small lockwood - propane injection problems?

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mk
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Post by mk » Thu Jan 29, 2004 9:11 pm

Ok, I hope the needle valve and/or the temperatures is/are the main problem(s) then.

If iget it running on propane I'll do some testing with liquid fuels by using a fuel oil burner. (->take a look at "tools and construction forum"->"liquid fuel vaporizer")

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Post by mk » Sun Feb 01, 2004 2:01 am

Aaaarghhh! I don't get my engines run!

Today I tryed the assembly without a needle valve. Well, none of my two engines wanted to run. Curious.
So I decided to build an engine as shown in the patent by making one engine out of my two. I just had to cut a bit and roll two cones. After welding all up I tried again...
...WITH the needle valve at the propane injection assembly I just get relatively small "pops" (or rather ONE single "pop") at the starting procedure, still having the same problem with the "burning torch"-effect inside cc at the injector outlet, which is getting out of cc by delivering more propane. I think that the needle valve just restricts the fuel flow (lowers propane speed), because I can "overfuel" the engine, while it's burning inside, it just stops burning when opening the needle valve near to maximum.
...WITHOUT the needle valve I just need to turn the main valve a bit, start the ignition source and blow air through the engine and I get (sometimes, but rel. often) a good "bang". But after that the engine returns again to this "burning torch". I tried opening and closing the main valve while blowing air into the intake and having the ignition switched on. The result: When opening the valve and closing it immediately it needs about 0.5sec (at least a noticeable delay) till the "bang" comes.
I didn't get the "howling mode" at this engine (may be because of the biger diameters compared to the small engine).

After all I think that there are two reasons why the engine(s) do(es)n't want to run:

1. Propane/air-mixture is insufficient. It seems that there are kinds of layers in the cc, what demands mixing them up first (reason for the delay?). May be I should place some kind of varporizer nozzle or let the propane flow into cc from the underside (I got the idea just now!) instead from above or the side. Placing the injector at the intake inline with the symmetrical line and differing the immersing length might also help.
2. The temperatures are too cold though that propane doesn't want to flow good enough. Temperature differences might also help layerizing. I placed an electric ventillation heating next to the bottle, but without any success.

So what do you think?
Attachments
engine2.jpg
Current assembly.
engine2.jpg (23.08 KiB) Viewed 8483 times
engine3.jpg
Better assemblies?
engine3.jpg (10.46 KiB) Viewed 8483 times

mk
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Post by mk » Mon Feb 02, 2004 10:30 pm

(A LITTLE) SUCCESS!

Today I built a new propane injector (->attachements) for getting a better mixture of air and fuel. After some testing with starting air positions and "taking-it-away-timing" I got my engine finally run. I had some pieces of paper with drawings being next to the intake, the running engine just blew them away! It also had a nice pulsating sound and was pretty loud! A light blue flame (about 2 - 3inches) came out of the intake while running (shows lean combustion at all!?). I didn't use a needle valve.

But there's a real "BUT" to mention: The engine just ran for about 10 - 15sec (no red hot glowing appeared), then it just stopped all at once. I started the engine 4 times (what was a headache), tried turning the main valve of the propane bottle and swithing off the ignition immediately after starting without any success.

Could it be that mixing of propane and air is still not good enough? After the first starts the propane bottle got cold (a thin ice layer appeared), I think this could be a reason, too, because some people wrote about problems with cold propane.

Are there eventually any suggestions (for improving the injector)?
Attachments
engine4.jpg
Changed injector assembly in the engine.
engine4.jpg (6.61 KiB) Viewed 8460 times
injector.jpg
The new injector with its dimensions.
injector.jpg (17.17 KiB) Viewed 8460 times
mk

Lawrence
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Post by Lawrence » Mon Feb 02, 2004 11:00 pm

I think the propane should be injected to the sides of the combustion chamber, or towards the inlet. Now the propane wil flow into the back of the CC, away from the 'turbulence zone' wich is were the intake enters the CC.

