Exhaust energy use 2011 (without FFE)

[marekk]

I have no idea what McClaren was up to when it comes to exhausts this year.

I've started this thread to discuss technical implications of exhaust gases energy use in 2011.

I've found only this one quoted mention of thread's topic in last very long post.

Guys, you are free to start new thread about copying RBR, drivers confidence and anything else if you want, but please keep this thread on topic.

[ringo]

sayshina, i respond in more detail when i get the egergy.

But most of what you are saying, moreso than I, is your opinion and is not fact.
Is it a crime that renault can make a better car than Ferrari, or that Mclaren can get something wrong?

Once again, the fact that McClaren have adopted Red Bulls solution for now does NOT mean the RB solution is better than the McClaren one. You're commiting one of the fundamental errors in scientific study. Just because B follows A does NOT mean A caused B. It doesn't mean A DIDN'T cause B either. You don't know. You need to do more testing. In this case you need to wait and see what McClaren does from here.

The solution is better than if they did not adopt it. So it is better. Had mclaren had their silly solution they probably would not have any points.
Whatever gives you more points is the only justification.
They adopted it for Now because it is better now, and its best to make hay while the sun shines.
Imitation is the best form of flattery.
I am not making any errors in scientific study. Mclaren's solution was not only slow it was unreliable. The testing times and comments from the team support this.

Copying the RB solution only means, ONLY MEANS, that the RB solution is working better than the McClaren solution RIGHT NOW.

Exactly. And the time to get points on the board is now. We don't know what the future holds.

Even if McClaren abandons their solution forever, that STILL does not necessarily mean the RB solution is better, it may only mean the RB solution is close enough to make the McClaren solution not worth fixing.

What!?! That would mean their solution is a pipe dream and not realistic at all, pun intended.
It's not worth fixing, i don't think it will return even in practice even if the 26 is a second faster than the redbull.
We don't even know what is anyway.

You're not going to take my word concerning driver conficence, which is fine.

No i hear you, but you're trying to cover up the car's performance with driver confidence as the sole reason Mclaren were 2 seconds off redbull.

On the other hand, if you had a problem that was causing the vehicle to behave unpredictably, even a tiny problem would cause a massive slowdown.

suppose the tiny problem was the exhaust?

Peformance is determined by the clock, big or small. A problem is a performance issue. Ferrari had a poor car in melbourne, and may have a good one in malaysia. Something on the car just wasn't working. Mclaren's case during testing it was the exhaust solution in isolation.

Your personal religeous belief in the great Newey notwithstanding, the teams don't yet know which solution is closest to the ideal, and you and I certainly don't know.

Well the same can be said of you and Ferrari or Mclaren.
I couldn't give a rat's bum about Newey and his cars. I'm a Mclaren fan, but the truth hurts.
Newey's no god, but the other guys are making him look like one.

You can make no intelligent claims as to which car will prove fastest this season.

That will change as the season progesses, but redbull are in the throne right now.
How's about this prediction?

Williams to be top 3 with new blown floor.

Back to the topic now.

[Sayshina]

I've started this thread to discuss technical implications of exhaust gases energy use in 2011.

I've found only this one quoted mention of thread's topic in last very long post.

Well, you're right of course. I'm sorry for letting myself get sucked in.

I think exhaust energy usage is 1% of the solution. We've seen lots of occasions where teams have chases 1%, so that's not nothing. However, I think Renault proves that it just isn't all that. Historically, when we've seen 2 radically differing concepts, 1 nearly always proves immediatly better. Think Tyrell high nose or semi-auto gearboxes.

To have such a radical departure and see very little difference says to me that the part doesn't have a major role to play to begin with. Assuming Renault hasn't stumbled onto a game changer, which present performance hasn't proven out, I expect we'll see 2 final exhaust solutions by the end of this season, again not counting Renault who will probably stick with what they've got regardless.

Solution 1 will probably be the RB/McClaren one, and it's too early to pick solution 2.

And no, I don't believe we'll see the original McClaren concept return, my argument regarding that had to do with the other party's assumptions. It could still prove better, but as I said, I think all of the exhaust concepts acount for 1% of the issue.

[marekk]

Back to the topic.

Using NASA's FoilSim III i've tried to asses how much downforce at race start one can have just from blowing all the exhaust gases under the diffuser, like RB7 do.

