Paul,

I often wondered why I like those disc impeller pumps so
much.  Then it
dawned on me.  Tesla turbine.

Not happy with how my ideal TC engine was physically
forming up I
decided
to give the Tesla turbine another look.  I spent a
sleepless night
designing a true spin muffler that would be driven by the
exhaust of the
rotary engine.  Size restrictions dictate a six inch
diameter turbine
section and perhaps one for each rotor housing.  A
common shaft is do
able and puts the bearings outside the case. Most of the
components
should be made from Inconel or even titanium. Stainless 316
is good
enough for the testing.  Laser cut plates
absolutely.  At least for the
13B the Tesla turbines exhaust could exit near the
intermediate housing
and  feed a small T4 hybrid turbocharger.  Tesla
turbines are tune-able
for the desired rpm output by removing or adding discs.

Most of Tesla turbines motors out there have been running
on high
pressure air or steam simply because it is available but
hot gases are
also possible depending on the ratio of inlet to outlet
port size.
Turbine efficiencies are quote at from 40 to
95%.The higher figure is
nonsense IMHO.  Centrifugal turbine are in their mid
50s at peak so I
suspect the lower quote is closer to ball park.  Axial
turbines are a
bit better but either of these high rpms or large diameter
turbine are a
logistic nightmare.  I have believe a T4 radial
turbine is not going to
be able to recover much more than 30hp. at speeds low
enough for a
traction drive to handle it. The mounting and connection
considerations
are also daunting.  This started to add up to
unacceptable weights.

I had orginally designed a spin muffler around a central
pipe punched
with bypass exhaust holes and a  with the
planned  turbine to be mounted
outside on the muffler case. Making the spin muffler
literally spin
saves space perhaps development time.  It it saves me
from having to use
a supercharger so much the better.

 I can see a few points that may increase the Tesla
turbine efficiency.
New spacing methods to lower windage,  texturing the
discs, and
eliminating skin drag loss on the outer end housings.
If nothing else
it would make a heck of  a quiet
muffler.Injecting air into the
exhaust nozzles would help contribute to a complete burn
and increase
inlet pressure.

Putting the turbocharger on the outlet of the Tesla's spin
muffler would
subject it  to lower temperatures.  Will it
work?  Who knows but at
least this is something I can build and test.

Anybody else have some thoughts on design feel free to
chirp in.
Depending how it mounted it could feed the power to the
accessory side
or the PSRU side of the engine with the obvious differences
in required
shaft lengths.

Now I am thinking to make a prototype with the housing made
of a six
inch
ID Inconel pipe.  Discs will be SUS316L.  2.0 mm
thick. Spacing at least
2.0 mm. Numerous discs. Both exhaust pipe rectangular
and tangentially
wrapping at least 60 degrees around the outer muffler
housing.


Doug in Japan


That is interesting.  I have been thinking along the
same lines
recently.  I'm building a 14" disc prototype.  I
guess my input would be
to consider water injection as well.  I've seen posted
the thought that
spacers on the periphery don't degrade efficiency.  If
you used wafer
thin ferrite magnets you might be able to use the turbine
as your
alternator.  I'd be very interested in seeing any
formulae you may have
found in your research to calculate efficiencies, etc.
Decker, Michael


If you'r suggesting the magnets are also exposed to the exaust stream, it's a
non starter. The magnets subjected to that high a temp. would surely reach the
Curie pt where the magnetic properties go to zero.
Robert



Michael,

I attached a file for you. Be warned. I don't think this guy has even
built a unit yet.  There is some accurate historical data there on sizes
verses output and some brief sentences of clarity but you have to filter
out a lot of other BS, speculation and rants. Pretty much what you find
when sifting through the Internet. I am still waiting from responses
from people who have actually made a turbine to run off car exhaust
gases.


Do you have Tesla's patent?  You can find it on  the Tesla group's
website in Milwaukee..

