WITH OR WIHOUT VALVES, WHAT IS MORE EFFICIENT

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Jim Berquist
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power from a P.J.

Post by Jim Berquist » Tue May 08, 2007 8:31 pm

Here you go. Eric's Ram Jet powered by a p.j.

Jim

http://www.youtube.com/watch?v=b0KJwa5iWTY
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celsius235
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Post by celsius235 » Wed May 09, 2007 1:54 am

I think that increase the pressure chamber is one way to optimize the SFC, but is very difficult to find any literature about the exhaust diameter pipe and the effects to reduce the diameter, you can see many times pulsejets that have problems to start but I only have seem one that explode by a detonation.


I appreciate in all cases your comments, always I assume that is to learn or understand better the pulsejet engines

Celsius

Eric
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Post by Eric » Wed May 09, 2007 3:02 am

What one did you see explode?

Eric
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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

Jim Berquist
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explode

Post by Jim Berquist » Wed May 09, 2007 2:26 pm

Exploding Pulse Jets are as rare as hen teeth.

I have heard of toasted fingers, noses, eyebrows, beards and the occational loss of a uncles shed.

Rolling balls of flames, grass fires, and even 20ft vapor ignitions. Fuel lines coming off a running P.J. causing a wipping snake of fire. One person even made a P.J. of ceramic that failed while running and it only split down the side.

No Gernading Pulse Jets!

Jim
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Rossco
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HYBID!

Post by Rossco » Wed May 09, 2007 10:32 pm

Hey C,

Youve got a little way to go! but dont let our comments here come as criticism.
Learn, review, amend, but most emportantly appreciate what is being thrown at you here.

Constant specific impulse solely can be compleatly disregarded (as a calculative tool) You need to get much more info on operation before you can start tossing wild formulas at these things.

Ah, im not going to lecture, I dont think i qualify to state much on the mathimatical side anyway!
Go get Graham's NudIs program/spreadsheet/calculator from this site.
Its a sticky in tools and construction.
Work out your equations to compare with the data retrieved from there, and then go for mathimatical improvements.

Pressure! yes, go for it!!!!!
Running a PJ with internal pressures of 50psi would sure be interesting...
There is reasons that they really have to work at these low pressures, big reasons to get around.
They are achieving comparible efficiency though, and you have to think of how!
As you have stated, the pressure gain is a, or THE key factor to constant burn engines. You try to figure a pj with a TSFC of 1.0 compared to a rocket, or jet running at the same pressure. Hey, even use the peak pressure of maybe 1.2 atm... This does not work does it?!!!

Now, to gain pressure in a pj takes energy, and a lot of it!
Your going to be supercharging it... now look at a supercharger.
2000 hp top fueler engine... supercharger that takes 3000 Hp to operate!
to make 6000 Hp !??? (go look the figures up, these are of the top of my head, and probably wrong)
Now... the added complexity in a pj (always bad for such a simple engine) and the power to run it... all its got? What then is the outcome? hopefully more than the "supercharger" is originaly taking from the engine!

I am still working with shocks in a pj... not easy, and not cheap in terms of power. To this date, i have not recovered the energy that i am expending... Im at another dead end road at the moment, something will come allong, i just play with other ideas till it does.

Most people talk of an exploding PJ when actualy refering to a tail implosion. (another lockwood issue)... (SFC of 1.0 out of a Locky... HHHHAAAAAhahahahahaha)
Very different case.
But hey! if you start running a yellow hot wafer thin engine with 50psi internals!!!! we'll be watching for you to be a the one to do it!.
I dream of my engines being able to blow!

I suggest to read some more.
Start coming up with a way to bump that pressure up, we will be happy to critisise... i mean help.
(and no, a smaller tail alone wont do it, you increase losses, and more)
Always happy to be proven wrong if something good comes of it!

Rossco
Big, fast, broke, fix it, bigger, better, faster...
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Eric
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Post by Eric » Wed May 09, 2007 11:27 pm

.... And the infamous Simpson tack welded tail pipe breaking open, and him making a big deal about it.
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

Irvine.J
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Exploding pj's???

Post by Irvine.J » Wed May 09, 2007 11:42 pm

Clatu Verata Nectu!!!!!!
Talking about exploding pj's made me think of that strange mystical simpson event.
Lol i must be bored.

One of my favourite semi-relavent lines....
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celsius235
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Post by celsius235 » Thu May 10, 2007 5:29 pm

Well, the weekend is very near, enjoy together.

About boomstick I prefer the Vulcan GAU-8/A 30 mm that you can see:

http://www.sirviper.com/fighters/a-10/6.jpg

This cannon can fire 4200 rounds per minute / 60 = 70 rounds per second

1 round = 0.2 kg of propellant

70r x 0.2kg = 14 kg propellant / second

ISP = 230s

14Kg x 230 = 3220 kg of thrust

Simpson Gun

10 rounds per minute / 60 = 0.16 r/s

1 round = 0.015 kg x 0.16r = 0.0024 kg / s

ISP = 200

Thrust = 200 x 0.0024 = 4.8 kg.

