2014-2020 Formula One 1.6l V6 turbo engine formula

[R_GoWin]

all types of engines seem to do some burning btdc
this is not wholly bad - most of that heat is still available for relatively efficient conversion to work

judging by the many schemes for lean homogeneous charge the heat 'insulating' benefits of charge stratification per se are more PR than actual
ie the overall AFR is the significant factor and the nominally homogeneous charge works just as well
lowering cycle temperature by increased air massflow is beneficial in-cylinder without disbenefit to the exhaust recovery
(and remember all cars used lean mixture till mandatory 3 way catalysts forced most/all running 4% rich)
...

Tommy Cookers - I can understand why you say that, because you can't just mash up a direct injector on any engine and expect to reap the all benefits of stratified charge. But there is a subtlety to how stratification is applied which helps to improve the overall efficiency with "heat insulating benefits". So its not PR and if the charge preparation is done carefully - it will work better than homogenous charge.

The trick is in getting a good port design to generate a bit of swirl as well. And lots of CFD to understand the in-cylinder charge motion and how it interacts with the sprays. Its a balancing act.

It is the swirl motion that brings about the 'insulating' benefits. Combustion products are lower in density to unburnt fresh air. So when you have that bit of swirl, the centrifugal forces acting on unburnt air will be more than that on burnt gas. This centrifugal force will pull the cool, 'heavier', unburnt air outwards radially to the liner walls, will form an 'insulating sheath', and keeps the lower density burnt products in the centre of the cylinder for longer. Hence by having the hot burnt products in the middle for a bit longer - you reduce heat rejection to the liner. As a consequence this improves the overall thermal efficiency.

[Cold Fussion]

It's not a fluid....

It's still making use of latent heat of vaporisation for cooling.

[PhillipM]

It's not a fluid....

It's still making use of latent heat of vaporisation for cooling.

It is, but it says any fluid. It's a solid.

[NL_Fer]

I though dry ice was common practice in f1 for years. They used to say it was for keeping the radiators cool before and after the formation lap. When the cars are idling on start/finish.

[PlatinumZealot]

all types of engines seem to do some burning btdc
this is not wholly bad - most of that heat is still available for relatively efficient conversion to work

judging by the many schemes for lean homogeneous charge the heat 'insulating' benefits of charge stratification per se are more PR than actual
ie the overall AFR is the significant factor and the nominally homogeneous charge works just as well
lowering cycle temperature by increased air massflow is beneficial in-cylinder without disbenefit to the exhaust recovery
(and remember all cars used lean mixture till mandatory 3 way catalysts forced most/all running 4% rich)
...

Tommy Cookers - I can understand why you say that, because you can't just mash up a direct injector on any engine and expect to reap the all benefits of stratified charge. But there is a subtlety to how stratification is applied which helps to improve the overall efficiency with "heat insulating benefits". So its not PR and if the charge preparation is done carefully - it will work better than homogenous charge.

The trick is in getting a good port design to generate a bit of swirl as well. And lots of CFD to understand the in-cylinder charge motion and how it interacts with the sprays. Its a balancing act.

It is the swirl motion that brings about the 'insulating' benefits. Combustion products are lower in density to unburnt fresh air. So when you have that bit of swirl, the centrifugal forces acting on unburnt air will be more than that on burnt gas. This centrifugal force will pull the cool, 'heavier', unburnt air outwards radially to the liner walls, will form an 'insulating sheath', and keeps the lower density burnt products in the centre of the cylinder for longer. Hence by having the hot burnt products in the middle for a bit longer - you reduce heat rejection to the liner. As a consequence this improves the overall thermal efficiency.

Turbulent jet ignition would turn everything we know about stratified charging on it's head though. The jets basically ignite an N-point star from the circumference to the centre.

[godlameroso]

http://energy.gov/sites/prod/files/2014 ... utland.pdf

[R_Redding]

http://energy.gov/sites/prod/files/2014 ... utland.pdf

Is that link Geo blocked or just dead.. I've never been able to download it (in the UK) since its link first appeared here.


edit .. yep...it seems to be geo blocked , I have been able to download it using a USA proxy with the anonymox firefox plugin.

