~~~~First Valveless!!~~~~

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_Rahul_
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~~~~First Valveless!!~~~~

Post by _Rahul_ » Sat Feb 17, 2007 8:41 am

Hi everyone..
This is my first "Valveless" pulse-jet ..( though I have made valved ones but not valveless till I hit this place!). Here are some pics .. it was made two weeks back but I didnt had a camera .. so, wen I got hold of this cellphone camera, wanted to share some pics!

Any Idea about the thrust it will produce?


Thanx larry .. took some help from ur models!!


All Mild Steel !!
1mm

images are poor quality but that's all I could afford till now!!
Just cant wait to run it after I get a new pump!!
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_Rahul_
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Post by _Rahul_ » Sat Feb 17, 2007 10:15 am

Oh .. just checked the post!!
the first one shows the cone made without welding ( but I did the welding to close the other end of the PJ), its gas welding!
the second one is the Pulse-jet and intake pipe, the way it will be attached!
The third one~~ the PJ and the intake pipe!

(In third pic u can see the place where I work ..and its not me in the pic!! LOL, )!!

Length of PJ: 700mm
tail pipe Dia: 40mm
Tail Pipe length: 485mm
intake pipe dia: 25mm
Intake pipe length: 150 mm

Any Idea about the thrust? Gonna run it soon, maybe this Sunday!!
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_Rahul_
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Post by _Rahul_ » Sun Feb 18, 2007 8:49 am

Okay, seems nobody's interested, or everyone's busy, but I did the first test run of the PJ. Didnt worked properly, just few blasts in the begining and then all went silent. I think I should use a sparking system for continous ignition! Man this Ain't no labor saving thing! Anyways .. off to building a sparking system.
Secondly the test was done without a pump. Just used a syphon .. and fuel was car petrol. Maybe the syphon could'nt supply enough pressure for the petrol to vaporize an mix with air.
Thirdly I didnt put anysealing on the joints.. but I dont think its leakin'! Can it be?

Okay can anyone tell me at wat pressure should I pump air in the PJ?
and whould should be the rate of fuel supply? Any ideas?
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~~~~First Valveless!!~~~~

Post by leo » Sun Feb 18, 2007 12:14 pm

Rahul your intake pipe is way to long, I don’t replayed on your post because in the picture it didn’t seem welded together yet, and in the sizes you give in the measurements it looks ok (if you meant inside diameters), the 1/6 ratio off inside diameter/length is a good starting point.
In your pictures its seems the length is twice that.
If you want the start on petrol you will need a pump with a good spray nozzle, else it will be very difficult to get it running.
Maybe its better to get propane for fuel.

Can you give a picture how your intake ended op?. also have you flared it.

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First valveless

Post by Irvine.J » Sun Feb 18, 2007 12:37 pm

Rahul I'd also like to see a picture of the completed engine. Its kind of hard to imagine how it looks with that intake pipe.

Can you get this engine to run on propane alone? Get your gasbottle and give it a try. If it works on propane then consider moving onto liquid. If you experience alot of problems with your propane, then liquid fueling will probably never work.

How are you /or planning to liquid fuel it? You want high pressure and low flow, if using a pump. Problem with my pump is its too high flow and not enough PSI.

Your starting air pressure should need not be more then 30psi, 30psi is a good round number.

As for fuel flow rate. Consider this...
you know its a 2.25lb engine, and we know its about 2.2 to 2.5 lbs per hour per pound of thrust. (2.25lb) So how many lbs per hour is the engine burning?

How many millileters per minute is that? :)

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Post by _Rahul_ » Sun Feb 18, 2007 5:05 pm

Hi leo and Irvine.J, looks gud somebody noticed the attempt!
Actually .. the pic shows the intake pipe waaay too big becoz I made it big in the beginning and it was rather cut to desired size ( its 150 mm from end to end now). I dont have a camera so I will try to get hold of it some day before this weekend!!
I didnt ran it on Propane yet and I was considering it to run on gas first .. atleast I will know if it works or is it born dead! LOL ! Well .. I dont get propane in here and hope to run it either on LPG or CNG ( preferably LPG!)
Plus I was damn exited to run this rusty thing that I couldnt wait for anything! It doesnt has a spark plug and no fuel pump. Now I plan to get a sparking thing and a fuel pump ( If I dont use gas!) Actuallly I can get around half a litre of fuel for testing for free but to arrange gas I would have to buy a gas cylinder and a gas regulator/valve, a pressure gauze and a fuel pipe .. that makes it around $25 and .. its a big sum of money over here for me .. ... anyways I will try to arrange it .. but still thinking about the liquid fuel. I am thinking to pump petrol using a pump and in the mid way while petrol is passing through the copper pipe I am gonna heat it so that the petrol may evaporate/vaporize to gas state and then I will try to run the PJ on it!! Although never tried it but its gonna be fun till the gas pressurises back into the fuel pump and the flame travels back to the petrol tank !!

