Jet Thrusters
v Info from Wikipedia v
A jet engine is any engine that accelerates and discharges a fast moving jet of fluid to generate thrust in accordance with Newton's third law of motion. This broad definition of jet engines includes turbojets, turbofans, turboprops, rockets and ramjets, but in common usage, the term generally refers to a gas turbine used to produce a jet of high speed exhaust gases for propulsive purposes.
A turbojet engine is a type of internal combustion engine often used to propel aircraft. Air is drawn into the rotating compressor via the intake and is compressed to a higher pressure before entering the combustion chamber. Fuel is mixed with the compressed air and ignited by flame in the eddy of a flame holder. This combustion process, significantly raises the temperature of the gas. Hot combustion products leaving the combustor expand through the turbine, where power is extracted to drive the compressor. Although this expansion process reduces both the gas temperature and pressure at exit from the turbine, both parameters are usually still well above ambient conditions.
The gas stream exiting the turbine expands to ambient pressure via the propelling nozzle, producing a high velocity jet in the exhaust plume. If the jet velocity exceeds the aircraft flight velocity, there is a net forward thrust upon the airframe.
Under normal circumstances, the pumping action of the compressor prevents any backflow, thus facilitating the continuous flow process of the engine. Indeed, the entire process is similar to a four-stroke cycle, but with induction, compression, ignition, expansion and exhaust taking place simultaneously. The efficiency of a jet engine is strongly dependent upon the Overall Pressure Ratio (Combustor Entry Pressure/Intake Delivery Pressure) and the Turbine Inlet Temperature of the cycle.
It is also perhaps instructive to compare turbojet engines with propeller engines. Turbojet engines take a relatively small mass of air and accelerate it by a large amount, whereas a propeller takes a large mass of air and accelerates it by a small amount. The high-speed exhaust of a jet engine makes it efficient at high speeds (especially supersonic speeds) and high altitudes. On slower aircraft and those required to fly short stages, a gas turbine-powered propeller engine, commonly known as a turboprop, is more common and much more efficient. Very small aircraft generally use conventional piston engines to drive a propeller but small turboprops are getting smaller as engineering technology improves.
The turbojet described above is a single spool design, where a single shaft connects the turbine to the compressor. Higher Overall Pressure Ratio designs often have two concentric shafts, to improve compressor stability during engine throttle movements. The outer (HP) shaft connects the High Pressure (HP) Compressor to the HP turbine. This HP Spool, with the combustor, forms the core or gas generator of the engine. The inner shaft connects the Low Pressure (LP) Compressor to the LP Turbine to create the LP Spool. Both spools are free to operate at their optimum shaft speed.
Most modern jet engines are actually turbofans, where the LP Compressor acts as a fan, supplying supercharged air to not only the engine core, but to a bypass duct. The bypass airflow either passes to a separate Cold Nozzle or mixes with LP Turbine exhaust gases, before expanding through a Mixed Flow Nozzle.
Forty years ago there was little difference between civil and military jet engines, apart from the use of afterburning in some (supersonic) applications.
Civil turbofans, today, have a low specific thrust (net thrust/airflow) to keep jet noise to a minimum and to improve fuel efficiency. Consequently the bypass ratio (bypass flow/core flow) is relatively high (usually much greater than 3.0). Only a single fan stage is required, because a low specific thrust implies a low fan pressure ratio.
Today's military turbofans, however, have a relatively high specific thrust, to maximize the thrust for a given frontal area, jet noise being of little consequence. Multi-stage fans are normally required to achieve the relatively high fan pressure ratio needed for a high specific thrust. Although high Turbine Inlet Temperatures are frequently employed, the bypass ratio tends to be low (usually significantly less than 2.0).
^ Info from Wikipedia ^
A Homemade Mini Pulse Jet Engine
The valveless pulse jet engine or pulse detonation engine is the most simple type of jet and is therefore popular among hobbyists as a DIY project. it is often referred to as a 'tuned pipe' because its operation depends upon making the parts the right size and shape so that it fires, or resonates at the engines natural, fundamental frequency.
