Blowing & Coanda

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Post Sat Mar 03, 2012 2:57 pm

Wisdom wrote:Image

There's a big slot there probably feeding another one directly behind it?


The question is.. Is this RedBull/Sauber solution the right path?

It is essentially doing the same as the Mclaren's too.. But does it blow the exhaust more efficiently?

It is very hard to tell as geometrically I think all three are similar in some ways.

The Sauber having an exhaust ramp.
The Red Bull having an "Exhaust bridge" complete with underpass
The Mclaren having a "coanda lowerator"

The Saubeer's I think has a problem with air coming off the flanks crossing the path of the exhaust as it shoots to the rear.

The Macleran one does not need a tunnel like the RedBull as it is overhanging the undercut already.

So despite my initial surprise... The RedBull concept is not that much different.. but IS IT BETTER than Mclarens?

less fuss for the exhaust? could be..
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n smikle
 
Joined: 12 Jun 2008

Post Sat Mar 03, 2012 5:24 pm

Ferrari and Mercedes must feel like deer in the headlights.

I am quite suprised by the redbull. The first iteration of exhaust pipe must have been compared to the diffuser blown version.

I guess both cars have the same dependencies to get optimal performance. The question is, which one is less sensitive?
Does have a surface to guide the gas makes it more steady?
Taking into account the distance from the exhuast exit to the diffuser, how effective is the reduced temperatures and speeds when they get to the diffuser?

All in all, suaber Mclaren and Redbull have a lead, but the good things about these regs, all things can and will be copied. Just that some teams are at a disadvantage.
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ringo
 
Joined: 29 Mar 2009

Post Sat Mar 03, 2012 5:32 pm

I'm not sure if RB's solution is doing the same thing as McLaren's. Maybe my eye isn't reading the flow right, but it seems more to me like the RB exhaust is being used to create a low pressure zone at the end of the tunnel, essentially sucking more air through the tunnel and depositing it over the diffuser.
Pup
 
Joined: 8 May 2008

Post Sat Mar 03, 2012 7:41 pm

Why move the exhaust outlet farther away for all your aero targets, wings, etc. as RB has done?

Is this really about just imparting addition energy into the body flows? The body flows are doing what you want, so why not increase them with the exhaust. In that context does it matter how far away you are from the aero targets?

Brian
Last edited by hardingfv32 on Sun Mar 04, 2012 4:06 am, edited 1 time in total.
hardingfv32
 
Joined: 3 Apr 2011

Post Sat Mar 03, 2012 8:47 pm

bhallg2k wrote:I think one of Red Bull's great strengths in recent years has been the incredibly tight packaging of components at the rear of the cars. If you want to maintain that packaging and have an outboard exhaust without falling afoul of the rules, the only option is to move the exhaust "up and away."

bhallg2k wrote:The "bridge" is just the most extremely undercut sidepod in F1 history. I think they're cramming all the air they possibly can down the middle in an attempt to force the exhaust to stay outboard.

In a manner of speaking, they're using the air flow over the car to seal off the exhaust so that the exhaust can seal off the air flow under the car.

That's f@^$!# brilliant, if you ask me.


(Is quoting yourself like referring to yourself in the 3rd person? Either way, Ben's just doing what Ben's gotta do.)
bhall
 
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Post Sun Mar 04, 2012 12:16 am

hardingfv32 wrote:Why move the exhaust outlet farther away for all your aero targets, wings, etc. as RB has done?

Is this really about just imparting addition energy into the body flows? The body flows are doing what you want, so why not increase them with the exhaust. In that context goes it matter how far away you are from the aero targets?

Brian


Two things at once, i think.

Using coanda means force acting normal to the leading surface.

With this solution they'll:

1. move upwards facing part of this force (lift) further away from the back of the car, which should help with balance
2. exhaust gases make their way to the floor mainly on the sides, so other component of this force acts outwards (symmetrical on both sides, so basicaly compensating), instead of acting rearwards (drag), as in McLaren & Co.
marekk
 
Joined: 11 Feb 2011

Post Sun Mar 04, 2012 9:55 am

I have learned from these exhausts & the discussion here that Coanda is much stronger on gasses than I had thought. Knew it was effective on liquids but had not realised it was this strong on gasses. Hence my looking forward to the CFD on the McLaren design. My understanding has been corrected & I thank you for it. Will be very interesting to see who copies who as the season progresses.
tok-tokkie
 
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Location: Cape Town

Post Sun Mar 04, 2012 11:55 am

What I'm still curious about is how much benefit the redirecting of exhaust gasses brings this year with the modifications to the ECU?

