Possible Simple Fuel Atomization Methods?

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larry cottrill
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Possible Simple Fuel Atomization Methods?

Post by larry cottrill » Wed May 18, 2005 7:46 pm

What does everybody think of these proposed simple methods to achieve liquid fuel atomization at the end of a fuel pipe? Pinch the tube end down tight, cut / file square, and modify as shown. Any idea how such crude methods might work, for either pressurized or suction-driven [carbureted] fuel delivery in the intake?

In both methods, the basic idea is that by cutting back farther past the pinch in the end of the pipe, the coarser the atomization will be, but the greater the fuel flow you will get. Such crude methods will probably work far differently at low pressure [suction feed] and high pressure [pump driven], I would guess.

All opinions / ideas welcome.

L Cottrill
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Liquid_fuel_atomizers.gif
Possible simple method for liquid fuel atomization in the intake throat. Drawing Copyright 2005 Larry Cottrill
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mk
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re: Possible Simple Fuel Atomization Methods?

Post by mk » Wed May 18, 2005 9:32 pm

Larry,

You don't want to use them for liquid fuels entering the final jet section, do you?

Due to experiments derived from and seen at the meet, I'd go for using them as vapore injectors only. Maybe pre-vaporization of liquid fuels by a heating coil around the engine body might help, but I'm not a real friend of such a technique.

As it was shown at the meet, the "Rosscojector" is a tube being completely squeezed at one end and having an angled spouting slit. It amazed me how much fuel passed the pinched zone, that did not show a kind of a visual slit! OK, Rossco squeezed the end with pliers, not with a vice.

Anyway, using more than one, two or three slits, what, of course, also depends on the diameter of the tubing, doesn't seem to be advantegous to me. A one, two or three slit/s or slightly triangular -- your drawing might be exaggerated, IMHO -- slit/s would make for a "Davejector". The "Davejector" is a closed end -- long cap -- tube with circular fuel ports and angular cuts. Not deep. They're done along the single fueling holes center line.
Make sure the squeezed tubing really seals -- I'd suggest soldering or welding -- if you don't want to get something mixed up in the results! OK, it depends one what you're planning to try/proof.

The "Rosscojector" and the "Davejector" were some of the things that really amazed me.

Just my two cents.
mk

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re: Possible Simple Fuel Atomization Methods?

Post by Rossco » Wed May 18, 2005 11:53 pm

Larry, i carefully explained how to do this in another of your threads, but like most untill they saw it in action, you didnt seem to think it was worth trying. Im not trying to sound pompas, even though it does to some extent.
This method works well for liquid after a vaporiser too, i know, that makes it mostly gas. Still, dont throw the idea out for lipuid fueling just because it does work for pressurised gas.

NOW, go and do something that will be the least intricate and time consuming that you have ever built. (i know that will be a strain for you, lover of overperfection) (meant hopefully obviously in a good way)

Grab a pair of side cutters, or pliers with a double crush cutting edge, and cut the end of a fuel line, at just under 45deg. Cut right through leaving a sharp edge. Stick it up your... intake, and fire away.
Dont worry that one, you cant see a hole/slit in the end and two you cant blow through it! It will work with propane behind it.
This first cut produces a very lean mixing flowjector, if you find it too lean just give the pipe a squeeze with the pliers across the length of the slit, just a tiny bit makes a huge adjustment.

Different diameter fuel lines give you different max and min flows within the flowjectors operating limits, although i have found it usefull to "overdrive" mine. I mean this by starting on vapour, and then increasing flow to liquid for a greater throttle. As soon as you hit liquid, the mixture changes hugely, so it will loose all the flow jector action. This is when the engine is up and running though, so it doesnt make a difference. For a huge locky, you would probably need about 3/8 line, with reall good pressure behind it, and on the oposite end, Mike's little pocket locky loves the tiny little stainless one made at the meet.

If you need to recut an injector, take a bit of meat off with the new cut, as any flat in the curve to the sharp edge will throw the action out.
There is any amount of reason for doing this. One huge one, and something to REMEMBER, the rosscojector is prone to block up! Especialy if in mild steel, but also because of the crap that comes out of old tanks.
Ive had all sorts of assumed pressure problems, thinking my tank was out, and uneeven or nonexistant flowjector action because of this. Very frustrating when you find what the problem was!

