2 stroke thread (with occasional F1 relevance!)

All that has to do with the power train, gearbox, clutch, fuels and lubricants, etc. Generally the mechanical side of Formula One.
Brian Coat
99
Joined: 16 Jun 2012, 18:42

Re: 2 stroke thread (with occasional F1 relevance!)

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Thanks for this link.

It's a PhD paper so it goes into a lot of detail about a limited scope.

It is a good paper but it does not help me much.

The presented CFD solution is not corellated experimentally and not compared to a 4V under the same modelling conditions, so the flow field described is probably correct (uses validated methods) but the magnitude of the turbulence delta to 4V cannot be accurately assessed.

There is no data about combustion and knock (modelled or experimental), stand-alone or compared to 4V.

Honestly, I'm not a BRV cynic / CFD Luddite!!

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

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Hello.

The following drawing shows the tumble flow into the PatRoVa rotary valve:

Image

The flow through the two windows causes a strong in-cylinder tumble (a twin symmetrical tumble at the one direction and a stronger single tumble at the other direction) without loss of Volumetric Efficiency (as in the Bishop Rotary Valve), enabling very fast burn rates (as in the Bishop rotary valve).

The single tumble, at left, fits with the geometry, shape and arrangement of the combustion chamber when the piston is close to its TDC.
In comparison, in the Bishop rotary valve engine when the piston is close to its TDC (wherein the combustion takes place) the combustion chamber extends normally (i.e. at right angle) relative to the tumble flow.


The superiority of the Bishop rotary valve over the conventional poppet valves in the F1 is indicated / shown / proven by the reaction of FIA (Fédération Internationale de l'Automobile's, from 1946).
In 2004, i.e. after some 60 years, the heads in FIA decided that a F1 engine should breath only through poppet valves!

Thanks
Manolis Pattakos

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

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manolis wrote:
The superiority of the Bishop rotary valve over the conventional poppet valves in the F1 is indicated / shown / proven by the reaction of FIA (Fédération Internationale de l'Automobile's, from 1946).
In 2004, i.e. after some 60 years, the heads in FIA decided that a F1 engine should breath only through poppet valves!

Thanks
Manolis Pattakos
Thanks for that Manolis, & yes the 'Luddites' who direct F1 want it tightly proscribed , so Bishop's idea never raced.
So of course, given the inherent working advantages of the 2T engine, it has been on the F1 'ban list' - a lot longer yet..
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

Post

Hello J.A.W.

It turns more pathetic / laughable if you follow the dates:

2002: the first (ever) V10 engines with Bishop rotary valve technology were built and tested exhaustively.

2003: a completely new V10 engine with Bishop rotary valve technology was designed and manufactured.

2004: FIA announced changes to Article 5.1.5 of the engine regulations banning rotary valve technology!



However, something doesn’t fit.

Reasonable questions:

Why Bishop rotary valve technology was never used in production engines, like, say, in sport cars and sport motorcycles?

Why didn’t they put the Bishop V-10 they prepared (it was ready and, as they claim, it had a substantially better reliability than the similar poppet valve F1 engines) into a supercar?



Another question:

In the PhD thesis (University of Newcastle, Australia) at https://opus.lib.uts.edu.au/handle/2100/248 (CFD of flow and combustion in the BRV cylinder), in page 13, something does not fit:

Image

A Specific Fuel Consumption (SFC) of 0.135Kg/kWhr (at 5,000rpm) means a 60% Brake Thermal Efficiency (BTE)!

For comparison, the BTE of the giant 2-stroke marine engines is by far lower (just over 50%, not near 60%).

Fortunately, this mistake is easily checked (the numbers do not fit).

Even if the Kg/kWhr is replaced by Kg/(hp*hr), it still doesn’t fit: the peak BTE becomes 44% (still high).

If instead of Kg/kWhr the correct unit is lb/(hp*hr), the peak BTE drops to 20%, which is too low.


Can anybody communicate with the Australian University Professor who wrote the above thesis?.

The Professor could answer the questions.

Maybe the Professor could comment on the PatRoVa Rotary Valve or he could give to his students a homework regarding the PatRoVa rotary valve.

Thanks
Manolis Pattakos

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

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Hi Manolis,

Seems like whoever was supervising the PhD student's thesis failed to check the presented data - as well as you did.
If you contact the engineering faculty there, maybe be you could embarrass them into some tangible support for your ideas.