14" is quite large to fly with and it will be heavy. More important it
will have to kept slow, probably under 3,000 rpms as it becomes a large
flywheel and can store a lot of inertia. The  G forces placed on the
discs is in relationship to their mass and rpms.  Heating the alloys
will weaken it even more.  There are other issues as listed below.

Some challenges for using any turbine on the aircraft bound rotary are:
Location, exhaust piping, loss of heat and energy in the piping and
turbine housing, means of bypassing the turbine,  vibration isolation,
isolating the hot components from other engine components while safely
exhausting the heat from the cowl.  Obviously you don't want hot things
near the water hoses, electrical wires, fuel line nor near any
alternator or magnets.  Electrical efficiency goes down as the heat goes
up.

With these points  in mind it is no wonder that turbine installations
tend to be on short well designed manifolds with little gas flow
resistance. The heat signature is keep small and it is relatively easy
to shield and exhaust.

With a Tesla turbine, nozzle design is important.  I'm still clueless as
to why though.  We do have an exhaust port that is about 2"  in
diameter.  Do we cone it down to inch, fan it out and wrap it around.
Coning it down will increase back pressure and concentrate the flow on
lets say ten plates.  Leaving it wide will let it hit twenty plate.
Narrow is good and lighter and allows flow to all come out of one side
only.We don't know if the resulting back pressure will harm the
engine performance.  So I have to  measure the necked down nozzle within
the Mazda turbocharger to get an idea of what it can handle. A boosted
p-port will be more robust no doubt.

Placement: If the unit is on the hot side of the engine and is to spin
the same way as the engine is rotating, the bottom of the Tesla turbines
 will have to be near or slightly above the exhaust ports. Clearing the
intake pipe become a limiting factor in diameter size. Farther from the
engine increases allowable diameter but also increases cowl size and
flat plate drag as well as increasing thermal losses, in the piping,
increases pulley mounting flange weight and increases bending moment on
the exhaust manifold.

Output: The shortest shaft length will be in direction of the PSRU but
this demands the redesign of the PSRU sun shaft and torque absorber.
Ditto pulley mount designs.  Add to this is the fact that the turbine
position will change a little when the exhaust manifold becomes hot.
The design has to allow for this movement or something is going to
crack. There are unused bolts on the side housing that can be used to
mount a angled plate with a bearing or two to handle the side force
exerted by the multi-v belt.  I chose the PSRU side because the  sun
shaft is supported by bearings on the engine side as well as the PSRU
side.  No overhang which would be an issue to resolve on the accessories
end side. I am planning a large six inch or more multi V pulley on a
keyed sun shaft that  encapsulates the torque absorber bolted to the
counter-weight.


Turbine challenge.  Telsa turbines work off of boundary layer adhesion
and are similar to the adhesion between discs in automatic
transmissions.  Instead of oil or steam this one is running on fluid
air.  How to calculate their  maximum hp rpm? Max torque is not at zero
rpms. like other turbines.  Minimal torque is not at maximum rpms
either.When forced to do work some slippage must occur if it
overworked.  This is a good thing. The unit can be closed coupled to the
engine because of this perhaps an sprague clutch could be used in case
it needs to be disengaged.  The  pulley ratio would be set to obtain
maximum turbine efficiency at say 6,000 cruise rpm.

I believe Tesla's first unit of six plates total, had an internal width
of less than one inch.  Disc dia. was 5.75" and it made about 30HP.
Assuming his air power source was stronger than exhaust power and we
will use more discs  I would be happy to get 15 HPs from each unit.

Paul what is the wasted power in kinetic energy coming out of the 13B at
200 hp setting.  80 hp?

I would also love to know what the gas pressure exiting the exhaust port
on a rotary is.  Velocity is probably near the speed of sound.


Doug in Japan

What is that file that you attached Doug? It had no file extension to identify it.

I think the kinetic energy is higher than 8O HP in a 250 HP p-port engine.