[Brian Coat]

It loaded OK for me so I don't think it is geo-blocked.

It is a paper on methods of IC combustion modelling using an improved turbulence model.

They'll have fun trying to model TJI ...

[godlameroso]

Not quite, RANS(Reynold's Averaged Navier Stokes simulations) based equations still form the backbone of LES(Large Eddy Simulations), the main difference is in RANS your averages are global, whereas in LES the Reyonolds averages are per mesh. You can have just as much accuracy using RANS as LES but LES requires far less processing power for equal or greater resolution. In either case your sub-models are still the primary factor to getting results that correlate with experimental values.

The point of all this is that since 2012 CFD in combustion has taken a big leap, and that leap has allowed the advances we're seeing today. A lot of engine development CFD starts in designing your mesh models which can take years, if you have a good model before everyone else you can literally be years ahead of the competition. Because the concepts and ideas you can develop depend dearly on the correlation that your model has on experimental values, and this is the 1st thing that needs to be ironed out before you can even have a direction to develop in.

It does partly explain why a certain manufacturer got it right before everyone else, and all the other manufacturers have been playing catch up ever since.

[ian_s]

Two injectors can be used in these engines.
One injector may be at the outer edge of the top of the cylinder and the other can be between the valves.
The regulations permit such an arrangement.

i thought the rules clearly stated that you can only have 1 injector per cylinder?

[Craigy]

Two injectors can be used in these engines.
One injector may be at the outer edge of the top of the cylinder and the other can be between the valves.
The regulations permit such an arrangement.

i thought the rules clearly stated that you can only have 1 injector per cylinder?

They do.

5.10.2 There may only be one direct injector per cylinder and no injectors are permitted upstream of the intake valves or downstream of the exhaust valves. Only approved parts may be used and the list of parts approved by the FIA, and the approval procedure, may be found in the Appendix to the Technical Regulations.

(from the 2016 F1 technical regulations, http://www.fia.com/file/38950/download?token=Nu_ymUVZ )

[PhillipM]

They do.

5.10.2 There may only be one direct injector per cylinder and no injectors are permitted upstream of the intake valves or downstream of the exhaust valves. Only approved parts may be used and the list of parts approved by the FIA, and the approval procedure, may be found in the Appendix to the Technical Regulations.

(from the 2016 F1 technical regulations, http://www.fia.com/file/38950/download?token=Nu_ymUVZ )

Doesn't forbid an extra indirect injector in a prechamber though...just says only one direct injector...doesn't have to be interpreted as only one injector that must be direct, could be interpreted as only one directly injecting into the chamber and as many as you like indirectly into a prechamber so long as they're not in the ports.

[Brian Coat]

PhillipM's interpretation of 5.10.2 may not be what FIA intended but it is what they wrote.

[gruntguru]

I doubt the FIA share PhillipM's interpretation. More likely Mercedes and Ferrari have made TJI work with a single DI.

[FPV GTHO]

They do.

5.10.2 There may only be one direct injector per cylinder and no injectors are permitted upstream of the intake valves or downstream of the exhaust valves. Only approved parts may be used and the list of parts approved by the FIA, and the approval procedure, may be found in the Appendix to the Technical Regulations.

(from the 2016 F1 technical regulations, http://www.fia.com/file/38950/download?token=Nu_ymUVZ )

Doesn't forbid an extra indirect injector in a prechamber though...just says only one direct injector...doesn't have to be interpreted as only one injector that must be direct, could be interpreted as only one directly injecting into the chamber and as many as you like indirectly into a prechamber so long as they're not in the ports.

The prechamber still counts as the combustion chamber, so for all intents and purposes whatever injects fuel in there is a direct injector. If it were not a direct injector, it would be a port injector injecting behind the valve which is now forbidden.