Same of studies of PULSE DETONATOR ENGINE have been inspired in rotary detonator chamber as Vulcan, when the revolving cylinder charge air/fuel, rotate to the ignite position.

This is a joke to understand that is possible to mix air fuel at high pressure when the SFC is very low, of course the petals chamber this is not the way but is a good beginning to start. In the other hand the pulses in the case that pulsejet are self ignited but maybe other way will be to try with spark by pulse to obtain the best charge of air / fuel.

This is not a pulse jet but is funny way to obtain cheap energy

http://www.metacafe.com/watch/446758/tu ... to_energy/

Celsius

Jim Berquist
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Post by Jim Berquist » Thu May 10, 2007 6:16 pm

Actually it's your basic fuel cell! It's the same way a breathalizer works. Yuck! Wrong end!

Lucky he didn't blow his fingers off and eat the nails!

How can you tell the differance of a Oral and a Anal termometer?

One don't tast so good.

Jim

Eddited : word thermometer
Last edited by Jim Berquist on Thu May 10, 2007 11:34 pm, edited 1 time in total.
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celsius235
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Post by celsius235 » Thu May 10, 2007 8:27 pm

Same time is a little difficult to me understand the mind of all that you write, and I am sure that I can not explain correctly too but in all cases I will try to be as the same level.

berquistj@peoplepc.com Actually it's your basic fuel cell! No, it isn’t

Methane has good properties as fuel and NASA has experimented with this fuel

http://science.nasa.gov/headlines/y2007 ... eblast.htm

And about the termomiter or thermometer differences, nothing to say. I am more interested in the rotary combustion chambers at high pressure.

Celsius

jawmo1
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Re: WITH OR WIHOUT VALVES, WHAT IS MORE EFFICIENT

Post by jawmo1 » Sun Sep 13, 2015 4:42 am

Dear Collegues here is jamo1,
Respectable Professor Bruno Ogorolec wrote recently to cancel feasibility of my proposal to use De Laval CD nozzle
in pulsejets.First reaction was that schockwaves and nrmal waves will plug throat,later he retracted becose when pe=po
shockwaves are out the nozzle, and a few days he said,as the flow is intermitent, De laval will not work.I have been retired of Forum studyin the way to design a steady state flow 1.- if intermitent, check Fourier or Laplace analysis and we can design a stady state flow,Theoretically is feasible,
2.-Ramjet is wonderfull, some researchers joined pulsajet nose and ramjet c.chamber and nozzle.My oppiion is a great diameter of nozzle and oblique schock,Is an idea.Need to study it.But me need keef in mind that flow waves can be controled by electromagnetic fields.
3.-My empathy is with amjet, center body,fuel manifold, flame holder, c.chamber small volume,high pressure,and stoichiometric propellants, pushed by an Inert gas and boosers or not De Laval CD nozzle.Ranjet alone with launcher reaches easy 4 Mach, with De Laval CD nozzle you have the launcher in there to take of,Perfect Gases Eq. a un aproch
and cars combustion cylinders say reduce Cylinders Vol, 1914 is i 2,6 liters , and 3 lts before.Eq. whose validity reach 3000 C , mention trends to try Volume od CC and effect on pressure in CC.Flame theory at 20 C,sea level,give us
2500K app. in flame, atomizing suitably propellants or gaseous mixture vapourized,at sub or supesonic is my proposal to dream to move an Stemme S10 without engine or propellers.TSFC ???? next time,Best Regards jawmo1

Rocket Man
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Re: WITH OR WIHOUT VALVES, WHAT IS MORE EFFICIENT

Post by Rocket Man » Sun Jan 17, 2016 1:42 am

It is not true that a pulse jet will not go faster than Mach .6.

America research in the 1950s on the JP-Loon project pulse jets reached 950 mph. Not much of the original research data is still available. See if you can find research data on the JP-Loon.

The German V1 had a very complicated fuel systems built into the engine. The engine started and idled at about 20% of thrust. The V1 launched with the engine at 100% throttle which reached a speed of 180 mph. As the V1 picked up speed ram air made the engine run lean so another fuel control gave the engine more fuel to 320 mph. The Germans made fuel system changes several times and the V1 engine was able to throttle up to 460 mph. The fuel system was replaced with a larger fuel system and the V1 reached 500 mph at the end of WWII. There was also a barometric pressure system built into the fuel system to reduce the fuel at high elevations. There was also a inertia sensor in the fuel system to increase fuel pressure at launch to allow for the sudden take off by the steam power launch system.

The JP-Loon project took it from there. By putting a restriction on ram air the German pulse jet was able to reach a speed of 950 mph. The military ruled the pulse jet has no military value it can only be reliable launched from a long stationary track. The military wanted mobile rocket launchers.

I have been doing research on pulse jet engines for 50 years. Pulse jets are very reliable engine with the correct design. I have engines that have run for 20 hour that show no damage to the reed valves.

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