A pressurized environment for the PJ

[ace_fedde]

In the “turbines driven by pulse jets” topic:
viewtopic.php?f=18&t=5269
I started to wonder what would need to happen to a pulse jet’s geometry to have it working in a pressurized environment. That’s not pressurized feed of the intakes but a (much) higher ambient pressure for the PJ, like a PJ working in a huge pressurized air tank.
In above mentioned topic I wrote:

Viv, and everybody else,

In the meanwhile I can’t get my thought’s off the pressurized environment for a PJ.
I might even have a purpose for it or a way to use it.

But my knowledge of pulse jets (specially in numbers) is to little to predict what’s needed to have a PJ working in a pressurized environment.

So I’ll open a thread in the valveless forum to ask for help, please join!

Fedde

To understand how I got there please start here in that topic:

viewtopic.php?f=18&p=63381#p63116

So my questions are:
Let’s say the environment is 4 atm (3 bar overpressure).
What would happen to the acoustics
What would happen to the (your) pulse jet’s geometry
If the geometry has to change, are there simple rules to calculate the changes

This is not a test, I really don’t know, please help!

Fedde

[Viv]

Hi Ace

Ok this looks interesting for a good discussion, for starters, can I point you towards Grahams Nudis application, you may be able to directly model what you want to do in that and compare the results for the same geometry between different ambient pressures.

Graham is the expert on his Nudis software though so I leave the field open for him

Viv

[ace_fedde]

Viv, Graham,

I tried Nudis to get working but it won't .
Same problem as Leo

Fedde

[metiz]

If you'd have a pulse-jet in a pressurised enviroment (up to, but not at detonation pressure) wouldn't all the different changes balance each other out, in effect changing nothing? With a higher ambient pressure, the fuel-air mixture will be compressed more so the deflagration process will be more intense. Would the outside pressure not slow the gasses down to about the same speed at normal atmospheric pressure (enough with that word!)

So much for gas. The acoustic waves would probable go a bit faster due to the denser air and higer temps though. Maybe the tailpipe could be a bit shorter? I guess that you could use the same calculations normally used to calculate the acoustic lengths of an engine in this atmosphere as long as you adjust for the increased pressure and temperature?

I'm going to stop here before I embarres myself even more.
If anyone wants their penny back, let me know

[metiz]

Viv, Graham,

I tried Nudis to get working but it won't .
Same problem as Leo

Fedde

Couldn't get it to do what you want it to (understandable) or can't get it to work period? Make sure the Nudis folder is in the root of your C:/ drive.

[ace_fedde]

Moved to:viewtopic.php?f=7&t=3588&p=63407#p63407
Fedde

[metiz]

Hmm I have a Dutch version of excel and at least I can get it to run
ok make sure you have the following files in your C:/nudis folder (probably does not matter but make sure "nudis" is in lower case)

folder "QSAVE"
.dat file "area"
.dat file "Geom"
.dat file "Inputs"
.exe file "NUDIS"
.xls file "NUDiS Analysis BooK R0xx"
.xls file "NUDiS C.dat Viewer BooK 0x"
.xls file "NUDiS Construction BooK R0xx"

To be on the save side, make sure all the file names are in the specified cases

make sure in excel you've got macro's enabled. Go to: extra>>macro>>beveiliging and at the tab "beveiligingsniveau" put it on "laag"
now go to "vertrouwde uitgevers" and make sure you check both tabs.

[ace_fedde]

It still doesn't work.
Let's move this part of the conversation to the NUDiS thread in Tools and Construction.
viewtopic.php?f=7&t=3588&p=63407#p63407

Fedde

[Viv]

So! struggling to stay on topic even though its my own fault for suggesting what turned in to the distraction

The answer to Metiz would be yes! I suppose every thing does get faster and hotter with all that it implies to the engines geometry

Viv

[ace_fedde]

So! struggling to stay on topic even though its my own fault for suggesting what turned in to the distraction

The answer to Metiz would be yes! I suppose every thing does get faster and hotter with all that it implies to the engines geometry
Viv

Now I hope there's somebody out there who can (and is willing to) make a design for a 4 atm. adaption, for any layout, while I'm strugling to get NUDiS to work
Just for fun, to have an example.

Then I will disclose( ) what I think is possible to do with it.
And no, that's not racing around an a pressurized tank

Fedde
(I'm using to many smileys, ain't I? )

[metiz]

Fedde
(I'm using to many smileys, ain't I? )

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Man I realy need a job - that took me like 2 hours

[ace_fedde]

And I was thinking, man, Metiz is online all the time. What's he doing? (no smiley)

[metiz]

And now you know! hehe

[ace_fedde]

What about the following idea? To be honest I really haven’t got a clue…

For 4 atm. First scale your PJ up, with the normal scaling values, for having it handling 4 times the airmass compared to the original.
Then “zoom” it back to the original length (with equal scaling values) for the 4 atm environment. The motor should look slimmer now.

Makes any sense? Or not at all?

Man I realy need a job

Metiz, since it appears that you have nothing to do and I still haven’t NUDiS running….
Get to work!! (with my thermonese please, dat rijmt!)

Fedde

[ace_fedde]

While I’m hoping that somebody is going to show me how to adapt a PJ to 4 atm, I’ll make a little side jump (or jump forward) from:
How to: 4 atm PJ, to:
How to: 4 atm environment for the PJ.

Simply putting the PJ in a pressurized tank doesn’t work.
It will pollute it’s own fresh air till there’s no more oxygen.
Also it hasn’t much use or fun that way. You’ll just hear the PJ banging around in the tank till it dies and that’s it.
If the tank is much bigger, more like a pressurized building with pressurized ventilation, it will work but….
I don’t have a 4 atm pressurized building and I don’t have a hardsuit and diving helmet so I can’t withstand the pressure in that building.

So could we take two pressurized tanks, one enclosing the inlet side and the other enclosing the tailpipe side?
Nop, the inlet also spews out exhaust gasses and the tailpipe also needs fresh air…

So now what
I think I already have an idea…

Now first come on with those 4 atm. PJ designs!!

Fedde