A pressurized environment for the PJ

[ace_fedde]

John,

Furthermore we should realize what we were actually doing by trying to make a PJ-prop. Actually we were trying to convert a (the PJ's) flow with a maximum exit speed of around 600 km/h into a much wider (the props) exit flow with again an exit speed of around 600 km/h. Looks impossible to me.

The fine pitch prop I was using would have created a large mass of relatively slow moving air ....................very efficient compared to an augmentor, the prop was an industrial fan designed for efficiency at modest rpm , same type as used on hovercraft . Most of the pics of my PJ experiment showed the prop adjusted to coarse pitch , this was intentional to prevent overspeeding of the turbine wheel until such times as early development work on getting the PJ gas producer sorted .
John

I’ll (gladly) take back those words then but the point was and stays that if one wants to achieve a goal by experimental means, one should first check if the goal is achievable at all, now it’s clear that you did.
The other way around, if one tries to achieve an experimental goal with existing means, one should check if the means can be truly means in that specific case. For example, if the experimental goal is driving on alternative fuel, the means cannot be water as a fuel (since water is already an end product of combustion)
Of course it all starts be more difficult and complicated if one wants to achieve an experimental goal by experimental means….

Fedde

[metiz]

For example, if the experimental goal is driving on alternative fuel, the means cannot be water as a fuel (since water is already an end product of combustion)

(...)

Your scepticism is fuel for my brain.

Fedde

Hmmmm

[ace_fedde]

Viv,

By the way John's engine I think was a valved engine so a little different to the others,

I noticed John used a valved PJ which is to my opinion a smart choice because a valver is not so sensitive as a valveless and produces more pressure.
If John used a valveless I might had to write:

Because, although John,
by closing the sliding sleeve changed the critical geometry of a PJ which should lead to performance loss of the PJ, and
by closing the sleeve he also made it impossible or fairly impossible for the PJ to displace fresh air by the tailpipe, which should also lead to performance loss of the PJ, and
by closing the sleeve, he caused the PJ to try to breathe through the turbine which should slow down (or reverse) the turbine,
the whole system immediately stopped working!! What more prove you will not get!

Meaning, we might not have had any useful test results at all, but now with the valver we have!

Fedde

[ace_fedde]

For example, if the experimental goal is driving on alternative fuel, the means cannot be water as a fuel (since water is already an end product of combustion)

(...)

Your scepticism is fuel for my brain.

Fedde

Hmmmm

Haha! prove me wrong

Fedde

[Viv]

Viv,

By the way John's engine I think was a valved engine so a little different to the others,

I noticed John used a valved PJ which is to my opinion a smart choice because a valver is not so sensitive as a valveless and produces more pressure.
If John used a valveless I might had to write:

Because, although John,
by closing the sliding sleeve changed the critical geometry of a PJ which should lead to performance loss of the PJ, and
by closing the sleeve he also made it impossible or fairly impossible for the PJ to displace fresh air by the tailpipe, which should also lead to performance loss of the PJ, and
by closing the sleeve, he caused the PJ to try to breathe through the turbine which should slow down (or reverse) the turbine,
the whole system immediately stopped working!! What more prove you will not get!

Meaning, we might not have had any useful test results at all, but now with the valver we have!

Fedde

Urghh No not at all



Viv

[ace_fedde]

I hate MS Paint Still I couldn't stop drawing with it.

Here is some more realistic idea for the cold and hot chambers:

Probably first you don't know what you are supposed to see .
You see a bend thermonese which blows it hot gasses through a augmentor over the CC. In this drawing the CC is placed directly in the augmentor. That's not meant to be and is there due to the drawing possibilities in MS Paint.
It should be after the augmentor so the augmentor blows the mixed and cooled down gasses over the CC to reheat them again.
The intake augmentors are of the Thunderchine style where the tailpipe also reheats the augmented gasses. Only in this case the augmentors reverse flow at the and of the tailpipe and are pointing back to the CC. At the and this flow merges with the flow of the tailpipe augmentor and can be fed to the turbine.

The blue cloud is the chamber that feeds both the inlets as the tailpipe with (completely) fresh, not warmed up by the PJ, compressed air.

Of course there will be accoustic issues and flow inefficiencies to be solved.
Another idea is a straight PJ with a flow reverser as augmentor at the end of the tailpipe, leading back to the CC. etc. etc.

Fedde

[GRIM]

Hi Fedde
I went down that road a bit , was fun but didnt seem to have the desired effect,

viewtopic.php?f=3&t=4906&start=0&st=0&sk=t&sd=a

From the moment that I started my very first pulsejet up I have had this dream of converting the radiated heat from the cc into useable thrust, I didnt realise my objective yet !!

However, another angle on this is efficient design , Look at the Thunderchine videos , it hardly gets hot , compared to some of my efforts that approach melting point , but produce little thrust,

Heres an example , the pipe just under the inlet augmentor actually started to collapse due to a lack of cooling

Fun stuff just the same

[Mike Everman]

That's some great pics. One day, the search function may allow "that pic of the curvy flamy huge augmentorish thing on a bench" ha ha

[ace_fedde]

Hi GRIM,

Thanks for joining!

I went down that road a bit , was fun but didnt seem to have the desired effect,

Tell me where that road is and I'll go all the way

viewtopic.php?f=3&t=4906&start=0&st=0&sk=t&sd=a

I read that thread many months ago and I thought: What the hell does he want to do? Appearantly I wasn't on that road yet! Now I am and I met you on the way

Heres an example , the pipe just under the inlet augmentor actually started to collapse due to a lack of cooling

I didn't hear (yet) Thunderchine doing that, did your Thunderchine already run longer periodes? Maybe it was caused by a ejector design error, leading to minor air transport through the ejector? (thus a lack of cooling)
How did the CC in the augmentor survive? Did it deform? Explode or implode?