The propane has only a limited time to mix up with fresh air, before the hot gasses return from the tailpipe into the CC. If the propane isn't injected into this 'turbulence zone' it just takes longer to mix with air, leading to a too rich mixture at the back of the CC.

Try turning that piece of pipe 180 degrees around, and see what it does


by the way, congratulations with your running engine ! :)
Last edited by Lawrence on Mon Feb 02, 2004 11:07 pm, edited 1 time in total.

marksteamnz
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Post by marksteamnz » Mon Feb 02, 2004 11:01 pm

See the picture of the Trike with the Lockwood. Notice how the bottle is mounted. Turn your bottle upside down as this will provide liquid propane. You may need a the needle valve back in the system to regulate the liquid flow.
Your injector should have its holes at right angles to the axis of the tube.
If you want to see a lockwood being started check out Bruce Simpsons site. He has a video clip. http://www.aardvark.co.nz/pjet/


mk wrote:(A LITTLE) SUCCESS!

Today I built a new propane injector (->attachements) for getting a better mixture of air and fuel. After some testing with starting air positions and "taking-it-away-timing" I got my engine finally run. I had some pieces of paper with drawings being next to the intake, the running engine just blew them away! It also had a nice pulsating sound and was pretty loud! A light blue flame (about 2 - 3inches) came out of the intake while running (shows lean combustion at all!?). I didn't use a needle valve.

But there's a real "BUT" to mention: The engine just ran for about 10 - 15sec (no red hot glowing appeared), then it just stopped all at once. I started the engine 4 times (what was a headache), tried turning the main valve of the propane bottle and swithing off the ignition immediately after starting without any success.

Could it be that mixing of propane and air is still not good enough? After the first starts the propane bottle got cold (a thin ice layer appeared), I think this could be a reason, too, because some people wrote about problems with cold propane.

Are there eventually any suggestions (for improving the injector)?
Cheers
Mark Stacey
www.cncprototyping.co.nz

resosys
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Post by resosys » Mon Feb 02, 2004 11:05 pm

Congratulations on getting it running.

It's hard to say why it won't run for longer than 10 seconds. I've had similar experiences with smaller engines. There are so many variables to these little monsters.

As the engine heats up, a lot of things are affected. I've heard pitch changes in the frequency of the engine. Also, the propane is being heated up in the injector tube. The intake air is also warmer once the engine starts to get hot.

You might have some luck adjusting the propane once it's running. It may be leaning out.

Chris

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Post by marksteamnz » Mon Feb 02, 2004 11:06 pm

See the picture of the Trike with the Lockwood. Notice how the bottle is mounted. Turn your bottle upside down as this will provide liquid propane. You may need a the needle valve back in the system to regulate the liquid flow.
Your injector should have its holes at right angles to the axis of the tube.
If you want to see a lockwood being started check out Bruce Simpsons site. He has a video clip. http://www.aardvark.co.nz/pjet/


mk wrote:(A LITTLE) SUCCESS!

Today I built a new propane injector (->attachements) for getting a better mixture of air and fuel. After some testing with starting air positions and "taking-it-away-timing" I got my engine finally run. I had some pieces of paper with drawings being next to the intake, the running engine just blew them away! It also had a nice pulsating sound and was pretty loud! A light blue flame (about 2 - 3inches) came out of the intake while running (shows lean combustion at all!?). I didn't use a needle valve.

But there's a real "BUT" to mention: The engine just ran for about 10 - 15sec (no red hot glowing appeared), then it just stopped all at once. I started the engine 4 times (what was a headache), tried turning the main valve of the propane bottle and swithing off the ignition immediately after starting without any success.

Could it be that mixing of propane and air is still not good enough? After the first starts the propane bottle got cold (a thin ice layer appeared), I think this could be a reason, too, because some people wrote about problems with cold propane.