The static pressure is only a few psi. What you are interested in is the dynamic
pressure. Lets say the exhaust speed is just subsonic at 600 MPH. Dynamic
pressure would be  936 pounds per square foot or 6.5 pounds per square inch.
Lets say we have ten small wings one inch square area with a lift coefficient of
one. Lets also say these wings are on a radius of 1.5 inches. The torque would
then be 97.5 inch pounds or 8 foot pounds at say 50,000 RPM. Turbine HP might
then be close to 77 HP. Close to your estimated 80 HP. Peak HP would occur
around 70,000 RPM so the HP might be as high as 90 or 100 HP.

Here is an update on the heat balance of the rotary engine.

Fully 154% of output power is wasted in the exhaust. In other words almost 384
HP is wasted in the exhaust of a 250 HP rotary engine. If we can recover only
25% of that it would be 96 recovered HP. With a few years of development we
might get up to 35% or 134 recovered HP. The BSFC would drop from .47 to close
..3. No gasoline burning internal combustion engine has ever been built to reach
that low of a BSFC. That includes the CW R3350TC and the Napier Nomad TC diesel.

Paul Lamar

Paul

Thanks for the calculations.  Considering an impulse turbine your
calculations make sense if that  calculated force is available. However
the reality is it takes less than 30 hp to drive a compressor with that
size of turbine to deliver the air volume the engine needs. I know this
because I have the data from  Rotrex supercharger that  uses a similar
compressor, at similar speeds and delivers similar lbs/per min.  and
still has to pay a energy loss penalty of the belt and traction drive.
Now I know you are going to say turbocharger turbines are over-sized to
provide quicker spool up. acceleration.  Perhaps 20% but 300%?Not
likely.Something is wrong with our assumptions about the kinetic
energy available or about the size of turbine needed to capture it.
Isn't dynamic pressure a function of manifold cross sectional area as
well as density?

In any case I am not sure this reasoning applies to Tesla turbines with
their enormous wetted surface area.

BTW I joined the  Tesla engine organization  to get some papers
explaining the fluid dynamics of how the turbines work.  One guy is
making a propane burner fired turbo turbine so we can pick his brain on
performance. Other links are for your viewing pleasure.  There are some
gems of information hidden away among piles of nonsense.  Bring a pitch
fork though:)  I am taking notes and cross referencing.  The last guy
Frank is rather unreal but one person on the RX7 club asked if dimpling
the discs would improve the Reynolds numbers.Could you explain what
this means?  I have heard of dimple textures on racing yachts and golf
balls lower skin resistance.  Since  a Tesla device  works with boundary
layer resistance we would want a good boundary layer.


http://www.teslaengine.org/main.html
http://www.fight-4-truth.com/Tesla%20Gas%20Disc-Power.html#T
http://www.rx7club.com/showthread.php?t=125445
http://www.frank.germano.com/index.htm


Cheers

Doug in Japan


You are absolutely right about the compressor HP requirements and that is why some people on here have destroyed five turbo charger turbines so far  in as little as 2 hours of use by running the Mazda turbo-ed engine at high continuous power. It is also why one can boost the Mazda engine to well over 400 HP per 1.3 L rotor. What you want in a turbo charger is instant spool up when the driver nails the accelerator pedal. That takes a lot of excess turbine HP.

A good  analogy is the high powered car itself. We all know it takes less than 40 HP to get the car to move down the freeway at 75 MPH. Why then do some people spend over 1.7 million dollars for a 1000 HP Buggatti Veyron with 25 times the necessary HP? Something like 30 have been sold in the U.S..


http://tinyurl.com/334kys

"Bugatti Veyron $1,700,000. This is by far the most expensive street legal car available on the market today. It is the fastest accelerating car reaching 0-60 in 2.6 seconds. It claims to be the fastest car with a top speed of 253 mph+".

Your Tesla turbine can have horrible efficiency and still work to turbo charge a rotary engine. Are you going to get good BSFC?  I don't think so. IMHO you would be better off with a larger, more efficient as far as back pressure is concerned, conventional radial inflow turbine. A turbo charged Mazda rotary engine has acceptable noise output. But hey more power to you :) All experiments are welcome.

Paul Lamar.