On a properly tuned engine, that is normaly relatively easy to start; the engine, small propane bottle, a Rosscojector and a CIG LIGHTER is all you need to cary! Get the injector flowing like starting an oxy, light it with the cig lighter as you bring it in line with the intake, and slide it up adjusting fuel and possition by feel until it locks up! This makes for a nice quiet start up, with no fuss of ancilory equipement. Adds to the impressive simpleness of an engine in demonstration too.

Now Larry, just butcher it! i can just see you carefully shaping it let alone FILING it. DONT. You dont have to put any work into this. Just do it.
The micro torn rough edge is i think a huge part of its effectiveness.

There has been requests to post something along these lines to explain the Rosscojector to those that werent at the meet in its own thread. Im not trying to hide it at all, and i do hope that as many people can get some use from it as possible. Ive just not got around to putting anything up. If anyone thinks this warrants a new thread, go for it, just quote me there i suppose.

One thing to note, again that this is very simple, but effective. I derived this injector from a full day on the lathe and workshop building countless flowjectors that came nowhere close to the effectiveness of this one for our purpose. I was doing all sorts of things like you propose Larry, in a vice, and this is the shape that you are after. Simple!

Rossco
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hinote
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Re: re: Possible Simple Fuel Atomization Methods?

Post by hinote » Thu May 19, 2005 12:45 am

Rossco wrote:

Now Larry, just butcher it! i can just see you carefully shaping it let alone FILING it. DONT. You dont have to put any work into this. Just do it.
YAAY, Rossco!!

I wish Larry could have been with us, at the PJ meet in California.

Like me, he would have learned a lot from you, Rossco. You can sense the location of the optimum fueling location--and using the "Rosscojector", you can fire an engine that almost everyone else has deemed useless.

I can assure the non-participants, there was a lot to learn by watching the real wizards at work. Rossco, Mikhail, and Marten--showed us the "right" way to do it!!

Rossco, I ran my "mini"-Escopeta for the last time yesterday--using your "Rosscojector" concept for fueling. It wouldn't run on anything else!

Thanks for your participation, and your contribution to our mutual effort.

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."

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re: Possible Simple Fuel Atomization Methods?

Post by Dave » Thu May 19, 2005 8:54 am

Pictures of two RoscoJectors made and used at the meet to fuel many an engine.

Dave
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RoscoJectors
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re: Possible Simple Fuel Atomization Methods?

Post by Dave » Thu May 19, 2005 9:15 am

From my prospective, the attached pictures show the two best little technical gems of the meet. The RoscoJector and the super simple battery powered sparker.

After the generators left, along with the car batteries, inverters and high tech ignition systems, we used this simple little grill liter to fire many an engine. It is hard to believe what you can do with one AAA battery and some potted electronics. I recently ordered mine direct from the manufacturer http://www.quikliter.com/cgi-bin/store/ ... =Quikliter and have already given myself an accidental shock therapy treatment. Although, I do have to report that my pulsejet addiction was not cured by the experience, I am confident that it will lite up just about any propane powered pulsejet engine.

Dave
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larry cottrill
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re: Possible Simple Fuel Atomization Methods?

Post by larry cottrill » Thu May 19, 2005 7:45 pm

Gentlemen ... gentlemen ... please ...

I don't know why I give the impression of favoring sophistication over simplicity. Nothing could be further from the truth. "Crude but effective" - that's my motto all the way.

I have no disdain for the Rossco stinger at all, for its intended purpose. It certainly gives you a quick and easy way of getting something started - even something unknown, or something recalcitrant to other methods. The best features of the Rossco stinger are that it is portable, immediately relocatable, and tunable. Unfortunately, its worst features are that it is portable, immediately relocatable and tunable. Whether you get the best from it or the worst depends on what you're doing.

I shouldn't be surprised at your response - you've all just witnessed the wonderful stnger / flowjector in action, with obviously brilliant results. But, I should have stated my requirements in my original post and perhaps you would have reacted differently. But, maybe not ...

