Odd Metal jars

[PyroJoe]

I'm not a photographer, both subjects are tilted. Must be the Methanol.

[PyroJoe]

Morning run of the 6" jar, temperature near 37 degrees F. Methanol fuel was boiling with vigor at end of run.
http://www.youtube.com/watch?v=qCQTdFHJKio

[Mark]

How much volume is the tank on the left and what diameter is the snorkel? I wonder how much a tapered tank differs from a cylindrical tank in snorkel-tank ratios. Seems as there is a taper, the strongest snorkel would probably be shorter than a similar length tank in a cylindrical design. The tapered tank sort of stages the reduction in volume, more of a gradual nozzle. I remember in one valveless article, an intake had good breathing and the other good mixing. Perhaps there is where the balancing act begins.

[PyroJoe]

Approx. 1451 cubic inches./ 23777cc
Snorkel is 1.5" pipe nipple.

I suspect the taper jars have a higher fill volume from the intake charge.

On cylinder types I typically see near 35-50% fill/combustion volume. On the tapered ones I suspect they fill somewhere between 50-65%
Also with less overhead volume, the frequency will shift higher.

You may recognize it from a previous attempt, I tried fueling with propane, top, bottom, intake and side. With internal ring and without.
Attempted gasoline, good fun in general but no breakthroughs or sustaining, the intake cycle never appeared adequate in depth or volume.
Once the tapers/volume are taken into account, it is near a 10" diameter jar.

Containment is high, and I wouldn't recommend it to anyone build this high on containment. If there is some hiccup in the cycle it could build pressure at an unacceptable rate.

I noticed in the cold runs with the 6" jar the initial whoosh occured very quick at times, almost a blast. I figure I will setup a camera behind Plexiglass, set the timer for the ignition and observe the damage from afar.

[Mark]

That ought to be fun to fire up. What shape is that from with the round bottom? If you are going to be doing the big stuff with methanol, it's much cheaper to buy it in gallons from a speed shop or other place that might have it. I bought 5 gallons my last trip and 7 the time before. And I almost bought a 55 gallon steel drum one time, when I had my Dodge Ram, but decided I couldn't use that much and it would be hard unloading it. You want to be extra careful with large metal containers and methanol though. A static spark could do you in. I have a pointy 5 gallon jug like they use in the speed shops.

[PyroJoe]

The bottom is from a propane tank. It previously had a better shape, but had to slice several inches to reduce the height.

Eventually would like to use methanol to start the cycle then transition to propane. Hopefully with the increase in size, it should be less sensitive to the transition.

Looking at using some type of surge suppression in the propane fuel line to dampen the pulses from the jar, and the initial surges when the main tank valve is opened. Maybe commit treason and use a regulator, ha

I think it will start ok as long as the ignition occurs at the top of the jar and the flame front moves downward in normal fashion.

A considerable hazard is if a spark enters and travels nearly to the bottom and then ignites. The flame front would move from bottom to top, encountering ever smaller dimensions.

[Mark]

I remember a guy from Marquardt drawing me what he said was the best mixing shape they found. It was a snorkel flush with a flat surface which induced swirls at the break. Yes it was a simple sketch, but I was wondering with a narrow neck if the entrained mass mixing would be less than that of a somewhat wider area for the inflow to affect. I wonder if Reynst's insert inside his combustors holds together the inflow and starts the break farther down in the tank?
Perhaps one contribution of having two snorkels as with the Chinese pulsejet is that it would provide better mixing. Mixing is certain a large part of the game whatever the physics. I wonder just how lively you could get a snorkeler if the mixing were no too lean and not too rich and there was no feedback dampening from fuel slosh? Fuel slosh may provide sudden cooling though which may be beneficial. Maybe it even cools the snorkel. It's too complex for me to know for certain without doing lots of experiments.
Again, I think it is partly a compromise between good mixing and good breathing or fitting the effect to the parameters of your engine design.
http://en.wikipedia.org/wiki/Marquardt_Corporation

[PyroJoe]

I thought this one by GRIM has superb ability to mix:

http://www.youtube.com/user/zodiac0545# ... zrKEmasVjk

Sounds like a angry bee!

[PyroJoe]

Although, each time the intake is split the boundry layer/circumference is increased. Three looks to be a good number, although the total circumference is nearly double of a single intake.

This may be offset if the area is increased, not necessarily a bad thing as more intake area can shift the frequency higher.

Have been considering this for the Kraken. Maybe aim three intakes into a single augmentor for each CC. Imagine how the three intakes would help mix ambient air into a augmentor.

[Mike Everman]

I usually consider the boundary layer in the intake to be .5mm thick, so I consider the area of the single minus 1mm, and the multi's with that subtracted from each as well. Only a little more complicated, but really, that assumes that the original single was dead on what it should be. <insert wild hand waving here, because throughout the cycle the boundary layer fluctuates wildly. As I recall, I'd calc'd the high at 1mm thick for about half the time...> ha

[PyroJoe]

There may be some additional benefit in flow coefficient for the smaller size also. Basically creating more sharp edge to flow around. As the total circumference increases, so does the exposed sharp edge.

[Mike Everman]

makes me think of all that discussion about Borda mouths. I've liked the sharp transition for the fact that it's going to have more impedence on the outflow and less for the inflow if the exit is a bit rounded, but I have little to hang my hat on vis whether it's better either way. in or out to be easier for the gas to go, who can say? At times I've advocated "make it go out as quickly as possible" so the partial vacuum goes lower, but is that better? IDK

[PyroJoe]

This weekend may be dodging rain for testing the large snorkler, have a shorty 1/4 length snorkel installed for the initial test. Will increase the snorkel length per each successful run. I remember back to the time, thinking the 6" jar was a risky venture.

May try the three intake system on a 4.5"CC engine before going bigger. Hedging the pressure/flow to the tail has worked well for me.

[PyroJoe]

Was warm(78F) and muggy(52%hum), Big jar ran about 44 seconds. Used a snorkel about half length of the original. No remote ignition, just made due with a long propane torch.
http://www.youtube.com/watch?v=EwNqvfbPNjs

[Mark]

How much methanol did you put in the tank? My snorkelers will rev up pretty good with just a little methanol a cup or so, but they like to have the bottom completely covered when sustaining over time. It gives them more fueling surface area.