Towards a wood fueled pulsejet

[ace_fedde]

Man, this thread is going fast.20 messages in one night!
vturbine, I would take that speedd as a forum's compliment for a good idea!

Joe, Viv,
Did anybody already build an run a PJ in jamjar-mode? I hear you think: What the hell is that suposed to mean .
I mean a jam jar with an intake and tailpipe, or, a batch fed PJ.
Imagine a CC, partly filled with fuel, with a intake a tailpipe pointing upwards, would it work?

I was thinking about something like this (left one)

If it works we might make (see right) the CC adjustable (thanks Viv for the idea, I mean thanks Reynst) to accomplish some kind of constant wood chip feeding. A grid might hold the chips at the bottom of the CC. Still there is a dish inside for the start-up-liquid-fuel.
Nice idea but probably the chips will not gassify fast enough…

The point is that there is a lot of airflow through a pj ,and I think the seperate gasifier is the way to go , or maybe some kind of coaxial combustor/gasifier

I do think that the gassifier and the pulse chamber eventually could be attached to eachother, however.
Possibly using some of the CC's heat to convert the wood. However, it might be a case of runaway as the temps increase.

Coaxial that’s what I was thinking as well. You’ll need a sxxtload of heat to produce enough gas for the PJ. Let the PJ deliver that heat (after starting up on gas or liquid. To prevent a runaway (if even possible, reachable) you’ll just need a release valve (don’t inhale!!)

The two main methods of pulling work out of the system would be a free piston, or a diaphragm -- well, not mentioning a turbine, because I wanted to get away from that into a linear system if possible. A piston tends to start looking like a linear piston engine, except for the fact that we're usng resonance instead of valves. So a diaphragm looks like the most "consistent" actuator to me in a "linear" concept system.

I expect that anything you’ll place in the PJ’s flow will distort the cycle. Me myself, I would go for a tubocharcher to extract work (will be described in my thread later, not proven to work yet though:
viewtopic.php?f=3&t=5377

Now if you really really really have to go with that linear alternator, I would suggest the following:

A free piston in a blind tube acting as a, as a, rotor? I mean, how the hell is a rotor for a linear called?

Fedde

[ace_fedde]

vturbine,

Can you post these items you mentioned (below)? Thanks!

By the way, a wood fired turbine has been done at least twice that I'm aware of. In one funded study a conventional turbojet engine was run on wood gas to determine erosion effects on the blades. I have that study.

In the other case a homebuilt converted turbocharger turbine was connected to a sealed combustion barrel with a spring loaded lid (safety release presumably) The compressor fed the wood fire, and the stack was fed into the turbine section. I have a film of that one running. It was made by Nye Thermodynamics.

Fedde

[vturbine]

Man, this thread is going fast.20 messages in one night!
vturbine, I would take that speedd as a forum's compliment for a good idea!

Well, I don't know. Having some doubts about it.

I wish I could scale it down to test more easily. Looks like I would have to build a big gas generator to feed a big pulsejet. The larger the pulsejet, the more likely it is to be able to work with wood gas.

Here are the problems I see:

1.) Generator basically operates at atmospheric pressure, requires vacuum from engine to produce gas. Throttles gas production according to need as expressed by the vacuum. This works great on a carbureted car engine, but not necessarily in a pulsejet, which seems to require fuel pressure. But then how to regulate gas production to fit engine needs? What's the feedback mechanism?

2.) Gas characteristics do seem "iffy" for the needs of pulsejets. Requires high volume, has low flame speed. Not proven yet either way.

3.) Pulsejets are an open system. Where and how to take off oscillatory motion? Some possibilities are in exhaust or intake pulses, but still, not defined very well yet. Will this affect the engine's ability to run?

I'm not giving up yet, but I have some serious thinking to do.

[vturbine]

vturbine,

Can you post these items you mentioned (below)? Thanks!

By the way, a wood fired turbine has been done at least twice that I'm aware of. In one funded study a conventional turbojet engine was run on wood gas to determine erosion effects on the blades. I have that study.

In the other case a homebuilt converted turbocharger turbine was connected to a sealed combustion barrel with a spring loaded lid (safety release presumably) The compressor fed the wood fire, and the stack was fed into the turbine section. I have a film of that one running. It was made by Nye Thermodynamics.

Fedde

Fedde, the forum wouldn't let me upload the first study as it is 3 megabytes in size, but I found a copy online for you.

Nye Thermodynamics sold me a CD 6 years ago with the film on it -- looks like they now stream it free on their website (which see). Film links below:

http://www.osti.gov/bridge/purl.cover.j ... bviewable/
http://www.gas-turbines.com/nt6/videos/ ... d-Res).wmv
http://www.gas-turbines.com/nt6/videos/ ... d-Res).wmv

[vturbine]

Fedde, actually the gas needs are fairly modest for PyroJoes machine -- on the scale of gas generators sized for autos. Roughly a 15 hp engine equivalent need. Calcs show a 4" gas generator throat would do it, but a 6" throat is the minimum recommended size to prevent chip bridging.

