75mm Locky Kazoo (say that 10 times fast)

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resosys
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Post by resosys » Sat Jan 10, 2004 6:45 am

Mike Everman wrote:IT PULSATES!!!!!

A pool of Methyl Alcohol in the combustion chamber, and a hair drier in my garage, good times! Of course, I have no hair on the back of my hand anymore...

Graham, I'll attempt a recording, but for now, it sounds like: "whoosh! loodle loodle loodle" ;-P
Nice work.

Mike, this hair burning thing is becoming a habit! Keep it up!

Chris

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Post by Bruno Ogorelec » Sat Jan 10, 2004 6:30 pm

Mike Everman wrote:Graham, I'll attempt a recording, but for now, it sounds like: "whoosh! loodle loodle loodle"
My careful acoustic analysis shows "whoosh! loodle loodle loodle" to be roughly equivalent to the frequency of 25 af/m (average farts per minute).

Not bad for a first try.

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Post by Bruno Ogorelec » Sat Jan 10, 2004 6:34 pm

Mike,

Work out a method to make the transitions neater and you are onto a very good thing indeed. Damn, I envy you. Very good work.

Bruno

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Post by Viv » Sat Jan 10, 2004 10:05 pm

brunoogorelec wrote:
Mike Everman wrote:Graham, I'll attempt a recording, but for now, it sounds like: "whoosh! loodle loodle loodle"
My careful acoustic analysis shows "whoosh! loodle loodle loodle" to be roughly equivalent to the frequency of 25 af/m (average farts per minute).

Not bad for a first try.
A slightly more scientific analysis of "woosh woosh lardle lardle" resulted in the attached spectrum.

It should be noted however this is with a British accent and it is as yet unclear how this will relate to an American designed engine.

Viv
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Monsieur le commentaire

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Post by Tom » Sun Jan 11, 2004 12:03 am

to state the obvious, Viv got bored.

:o)

Tom

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Experience speaks more then hypothesizing ever can. More-so in chemistry.

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Post by Mike Everman » Sun Jan 11, 2004 3:43 am

Viv-
It's more loodle than lardle, so you'll have to lose that bump at 300 Hz!
Mike
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Progress

Post by Mike Everman » Sun Jan 11, 2004 7:25 am

Today I made a 6mm copper stinger with several 1mm holes in it per Graham's suggestion, and ran it down the intake, feeding propane in various places and lighting from the outside. Lots of whooshes and a fairly quiet resonating sound, but so far just burns fuel I think.

Monday I'll be able to try with sparkplug and compressed air for starting, but today it's a hair dryer.
It seemed fuel starved so I drilled out the restrictor on the coleman stove valve I had, but this made the adjustability too coarse. I need to put a needle valve on there, and I also fear a few other variables:

That the stinger is too large in diameter and throws off the intake area. I'll get something much thinner. I agree with Graham that I need to find out where to put the fuel inlet before I drill a lot of holes. I do want to mount the fuel inlet so I can aim it various directions in the chamber.

While I've hand flared the intake, I still have not trimmed it especially straight yet.

I've left some of the squeezed areas fat, because it's easier to squeeze more, so perhaps it breathes too well at the moment, but other things need to be right first.

My spreadsheet calculator for determining the squeeze does not model the actual resulting shape well, making for improper areas on the outset, but the geometry is so different anyway, I figured it was a 50-50 thing whether it would hurt in the end.

I'll post some pictures and video tomorrow.
Mike
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LK gets a butt lift.

Post by Mike Everman » Sat Jan 31, 2004 9:26 am

Made an extension for Locky Kazoo from three wraps of aluminum flashing and band clamps. It's a wierd shape to get a good adjustable tail, but this seals pretty well.
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Post by Graham C. Williams » Sat Jan 31, 2004 1:32 pm

and a fairly quiet resonating sound
Dear mike.
Ok this sounds as if you may be going in the right direction. Was this with the tailpipe extension on?
Where was the stinger when you got this quiet resonating? (Diagram please)
We have certainly had motors running in Lockwood mode with quite a small dia. stinger - not at full power but well enough to demonstrate the correct fuel location.
The first things that come to mind now are, in no particular order:
Turbulence and mixing - small motors the time allowed for this is very short as the overall cycle time is short. The critical area is where the induction pipe and the front cone into the combustion chamber meet.
Fuel pressure and flow rate - on small motors it can be a little difficult to get starting values correct.
Cold motor - One small Lockwood would only start when good and warm
Induction pipe lip - The roll on the entrance to the induction pipe is very important. It can make the difference between it running and not.

Personally I'd start with the Induction pipe. Find someone with a Jenny (I think it's called) who can put a good roll on the induction lip, about 4-5mm radius. Then re run your tests.

Would you please detail for us your fuel delivery system up to the stinger? I have this idea that you are using a camping type stove.

I'm sure I've forgotten something - the good folks of this forum will correct me as they see fit. Remember make only one change at a time and keep notes.
Best Regards
Graham.

