12 a

2018.03.05

Hello Paul,

don't know, whether you will "publish" the following notes ;-)

With regards to the "cut outs" in the sliding surface / trochoid housing ...
see patents US 3.393 <https://maps.google.com/?q=US+3.393&entry=gmail&source=g>.666 (1966) + US 4 <https://maps.google.com/?q=1966%29+%2B+US+4&entry=gmail&source=g>.040.392 (1976).

Better than reading a long text is playing around with a "paper made RE" or
a plastic model. Enclosed you will find 2 PDF files with 2 "engine sizes".

Can print it out + cut out the rotor. It's not necessary to cut out the
gears + to shorten the teeth a bit (lot of work).

Moving direction is clockwise.

The bold horizontal bars shall indicate the pressure difference between two
chambers.

Recess shapes are examples only. (flat Mazda MDR, flat OMC / F+S style, AVL
style).

The thin lines + numbers stand for degree of eccentric shaft. 0 degrees is
Top Center at combustion side. (Rotor tip pointing to the "0" line).

Sorry for the low quality - drawings are "generated by Access" + I'm a
layman in graphics ;-)

Nothing very exact - points are very small rectangles, positioned by "left"
+ "top" corner ...

If you lay down the rotor with an apex near to the short axis + let the
rotor "move" a bit forward + backward, you will see, that there's a huge
amount of leakage + you would not need any seals anymore ;-)

Your solution may look a bit like this ...
    _    _
____|x|__|x|____ < housing with "channels"
---------------- > apex seal during "passing by"
x > leakage areas


Turbulence ...
yes, it's true, turbulence will enhance combustion. Flame front surface will
be enlarged + burning speed will increase. But, too much of turbulence will
rise heat losses to the walls. The key is to get the right balance.

Look at the patent Wo 2013.017.232 <tel:2013.017.232><tel:2013.017.232 <tel:2013.017.232>>, showing refined versions of reccesses
with smooth transitions.
Result of CFD simulations of over 100 different combinations of spark plug
positions + recess shapes.

Hardware used by AVL may be something like that:
HPC cluster with 320 (three-hundred-and-twenty) CPUs (3,6 GHz Intel Xeon) +
300 GB RAM (not MB !)
Even with this resources a single simulation will usually take several weeks
;-)

Another interesting patent is US 3.398.724 by Daimler-Benz (1966). This
patent is worth to be read twice + carefully. Don't miss the description of
figure 7 ;-)

More interesting stuff you can find in / at the WWW, e.g. ...
Effect of Spark Plug Arrangement on Flame Propagation of Rotary Engine
(Mazda 2009)

Amelioration of Combustion of Hydrogen Rotary Engine (turbulence by vortex
blade)
(Mazda 2012)

Some rules of thumb ...
# best BSFC is reached with a far leading recess
# max MEP you will get with a centered recess
(so a combination / blending is preferred)
# intensive combustion at the T section will rise heat losses + BSFC only
due to cardboard-thin "chamber" with very bad S/V ratio
# you should provide as much mixture / chamber volume as possible at the
spark plugs + downstream / in direction to the L apex
# depth of the recess opposite to spark plugs should be as deep as possible
- less quenching of flame kernel
# always think of recess position + spark plug position as an "integrated
whole"
# influence of seals is much greater than e.g. that of heat loss or crevice
volume
# ...

+ a - sometimes forgotten - truism ...
chemical reaction (combustion) will only happen between fuel + air, if the
fuel is vaporized. So try to avoid wall films + big droplet sizes (multi
hole injectors may be a solution)

Well, I guess, that's enough "blah blah" ;-)


Best regards

Franky / Frank Herfert

******

BIG BIG Thank You to Frank  for putting this together... especially for pointing me to the relevant patent numbers... saved me a lot of time wading through the haystack to find the needle I was looking for.

And a big thank you to you Paul for putting out the word... much appreciated.

Frank's comments to go with his drawings are very good as well as his "rules of thumb"... excellent material. Some things I had thought of already... But others I hadn't...he shed some very good light on the problem.

I expect I'll have more to say (or questions) when I get a chance to dig into this further, but for now, again, thanks.


Don't remember if I mentioned it... But I bought the rotary snowmobile engine yesterday... Can't wait to tear into it...LOL

Regards,

Ethan Stinar


The problem with those snow mobile engines is they are charge or air cooled rotors.
That is a BSFC penalty. Typically they are well over .5 while a oil cooled rotors, like the Mazda, are .47.

It is best to do combustion chamber research on a Mazda engines.

I was disappointed in that Mercedes patent because they did not mention squish flow :-)

BTW Frank has the world's largest collection of Wankel patents and
if you want to obtain one for reference use this web site.

http://www.pat2pdf.org/pat2pdf/foo.pl <http://www.pat2pdf.org/pat2pdf/foo.pl>

Frank will be helping me with a TTC conference April 19th 2018 in Friedrichshafen Germany
at a large air show called Aero. Thanks again Frank.

The Wankel aircraft engine is once in a 100 year engine development.
It never ceases to amaze me more people don't understand that.
The TTC demonstrates that quite clearly.

https://www.youtube.com/watch?v=Xe1lwc3fxfs <https://www.youtube.com/watch?v=Xe1lwc3fxfs>

Paul Lamar

Thanks again... Good info.

reg. combustion chamber research...yes, a full size Mazda engine would be best. The snowmobile engine is my quick, dirty and cheap way of testing a couple of ideas before I go through the trouble and expense of a full size experiment... and on a couple different ideas that involve "creative destruction", lol, of the various parts.

Ethan Stinar

Your wasting your time and money working on a charge cooled rotor
with a host of irrelevant other problems.

We are in the single digit realm of being equal to a piston engine BSFC.

Paul Lamar


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