If you think you have seen them all...

[Bruno Ogorelec]

... take a look at this one.

I don't have the measurements, but it's about man's height. Works very nicely, too. Well proven and tested by a respectable scientific, engineering and industrial team. Best of all, you can buy it.

[Bruno Ogorelec]

Here's a straight-piper version.

[Bruno Ogorelec]

Here's how it looks at full tilt. Note the neat 'thrust augmenter' grasped by the 'tentacles'.

[Mike Everman]

what the heck? where did you find that one? what are the stats?

[Bob]

interesting design !
I wonder if its as noisy as it LOOKS to be ? hehehehe
looks like its about to melt down too !
....
can't help but wonder why a thrust augmenter on the intake when its the least powerfull thrust of all of the outlets.... probly because it was convienient ! heheheh
any figures on the thrust Bruno ?
thanks for the pics
Bob......

[Eric]

Well judging from the flame ejection I would guess that there might be a decent quantity of heat to cause expansion, there do appear to be some small augmenters on the exhaust too. Is this a propulsion engine or some elaborate heater designed to maximize exhaust pipe surface area to volume?

Eric

[Bruno Ogorelec]

Before we proceed to explanations, here's a video of a model with even more 'tentacles' making noise and flames. You acoustic types can probably deduce certain things from the analysis of the sound the thing is making. Now that I have seen this, the role of the 'augmenter' is even less clear than it used to be. You may have noticed I've been using quotes with 'augmenter'.

[Mike Everman]

wow, that first augmentor looks like an afterburner.

[hinote]

Well judging from the flame ejection I would guess that there might be a decent quantity of heat to cause expansion, there do appear to be some small augmenters on the exhaust too. Is this a propulsion engine or some elaborate heater designed to maximize exhaust pipe surface area to volume?

Eric

Whether or not the "add-ons" are augmenters or a part of the exhaust--the "real-world" reason appears to be that the central augmenter is a tight fit to the constant-diameter exhaust tubes; this would mean that it couldn't be slid into position if tail megs were employed.

[Bruno Ogorelec]

wow, that first augmentor looks like an afterburner.

That's exactly what I thought when I saw it. An afterburner that's not designed to produce more thrust, but probably more heat.

[Bruno Ogorelec]

OK, here comes the explanation. As ever, Eric was quick to spot things.

Those things are produced by an outfit called EM Group, based in Maastricht in the Netherlands. It seems to be a group of boffins from the University of Eindhoven who put together a cooperative designed to turn their ideas into commercial projects.

I have not been able to find out very much, and some of the above is conjecture.

They are either licensing their technology to industrial outfits or have industrial outfits of their own. In any case, they will sell you standard combustors or tailor-make one for your purpose. The main purpose seems to be industrial drying.

The combustors work on propane, but at least one burns powdered coal. The video of the powdered coal thingy is especially interesting. It's big and I have not uploaded it, but you can find it here: http://www.emgroup.nl

How do I know all this?

Some time ago, the company, EM Group, sent me a leaflet on their pulse combustor. It was accompanied by some data.

What they say is that it is a 2-step pulse combustor. The really high temperatures are achieved in the second stage -- the one that looks to our eyes like a thrust augmenter. It is at this second stage that fuels other than propane can be used.

The frequency is said to be adjustable from 40 to over 185 Hz. Eric, what you thought were augmenters on the tailpipes are probably tuning extension sliders.

The company claims to have “compiled the know-how (…) to calculate, design and operate pulse combustor-based processesâ€

[Hank]

Check out the heat/cool patterns near the open (far) ends of the "Tentacles". Their consistency in both size and placement shows the stability of the turbulence in this portion of the duct.
It appears the fellow in the video is tossing something into the intake that makes the operation way more excited.....Magnesium Powder, perhaps?

[Mike Everman]

most likely coal dust, though it could be cup-o-noodles for all I know.

[leo]

And one other Dutch company making pulse combustors.

http://www.dlfsustainable.nl/

[Bruno Ogorelec]

most likely coal dust, though it could be cup-o-noodles for all I know.

Yes; it would probably burn the same way, ha-ha-ha...

Here's a picture of a layout I toyed with late in 2003. I designated it SP-18. No one I showed it to liked it very much. Ah, well...

(To be frank, the only serious reason to use this layout had nothing to do with its inherent properties as an engine -- I just thought it would be neat to use tailpipes as structural members. Which may not be a very sound idea, given that it's exposed to so much heat.)