Fun stuff just the same

Always!!

Fedde

[GRIM]

I didn't hear (yet) Thunderchine doing that, did your Thunderchine already run longer periodes? Maybe it was caused by a ejector design error, leading to minor air transport through the ejector? (thus a lack of cooling)
How did the CC in the augmentor survive? Did it deform? Explode or implode?

I was refering to the semi oval engine , and yes the ejector was poorly designed , the ejector in this case actually insulated the exhaust tube underneath it , Thunderchine WONT have this issue as the ejectors are very different , and will actually cool the exhaust , and more importantly "use" the heat to increase thrust ,

The cc inside the ejector ran quite cool and there was no implosion, explosion or other thermal issues , but the whole concept failed to produce a thrust increase in comparison to a unshrouded engine ,

[ace_fedde]

GRIM,

I didn't write it clearly but I know you were not refering to Thunderchine. I just wondered if something similar would happen to Thunderchine (although I don't expect it to happen due to the expected immense ejector flow).

All this info will be very useful to me, especially becuase in my project (if it's going to be build) the pressure and pressure differences will be much bigger than In a normal PJ, as might be the temperature
Probably will be just trial and error and trial and...succes?

Fedde

[vturbine]

You guys know you can't heat air or transparent gasses with radiant heat right?

If you want to heat the air passing over the CC, you better fin that CC to increase its contact area.

Stainless makes a lousy exchanger fin, too.

I doubt any good conductor would survive the heat, and welding it to the SS CC would be a feat.

I suppose you could build the shroud out of heavy aluminum, anodize it black to absorb the IR from the CC and fin that internally.

Lots of skin friction, though. That's what a heat exchanger is. Contact transfer. The more contact, the more heat exchanged.

[ace_fedde]

vturbine,

Haha, I just wanted to revive this thread with the following post but you were first.

I just found two crappy turbo's, crappy but compleet (one stucked). I knew I had them but I had to search them in the stacked freight "room" (don't know word for that) of my canal-freight-ship-house-boat (V., this must interest you, haha. I read your profil on Youtube).
Because the ship is now stored, and I'm not living on it now, I'm not there very often. That's why it took me so long.

These are the turbo's:
http://eng.turbo3k.com/catalogue/d-391/
http://eng.turbo3k.com/catalogue/d-1043/

Don't worry about what you see; fixing old and stuck stuff is my speciality and passion. But, I could use some advice though since I never rebuild a turbo: What else, except for the bearings, I have to check? Are there any topics in the Gas Turbine forum about restoring turbochargers? I didn't check yet .

And who (John? ) can tell me where I can find the compressor/turbine maps for these turbo's? I googled a lot but didn't find anything.

If you want to heat the air passing over the CC, you better fin that CC to increase its contact area.

Already planned that, not only for a better heat transfer but also for strenghtning the CC. The usual max. pressures in the CC will be multiplied by the delivered pressure (from the compressor) and the internal temperatures are expected to be higher. So I'm afraid the usual PJ design will not survive but melt and/or explode. If I fin the CC and connect it in that way to the shroud, the CC will be stronger and slightly cooled. So the fins also become ribs. Also the shroud will be pressurized, decreasing the CC stress from within.

Stainless makes a lousy exchanger fin, too.

That's fine for the CC´s material because I see the radiant heat as a loss, not as a product. Stainles hopefully keeps more heat in the exhaust gasses, causing more expansion/flow. The fins however should not be made of stainless, preferable copper.

I suppose you could build the shroud out of heavy aluminum, anodize it black to absorb the IR from the CC and fin that internally.

And of course with isolation material on the outside to avoid new heat losses. Nice idea , didn't think of that yet.

Lots of skin friction, though. That's what a heat exchanger is. Contact transfer. The more contact, the more heat exchanged.

Have to find a balance there between cooling the CC just enough and not restricting the flow to much.


But first I want to keep it simple. Just drive a turbocharger with a PJ, and the PJ with the turbocharger. No heat exchanging and high efficiency goals, nor high pressures. Just make it work will be difficult enough because of expected accoustic distortions that have to be avoided somehow.

Fedde

[vturbine]

vturbine,

I just found two crappy turbo's, crappy but compleet (one stucked). I knew I had them but I had to search them in the stacked freight "room" (don't know word for that) of my canal-freight-ship-house-boat (V., this must interest you, haha. I read your profil on Youtube).

But first I want to keep it simple. Just drive a turbocharger with a PJ, and the PJ with the turbocharger. No heat exchanging and high efficiency goals, nor high pressures. Just make it work will be difficult enough because of expected accoustic distortions that have to be avoided somehow.

Fedde

Yeah, I built a houseboat in Vermont and took it down the coast and across Florida and Lake Okeechobie and up to Sarasota. Boats wreck your tools and good stuff!

I would think someone had already done a simple pulsejet to turbocharger hybrid already. It seems a natural combination. Not sure about going the other way. Why would it need to be a pulsejet if you have a compressor?

[Viv]

Hi Fedde

Yes your little thread was on my list of things to give a kick to but i have been caught up in launching a new company so to busy to post, those turbos look nasty by the way

Hi V yes some people did try a pulse engine / turbo combination, one guy is John who does know what he is talking about and the other guy was a make believe turbine expert who just made a load of fantastic claims, Johns account is the one to read for some credible results and conclusions.

Viv