Interested? No.2 (in liquid)

[PyroJoe]

Hi all,
This contest is basically the same as the 1.5L Max Valveless Contest, except the fuel would be restricted to unpressurized (room/ambient temperature) liquids, no pressure taps from the combustion chambers, no pumps, no changing the liquid to a gas to build pressure before a nozzle, etc.

There may be some discussion in using a propane stinger to start the engine, but removed after start up.

A bonus could be added for each 10% of throttle range achieved.

Joe

[larry cottrill]

Joe -

Now your talking. Man, I like it!

L Cottrill

[Mark]

Just the idea of using gasoline or alcohol in any lightweight package and having it work as well as a heavy pressurized propane cylinder would be an advancement for those that want to fly a craft or don't like to lug around a tank that is heavy, chills up, and has special hoses and fittings - the simple fuel tank that could. Now sure it has been done before. But perfecting or coming up with novel ways to run a valveless without the "half rocket fueling method" (propane) might be akin to learning to ride a bike all over again. ha
Later, can we have a solid fuel category, say using charcoal or coffee creamer? How neat would it be to make a jam jar that you shake to get the particles in the air and then have it light and sustain/updraft a mist of particles for the following pulsations. I recall the coffee can/flour trick with a candle and all. But that is just a one time pulse. Of course coal fired Reynsts and pulsejets have been around for some time but I suspect that they were busy creatures having the benefit of working on a large scale. I wonder how the fuel feed mechanism worked?
http://www.practicalchemistry.org/data/ ... mb-205.jpg

I remember seeing a pound of airfloat charcoal in an amber jar with a label. One pound was a very large/enormous jar, the stuff is so fluffy, like talc, like the aerogel of powders. ha
http://www.highqualitychems.com/servlet ... OAT/Detail

[PyroJoe]

Have often considered 1/2 filling a big draft engines with charcoal briquettes and starting it with propane. The thought of non stop, fully automatic flaming briquette shooter (with no off switch) is a little frightening even for my antics. ha

I reckon they probably used some type of small auger to feed the powder fuel back in the day.

Joe

[larry cottrill]

Later, can we have a solid fuel category, say using charcoal or coffee creamer? How neat would it be to make a jam jar that you shake to get the particles in the air and then have it light and sustain/updraft a mist of particles for the following pulsations. I recall the coffee can/flour trick with a candle and all. But that is just a one time pulse. Of course coal fired Reynsts and pulsejets have been around for some time but I suspect that they were busy creatures having the benefit of working on a large scale. I wonder how the fuel feed mechanism worked?

In the Lionel electric "steam engines" there is a little sleeve-and-piston setup that gets kicked by a cam-operated lever as the engine moves. This blows a puff of air into the smoke chamber where a "smoke pellet" (basically an aspirin tablet) cooks on an electric element, releasing white smoke. The synchronized puffs from the piston thus blow puffs of smoke up through the stack. The effect is actually quite realistic, since its speed rises and falls with the speed of the loco.

In a pulsejet, especially one that is meant to run for long periods at a single power level (like an industrial heater or something), we could do a similar thing to create a powder feed. You would design a "piston on a spring" so that its natural period of oscillation would be IN TUNE with the expected frequency of operation. The natural cycling of the engine would throw the piston/spring into synchronized oscillation, and the puffs of air would blow through or across a small pan of powdered fuel so it gets inducted in. What keeps up the level of powder in the pan "will be left as an exercise for the reader." Ha.

L Cottrill

[Ghrey]

What would the duration on this contest be?

Or perhaps better phrased; Do you have an end date in mind?

[PyroJoe]

Haven't set any dates yet, it could be a annual or bi-annual, and ongoing. Maybe falling on a significant date to the valveless jets.

Open to suggestions.

Joe

[Ghrey]

I will see what I can do, I have something promising in this general area, but my time is limited.

The prototype, made many years ago, was an excellent flame thrower, More work is needed.

I will post again when I have More.

[PyroJoe]

I also have a great deal of work to be done. Maybe 2 more engines before dialing from propane to liquid.
Joe

[HPSCL]

This topic has me VERY interested! I had an instant brainstorm, as soon as I read it, but invite the senior members of this forum to pick it apart, if it seems unfeasible to them.

A simple carburetor has fuel drawn out of it and into the engine, by the vacuum that is created by the piston(s) moving downward on the intake stroke. The fuel pump's only purpose, is to keep the carburetor's fuel bowl full, when the engine is at a greater elevation than it's fuel source (i.e. - the fuel tank)

If the engine were only to be operated on a flat surface... and the fuel source level was above the level of the engine's carburetor, then there would be no need for a fuel pump... the fuel would be gravity-fed.

