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Paul, and Group,
I wanted to run something by you to see what you think of it. These
newer turbo-compound trucks are using the axial flow turbines because
they are more efficient in the RPM range where an engine might operate.
I had a thought about how we usually will be running a specific RPM in
cruise and only slightly more at WOT. My suggestion is this, why not
optimize an axial flow turbine for cruise, and then gear it directly to
the e-shaft?
At idle or low RPM the turbine might even be a drag on the
engine, though a small one. This wouldn't be a big loss though
and the
muffling we would get from the turbine would be worth it. As the exhaust
flow increased the turbine would start to produce power. Recovery at
lower RPMs might be a fraction of what it could be with a variable speed
drive, but we wouldn't be operating in that range for long. As
the power
rose to at least cruise RPM the turbine would be in it's near
optimum
range and greatly improving BSFC with the minimum loss. Max RPM at WOT
wouldn't be much higher and the engine would still be recovering
considerable HP from the turbine, though not the optimum available
through a variable speed gearbox.
All the while we would need less of a
muffler after the exhaust was run through the turbine. The connection
could be simple like a multi rib flat belt or even a direct drive chain
or gear drive. We wouldn't be recovering much at low RPM's
but as we
have mentioned so many times before we wouldn't be at those RPMs for
long. The losses wouldn't be any different from the losses caused
by a
heavy muffler system used to quiet the engine anyway. This idea would be
like the really large turbine you have drawn in the past, but could be
done with a more conventional look to it. So what do you think of this
idea? It is nowhere near as elegant or efficient as the traction
drive,
but in the optimized RPM band it might be almost as good with a very
simple setup. I believe it would work. Tell me I'm wrong.
Bill Jepson
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These turbo charger variable angle vane devices work on axial flow
turbines
as well as radial flow turbines to broaden the turbine HP range over
a range
of engine RPM and power. It is very similar to changing the A/R
on a radial
turbine. In effect they are choking the exhaust pipe. They are very
simple devices.
If you add a one way clutch to the turbo compound (TC)
turbine output shaft
the TC turbine will not be a drag on the engine when the engine is
RPM is
higher than the RPM the TC turbine output shaft can generate.
Paul Lamar ...No rotor no motor.
OK, here is some drawings of what I understand Mr. Jepson to be
talking about.
"My suggestion is this, why not optimize an axial flow turbine for
cruise, and then gear it directly to the e-shaft?"
*Time is the Enemy.
*
Bill, I love your idea of gearing an axial flow turbine directly to
the e-shaft.
Time, however, is the enemy of all turbocompounding systems. Even
though the exhaust gasses zoom out of a p-port rotary engine at
supersonic speeds, the gasses still take time to exit the housing,
slide along the exhaust tubing to the end of the engine, and then into
a turbine. One example is Mr. Lamar's Axial-flow turbocompounded
rotary engine.
http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Turbo-compoundRotaryEngineeringDraw.jpg
<http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Turbo-compoundRotaryEngineeringDraw.jpg>
The energy thus generated is so out of phase with the power generated
by the e-shaft that it necessitates clutches, viscous dampers,
epicyclic gears, infinitely variable gears, etc., etc., ad nauseum.
Notes:
a. The test subject is the Mazda Renesis engine.
b. All drawings rendered in the CAD program BOTE v. 1.0 with no patches.
*Strategies for Victory:*
1. Mount Turbines Directly to the E-shaft
2. Use a Multistage Turbine as a Single Stage Turbine
3. Turn the Side Port into a P-port
1. Mount Turbines directly to the E-shaft
We do not mount the turbocompounder fans on a separate shaft and gear
it directly to the e-shaft. The e-shaft itself is the shaft on which
we mount the turbocompounder fans. Here is a simple diagram:
http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Exhaust_Thru_Coaxial_Turboc.png
<http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Exhaust_Thru_Coaxial_Turboc.png>
A Turbocompounder Fan mounted on e-shaft with the Rotor
This keeps with the KIS principle. Only one shaft, with the rotors
and the turbocompounder fans mounted directly to it.
2. Use a Multistage Turbine as a Single Stage Turbine
"What nonsense is this? How can a multistage turbine be a single-stage
turbine at the same time? Doesn't Les even know English?"
I love Merle Zingg's multistage turbocompound idea. I also know that
Time Is The Enemy. So, to accomplish both goals, I put a turbocompounder
fan just outside each side port of the Renesis engine. Here is a
simple diagram.
http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Plan_View_from_Top_001.png
<http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Plan_View_from_Top_001.png>
No single stage of the turbocompounder will need to do any more work
than any other stage. Every stage is exactly as close to (or as far
away from, depending on your point of view) the exhaust. Also, since
no single stage must deal with the power of the entire rotary engine,
the stages can be smaller.
You can use a blowdown fan, just like the blades of the R3350TC that I
copied in this diagram:
http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Fan_Blades_001.png
<http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Fan_Blades_001.png>
Or, if you think another type of fan will do better, go for it! :-)
If two fans in between the two rotors is too complex, too far away from
the KIS principle, put two rows of fan blades on one fan. Each set of
blades would be turned to face the exhaust of one of the side ports of
one of the rotors. Here is a simple diagram:
http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Two-Tier_Fan_Blades_Opposing_001.png
<http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Two-Tier_Fan_Blades_Opposing_001.png>
The exhaust of one rotor would pass through one set of blades, and the
other rotor's exhaust, coming the opposite way, would pass through the
other set of blades, like this simple diagram shows:
http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Two-Tier_Fan_Exhaust_Flow_001.png
<http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Two-Tier_Fan_Exhaust_Flow_001.png>
3. Turn the Side Port into a P-port
"What is this guy talking about? To make a Renesis engine a peripheral
port (p-port) rotary engine, you must close up and get rid of the
Renesis'
existing side ports! How is this going to aid Bill Jepson's idea of a
directly-geared turbo-compounder at all??"
Well, be patient and let me explain.
The Well-Tempered Side Port
Here is a diagram of a regular side port. The exhaust flows out of
the epitrochoid, through the side ports and out into the exhaust system.
The exhaust must make an S-shaped curve to exit the engine, as the
diagram shows.
http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Regular_Side_Port_001.png
<http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Regular_Side_Port_001.png>
Diagram A. Regular Side Port
The P-port Side Port
Instead of optimizing the side port to exhaust the engine, we optimize
the
side-port to direct the exhaust gasses onto the fans sitting right next
to each rotor, as per this simple diagram:
http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Reshaped_Side_Ports_001.png
<http://s12.photobucket.com/albums/a234/JacobPotts/Atom/Turbocompound/?action=view¤t=Reshaped_Side_Ports_001.png>
The exhaust gasses blast straight out of the rotor onto the
turbocompounder
fan, waiting just an inch away. To travel one inch at supersonic exhaust
speeds takes a tiny fraction of a second. Time, The Enemy, is defeated.
This design, I think, meets everyone's criteria:
1. The turbocompounder, per Mr. Jepson, is "geared" directly as
possible to the e-shaft.
2. The turbocompounder is multistage and, therefore, more efficient,
per Mr. Zingg.
3. The system is simple, per Mr. Lamar's dictum.
What do you think?
Les Nordman :-)
What type of alloy would these fans need to be ? HMS1011 or similar NiCr
? The temperature and shock waves would seem to be higher than the
conventional turbocharger sees. What ever the metal, they all look much
heavier than a geared fan that is only a few inches in diameter. Just
making the e-shaft that much longer would weigh more than the gearbox
and fan similar to a turbocharger - right ?
I think if weight did not cost us HP, like in a boat, this is a great
simple idea.
-dave
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