For 350mm chord and 200mm span at about 9 degree angle of attack, exhaust flow with 72 m/s will give about 360N. It's not a hell of lot of downforce, but it can definitely help to accelerate IMO.

One side effect - if wheels start to spin, revs,exhaust flow speed and downforce increase - sort of traction control.

@sayshina: Still early days, we will see in a couple of races for real, but Vitaly Petrov improved in Melbourne his qually lap by 1,4s. Even if we count DRS (0,8s) KERS (0,3s) and his skill's improvement (0,3), they made up for lost DDD at least. And 2009 DDD was WDC/WCC wining device.

For comparision - Button was slower this year by 0.2s, Rosberg 0.6s, Alonso 0.8s and Barichello 1s.
Except RBR, Renault and McLaren (but only Hammilton) all teams where slower 2011 then 2010 by significant margin.

[Sayshina]

I'm not saying the Renault solution is actively slowing them down. But if you're going to blaze a trail you need a very good reason, especially if you're now needing to move well established and "safe" parts like black boxes.

But we've seen game changing tech come along before, and it normally makes such an improvement that everyone else is simply forced to follow quickly. High noses, semi-auto boxes, ground effect, ect. Renault will have been working with physical parts for around 3 months by now, so it's getting a bit late in the game for it to suddenly "come on" now. Still possible, but I'm not holding my breath.

I have real doubts that you'll see an actual 360N once you've acounted for all the energy losses. Also, when you get wheelspin you'll lose squat, and when the rear springs back up to equilibrium the flow in the diffuser is going to do its best to separate. So sort of an anti-traction control.

Yes, it is early days and I've been lecturing people on how you can't make assumptions based on 1 race. Button's time for example could easily be down to getting stuck behind someone. Ferrari clearly had a horrible weekend, and Mercedes is going to have good and bad races for the next couple of years.

I seriously doubt any of the teams will manage to fully make up for the DDD loss any time soon, possibly all year. But I think the biggest impact of that loss is increased pitch sensitivity, rather than total downforce.

On the other hand, taking the exhaust out of the diffuser and blending it in from some distance away seems like it ought to improve pitch sensitivity.

[marekk]

I have real doubts that you'll see an actual 360N once you've acounted for all the energy losses. Also, when you get wheelspin you'll lose squat, and when the rear springs back up to equilibrium the flow in the diffuser is going to do its best to separate. So sort of an anti-traction control.

But I think the biggest impact of that loss is increased pitch sensitivity, rather than total downforce.

Can't argue without real world numbers, but exhaust stream goes more or less directly to outer diff sector, and flow's path is short.
Additionally they can run engine mapping aimed at extra high exhaust flow at the start of the race. So lets gamble 300N. Still something.

Regarding wheel spin - i meant just first few critical meters, after that you are of course right - diff efficiency is far more important than direct downforce gain from exhaust blow.

On the other hand, taking the exhaust out of the diffuser and blending it in from some distance away seems like it ought to improve pitch sensitivity.

Exactly. Diff's pitch and ride hight sensitivity should improve with decreased viscosity of air.

[shelly]

I think that at least in rbr case there is a connection betwen exhaust positoning and high rake, exhausts having the effect, amongst others, to compensate with their mass flow the higher clearance from the ground of raised diffuser

[horse]

That's an interesting concept. Whether a blown diffuser allows you to run a steeper diffuser angle while reducing the ride height at which diffuser stall occurs?

[shelly]

That's an interesting concept. Whether a blown diffuser allows you to run a steeper diffuser angle while reducing the ride height at which diffuser stall occurs?

I am thinkink about a different scenario, in which exhaust mass flow helps you gattin downforce from a rear end with higher than usual ride height

[Leon]

very interesting article ))

"Simply put, the more fuel burned, the more exhaust is produced and potentially more downforce. Since the RS27's fuel consumption rate is extremely good, the Renault-equipped teams were able to burn 10 percent more fuel than normal during the Australian Grand Prix without running out of fuel, therefore giving more exhaust flow to its partners using the blown diffuser."

http://www.pitpass.com/fes_php/pitpass_ ... t_id=43254

[marekk]

That's an interesting concept. Whether a blown diffuser allows you to run a steeper diffuser angle while reducing the ride height at which diffuser stall occurs?