This pulse jet is made from modified copper plumbing parts. Due to the materials used it could only be safely operated for a few seconds, but this was enough to demonstrate the principles of operation. The fuel was provided from a cheap blow torch and was injected into the combustion chamber. This chamber also contained a tiny homemade spark plug. The spark rate could be controlled by varying the power to a HV capacitor connected in parallel with the spark plug.
This image show the basic 'tuned pipe' without the spark plug and gas supply. Tuning was achieved by altering the length and width of the parts used. This was quite simple as there are wide range of plumbing parts that will easily fit together.
More details on the DIY Devices page
The information provided here can not be guaranteed as accurate or correct. Always check with an alternate source before following any suggestions made here.
The fuel inlet is just a brass pipe like the ones you find in a hobby shop, soldered into position.
The rest of the jet is made from standard copper plumbing adaptors. The combustion chamber is the only modified part. It is made from two adaptors that are used to connect a small diameter pipe to a larger one. These are cut shorter and soldered end to end. The main drawback of this is that the solder will melt and the device will fail (or even explode) after a short time.
Rember im only 15-16 years old. This jet works to we that is to say me and my friend tested it.
As it picked up speed the fuel run out.
Thanxs James
P>S I am also just 15
P.S. I'm a Mechanical Engineering student finishing my undergrad degree on related topics.
In any case, you could power your jets on hydrogen derived from water. If you have any electronics experience, make a high voltage, low amp square wave (pulse) controller unit with a frequency of 42.8 khz. Search the web, there are over-unity sites with info.
Search for "peswiki video" or "pesn" for more info. Also, search for "runs on water" videos on youtube or google video. That's one place to get started.
Free energy should always be free... like freeware should be free or freedom should be free, with no strings attached. We must be responsible with our freedom and free energy. It's our duty.
If anyone comes up with a jetpack idea that runs on Hydrogen, keep it under wraps until you're ready to actually test it. Make sure it passes all safety codes and make us all proud.
:)
I suppose theoretically it would be best to use smooth curves as this will reduce internal drag and turbulence inside the engine. I am unable to say if square tubing is enough to prevent a jet from running correctly but it probably doesn't help.
you know that feel you were talking about this was as close as i could come for the tubes i have.
dose it look right?the inlet 20mm tail pipe 23mm and the combustion chameber 70mm.
dont worry about the cracks i havent welded it yet.
After the fist fuel detonation a vacuum remains inside which draws in fresh air/oxygen and also some of the flame in the exauhst to start the next detonation.
If the chamber is too large (or pipes are too narrow)not enough air will get back in time for the next pulse.
I can't see the end of it on your picture, but maybe the longer pipe shoud taper outwards a little. You could also try a more volatile fuel mix. Adding a few drops of lighter fluid into the combustion chamber can allow you to have a stronger detonation for at least a few pulses. Once it is warm it evaporates and mixes with your gas to give a boost in power but it won't last long. Make sure you don't add too much though as you don't want it firing burning liquid out of the exahusts.
Where practical it is often useful to make many parts of a project adjustable or interchangable so that you can learn how each adjustment will effect the overall performance.
If you increase the diameter of a pipe, try to use a pipe the will allow a smaller one to fit inside. This allows you to easily change the inner diameter of the pipe. You can see an example of this on the DIY page where the top image shows the opening nearest the combustion chamber. There is a n extra bit of pipe inserted just to narrow that part a little.
If your jet is only firing when you are blowing the start air into it, then you would possibly need to increase the diameter of a pipe.
whitch pipe should be increased?
the inlet i have is 23mm and the tail pipe is 20mm and they fit in each other.
The combustion chameber is the most important as it provides power to the tail pipe and the vaccum. the other pipes are adjustable. the pipes have to arranged in such a way that the sonic wave length can become posible in the chamber.
The short pipe provides most of the thrust and also is where most of the the fresh air is sucked back in.
