|
Welcome back,
you're just in time for another update of the site. This
time out we are going to do a little 3D modeling of the
new combustor. Although we tend to do a lot of "Redneck
Engineering" here at Bad Brothers, we do actually spend
some time with our designs.
Designing the
combustor in 3D allows us to have the parts we need cut
via a waterjet machine. For those of you unfamiliar with
the process, a high speed jet of water is aimed at the material
to be cut and it slices through. Tiny abrasive particles
in the water help the cutting process, but mainly it is
just the speed and strength of the water that does the job.
Thick steel can be cut easily using this process, and the
result is a perfect part, ready to be used with little or
no cleanup of the edges.
SolidWorks wire frame mode
We use SolidWorks
3D modeling software here at Bad Brothers. It is a great
package that is easy to use, with lots of helpful features.
The image above is the assembly of the combustor being designed
in SolidWorks and displayed in wire frame mode.
SolidWorks shaded mode
Once you get
the hang of SolidWorks, you can easily design parts and
assemblies in no time at all. It is not really like designing
3D worlds and parts for animation though. SolidWorks has
a technical feel about it, and that is where it excels.
The image above is the same as before, but is displayed
in shaded mode.
SolidWorks render mode
To create something
like the combustor above, each individual part is made first.
Then all of the parts are put together into an assembly.
Later, you can change a part, and the assembly will be automatically
updated. Say we need to make the combustor length smaller.
All we have to do is make the outer combustor part shorter,
and the assembly is automatically put together with the
updated part. The image above is the same as before, but
has been rendered with textures and materials to make it
look more realistic.
Combustor
The combustor
is being redesigned to be modular. The old combustor had
the outlet welded into place, but the new one will bolt
on instead.
Combustor
By taking this
modular approach, we can find out what works and what doesn't
and fix it more easily. If this design had been used on
the first combustor, it would have been very easy to remove
the exhaust section where the pipe was too small, and replace
it with a larger section.
Combustor
You might also
notice that the new combustor will be much larger in diameter
than the old one. This means that we will have to mount
it in a different location, as this one will not fit under
the fairings,or body panels, up front.
Combustor
This new combustor
will mount side to side instead of front to back on the
bike. It will fit right underneath the turbine section of
the turbocharger. Only a slight bit of the combustor will
protrude from the right side of the bike. Although it will
keep the bike from being able to lean hard in a right hand
corner, that is not really the purpose of the bike. It will
allow for a 45 degree lean however, which will be sufficient
for everyday riding.
Exploded view of the combustor
The new mounting
location will also mean that there will be less modifications
to the fairings, or body panels, than before. Another nifty
extra that came about from the new location is that there
will be ample room for the oil tank and pump under the compressor
of the turbo as well.
Now is also a
good time to point out the fuel injector locations. Look
closely and you will see the 5 little pipes protruding from
the combustor end cap. The 4 outer pipes are for the diesel
injectors, and the middle one is for the propane injector
used for starting. The 2 holes near the injector pipes are
for the spark plugs to ignite the combustor. I will be using
2 spark plugs on this combustor to try to get a reliable
ignition.
End ring drawing
Well, for all
of you who want to get a good idea how I design and build
my gas turbines, now is your chance. The drawings here are
the actual drawings I am using to make this engine. Don't
worry if you can't see the markings very clearly, as I will
make plans available later along with a bill of materials
and suppliers.
Combustor cap drawing
This is the combustor
cap that houses the fuel injectors. It will be held to the
rings pictured above with 12 bolts for easy removal. The
rings will be welded to the combustor housing, or pipe.
The center of those rings is designed to hold the flame
tube in the center, and the caps will secure it in place.
The dimensions include tolerance for expansion of the flame
tube as it gets hot.
Combustor end cap drawing
This is the drawing
of the combustor end cap. The exit size is exactly the size
of the inlet to the turbine housing. The neat thing about
this design, is that if the gasses can not flow freely enough
after testing you can add a spacer in between the ring and
cap to divert the flow better. As I said, a modular approach
will make things easier.
Fuel injector tubes
These little
guys are so simple, yet a bit goes in to making them. They
are the fuel injector tubes. These tubes pass through the
combustor end cap and are welded in place. The fuel injector
threads into one side, and the inlet pipe threads into the
other. They are threaded with 1/8th NPT pipe threads. They
sure will look good with braided stainless lines going to
them, or even flare fittings and rigid pipe.
Also nice about
having 5 injectors, is the ability to control them each
individually. If you have one side of your flame tube hotter
that the other sides, you can adjust the fuel to keep the
burn even. About the 2 spark plugs again, I would like to
be able to start the turbine without a propane pilot, and
this may be a way to get better ignition and have a better
chance of doing so.
More updates
on the way, and more goodies are heading to the shop. Looks
like we are in for some work to get done. Hopefully a lot
of updates coming in this next month. Thanks for reading,
and for supporting us.
Russ W. Moore
Bad Brothers Racing
Go
to Section 16
Return
to the Main Jet Bike Page
|
