F1technical.net

Tommy Cookers wrote: ↑

17 Apr 2017, 18:36

now here's a useful reference that I've just rediscovered (originated by another poster) flame speed measurements in a Ferrari F1 V8 at 16000 rpm etc http://ltces.dem.ist.utl.pt/lxlaser/lxl ... 12.2_6.pdf

Interesting paper. One nice takeaway is that flame speed (for that engine) sits around 1.5 x mean piston speed.

Quote from http://www.egr.msu.edu/zhug/Conference% ... zation.pdf

"The distributed ignition sites have also resulted in significant reductions in spark timing for the jet ignition system when compared to the lean spark ignition operating conditions. It is noted that the jet ignition pressure rise rates can also be controlled to typical stoichiometric spark ignition levels using an ultra lean main chamber. However for equivalent stoichiometric conditions, jet ignition combustion typically has pressure rise rates which are approximately 50% higher when compared to spark ignition combustion."

Combustion pressure rate rise speed/'late advance' of ignition is of course, a desirable feature of HCCI...
..& if/when that particular 'genie' is 'mastered', is promising, esp' being an item Honda has delved into..
..re-named - over the decades - as "Activated Radical Combustion", but its clearly still problematic, for F1..

Is the chemical/pressure/heat synergy showing incipient 'quantum' *fluctuations?

*Or are the sophistications of the the technicalities.. just saying.. 'fluc-u-asians'.. (-joke-)..

An archived article by Kevin Cameron wherein he includes/describes certain transonic DI issues..

http://www.dynotechresearch.com/blog/ar ... nYear=2013

Is unstable HCCI/deto the root cause of the destructive 'vibes' Honda-McLaren are presently stymied by?
Or is it crankshaft architecture/crankcase harmonics/resilience complexities added to ''...Radical Combustion."?

Intake and exhaust pressure(back pressure in exhaust case) interaction with combustion process, and resonant vibrations in the combustion chamber causing jet instability. Some of it is NVH related.

FIA Technical Regulations 2018 Published 30/04/17 NEW RULE.

5.6.8 Engine plenum (as defined in line 4 of Appendix 2 to these regulations) air temperature must be more than ten degrees centigrade above ambient temperature.......

For me, an interesting new regulation for 2018. I had a suspicion that one of the manufacturers was using a Ranque-H tube or similar to reduce inlet air temp. Also the possibility that they used the hot side to warm fuel temps, or you could feed back into the turbo. Remember way back in this thread, somebody posted a pic of the Ferrari pit wall data display, which showed a much higher than conventional fuel temp. It would be easy to have an engine mode that switched some of the compressor output through the tube. Personally, I would think about designing it into the compressor outlet housing. Of course you could also......

Interesting new rule, but if they found an efficient way of cooling or keeping the intake manifold air temps down why would it need to be restricted?

I have never used or come across a fuel I wanted hotter, I have always tried to keep them cooler, why would they want to do this? They are no longer running the same "exotic" fuels they ran in the turbo '80s.

(hotter) to combust at leaner AFRs than otherwise possible ?

What is to be gained with this limitation?

Perhaps it has something to do with the fuel density and volume related to higher temperatures?

Yes, I am surprised. Low intake temps reduce the boost requirement and possibly allow higher CR but apart from the latter restraint, TE (and therefore power under this formula) is actually reduced by intercooling.

How do they define 'ambient' temp?
Is it based on the track tower weather station data,
the air measured at engine level above the track,
or air at/in the engine ram intake?

Engine Tuner Wed May 03, 2017 8:51 pm wrote:I have never used or come across a fuel I wanted hotter, I have always tried to keep them cooler, why would they want to do this? They are no longer running the same "exotic" fuels they ran in the turbo '80s.

Tommy Cookers wrote: ↑

03 May 2017, 23:04

(hotter) to combust at leaner AFRs than otherwise possible ?

TC, gruntguru et al discussed this back in 2014 & 2016 My combustion chemistry is a bit rusty, so maybe someone else could detail the advantages. I am also interested in what you would be able to use as an ignition inhibitor in the fuel.

Gruntguru Fri Apr 01, 2016 7:01 am wrote:Despite many protests around these parts, I am quite sure fuel heating is desirable in a "fuel-efficiency" formula. (Same goes for charge air temperature). It is inconceivable that ambient temperature would by some coincidence turn out to be the optimal value for efficient combustion. If you accept that premise, it is also unlikely that the optimum fuel temperature at a particular engine operating point will also be optimal for all other operating points.

The obvious consequence is that fuel temperature will need to be constantly (and rapidly) adjusted to match the continuously changing engine operating point.

You could look up butanol use in HCCI research..

J.A.W. wrote: ↑

04 May 2017, 03:20

How do they define 'ambient' temp?
Is it based on the track tower weather station data,
the air measured at engine level above the track,
or air at/in the engine ram intake?

5.6.8 Engine plenum (as defined in line 4 of Appendix 2 to these regulations) air temperature must be more than ten degrees centigrade above ambient temperature. When assessing compliance, the temperature of the air will be the lap average recorded, by an FIA approved and sealed sensor located in an FIA approved location situated in the engine plenum, during every lap of the race. The first lap of the race, laps carried out whilst the safety car is deployed, pit in and out laps and any laps that are obvious anomalies (as judged by the technical delegate) will not be used to assess the average temperature. The ambient temperature will be that recorded by the FIA appointed weather service provider one hour before any practice session or two hours before the race. This information will also be displayed on the timing monitors.
2018 F1 Technical Regulations 40/103 30 April 2017 © 2017 Fédération Internationale de l’Automobile

Vortex37 wrote: ↑

05 May 2017, 18:38

J.A.W. wrote: ↑

04 May 2017, 03:20

How do they define 'ambient' temp?
Is it based on the track tower weather station data,
the air measured at engine level above the track,
or air at/in the engine ram intake?

5.6.8 Engine plenum (as defined in line 4 of Appendix 2 to these regulations) air temperature must be more than ten degrees centigrade above ambient temperature. When assessing compliance, the temperature of the air will be the lap average recorded, by an FIA approved and sealed sensor located in an FIA approved location situated in the engine plenum, during every lap of the race. The first lap of the race, laps carried out whilst the safety car is deployed, pit in and out laps and any laps that are obvious anomalies (as judged by the technical delegate) will not be used to assess the average temperature. The ambient temperature will be that recorded by the FIA appointed weather service provider one hour before any practice session or two hours before the race. This information will also be displayed on the timing monitors.
2018 F1 Technical Regulations 40/103 30 April 2017 © 2017 Fédération Internationale de l’Automobile

That could be a problem, where 2 hours before a race may be hot but by race time a cool front has passed through and the air temperature dropped by a long way....