How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
n4rf
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Re: How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

Post by n4rf » Sun Feb 12, 2017 11:12 pm

Tommy Cookers wrote:we have seen from Honda via Green Car Congress that gasoline homogeneous 2 lambda is possible ......
only with port injection (charge preparation) combined with charge heating combined with a lot of turbulence, and only at low rpm

unless the F1 fuel has the combustion properties of a small gas molecule how will it combust fast and fully beyond 2 ?
(by stuffing it with 'natural' dissolved propane/ethane as I suggested 2-3 years ago, and maybe the pre-chamber/TJI is mainly such gas ?)
Regarding homogeneous Lambda 2: The current development is for DI, no charge heating and significant rpm and load range (basically the part of the engine map you can cover with the amount of air you can provide at a certain engine speed with the given turbocharger). But that's a side note here, because that's development for series production. The one I'm talking about is not even involved in F1.

The "standard" approach to get really lean (beyond lambda 2) is to go for a stratified combustion system, so inhomogeneous charge preparation where you have an ignitable air/fuel mixture at the spark plug, but not close to the surfaces of the combustion chamber. That also has benefits with the amount of heat transferred to the cylinder, piston and head. However, the charge motion design is quite a challenge, especially over the time of a production vehicle, not so much for motorsport. Hence, only Mercedes is still doing it in a couple of engines for series production.
For F1, I would assume that some kind of inhomogeneous charge preparation takes place, what with the alleged prechamber/TJI situation of different manufacturers and what not. That's probably all I should say in that regard, since it's one of the more closely guarded areas of these PUs.

The findings from the current F1 developments should be interesting for future road use to some regard, which is interesting. Since in the EU WLTP+RDE regulations are now relevant, there's very little chance to avoid the GPF and fuel consumption targets are going to be more difficult. Maybe that will allow for the increased costs of lean exhaust aftertreatment for gasoline engines. That would open the chance of seriously lean burning engines with immense potential in terms of thermal efficiency. Interesting times ahead :)

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Re: How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

Post by gruntguru » Mon Feb 13, 2017 12:38 am

Tommy Cookers wrote:we have seen from Honda via Green Car Congress that gasoline homogeneous 2 lambda is possible ......
only with port injection (charge preparation) combined with charge heating combined with a lot of turbulence, and only at low rpm

unless the F1 fuel has the combustion properties of a small gas molecule how will it combust fast and fully beyond 2 ?
(by stuffing it with 'natural' dissolved propane/ethane as I suggested 2-3 years ago, and maybe the pre-chamber/TJI is mainly such gas ?)
In terms of lean-limit extension, TJI is a significant step beyond what Honda did in the Green Car Congress article. Lambda 2.0 is straightforward using TJI and without the intake heating and mixing used by Honda.
je suis charlie

n4rf
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Re: How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

Post by n4rf » Fri Apr 14, 2017 3:30 pm

Just as an update from discussions I've had with a number of colleagues that are also involved in the latest research for gasoline engines (I'm more on the controls side of things):
We think the most likely is, that the teams are running homogeneous charge in the region of lambda 1.2 to 1.5. The pre-chamber might very well be a "conventional" pre-chamber spark-plug, which has been in research heavily some almost 10 years ago. The tricky part is, to get the spray targeting and the injection timing of the DI injectors just right, so the perfect amount of fuel gets into the pre-chamber to achieve a desirable combustion behaviour inside it. This combustion will then push out through all of the holes in the pre-chamber in order to ignite the charge inside the cylinder as fast as possible. Whether or not there are flames coming out of the pre-chamber or just a high-velocity flow of combustion-products with a high temperature, this is both possible and an interesting discussion point. Basically depends on the size of the holes (below a certain size, they stop the flames).
Generally, the mentioned lambda range will give you the best thermal efficiency. However, the burn velocity tends to be low, which in turn reduces the thermal efficiency of the engine. From a theoretical standpoint, the ideal situation would be to burn the entire charge in one instance. The pre-chamber system helps with achieving exactly that.
So, in general, the technologies that are used are not necessarily new. It's just that they have taken it to the next level, with the sheer amount of resources these manufacturers have. Especially considering, there's almost no price-limit to the engines and at the same time no emissions legislations.
The problem with the, presumably, used lambda-range is, that it is precisely, where the NOx emissions have their peak in an emissions over lambda diagram. Thus, it is questionable, whether this will be road relevant in the future. Certainly only with lean exhaust after treatment measures that are not necessary for lambda 1 operation.
Another extreme are the immense combustion pressures and pressure gradients that you get from this combustion process. Certainly a big mechanical challenge for the piston, crankshaft, conrod and conrod-bearing.