The Cross Rotary valve has been around for 90-odd years & has yet to overcome its inherent design issues.
Here below is a fairly recent Australian back-shed attempt at the Cross R-V.

http://www.shannons.com.au/club/news/ol ... t-fighter/


FYI, the published figures for the final, most developed version of the Napier Sabre 36 litre sleeve-valve aero-engine
gave 205 g/hp/hour as cruising ( @ 50% power)fuel consumption, & BMEP of 22.6 kg/cm2 at take-off rating on ADI/70.6 in Hg MAP.
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

Post

Hello J.A.W.

You write:
“the published figures for the final, most developed version of the Napier Sabre 36 litre sleeve-valve aero-engine gave 205 g/hp/hour as cruising ( @ 50% power)fuel consumption, & BMEP of 22.6 kg/cm2 at take-off rating on ADI/70.6 in Hg MAP.”

With 205g/hp/hour (i.e. 280gr/kWh) at cruising (50% of peak power) the BTE is 29.3%, not too good.

For long lasting flights they should focus more on the fuel efficiency and less on the lightweight-ness of the engine.

For instance:

With, say, 1,500hp at cruising, the Napier Sabre consumes 0.205*1500=307Kg of fuel per hour.

For a 7 hours flight (3.5 to go and 3.5 to return to the basis), it means 2,152Kg of fuel, while the dry weight of the engine is only 1,070Kg.

A hypothetical aero engine having 40% BTE (205gr/kWh, 150g/hp/hour), would consume, for the same flight, 1,575Kg of fuel, i.e. 577Kg less fuel.

Even if the hypothetical engine weights 50% more ( 1070*1.5=1,605Kg) than the Napier Sabre, the winner is the hypothetical engine, especially if you take under account the substantial smaller and lighter tank required for the additional fuel for the Sabre and the cost of the 27% less fuel required.

It is like the modern aero Wankel rotary engines.
They appear lightweight (recently the CEO of Martin JetPack decided to replace their own 2-stroke engine by a “lightweight” Wankel rotary), but if the required fuel is taken into account (and its cost, as well) they are not really good.



The 24-cylinder 48-piston 29-liter 4-crankshafts experimental Junkers JUMO 223 2-stroke Diesel aero engine:

Image

weighs 1400kg. With 175g/hp/hour, i.e. 238gr/kWh, i.e. 34.5% BTE, it needs for the same flight 1,837Kg of fuel, i.e. 313Kg less fuel.

1,400 - 313=1,087Kg, just 17Kg more than Sabre's 1,070Kg during take-off.
Taking into account the additional weight of the fuel tank of the Sabre (to contain 313Kg more fuel), the winner is the Diesel.

(the only 34.5% Brake Thermal Efficiency is strange: other Junkers JUMO aero Diesel 2-strokes have a substantially better BTE; for instance the Junkers JUMO 205 at cruising consumes 216gr/kWh running at 38% BTE)


The Junkers JUMO Opposed Piston engine use two or more crankshafts and several heavy gearwheels for their synchronization.
Too many and heavy parts.


Compare to the PatAt Cross Radial 2-stroke Diesel with the Junkers JUMO 2-stroke Opposed Piston engines.
The first has a short crankshaft with a single crankpin driving four pistons.
In the Junkers JUMO 223, there are four crankshafts, each having 6 crankpins (i.e. 24 crankpins in total, i.e. one crankpin per two pistons), there are also several heavy gearwheels.

Image

One of the built-in characteristics of the PatAT Cross Radial is that it achieves as asymmetric transfer as desirable.

Objections?

Thanks
Manolis Pattakos

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

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To be fair Manolis, the Sabre was primarily a fighter aircraft engine, & as such was optimized to offer its sole pilot/operator
an easily managed, throttle responsive mill, with many automated features & the ability to run hard as required.
A favourable power-to-weight ratio was a primary attribute of aero-engines, particularly hi-po fighter mills.

By contrast, many of the larger US radial engines were intended to be fettled in operation by a dedicated Flight Engineer,
who would be occupied in observing instrumentation & manipulating the various controls to keep things in a steady state.

Those big radials were fairly intolerant of abusive mis-handling , whereas like a thoroughbred G.P. engine, the Sabre
was reported to have '' loved tough handling, & never objected to maximum revs & boost for extended periods."

& Len Setright wrote :"...the Napier Sabre could blip up & down the rev-counter scale like a car engine."