And for fuel flow rate ..
As for fuel flow rate. Consider this...
you know its a 2.25lb engine, and we know its about 2.2 to 2.5 lbs per hour per pound of thrust. (2.25lb) So how many lbs per hour is the engine burning?
:?: :?: :?: 2.5 lbs per hour for every single pound of thrust? If this is a 2.25 pounds of thrust producing engine .. its around 5.6 pounds of fuel per hour? but doesnt different fuels have different specific heats? I assume petrol can cause more expansion in gas rather than LPG. and thus leading to higher thrust or maybe wastage of fuel .. which means leser petrol would be used for same thrust as that of propane or LPG .. right .. am I? :?: :?: :?:

Just a bit confused .. maybe ... it doesnt feels gud after ur PJ shuts up after a big burp!! Isn't it?

Anyways I even tried to put it on fire by spillin petrol inside the tail pipe and flaring it from tail end to combustion chamber .. It gave some signals of life before everything went on fire!! I assume I was pumpin' too much of fuel .. is was pretty scary .. though!!( Hell .. wont use a syphon again!!)
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Post by Irvine.J » Sun Feb 18, 2007 11:44 pm

Rahul dear boy,
LPG IS propane - (Liquid Petrolium Gas) :)
You dont need a regulator, just the gas hose, and a fitting to screw on to the hose and silver braze your copper pipe to it.
Although never tried it but its gonna be fun till the gas pressurises back into the fuel pump and the flame travels back to the petrol tank !!
Man do not try and heat gasoline in the pipe to atomize it without a one way valve or it will go back into the tank. If you have a pump great, but that opens up a whole new can of worms. Keep trying to get the fuel to atomize itself, make smaller holes, and cut your fuel flow back.
:?: :?: :?: 2.5 lbs per hour for every single pound of thrust? If this is a 2.25 pounds of thrust producing engine .. its around 5.6 pounds of fuel per hour? but doesnt different fuels have different specific heats? I assume petrol can cause more expansion in gas rather than LPG. and thus leading to higher thrust or maybe wastage of fuel .. which means leser petrol would be used for same thrust as that of propane or LPG .. right .. am I? :?: :?: :?:
Your right about different fuels giving you better fuel economy. Higher thrust no not really, just less fuel to get maximum thrust. Assume first up its SFC is about 2.5, get 100mls of fuel in a container and experiment with your flow rate. If you could get some LPG you would be able to switch over, which would be much easier then starting cold on gasoline.

Goodluck, I wouldn't be wrapping my fuel line around without some pretty serious thought.

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Post by _Rahul_ » Mon Feb 19, 2007 12:48 pm

K .. this is what I was considering in my maths class ...
If the combustion chamber is heated to a fairly good temperature before the PJ is started .. I hope I can get it started directly on liquid feul ( if the fuel is petrol !)! Becoz as the liquid petrol enters da hot combustion chamber it must atomize ( as petrol doesnt catches fire till it gets some sparks .. and it will just vaporize to gas state as it comes in contact with heated metal sheets!! ) .. this can in a way even put off the need for a good valve or anything like that! Nor will it need a diffuser then! andd I assume that if this rusty lil monster once got started .. it will be hot enough on itself to vaporize the petrol and there wouldnt be need of any external heating! Maybe that's why PJ's on liquid fuels are hard to start ? Is it?
The second thing is that I was giving thought to use oxygen from the oxygen cylinder( used for gas welding!) instead of normal air from the compressor .. although I have not thought about it at all .. just it came in my mind while I was writing this post .. will it be helpful in starting .. even if not sufficient air .. it will get plenty of oxgen to begin with!! Or will it be the other way round? enough oxygen for free flowing petrol .. sounds like a bomb .. ain't it? Well .. this idea has already scared my co-workers indeed!!

Thanx guys .. for ur brilliant suggestions!!
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Post by Irvine.J » Mon Feb 19, 2007 1:03 pm

The second thing is that I was giving thought to use oxygen from the oxygen cylinder( used for gas welding!) instead of normal air from the compressor .. although I have not thought about it at all .. just it came in my mind while I was writing this post .. will it be helpful in starting .. even if not sufficient air .. it will get plenty of oxgen to begin with!! Or will it be the other way round? enough oxygen for free flowing petrol .. sounds like a bomb .. ain't it? Well .. this idea has already scared my co-workers indeed!!
Oh dear god NO!!! BAD RAHUL!!! VERY BAD!

