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