If you had a smaller diameter pipe, feeding into the intake tube of a pulsejet... The air rushing down the intake tube would create a vacuum (in the smaller tube) as it passes by the opening of the smaller tube.


There are small carburetors, for anything from a 2-cycle chainsaw, to a moped / go-kart / motorcycle. If an adapter was made to connect the carburetor to the smaller intake tube, then the pulsejet engine could run off of a carburetor (if the carb was jetted properly, for the airflow of the engine)



I went BACK, to the topic of "Thundechine starting problems" and re-read part of a reply by Post by milisavljevic on Thu Mar 12, 2009 12:58 pm:

In the case of Thunderchine, its twin intakes can easily pump in air at rates of 1500 lbs per hour or more.

...And then proceeded to look up how much a cubic foot of air weighs. Seems as though a cubic foot of dry air weighs 1.2 ounces. If the Thunderchine's twin intakes can pump 1500 lbs. per hour, then that is equal to 25 pounds per minute.

25 lbs. per minute
25 x 16 oz. = 400 oz.
400 oz. per minute
400 oz. per minute / 1.2 ounce =
333.33 cu. ft. per minute

So... unless I'm TOTALLY screwing this up... Can even the Thunderchine run off of a simple 4 bbl automotive carb?

Now, for the really cool part part:
The pulsejet, if setup like the concept drawings, could easily be started by:

1.) Turning your ignition on.
2.) Blowing air down the INTAKE TUBE of the pulsejet engine.

The air rushing down the intake tube, past the small opening of the smaller tube (that the carburetor is attached to) would create a vacuum. This vacuum would draw fuel out of the fuel bowl of the carburetor, via the idle circuit. The engine would start (and continue to idle) and then the pulsejet would be "throttled up" by simply opening the throttle of the carburetor.



---The above pictures are just concepts of different setups and not to be taken literally.

[Mike Everman]

I'm sure no one here can say that this will or won't work. I don't know what to think about the branch, but it sounds worth a try. i do wonder if it is worth the effort, when a simple needle valve across the proper intake does work well (see Laird Chinese). having the branch like that is reminiscent of several ideas that I like to call "flowcentric", where the flow is imagined to rush by its opening "going where we want it to", and it works like that to an extent; Rossco had some motors that wouldn't pump out the intake, but the pressure and rarefaction waves definitely go everywhere, and I don't think he ever got the impression (at least the early ones I saw, and one he made and gave to me) that there was much thrust going on, but they did run.
Beautiful illustrations! Is that sketchup? Very nice, and good work. I think you should try it! That being said, again I don't think one gets much better than a chinese or linear layout with no shenanigans going on with branches and reversals and notions of (Mark this is for you...) fluidic capacitors. (I know you're not pitching anything silly; just up on my box for a rare minute.) Just a straight shot in and out with as little obstruction or abstraction as possible.
There is one most important thing with a good pulsejet, and that is it gets the gas out as fast as possible, so the low pressure phase goes as low as it can, for the great benefit of what follows. That is why motors with features like Tesla valves will be doomed to "it runs, but..."

I love the idea of a liquid fuel contest of some sort. I've been very distracted and have both not contributed nor brought to an end the 1.5L contest. I hope someone will take the lead on this one and make it a real contest, though I know not what form it will take.

[Dang911]

Later, can we have a solid fuel category, say using charcoal

GE on and off since the mid 70's has been experimenting running a turbofan on clean coal technology, while successful at times it was very crude.

[larry cottrill]

Last Friday I had Matt Russell weld liquid fuel port "mounts" onto my stainless Lady Anne at two positions on the intake. These were small SS hex nuts, sized properly to hold the fuel metering jet from my old Dynajet (valved) engine. The welding went beautifully, but of course the threads needed to be "run out" with a small tap afterward to make sure they were completely clean and easy to thread into. This was difficult in stainless, required a good grade of cutting oil, etc. I was successful with the first one (deep in the intake), but on the second location (halfway down the intake), I stupidly broke the tap off in the hole! So, now, I have to somehow get that third of a tap out of there. Aaaargh ...

The deeper location is perfectly usable for experimentation. The Dynajet metering jet is very finely made, and should work. It is too short to make it into the middle of the air flow, but at least should get past whatever "boundary layer" there is in the intake pipe. Its location is just a few mm short of where the intake pipe "breaks" into the chamber port. Unfortunately, I have no idea when I'll get to try it.

L Cottrill

[Sebastian LFT]

Anyone ever try slapping on ye old skinner union carburetor on a valveless? Better yet how about a mikuni vm type carburetor for throttle experimentation?