I am thinkink about a different scenario, in which exhaust mass flow helps you gattin downforce from a rear end with higher than usual ride height

That's quite possible IMO, at least for the outmost, blown part of diff.
More rear ride height means more rake, so more steeper diff angle and increase in outlet/inlet area proportions. By forcibly blowing some gases into inlet, you fill this increased void and prevent diff stall.

[shamikaze]

Currently the exhaust-gasses are evacuated via 2 pipes (1 for each cylinder bank) and each exhaust-pipe receives an pulse of hot air for every 90° of crank-rotation) with both the pulse between the 2 exhausts being off-set by 45° crank-rotation.

Would/Could a single exhaust-outlet bring an advantage (merging the exhaust-gasses of the 2 banks before exitting into atmosphere). Theoretically, the exhaust flow would be twice as stable (gas-pulse every 45° of crank-rotation as opposed to 90°C before) from a single exhaust-outlet. That outlet would/should have a slightly increased diameter to allow for the increased volume of exhaust-gasses. Whith carefull design, exit-velocity of the air shoul be increased.

Maybe the McL's "Octopus-system" was designed to act like a bag-pipe to "store" the exhaust-air and push it out a sngle outlet as a more continous air-stream. (pure speculation obviously). The success of this depends on a nr of items such as back-pressure to valves, containtment of this very hot air and sheer air-volume and where to put it inside the chassis.

The exit of this air-chamber could probably be pointed at a very strategic / beneficial location. Probably would be mostly hidden from view and has high-energy (gas-flow) potential.

Just a idea I got this morning look at the Ferrari exhast pic's.

Feel free to take your best shot at it

GReetz,

S.

[shelly]

I think yours is a very good idea: if I understand it correctly, you see that one of the advantage of the octupus is creating a plenum with less obscillating exhaust flow from its openings.
I would add that maybe creating a plenum would be an advantage also in reducing throttle on-off flow obscillations.
Disadvantages:
-you get some losses in the chamber
-you need a big chamber to have advantage
-you need to build it with heat ressitant material such as pyrosic
-you need to circumvent the rules about exhaust exits being only two; even if you make the octopus be counted as bodywork and not as exhaust, you are still limited in number ad positio of exhaust

Apparently mclaren found its way around most of this, but has for now been stopped by regulations on pyrosic.

The concept of plenum is very interesting, we have seen it drive ariboxes design from the 90s. Even wiht airboxes the plenum function is to have a more constant pressure zone between air inlet and engine intake, to exploit better ram effect.

[Sayshina]

I think that at least in rbr case there is a connection betwen exhaust positoning and high rake, exhausts having the effect, amongst others, to compensate with their mass flow the higher clearance from the ground of raised diffuser

That's an interesting concept. Whether a blown diffuser allows you to run a steeper diffuser angle while reducing the ride height at which diffuser stall occurs?

A few years ago during the first go-round of blown diffusers, someone in F1, maybe Gascoyne or Simmonds, said that was what they were all about. You run your rake so steep that your diffuser is already trying to stall when neutral, so normally you'd expect it to stall every time you shifted the AoA, which is to say constantly. Then you aim the exhaust energy along the upper edge, trying to force the flow to stay attached.

So assuming he was telling the truth, the work is coming from the underbody, not the exhaust.

Regarding the plenum, lots of small peaky high performance engines utilize the concept, a 4-into-2-into-1-into-2 motorcycle exhaust being quite common. The collectors don't need to be particularly huge, but as far as I know it's done solely for improved powerband.

You'd lose tons of energy while you were still in the exhaust, and losing that energy inside the sidepod effectively transfers it to the cooling system.

You'd change your engine tuning, possibly not enough to need different cam timing, but that's not out of the question. I'm not sure Mercedes would be much interested in going down a tuning path solely for McClarens sake. And making tuning changes these days is somewhat dificult.

I don't see why you'd need more or less than 2 final exhaust exits, at least not for the plenum concept to be viable. It will still even out the flow regardless.

I'd expect your minimum plenum volume might look something like 4 liters? So not impossible to package, but the ideal placement would seem to be right above the gearbox or thereabouts, and teams are moving suspension parts inside the gearbox in order to free up a lot less than that much volume.

[marekk]

-you need to build it with heat ressitant material such as pyrosic

Not quite sure if even pyrosic (long term heat resistant up to 1000 degree celsius) will be good enough, considering they burn up to 10% of fuel directly in exhaust pipe with retarded ignition.
We've seen at times nice blue flames (+2000 degree) out of pipes.