Curiously, one of the objections R-R put up to excuse their not flying Ricardo's V12 Crecy 2T engine was the concern
that it would be 'too much ' for a Spitfire airframe..
Just why they didn't obtain a Tempest for testing it - which could readily accept a Sabre at max take-off boost - seems a tad odd.
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).


manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

Post

Hello J.A.W.

You write:
“To be fair Manolis, the Sabre was primarily a fighter aircraft engine, & as such”

I tried to figure out that while the weight of the engine is crucial for an airplane / helicopter / flying vehicle, more important is the overall weight during take off.

With a more fuel efficient engine, the range gets longer and the airplane safer.


Depending on the application, a heavyweight Diesel having substantially lower SFC than a lightweight Wankel, may be preferable.

In most cases a lightweight Diesel having substantially lower SFC than a lightweight Wankel or than a lightweight spark ignition engine, is the reasonable choice.


By the way, here is a PatMar Twin:

Image

With two balance webs on the counter-rotating-camshaft, the even-firing Twin-cylinder PatMar gets as vibration-free as the conventional four-in-line 4-stroke engine.

For instance, suppose the above Twin PatMar has 55mm bore, 130mm stroke (i.e. 2.36 stroke to bore ratio and 618cc capacity) and replaces the TurboDiesel of the Punto 1.3 turbo Diesel.

At 4,000rpm, wherein the engine of the Punto makes its peak power, the PatMar Twin with the long stroke has only 17.3m/sec mean piston speed


The PatMar is a two-stroke port-less through-scavenged crosshead engine having true four-stroke lubrication, true four-stroke specific lube consumption and true four-stroke scuffing resistance ( more at http://www.pattakon.com/pattakonPatMar.htm )


Does it solve / cure several long lasting issues / problems of the 2-strokes?

Thanks
Manolis Pattakos

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

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Hi Manolis, with oil injection metered into specific areas, consumption/loss by crankcase scavenged 2Ts can match 4T norms.

As for an Australian academic 2T research ( DI/Jet ingnition) thesis,
..here's one that cites your work: https://researchbank.rmit.edu.au/eserv/ ... /Jiang.pdf
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

Post

Hello J.A.W.

Thanks for the link.

Quote from page 104 of the link:

RECOMMENDATIONS FOR FUTURE WORK
During this research, a range of two-stroke engine parameters and data have been tested and modeled. However, the engine design may be further optimized for increased efficiency and power density.
Suggestions for further modeling work include:
- Supercharging and asymmetric port timings may further improve both engine efficiency and power density.
. . .”

End of Quote.


Quote from page 16 of the link:

“Asymmetric port timing

Image

Fig 2.7 Asymmetric port timing diagram (Pattakon 2014)

In non-symmetrical port timing, the opening and closing of the intake and exhaust is not-symmetrical which leads to much more complex design.”

End of Quote

Regarding the “much more complex design” of the PatAT or PatATi 2-stroke engine, I count only three moving parts in total: a crankshaft, a connecting rod and a piston (i.e. as in the simplest 2-stroke conventional engines):

Image

(stereoscopic animation; instructions on how to “look” at it, at http://www.pattakon.com/pattakonStereoscopy.htm )

The three moving parts are modified to offer both: asymmetric transfer and asymmetric intake.

Is it a “much more complex design”?

A decent modern 2-stroke needs an additional mechanism to control the intake (like a reed valve, or like a rotary valve) and compromises with an inevitably symmetric transfer (the exhaust port stays open substantially after the end of the transfer).
In comparison, the PatATi, without using reed valves or rotary valves or anything else than its crankshaft - connecting rod – piston - casing, achieves a highly asymmetric and efficient intake, and a highly asymmetric transfer (if desired, the transfer ends after the end of the exhaust).

The PatATi is simpler (because, among others, the PatATi uses fewer parts) and better (because, among others, the PatATi offers new options / capabilities not possible before).



You write:
“with oil injection metered into specific areas, consumption/loss by crankcase scavenged 2Ts can match 4T norms”

Orbital tried it but it seems it was one of their weak points (lube starvation).
As regards the bearings (plain bearings or roller bearings), one can solve the problem by sealing them (not easy, but possible).
But the lubrication of the piston skirt / cylinder liner is a difficult to solve problem.
The leaning of the connecting rod creates significant thrust loads between the piston skirt and the cylinder liner.
In the 4-stroke engines and in some versions of the PatAT like:

Image

there is a thick oil film between the piston skirt and the cylinder liner enabling "hydrodynamic" lubrication as in the plain crankshaft bearings.
The idea is: “to "over-lubricate" the cylinder liner, apply an oil scraper ring, and then collect the surplus oil, clean it, and recycle it”.