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Post by Mike Everman » Sat Jan 31, 2004 5:00 pm

Graham, here's some photos.
I haven't tried with the extension yet.
The fuel feed is as shown, no other valves. I'm wanting to at last drill a hole in the side and point the pipe in, getting rid of the stinger.
The quiet resonation is like jam jar style, much too low frequency.
I tried several locations within the intake transition, but I'll be trying again with the extension today.
Induction lip is crude, but if I trim it and start over it's length will be too short... I need to grind it more straight.
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Post by Graham C. Williams » Mon Feb 02, 2004 12:48 am

Dear Mike.
Many Thanks for the pic's.
First thoughts.
1) Keep with the stinger for a while - remember one variable at a time.
2) I strongly feel that you must do something about that intake. It's too much of a discontinuity for the incoming air.
3) Have you checked that the sparkplug hole has no leaks?

A lip for the induction pipe - some thoughts.
The lip need only stay in place for 5 - 10 seconds to show that that's what’s needed. Perhaps some modelling clay or ‘bath sealing’ Silicone will do the job. The point is to get a good smooth entry for the air. A bead of about the correct dia. laid top and bottom and smoothed into the metal.
Anyone else go some good ideas?

Checking back through this thread you said that you had resonance with a pool of Meths in the combustion chamber. Was this before or after you removed the original induction mouth?

Another thing that's playing on my mind - Boundry layer/Friction effects of a squashed pipe.
On the one hand I'm reasonably certain that, under most conditions, nonsteady flow blows away the boundary layer, but does this apply during the start-up period, when the pressures and flow rates are low? I'm not sure. Perhaps some of you aerodynamics people know the answer?
For the moment lets assume that during start-up, the normal boundary layer that applies to a circular pipe of 75mm dia. is maintained when that pipe is squashed to whatever is needed for your induction pipe, what would be the results?
The combustion confinement will be very good, but on the other hand it'll take a while for fresh air to get back in (turbulent boundary layer/frictional effects.) Something like a 6mm gap between two plates acting (from the point of view of the airflow) as if it were a 1mm gap.
Following this line of thinking it may be that the induction pipe is not only acting as if it were much longer than it is but also more squashed than it is. In this case the answer is to open it up a bit - increase the gap between plates.
If it's the case that resonance was better with meths as the fuel then the above may be the case.
But like I say, I don't know.
How is it going with the long tailpipe?

Best Regards
Graham.

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Post by Mike Everman » Mon Feb 02, 2004 8:35 am

Graham,
I didn't get to try the engine today, perhaps at lunch tomorrow I'll bip on home and try it. I'll keep the stinger for now, as I have no good method of sealing a port. I'll be starting my welding practice this week also.

The picture does not show it well, but there is a rolled lip at the intake, though I'm sure it could stand more; I'll post a better image. I've left the squashes a bit fat, but I think maybe not fat enough. I like the idea of correcting the area considering the reduction in that area due to boundary layer thickness; hmmmmm; faaaaascinating. how thick is the boundary layer, do you think?

I also wanted to have a bit of a correction (I believe in the same direction, ie: greater area) for the scale down from a known 150mm diameter CC. I think the change in Reynolds number as size is reduced should point the way, I need to crack the books again!
Mike
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Post by Mike Everman » Mon Feb 02, 2004 8:58 am

Here's the intake flare. Perhaps I should next time mimic those big flares, more like a diffuser, as on Chris's intakes?
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Constant Perimeter and Boundary layer

Post by Graham C. Williams » Thu Feb 05, 2004 1:52 am

Dear Mike.
I've been having fun deriving your constant perimeter squashed pipe figures then making all sorts of assumptions and guesses about boundary layer, adhesion and viscosity things.
It was Nick who put me onto this. He's built himself a Tesla Turbine.
I have a spreadsheet in the making and will post it to you at significant stages. But promise not to laugh too much at all the assumptions/guesses I've had to make.
The executive summery-
I think you need to increase the induction pipe gap and the exhaust pipe gap. But first the induction gap. (The lip is still very important.)
- Then try running the motor on meths.

Best regards
Graham

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Post by Mike Everman » Thu Feb 05, 2004 8:04 am

It is fun. Came to the same conclusion ("open it up"), and I was planning to plot the reduction in area due to a range of constant boundary layer thickness (arbitrary) and see the sensitivity. Smashed sections will be highly sensitive, whatever it is. The pure geometric conversion calls for very narrow slits, values that I'd expect to be in the range of a single boundary layer. Boundary layer "thickness" being what it isn't, I'd more precisely define it as "the quest for the squashed dimension with identical flow rate to it's former diameter".

I have to make a wedge or something to open it up. I can't find any more of this tubing! Think I'll do a 6" dia next.

I quasi-patiently await your spreadsheet and assumptions. I'll keep reading up on compressible flow. Times are interesting, I don't get to push as much fuel around as I like, but there's always time for a jam jar!
Mike
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