gruntguru
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Re: How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

Post by gruntguru » Fri Apr 14, 2017 11:12 pm

The road relevance will come with TJI plus auxiliary injector which has been capable of lambda 2.0+ and single digit NOx.
je suis charlie

PlatinumZealot
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Re: How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

Post by PlatinumZealot » Wed Apr 19, 2017 10:44 pm

n4rf wrote:
Fri Apr 14, 2017 3:30 pm

The problem with the, presumably, used lambda-range is, that it is precisely, where the NOx emissions have their peak in an emissions over lambda diagram. Thus, it is questionable, whether this will be road relevant in the future. Certainly only with lean exhaust after treatment measures that are not necessary for lambda 1 operation.
Interesting. Andy Cowell did say that these engines are down-right nasty towards the environment.
"Raindrops .. drop top!"

J.A.W.
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Re: How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

Post by J.A.W. » Thu Apr 20, 2017 9:28 am

PlatinumZealot wrote:
Wed Apr 19, 2017 10:44 pm
...Andy Cowell did say that these engines are down-right nasty towards the environment.
Yeah... no news as such, there though.. & since when, has GP racing - ever actually been 'green'?

Like, apart from from putative grandstanding, such as loudly noting a ban on heavy TEL fuel dosing..
..but slyly still allowing TEL usage in fuel ( let alone lubricants) - well beyond road-legal 'unleaded' levels..
Dr Everett V. Scott sez.. " I happen to know a great deal about a lot of things."

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Re: How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

Post by PlatinumZealot » Thu Apr 20, 2017 6:18 pm

Exactly my gripe with this "Fuel flow limit." It is smoke and mirrors. It makes the engines seem green but they actually aren't. The rear jack-man probably loses a few years of his life standing behind those things.
"Raindrops .. drop top!"

JonoNic
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Re: How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

Post by JonoNic » Thu Apr 20, 2017 9:15 pm

I recently learnt that fuel can be microwaved to boiling point without combustion taking place unless an external ignition point is created. (Yes, a very stupid experiment but with a very boring outcome - absolutely no one was harmed :D ). The fuel boiled quickly once it was microwaved.

My question is: Would it be possible to heat fuel by microwaves to speed up the filling of the combustion and pre-combustion chamber?

As we all know that rapidly moving particles are excited neighbouring particles and eventually moves away from each other as in a gaseous state.
Always find the gap then use it.

gruntguru
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Re: How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

Post by gruntguru » Fri Apr 21, 2017 1:07 am

No need for microwaves. Can use coolant or exhaust heat and a heat exchanger to heat the fuel.
je suis charlie

gruntguru
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Re: How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

Post by gruntguru » Fri Apr 21, 2017 1:48 am

PlatinumZealot wrote:
Thu Apr 20, 2017 6:18 pm
Exactly my gripe with this "Fuel flow limit." It is smoke and mirrors. It makes the engines seem green but they actually aren't. The rear jack-man probably loses a few years of his life standing behind those things.
The cars are undoubtedly "greener" if not totally "green". The quantity of fuel burnt alone tells you a lot about emissions. Of course the big one is the technology being developed - which will make a difference to road car emissions and efficiency.

And then you have the reduction in noise pollution . . . :wink:
je suis charlie

J.A.W.
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Re: How are burnt pistons avoided at lean AFR seen in F1 hybrid engines??

Post by J.A.W. » Fri Apr 21, 2017 5:43 am

gruntguru wrote:
Fri Apr 21, 2017 1:48 am
PlatinumZealot wrote:
Thu Apr 20, 2017 6:18 pm
Exactly my gripe with this "Fuel flow limit." It is smoke and mirrors. It makes the engines seem green but they actually aren't. The rear jack-man probably loses a few years of his life standing behind those things.
The cars are undoubtedly "greener" if not totally "green". The quantity of fuel burnt alone tells you a lot about emissions. Of course the big one is the technology being developed - which will make a difference to road car emissions and efficiency.

And then you have the reduction in noise pollution . . . :wink:
Classic!

Sound quality, & not noise volume? Or is it reverse-wise ?

( & quietly, best not mention the reports of excessive lubricant consumption..
..the mysteriously unknown/unregulated composition of which..
..would likely rapidly poison the green mandated exhaust cleansing catalysts..
..that is - if - GP machines were fitted with 'em..)
Dr Everett V. Scott sez.. " I happen to know a great deal about a lot of things."



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