A diaphragm could be located where pulses were focused. Maybe some kind of interference effect even. Possibly as Grim said several diameters outside of the intake or exhaust. Maybe some kind of augmenter for pulse energy. Maybe his Borda mouth is that, in fact. I don't know, seems kind of early to worry about it. Don't even know if a pulsejet can run on woodgas. That's the first thing to find out.

As mentioned earlier by Rosscoe, I believe, chips bounce in a jar and head out the outlet as a fountain of incendiaries.

I'm thinking about this, because I would really love to make a first pulsejet as a unified jar-like popping generator. But we have to keep the embers in.

[vturbine]

Okay, what about this?

viewtopic.php?f=3&t=967&p=64285#p64285

[PyroJoe]

Some time ago I fueled my '52 Farm-All 4 cyl. tractor with the same injector I used with the big draft. Completely the same setup. The tractor uses about 4 times the amount of fuel the big draft would need, even at idle.

Slow flame speed may allow the use of the propane tank as a CC. Translates to lower peak pressure, that deep slow v-8 sound. May make it easier to hit the 60Hrtz range. If you want to start with the 5" CC go for it! Use propane to get a feel for the operation and study of the engine characteristics.

The fuel/air isn't as important as you may think (with this engine). I have often, tested gasoline poured in the CC of the big draft,(not recomended) leaving the fuel air mixture completely to what can be produced from the fuel pool. It will run for many seconds until it goes rich or lean. This condition represent NO fuel flow or injection! ha

[vturbine]

Some time ago I fueled my '52 Farm-All 4 cyl. tractor with the same injector I used with the big draft.

Ha -- wonder if that would work with my '51 JD Model M.

[ace_fedde]

Mark,

Several years ago I emailed this company because they mentioned that Reynst was born in the Netherlands. Yet in my copy of Pulsating Combustion the bio states Reynst was born in Java.

Well Mark, back then Java was a part of the Kingdom of the Netherlands. And Reynst was a real dutch, as is De Rijke (Rijke tubes), as is Metiz , and of course me!

vturbine,

Fedde, the forum wouldn't let me upload the first study as it is 3 megabytes in size, but I found a copy online for you.

Thanks!

Fedde

[vturbine]

Slow flame speed may allow the use of the propane tank as a CC. Translates to lower peak pressure, that deep slow v-8 sound. May make it easier to hit the 60Hrtz range. If you want to start with the 5" CC go for it! Use propane to get a feel for the operation and study of the engine characteristics.

Well, Joe, I tried to build the 5" mini-pyrojoe today, but didn't do a great job. First, forgot my slip roll can't roll anything less than 3" diameter, so I couldn't do the cone that way. Then I tried clamping and heating the pipe at the mouth with the torch and levering it out with pipe -- that wasn't a brainstorm -- got a little bit of flare, but used a lot of gas up playing around. So then I dragged out my charcoal melting furnace, and stuck the mouth in there. That heated up to red a lot faster than the torch, but I could barely hold the pipe to put it in the vice even with welding gloves on, because whenever it was in the fire it would act like a chimney and heat the whole length up. So got only a little more flare that way. Finally I turned a hardwood taper, soaked it in water, pulled the tube out of the fire and hammered that into the hot end. That did a better job. But I still never got it flared as much as your cone. Maybe 1.75" out of the required 2.25".

Then I tried to tack the tube to a flat plate for the end of the CC after drilling out the hole in the center of the plate. I promptly burned through the tube (it's tube not pipe, and flaring it thinned it even further). So I decided to braze it, even though that's not ideal for a pulsejet, either. That was a messy job after the welding screw-ups, but by now I'm going, "what the heck, grind it back."

So anyway, I've got a start on it. Probably nothing I did improved it!

[PyroJoe]

Looks good!
Adventures in pulse combustion fabrication.

No worries on the cone, 1.75" flare should give good odds of running. The one thing this will affect is the intake size. If you haven't cut it yet, try stay under 70% of the tail pipe diameter for now. No need to be concerned with a intake pipe at this time. Start out jam jar style.

Take some time to dress up the area where the CC meets the tail pipe, file down any irregular bumps or slag in this area. Turbulence in that area can be a big problem.

If reached testing stages tomorrow, start at about 45 degrees tilt on the tail and vary the angle to get a feel for how much draft she will make. If everything goes well you will have an intense desire to bring up the fuel and make her run stronger(bittin by the PJ bug). If you bring up the fuel and she keeps stumbling, then the intake hole will need to be enlarged. slowly increase the intake diameter, testing about every 2% increase.
Avoid going over 85% tail pipe diameter at this point.

Try to avoid high flow rate with the injector, if she is hissing, she has to much flow.