Are there eventually any suggestions (for improving the injector)?
Cheers
Mark Stacey
www.cncprototyping.co.nz

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Post by Mike Everman » Mon Feb 02, 2004 11:51 pm

Any way to get a pressure gage on the tank? Sounds to me like your tank is already really cold, and the fuel is being cooled so much further just from escaping the tank that it's lost the ability to gassify. Put an electric blanket around your tank. (on "Low" ;-)
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mk
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Post by mk » Tue Feb 03, 2004 9:14 am

Yeah, the bottle IS cold. There was a temperature rise during the last days (~10°C are better than ~-3°C!), may be that helped. I can just heat the bottle with an electric vetilation heating system, what's really not as effective as a blanket.
I'll try some other things with my injector. News coming soon.
mk

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Post by Mike Everman » Tue Feb 03, 2004 4:04 pm

Wunderbahr!
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Post by mk » Thu Feb 05, 2004 10:33 pm

(REAL) SUCCESS!

I built the new injector today (->attachement) and the engine started nearly at once (no excessive testing like monday)! There was just needed some pre-heating with the hot-air gun. First there were just some good "bangs", which became more aggresive with a higher engine temperature, suddenly the engine began to run and didn't stop at all! I didn't use a needle valve, so I tried some throttle with the main valve of the bottle. The result: I could nearly close the valve completely and the engine went on at a low amplitude. Just opening the valve suddenly to "3/4 open" (full opening might be possible) and I got the response: a multiplication of the amplitude, red hot glowing (cc and tail pipe intake about 3.5inches), light blue flames out of the intake nozzle (also or rather especially at 3/4 valve opening) and a shaking workbench (with the old injector the engine wasn't throttable at all; it showed soot around the holes -> no good vaporization)! Even the small shelve began to shake, whereof a lot of stuff, like cans (or tins - if you prefer) fell down. The shelve was approx. 1.5feet away from the running engine (neither the intake nor the exhaust pointed on it)! Some pieces of paper were also blown away, more powerful than a few days ago.

I'll try to get a camera during the next days for making some pictures.
Mike wrote: Wunderbahr
You can speak German?!
A hint: German language, hard language! (...nahh, it doesn't sound very well in English.)
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injector_2.jpg
The new and very well one...
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mk

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Post by Bruno Ogorelec » Thu Feb 05, 2004 10:51 pm

Great stuff!!! Congratulations! I like your injector very much. Gary Robinson in Australia made a similar one shaped like a ring a few years ago to use on the engine he built to see if my Unicone idea worked. (Eventually it did!)
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Gary gas jet ring.jpg
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resosys
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Post by resosys » Thu Feb 05, 2004 11:01 pm

mk wrote:(REAL) SUCCESS!
Congratulations! I love seeing this stuff on the forum. I also love that feeling I get when a pulsejet comes alive for the first time.
I'll try to get a camera during the next days for making some pictures.
That would be great.

Nice work on the injector. It would be interesting to see if it would run on a liquid fuel with that.

Chris

mk
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Post by mk » Thu Feb 05, 2004 11:15 pm

It could be really advantegous. I would place the vaporization holes sloping a bit towards the centre line of the cc, towards the tailpipe (drilling them would be easier, too), flowing into the incomming airflow in an ~80° angle if you will. Holes at the rim, parallel to the airflow, wouldn't be as good. The whirls of the incomming air would cause an underleaned mixture in the inner zone of the cc and an overleaned at the outer zone, towards the walls.
Let me know how you are getting along with this injector ring, which reminds me a bit at model turbo jet engines injectores, especially of Kamps' ones.

By the way: Thanks to all the people, who had given me some hints! Being successful within approx. two weeks wouldn't have been realizeable for me.
mk

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Post by Mike Everman » Thu Feb 05, 2004 11:18 pm

You can speak German?!
Ich spreche nur ein bischen mein freund!
Tchuss
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