I'm not asking for an easy starting method for unknown or recalcitrant engines. What I want is a simple method to experiment with liquid fueling within the intake of an engine that is already known to start and run well on flammable vapor. The only functional resemblance to the Rossco stinger is that I have to be able to make it with nothing more sophisticated than hand tools and a vise. I have to be able to experiment easily with a range of sizes. I don't want to vaporize the liquid and I don't want to pump the liquid - those are complications and add weight. I want to use liquid fuel in something close to real carburetion, determining definitively and once and for all time whether that can work properly in a good working valveless engine.

I'm not interested in a better way of starting and running an engine on a test stand withg pressurized vapor. I want to start and run an engine buried in a hollowed out block of balsa, working through a hatchway just big enough to get my hand in, with a polyethylene bottle or tin can fuel tank holding alcohol, kerosene or gasoline. I'm not after the perfect engine so much as the most nearly perfect flight propulsion system with all ancillaries as simple, lightweight, reliable, safe and easy-to-use as man can make them. A small external supply of compressed air for starting is NOT unreasonable, a la Dynajet. High voltage spark is not unreasonable [especially with the unit pictured above - wonderful!] though glow ignition [with alcohol fuel] might be somewhat more marketable. In terms of starting and running, the main goals are ease of operation, simplicity and absolutely consistent function. Nothing less will do. I don't have to have more thrust than the Dynajet to succeed - I DO have to have something that's easier to get in the air successfully - a higher fun-to-effort ratio!

I don't think we're going to do that with pressurized gas. I don't think we're going to do it with batteries and pumps. I think it almost has to be ordinary liquid fuel, sucked in by the natural action of the engine intake. Mark has shown a historic example of it being done with a Chinese style engine on a racing plane, so we know it can work - we just don't know how well. But to make that work, I need a simple way to get effective atomization in the intake throat, and that's what I'm getting at here.

L Cottrill

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re: Possible Simple Fuel Atomization Methods?

Post by mk » Thu May 19, 2005 9:55 pm

OK, Larry, your purposes are quite different. Surely my post pushed everything to the "Rosscojector" direction.

You don't really know if it'll work until you try your ideas, but I doubt the end shapes are good for atomization of unpresurized liquid fuels. At least when assuming a center line parallel position of the tubing.
I also wanted you to know that a squeezed end only is by no means sealed. Just as the "Rosscojector" reveald.
The best way, IMHO, still is a perpendicular positioned metering jet regarding to the airflow and a simple hole. Eventually with a shielded port and/or bypass pre-mixed with air, like piston engine carburettors are using. The conditions are not THAT different in pulse jets. The airflow through the carburettor is also of pulsating nature in piston engines!

But don't rely on my thoughts. I don't have any experiences in pulse jet liquid fueling.
mk

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re: Possible Simple Fuel Atomization Methods?

Post by Jmitchell » Thu May 19, 2005 11:34 pm

A circuit with a MOSFET would be much more stable, and heat lesss.

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Re: re: Possible Simple Fuel Atomization Methods?

Post by resosys » Thu May 19, 2005 11:55 pm

Jmitchell wrote:A circuit with a MOSFET would be much more stable, and heat lesss.
Yep, it's in the works and there is a nice circuit somewhere on the forum that uses a mosfet.

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re: Possible Simple Fuel Atomization Methods?

Post by Rossco » Fri May 20, 2005 1:31 am

OK, gotcha Larry.
Sorry, went on half cocked again.
Ed started a similar thread. We should keep our efforts combined really.

You dont like my vaporisation idea? I think that vaporising the liquid, and using this to pressureize the fuel is a great way of using some of that wasted heat? What are your thoughts on such a system? As you say, a separate starting system is acceptible, so what are the flaws in this that you see?
Carburation is messy in my opinion in such an engine, why bother when weve got such a greater energy source on hand than a meagre pressure difference (average pressure difference). Or do you also suppose to tune a fuel system to optimise the frequency of the engine?

This again is very hard with liquid, as it does not compress, a relitively large volume has to be moved at an instant. Where the same fuel, as a vapour, can be set into a resonant pumping action relitively easily, with the dampened fuel oscilation would act as a flash boil cycle that would not directly effect the injection into the engine.

There is then the reliability issue, which i think does not favour a carburation system at all. Minimal pumping effect, instability of levels (you are thinking flight engine?), and cut out due to an air bubble or lock causing all carburation action to cease, and not able to auto restart.

