Search found 613 matches

by pezman
Tue Jan 11, 2005 2:57 am
Forum: Valved pulsejet forum
Topic: A possible fractal in a pulse combustor ...
Replies: 22
Views: 6951

Re: A possible fractal in a pulse combustor ...

Holy Sierpinski, Web Pilot!
by pezman
Mon Jan 10, 2005 6:06 pm
Forum: Valveless pulsejet forum
Topic: Proposed experiments for FWE
Replies: 22
Views: 6436

Re: Proposed experiments for FWE

I think most arguments that rely on long-term standing wave acoustics rely on an assumption that the pulse-jet is self-sustaining. Although the extreme simplicity that arises from self-sustaining combustion is part of the pulse-jet charm, I think that a lot of biased thinking arises from the pursuit...
by pezman
Mon Jan 10, 2005 5:31 pm
Forum: Valved pulsejet forum
Topic: A possible fractal in a pulse combustor ...
Replies: 22
Views: 6951

Re: A possible fractal in a pulse combustor ...

A fractal is something that has a "fractional" Hausdorf dimension. Basically, Hausdorf dimension can be measured by covering the picture with evenly divided squares (or cubes, or hypercubes etc. depending on whether the plot was 2d, 3d, 4d etc.). The Hausdorf dimension is the log of the rate at whic...
by pezman
Fri Jan 07, 2005 10:40 pm
Forum: Valveless pulsejet forum
Topic: Increasing Flame Acceleration
Replies: 24
Views: 7809

Re: Increasing Flame Acceleration

I thought that I read that ddts can occur in pipes that are as small as 1/3 scale size in diameter, and that DDT run-up generally gets shorter as pipe diameter decreases (up to a limit -- maybe when diameter equals scale size?). I looked up the scale size for propane-air in the caltech database a wh...
by pezman
Fri Jan 07, 2005 9:27 pm
Forum: Valveless pulsejet forum
Topic: Increasing Flame Acceleration
Replies: 24
Views: 7809

Re: Increasing Flame Acceleration

Cool, a PDE guy! I haven't used Schelkin spirals or other obstruction stuff, but I have built some crude prototypes that used momentum changes to get high compression and turbulence -- basically a two-step combustion process. The resulting pulse is probably not a detonation, but it is very intense -...
by pezman
Thu Jan 06, 2005 3:17 pm
Forum: Valved pulsejet forum
Topic: Phase Portrait of Data Generated by P-C Valve Model
Replies: 18
Views: 6291

Re: Phase Portrait of Data Generated by P-C Valve Model

Wow, about the last place on the net that I expected to see a Poincare map!. This result suggests that you can easily synchronize pulse jets by coupling their pressure signals and/or control them using OGY-like controllers. How easy would it be to set up your simulation to couple two pulse jets -- p...
by pezman
Wed Jan 05, 2005 5:16 pm
Forum: Valveless pulsejet forum
Topic: FWE Theory - Focused Wave or NOT Focused Wave?
Replies: 92
Views: 36351

Not as if PSU PSUCKs!

I think that PSU's aero department is pretty well regarded (ranked 10th best undergrad school for aerospace engineering), so it should at least be a decent springboard for getting into grad school -- and folks seldom pay tuition while going to grad school. They take it out of your hide. If you want ...
by pezman
Mon Jan 03, 2005 11:29 pm
Forum: Valveless pulsejet forum
Topic: FWE Theory - Focused Wave or NOT Focused Wave?
Replies: 92
Views: 36351

Re: FWE Theory - Focused Wave or NOT Focused Wave?

Nice Schlieren image! Did a member of this forum take that picture?
by pezman
Wed Dec 29, 2004 8:16 pm
Forum: Tools and Construction
Topic: Site with some nice tips on construction
Replies: 5
Views: 3330

In engine spark strip suggestion

I think that mica might be durable enough to hold a spark strip. Cut, say, a 3" x 2" slot in the engine chamber. Get a 4" mica window and screw it to the interior of the combustion chamber so as to cover the hole. Put a bunch of small stainless bolts through the mica. Connect the hv to the screw far...
by pezman
Wed Dec 29, 2004 6:58 pm
Forum: Tools and Construction
Topic: Valve mterial?
Replies: 3
Views: 2438

Valve mterial?

I had an old tape measure fail recently and as it's guts spilled out, I realized that the spring inside is thin spring steel (of the blue variety). I think that you could fabricate some small v-valves or maybe a "U" valve (i.e. a 1" wide strip of steel covering two slots and held in place by a pin, ...
by pezman
Wed Dec 29, 2004 6:26 pm
Forum: Gas turbine forum
Topic: For the Birds
Replies: 1
Views: 2051

Re: For the Birds

And in a closely related story, RR sought the following patent:

http://patft.uspto.gov/netacgi/nph-Pars ... /6,733,379
by pezman
Wed Dec 29, 2004 3:50 am
Forum: Tools and Construction
Topic: Site with some nice tips on construction
Replies: 5
Views: 3330

Re: Site with some nice tips on construction

Well, my real name is Mike too, so here's the link: http://www.burntlatke.com/strip.html I think that this technique is totally the way to go -- rid yourself of those hideous welded on spark plugs. The trick is to find an insulator that can stand the shock and heat inside the engine and still hold t...
by pezman
Wed Dec 29, 2004 12:50 am
Forum: Valved pulsejet forum
Topic: Pulsejet construction
Replies: 33
Views: 15852

Re: Pulsejet construction

Yes, I have run it continuously for a pretty long while. The voltage when powered with 120vac is more than enough to get a spark plug to spark even with the gap torn off (i.e. the spark jumps the gap from the electrode to the rim -- 3/16" inch maybe?). I think that the transformer is 50:1 so it's pu...
by pezman
Tue Dec 28, 2004 5:20 pm
Forum: Tools and Construction
Topic: Site with some nice tips on construction
Replies: 5
Views: 3330

Site with some nice tips on construction

I found a site that is devoted to spud guns, but it has a lot of useful information that can be applied to pulse-jet construction. The guy is definitey no spud -- there are calculators for making combustion chambers, detailed fabrication tips and even he occasional poetic/pithy zinger (e.g., "a supe...
by pezman
Tue Dec 28, 2004 4:42 pm
Forum: Valved pulsejet forum
Topic: Pulsejet construction
Replies: 33
Views: 15852

Re: Pulsejet construction

I took the trnsformer out of my Walmart bug zapper ($15) and it works fine as an ignition coil. I can generate a nice spark with a 9v, 300ma transfomer and an even nicer one with a 30v transformer - so a 12 volt car battery or gel-cell should work fine in the field. Basically, I'm trying to build so...