If the combustion chamber is heated to a fairly good temperature before the PJ is started .. I hope I can get it started directly on liquid feul ( if the fuel is petrol !)! Becoz as the liquid petrol enters da hot combustion chamber it must atomize ( as petrol doesnt catches fire till it gets some sparks .. and it will just vaporize to gas state as it comes in contact with heated metal sheets!! ) .. this can in a way even put off the need for a good valve or anything like that! Nor will it need a diffuser then! andd I assume that if this rusty lil monster once got started .. it will be hot enough on itself to vaporize the petrol and there wouldnt be need of any external heating! Maybe that's why PJ's on liquid fuels are hard to start ? Is it?
To be totally sure what your talking about, try to write what you want to say without the use of terms like "Da , lil, becoz" etc etc. We may interpret what you are saying incorrectly and give you improper advice.

Now, a hot CC always helps, but you will find it difficult especially if unfamiliar with a PJ to get it running on liquid from a "Cold start". You WILL still need a good flow restriction system.
Just find some propane to get an idea of whats going on.

I AGREE WITH EL-KABLOOEY PUT AWAY THE GASOLINE!
Last edited by Irvine.J on Mon Feb 19, 2007 2:23 pm, edited 1 time in total.

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Post by El-Kablooey » Mon Feb 19, 2007 1:28 pm

Rahul, I'm not being a jerk here, although it may sound like it. I am VERY concerned for your safety. Please do yourself (and any innocent bystanders) a favor and stop experimenting until you have done ALOT more reading. Please stay away from petrol for awhile, you are going to get burned with it. BY FAR the best/easiest/safest fuel is propane (LPG). Find some! If you don't, you aren't likely going to have any luck starting your engine. You will however be very likely to set something/someone on fire.

Just my 2 cents... Slow down and be safe!

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New Engine

Post by larry cottrill » Mon Feb 19, 2007 2:50 pm

Rahul -

I have to agree with the others. Propane vapor is easy to use, and reasonably safe. You are controlling the vapor directly, and that's what you want for easy experimentation. If you live in a warm area, even Butane should work and might be more available for you (BUT, I don't think we've seen anyone use it successfully, so far - in cool temperatures, it is hopeless).

Can you post a drawing with ALL the final dimensions of your engine? If you can do this, I can run it through UFLOW and see if I think you're close to resonance with your pipe lengths and diameters.

L Cottrill

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Post by _Rahul_ » Mon Feb 19, 2007 7:21 pm

Well . thanx for serious concern .. I am not testing anything without giving it a complete thought anymore! Here is the detailed drawing for the Pj I built. It may look a bit awkward the way the dimensions are marked as I didnt had AtuoCad or ProE installed at the moment .. so I tried it in sketchup!

Okay guys .. am looking forward to ur advice .. and trying to collect stuff for LPG. To be truthful I always feared that using propane/LPG .. the flame would travel back to cylinder full of high pressurised gas that's well known for its combustion. real clean fuel?A little leak can prove dangerous. Plus I dont have good smelling capability so it means I cannot detect the leakage till it had leaked enough. ... maybe the most probable reason I was keeping a distance from it!!

Thanx Larry .. would be waiting to see if this PJ stands some chance in the "uni-flo" test!!

To be totally sure what your talking about, try to write what you want to say without the use of terms like "Da , lil, becoz" etc etc. We may interpret what you are saying incorrectly and give you improper advice.
Advice accepted and I will take care of it in future. Well, using proper language also makes one look sensible .. and I will take care from next time onwards! anyways .. da->the;lil-> little and becoz-> because.
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Post by _Rahul_ » Mon Feb 19, 2007 7:54 pm

Pic ..
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Post by heada » Mon Feb 19, 2007 8:05 pm

Rahul,

Because LPG is pressurized, the risk of flame traveling back into the tank is very small. Also, I think there would not be enough oxygen to allow the LPG to burn within the tank. You can lower the risk of a flame traveling back into the tank by installing a one-way valve into the fuel line. While both propane (the gaseous version of LPG) and petrol gas are heavier than air, propane is lighter than petrol gas and so will dissipate faster if there is a leak.

As long as you respect your fuel and take any precautions needed, you should be fine.

-Aaron

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Testing for Leaks

Post by larry cottrill » Mon Feb 19, 2007 8:15 pm

Rahul -

There is a safe, cheap, easy and effective way to test your setup for leaks. This will work well for about any flammable gas I've ever heard of.

Mix up a little jar of soapy water and keep it near your fuel outfit, along with a little brush (like a parts cleaning brush or something). Whenever you want to test (every time you open the valve to pressurize the system, if you want), just apply a brushful of the soapy water on every connection, letting it run down around each joint. Even the slightest leak will show as expanding soap bubbles. You can rinse the soap off with clean water after the test if it bothers you.

This test will clearly show any joint that isn't tightened up like it should be, and even detect a leaky valve stem. And the soapy water is perfectly safe to use around flammable gas.

L Cottrill

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