Even when exhaust blowing was utilised in the McLaren's by Newey years ago, I believe one of the big issues was that the performance was indeed very throttle sensitive. I believe one of the ways to decrease the sensitivity was to move the exhaust further away from the rear of the car until they found a decent compromise. One could assume that they found a balance, but it's unclear if they were using engine management techniques back then to aid this.

In the last few years this was obvious with the hot and cold blowing that almost all teams ran.

With these ECU restrictions will such a setup still be very throttle sensitive and how will the teams try to optimise this?
lombers
 
Joined: 5 Feb 2012

Post Sun Mar 04, 2012 1:18 pm

lombers wrote:it's unclear if they were using engine management techniques back then to aid this.

They didn't. Which was why it was throttle-sensitive.
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raymondu999
 
Joined: 4 Feb 2010

Post Sun Mar 04, 2012 5:48 pm

lombers wrote:With these ECU restrictions will such a setup still be very throttle sensitive and how will the teams try to optimise this?


The restrictions are mostly to do with the throttle 'I believe'. Now the throttle is processed through the ECU, but you still have no restrictions on fuel and timing maps.

How much of an average lap will this be a problem, 20% 'I believe'. It will be a good challenge for the drivers. Help demonstrate the ones with better skills.

Brian
hardingfv32
 
Joined: 3 Apr 2011

Post Sun Mar 04, 2012 5:58 pm

tok-tokkie wrote:I have learned from these exhausts & the discussion here that Coanda is much stronger on gasses than I had thought. Knew it was effective on liquids but had not realised it was this strong on gasses. Hence my looking forward to the CFD on the McLaren design. My understanding has been corrected & I thank you for it. Will be very interesting to see who copies who as the season progresses.


Yep,



and:



All it takes are the dregs from the aero space industry to create an innovative F1 car. The engineers only have to be well read to suggest putting these ideas on the cars.
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ringo
 
Joined: 29 Mar 2009

Post Sun Mar 04, 2012 6:33 pm

ringo wrote:All it takes are the dregs from the aero space industry to create an innovative F1 car. The engineers only have to be well read to suggest putting these ideas on the cars.


I say the 10 deg angle of the floor of the McLaren exhaust channel precludes a valid implementation of the Coanda Effect.

Can you demonstrate or illustrate how it is done in the McLaren exhaust channel? In all my research I can find no illustration of a Coanda Effect system that does not have the flow axis starting at less than a 90 deg angle or less to the flow surface. Tangental to the radius of the curved surface.

Brian
hardingfv32
 
Joined: 3 Apr 2011

Post Sun Mar 04, 2012 7:34 pm

@brian: the curved surface for coanda effect in the mclaren is hidden in the housing of the exhaust: there is a convex ramp just outside the circular exhausts exits.
It is this ramp (very evident on first iteration ferrari also) that manages to deflect the exhuast plume down.

Look at the curvature of the black ramp in the mp4-27, of the metal ramp in the ferrari. Then you'll see somthing similar to the back of the spoon which is often mis-usde as coanda effect example
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shelly
 
Joined: 5 May 2009

Post Sun Mar 04, 2012 7:50 pm

shelly wrote:there is a convex ramp just outside the circular exhausts exits.


Yes, I acknowledge that, but this ramp must start at an angle of 10 deg below the axis of the exhaust flow. It is this 10 deg angle that I say neuters the Coanda Effect. I simply can not find any example of an angle beginning used at the flow outlet.

I am questing whether the flow attaches to the surface of the curve surface because of the 10 deg angle.

Brian
hardingfv32
 
Joined: 3 Apr 2011

Post Sun Mar 04, 2012 8:06 pm

The exit of the exhaust pipe has to point upwards by 10 degrees. Bodywork has to stay clear of a conical section with a 3 degree divergence from the exhaust exit (not from the horizontal). Hence, one can place the beginning of the bodywork pointing 7 degrees upwards and perfectly tangential to the exhaust cone. It is only 3 degrees Coanda has to "jump", and the expansion out of the exhaust can make the transition better than tangential, as the real exhaust probably expands beyond the limits of the 3 degree cone at some point close to the pipe end.
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