Keep in mind that braze will probably be a safety hazard if she gets up to a good speed.
Gee, just noticed how much biomass is in the background.
Joe

[Mark]

Mark,

Several years ago I emailed this company because they mentioned that Reynst was born in the Netherlands. Yet in my copy of Pulsating Combustion the bio states Reynst was born in Java.

Well Mark, back then Java was a part of the Kingdom of the Netherlands. And Reynst was a real dutch, as is De Rijke (Rijke tubes), as is Metiz , and of course me!
Fedde

I guess that's one of those gray areas if it's not spelled out. When I was 8 years old I lived on a USAF Spy Base in Peshawar, "West Pakistan".
I wonder if Reynst might have been inspired by some jam jar volcanic activity, say witnessing some rumblings or chuffing of those giant stone jam jar cones or snorkelers living in Java? ha ha
http://en.wikipedia.org/wiki/File:Semer ... Temple.JPG
http://cgz.e2bn.net/e2bn/leas/c99/schoo ... ucture.jpg
http://www.geocities.com/thalsena/oldindia.jpg

"There are many wonderful experiences I can think of, it is very hard to choose. Each volcano I have visited has its own set of special memories. I suppose the winner has to be my very first visit to an eruption at Kilauea. It was my first week on the job as a very green young kid at HVO (Hawaiian Volcano Observatory). The East Rift eruption was still in the single digit episodes, and Pu`u `O`o was only 20 m tall, barely a blip on the rift zone. Low, intermittent lava fountains huffing and chuffing above us, I followed Ed Wolfe out over pahoehoe from Pu`u `O`o, still glowing in the cracks below my feet. I could not believe I was there, honored to have the opportunity, and in awe of everything I saw."
"What was the strangest experience you ever had on a volcano? Has anything weird ever happen to you?"
"Working on the west flank of Kilauea, I used to spend nights camping alone at a place called Pepeiau at the edge of the Hilina grasslands overlooking the south flank. On still evenings, just after sunset, the profile of Mauna Loa still visible in the western sky, I would sometimes hear a deep, faint “hum.” The sound would continue for hours and then slowly fade away. I could not explain where it came from – it appeared to have no directionality and it did not vary in pitch as it might if it were related to wind or surf or distant machinery or traffic. I did not hear it while camping on other parts of the volcano’s west or south flank. On two occasions I had company who could verify the hum. I still can’t explain the Pepeiau hum."
http://74.125.47.132/search?q=cache:X4s ... clnk&gl=us

"Then an amazing chuffing noise announced the start of the show. "
http://www.glnow.com/photos/Costa_rica/ ... olcano.htm

"In June 1988 the active vent was higher and larger than in August '86, with small-scale vulcanian activity sending up roiling ashy clouds, and making "chuffing" noises. The cone was approachable, but not with total safety; in this photo, the person descending from the rim of the cone is doing so in haste, fleeing the rain of ash and hot rocks from an unexpectly strong "chuff".
http://74.125.47.132/search?q=cache:rc- ... clnk&gl=us

"Back in 1959, Kilauea Iki was filled with a lake of undulating molten lava more than 400 feet deep; eventually it drained away into the vent called Pu'u Pua'i, leaving a "bathtub ring" of lava around the crater walls. In the late 1960s, I found the crater floor still a scene from Hades -- dark, hot underfoot, ominous, filled with steam chuffing out of a latticework of cracks."
http://74.125.47.132/search?q=cache:-0M ... clnk&gl=us

[vturbine]

Looks good!
Gee, just noticed how much biomass is in the background.
Joe

Yes, I have 67 acres of biomass. None of it farmable because of the slope. Unless you wanted to grow brush and trees. Actually you don't have to grow brush. You can't avoid growing brush here. I have a 6" chipper for the tractor. I've experimented with coppicing, as well. Wood chips are also purchaseable from a local mill at $35/ton.

Or if you're unaware they can be burned cleanly in a raw state, you can buy those same chips converted into pellets at the local Home Depot for $350/ton. The energy you get out of those pellets is probably equivalent to the amount required by grinding the chips into sawdust, mixing with water, extruding, drying, bagging, transporting and storing them, hence the need for the extra $315 to cover the fuel and infrastructure cost of of doing all of that. Well, of course minus profits along the way.

Actually, I'm wrong. I don't think I can buy chips from the mill anymore. They mentioned last time that it might upset the pellet company if they found out I was buying them. My last purchase of ten tons was hush-hush under the table like. Oh, the shame of it!

[vturbine]

Looks good!
The one thing this will affect is the intake size. If you haven't cut it yet, try stay under 70% of the tail pipe diameter for now. No need to be concerned with a intake pipe at this time. Start out jam jar style.
Joe

Joe, do you mean If I don't put the intake in yet, and use methanol it might run as-is? I don't have propane yet, that will take some work.

[PyroJoe]

Correct, no intake pipe yet, just a hole in the front plate.
No propane, well, do you have wood gas available?
Methanol may be bang-ish with that 5" CC.

Joe