Hi everyone,
It has come to the most puzzling mystery behind all gas turbine engines, the combustion chamber.
But, I will try to uncover this mystery, so there is no time to waste.
To start off, I went all over the internet (very useful) to find some ideas
and information on the subject,
most of the flame holders in these combustors had the same general hole pattern, small holes near the
fuel injector, then toward the center the holes got a little bigger, and last there were bypass holes to cool
the hot gases. Oh lord, some of this stuff gets pretty scientific, there is an infinite number of ways you could
build a combustor. Without further delays, here is my idea, based off other designs I have seen.
What I thought will work good is a combustor that is 12" long and 4" in diameter, I thought that inducing a swirl
by offsetting the air intake to work like a cyclone vacuum cleaner would help in mixing the fuel and air, then
making a flame holder with regularly spaced 1/4" holes as seen in the picture above, for a propane injector I
drilled a hole in the middle of a 3/8" brass plug
then countersunk it to help in distributing the gas.
Injector in the picture below.
Now the part that everything hooks together, the combustion chamber.
To start out,
I made a paper template that would help me in creating the proper taper for the combustor outlet,
then I took a 4" piece of pipe and cut the angled notches that will allow me to make the proper bends.
To bend the pipe with its 1/4" thick wall will require heating the steel red hot with an oxy acetylene torch,
even with this amount of heat it still took quite a bit of work to bend the steel, in the
picture above, this is the result of everything I have done so far.
This is what the combustor looks like after welding and grinding the bends.
Sadly enough, this is the only picture of the flame holder before I modified it, all of the holes are 1/4" in
size, I remember
drilling 51 holes.
Up to this stage I was able to test the combustor, I didn't have a spark plug installed yet, but I was able to turn down
the air supply and light it up with a match, after I had a crude yellow flame coming out the back I gave it full air flow
from the shop vac
the flame sucked up into the flame holder, so I added more propane then it really started to roar,
I added a little more propane, combustion was still very stable as it shot a 2 foot flame out the back as seen below
Below left, the flame while fully contained in the combustor.
 
For now, I have a functional combustor but I'd really like to see the flame just a tiny bit more even while the fuel is being poured on in the photo to the right, i'm afraid this will create a hot spot on the turbine when throtting up, and even while idling either way this spot will be hotter through all of the power range, I'm ok with it for now but I'd like to have it a little better, I'm planning on revistiting this issue later on.
Until the next page, see ya later, Heath Jepson.
|
