Design a better augmenter.. No generic formulas needed.

Moderator: Mike Everman

Post Reply
Eric
Posts: 1859
Joined: Sat Oct 04, 2003 1:17 am
Antipspambot question: 0
Location: United States
Contact:

Design a better augmenter.. No generic formulas needed.

Post by Eric » Tue Mar 23, 2010 5:15 am

So I was taking a few shots of some pulsejet plume vorticies and got some interesting results.

One looks kind of like a goat sitting, licking its back.

The other one looks a lot like an angel with hands extended.

Ink blot shapes aside, they are a good visual representation of what happens behind an engine each cycle, and why augmenters work, and why they are shaped the way they are.

A little trick you can do to design a very well optimized augmenter is to fill the engine with a large charge of propane and air, and take a long exposure picture of the path the exhaust plume takes. You can see the vortex shape and path quite clearly, and its shape will literally help you define a perfect custom augmenter, no math, no generalized formulas. It will also give you a good idea of where the augmenter needs to go. Nice being able to see things that would otherwise be invisible eh?

The best way to do it is to do a number of shots, and super-impose them in a photo program, so you can average the results.
overlay.jpg
The front geometry and the expansion point are important, but the length of the expansion can vary depending on how big and heavy you want it to be. Even though the generalized augmenter formula dont perfectly apply to all engines, you can certainly see the correlation between plume, and augmenter design.

The two short fat plumes are from 8" long straight tubes, simple fireball launchers, the next from a chinese valveless.

Over fueling the duct does not really provide any more bang than the normal operational size charge, but it does fill the vorticies with burning gas for us to see.
Attachments
flow3.jpg
flow2.jpg
flow1.jpg
flow.jpg
Image

Talking like a pirate does not qualify as experience, this should be common sense, as pirates have little real life experience in anything other than smelling bad, and contracting venereal diseases

WebPilot
Posts: 3716
Joined: Tue Dec 07, 2004 6:51 pm
Antipspambot question: 0
Location: 41d 1' N 80d 22' W

Re: Design a better augmenter.. No generic formulas needed.

Post by WebPilot » Tue Mar 23, 2010 6:17 am

Those are really pretty 'filamentary' pics or 'spider webs', Eric.

I'll have to see if I can do that on Linux.
Last edited by WebPilot on Tue Mar 23, 2010 7:42 pm, edited 1 time in total.
Image

Viv
Posts: 2158
Joined: Sat Oct 04, 2003 2:35 pm
Antipspambot question: 125
Location: Normandy, France, Wales, Europe
Contact:

Re: Design a better augmenter.. No generic formulas needed.

Post by Viv » Tue Mar 23, 2010 4:06 pm

Hi Eric

Actually I saw Jane Mansfield in the second photo ;-)

Viv
"Sometimes the lies you tell are less frightening than the loneliness you might feel if you stopped telling them" Brock Clarke

Viv's blog

Monsieur le commentaire

Kool
Posts: 115
Joined: Wed Oct 01, 2008 7:39 pm
Antipspambot question: 125
Location: The Netherlands

Re: Design a better augmenter.. No generic formulas needed.

Post by Kool » Tue Mar 23, 2010 4:48 pm

Nice wallpapers :)

Ray Lockwood tried it in a water tank.
Than is the way how you did it way clearer :mrgreen:
Attachments
Hiller_Vortex.jpg
Ring vortex formation
...It's better to generate heat efficiently, than recover it efficiently...

Mike Everman
Posts: 4934
Joined: Fri Oct 31, 2003 7:25 am
Antipspambot question: 0
Location: santa barbara, CA
Contact:

Re: Design a better augmenter.. No generic formulas needed.

Post by Mike Everman » Tue Mar 23, 2010 5:01 pm

Neet!
In the second one, I see a badger making an unsuccessful grab at a piece of toast.

This is very nice work, thanks for sharing!
Mike
__________________________
Follow my technical science blog at: http://mikeeverman.com/
Get alerts for the above on twitter at: http://twitter.com/mikeeverman

WebPilot
Posts: 3716
Joined: Tue Dec 07, 2004 6:51 pm
Antipspambot question: 0
Location: 41d 1' N 80d 22' W

Re: Design a better augmenter.. No generic formulas needed.

Post by WebPilot » Wed Mar 24, 2010 4:08 am


 I now know how you did it. You had me "going there" for a bit.

Image (c.t.)
Image

Ghrey
Posts: 286
Joined: Fri Feb 15, 2008 8:41 am
Antipspambot question: 125
Location: Studio City, California
Contact:

Re: Design a better augmenter.. No generic formulas needed.

Post by Ghrey » Sun Mar 28, 2010 9:55 am

Wow that's really cool. Thank you for that.

Wonder if I can capture a pic. of flame behind the tiny little things I am currently fiddling with....
In the process of moving, from the glorified phone booth we had to the house we have.

No real time to work on jets, more space, no time.

Life still complicated.

Rocket Man
Posts: 144
Joined: Sat Sep 26, 2009 9:59 pm
Antipspambot question: 125

Re: Design a better augmenter.. No generic formulas needed.

Post by Rocket Man » Sun Mar 28, 2010 9:35 pm

Image

Post Reply