I found it very very interesting to read of the droplet splash info someone recently posted! (thanx for that to whome i should credit) And Bill Hinote hit it right on the head in an instant! "so we have been designing carburetors the wrong way for the last 100 years". (or something along those lines)
This theory again points to working with greater pressure than negative pressure.
Atomisation is spread out over a longer period of time this way and ingested as needed, rather than all happening in a fraction of a second in a very short distance, not only to atomise, but to mix.

I look at the fueling issue, as what can we afford to loose?! I see three, in order; Radiated heat, Foward pressure and foward gas velosity. Utalise these energy sorces to do something that is beneficial indirectly to thrust, wether its to use a more dense fuel, or get weight down, and they are efectively no longer an undesirable atribute, rather a power take off system.

Rossco

PS. Im not stirring Larry, this is a great topic, lets get some concepts out into debate. This is saving experimenting time, by pointing out issues that need to be addresses before steel gets cut.
And i dont think that you do know what simplicity is! or the way to get there at any rate! HA, just wait til you meet me.
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hinote
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Re: Possible Simple Fuel Atomization Methods?

Post by hinote » Fri May 20, 2005 1:44 am

Larry Cottrill wrote:What does everybody think of these proposed simple methods to achieve liquid fuel atomization at the end of a fuel pipe? Pinch the tube end down tight, cut / file square, and modify as shown. Any idea how such crude methods might work, for either pressurized or suction-driven [carbureted] fuel delivery in the intake?
Larry--this MAY be a good idea, and a workable concept.

I suggest that discussion on the Forum is worthwhile--but doesn't really get the hardware done. Why don't you build one of these, and see how it does at atomizing fuel?

I would like to see a mildly pressurized system, using bleed-pressure from the engine itself. More small holes, to create a broad-area based outflow of atomized fuel?

My only comment would be that a stable running engine with your proposed system MAY be achievable--but starting the darned thing may be the biggest stumbling block.

Experimentation required!!

Bill H.
Acoustic Propulsion Concepts

".......some day soon we'll be flying airplanes powered by pulsejets."
Last edited by hinote on Fri May 20, 2005 1:45 am, edited 1 time in total.

Rossco
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re: Possible Simple Fuel Atomization Methods?

Post by Rossco » Fri May 20, 2005 1:54 am

Ben, i did this, and it pumps like mad! With great fuel lift, what i didnt get is any of it actualy being able to be used in the engine.
Atomisation, granted i didnt really fiddle with, i was just after the flow through such a sucker, and it definitely works! and only in one way too, so that was achieved.

What methods are there in a venturi section that sucks like this, and also atomises? Any nozzle in there would, in my mind, throw out the suck. Then what sort of mixing method could then be fitted in aft of the venturi? We quickly run out of room let alone time!

Rossco
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re: Possible Simple Fuel Atomization Methods?

Post by ed knesl » Tue May 24, 2005 2:57 am

We all know that carburators are on the way out in all automotive
industry. There is a good reason for that. Not very efficiant or trouble
free.
Due to high frequency of pulse jets and lack of valves, thare is litle chance
to achieve good atomization.

I greatly favor Roscco's oppinion about liquid fuel vaporization.
Do you remember Coleman, Primus and other's lanterns, camping stoves and even heaters ? These darn things always worked ! You can use the whole thing including the pump pressurised tank !

I am going to gut one of my old lanterns and try the original "generator"
as they called it. It has self cleaning needle, and throtle control.

I fully understand Larry's effort, maybe there is a way around it !
Let's keep trying !

Rossco is a good guy, no matter what you, fellows say, and he is
Austraaalian! ( Haa Haa)

edk
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Bruno Ogorelec
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Re: re: Possible Simple Fuel Atomization Methods?

Post by Bruno Ogorelec » Tue May 24, 2005 1:02 pm

ed knesl wrote:Do you remember Coleman, Primus and other's lanterns, camping stoves and even heaters ? These darn things always worked ! You can use the whole thing including the pump pressurised tank !

I am going to gut one of my old lanterns and try the original "generator"
as they called it. It has self cleaning needle, and throtle control.
Finally a voice of reason. I've been saying this for years, but people think I'm daft just because I don't build engines. No one will listen.

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