A substantially thinner oil film is adequate to keep the piston rings from contacting the cylinder liner.

In the PatAT engine in the above animation:

The crankcase has four-stroke lubrication.
The scraper ring at the middle of the piston, above the wrist pin, scraps the surplus of oil from the cylinder liner back to the oil pan, from where it is cleaned and recycled.
The cylinder liner area the scraper ring sweeps, is rid of ports.
The path of the lower compression ring and the path of the oil-scraper ring intersect just below the ports.

As in the four-stroke engines, the tiny quantity of lubricant that passes "above" the oil scraper ring lubricates the compression ring(s).


In the conventional 2-stroke the piston skirt abuts on the cylinder liner and transfers similar trust loads; but now there are ports onto the cylinder liner, and the piston skirt passes over these ports. A thin oil film increases the friction and, sooner or later, allows the scuffing. A thick oil film reduces the friction and the possibility for scuffing, in expense of higher specific lube consumption and of worse combustion and emissions.

Achates Power tried the double sided crankshafts architecture in their Opposed Piston Diesels in order to minimize the thrust loads on the cylinder liner.

Image
According them, they achieved specific lube consumption as low as in the 4-stroke engines. The strange thing is that now they are back to the conventional Opposed Piston Design as proposed by Junkers and others long ago.


Another interesting solution of the lubrication problem in the 2-strokes is applied in the PatOP engine:

Image

and in the OPRE engine (here they are shown the parts of the OPRE prototype engine; spot on the piston structure and on the location of the wrist pin):

Image

Quote from http://www.pattakon.com/pattakonOPRE.htm :

“The transfer of the wrist pin - i.e. of the thrust loads - away from the hot combustion chamber and away from the ports, solves another problem of the opposed piston engines: it allows "four stroke" like lubrication and oil consumption.
OPRE's piston skirt can avoid the touch with the hot cylinder wall because the thrust loads are taken at the other side of the piston, onto the cool, rid of slots and well lubricated cylinder wall of the scavenging pump.
In comparison, the piston skirt of the conventional opposed piston engine thrusts heavily onto the hot, especially at exhaust side, cylinder wall, around the port area where the openings restrict the contact surface, requiring plenty of lubricant and inevitably resulting in lubricant consumption.”

End of Quote

Thanks
Manolis Pattakos

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

Post

Hi Manolis,
..by 4T oil consumption norms, I meant that even a high-end maker such as BMW advises that ~ a litre/1000 km is 'normal'..
BRP E-TEC 2T mills run up to 100-1 ratio of discretely injected oil, ( which is not 'dirty' used sump oil either, of course).

I trust you can obtain useful support for your innovative designs, inc' funding to assist with R & D of 'in-metal' work.
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

Post

So whatever happened to the 'Ryger'?

This design may have certain similarities perhaps.. https://ntrs.nasa.gov/archive/nasa/casi ... 048177.pdf
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

J.A.W.
109
Joined: 01 Sep 2014, 05:10
Location: Altair IV.

Re: 2 stroke thread (with occasional F1 relevance!)

Post

This research paper from nearly 60 years ago.. may yet be of interest to those with an interest in 2T engine functions.

http://nvlpubs.nist.gov/nistpubs/jres/0 ... 25_a1b.pdf
"Well, we knocked the bastard off!"

Ed Hilary on being 1st to top Mt Everest,
(& 1st to do a surface traverse across Antarctica,
in good Kiwi style - riding a Massey Ferguson farm
tractor - with a few extemporised mod's to hack the task).

manolis
107
Joined: 18 Mar 2014, 10:00

Re: 2 stroke thread (with occasional F1 relevance!)

Post

Hello J.A.W.

I tried a few times to download the pdf of nasa.gov “unsuccessfully”.

The other pdf shows a clever way to check the scavenging characteristics of a 2-stroke. Without the modern high-tech sensors and equipment, those people had to use a bigger percent of their brains.

I still try to find out what is the difference of Ryger’s engine from the conventional 2-strokes.
Thousands of articles, but nobody can say for sure the difference.
Making a new or “new” engine or mechanism is, no doubt, applaudable, no matter how wrong / unclever was the promoting policy used by Ryger and Ryger’s team.

Thanks
Manolis Pattakos

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