The inrushing air collides with the fuel and hot gasses from the tail pipe which then detonate again. With smaller jets like these is can be difficult to get the amount of fuel/air correct.
Your tailpipe must also be long enough to contain the pressure waves. If it is a bit too long then your jet should still run, but if too short then it wont be able to self sustain the fuel ignition.
I'm not sure about using glue and plastic pipes for your jet. The metal will get very hot when active which will probably melt the glue and the palstic.
I don't know what dimensions your parts must be, maybe you could compare with some plans or another project like this homemade turbojet.
coffey:
Sorry, I don't know. Never used a car turbo or oil system before. Maybe the link above will help.
I don't know how much the bubbles would effect the operation of it. If they are only small then I guess it shouldn't be a problem. Just look at it as a musical instrument. If you think it would stop it playing properly then it is probably going to effect performance.
1. Its dangerous!
2. Its dangerous!
And,
3. Its dangerous!
Now I know that technically that’s only one thing, but I thought it was such a BIG one, I'd mention it three times! One slip and you could be scarred for life, or worse! If you’re a knowledgeable adult and you’re careful, it’s a big risk, but so are many things. If your a thirteen year old who wants to build a pulse jet skate board, DONT DO IT; IT WOULD BE THE MOST DANGEROUS VEHICAL ON EARTH!!! I think this site is one of the most interesting and brillant sites on the web, with some of the most interesting projects, but its importain to do a lot of background reading before messing with high force/temp devices.
As for the jet powered bike.. I think there are many enthusiastic individuals eager to make something cool to show their friends. Most people underestimate the the complexity of the project or the level of commitment requried. Fortunatley these people are unlikley to ever produce any sort of working jet powered vehicle.
This obviousley doesn't mean that they wont hurt them selves while trying. The best I can do is provide good information, and this medium for allowing the exchange of ideas and information.
There are also no step by step instructions so people can't just try to replicate a project. It is important that anyone making these sorts of projects should know enough about the subject so they can complete it safley.
of the type made by MicroJet I would like to get an FXR 100 which weighs about 10 lbs and generates 95 lbs of static thrust. i plan to try using oxygen enriched fuel.
I want to take this engine to high altitude.
I would be interested in any info related to aquiring one of these engines(the factory has not responded to my quries.
looking for info. I will describe my project if you reply.
Willie
My e-mail is willlielinn@yahoo.com
thanks
Please do be careful when working with these things so that you can grow up and continue to build ever more complex and impressive stuff. You are very fortunate to grow up with the Internet, let me tell you! Follow your curiousity and some day you'll be rich, or at least happy... Always keep a fire extinquisher near by!
Peace,
Old geek guy
should i introduce a spark plug to help?
im a little worried that the spark plug will change the diamentions of the jet and reduce its frequency.
i would like to know the in's the outs whatever you can share with me. I have just finished my shop in my garage and am now ready to start production on my propulsion hobby that has always interested me if you have any insight on this subject please feel free to e-mail me at CRISTO.ALLIANCE@GMAIL.COM
lol and a whole bunch of other stuff..;) hey rmcybernetics, jlnlabs great job on your stuff!!
would be great to see a coment on this.
This is going to be a seriously hot pipe.
I have witnessed a brand new principle for a petrol powered engine, I have seen and heard the first and only engine of this kind in the world. THIS IS HISTORY!!!
this image is resized to hide the working principle of the new engine.
I an kind of scared to show how it works, because it's top secret and the only reason that I saw the engine was pure luck. right place at the right time.
Any body that is interested plz e-mail me @ rainerfilm@gmail.com
Don't expect to see any images, I am planning on selling them on e bay.
look buddy, your fans are going to catch on fire, (if there plastic) hey but dont stop trying ! the thing your going for it compressed air- first induction,bring air into your tube-next compresion, sqeeze that air down so it is consentrated - next ignition, light that commpressed air on fire with fuel- expantion, that compressed air will expand and grow larger! makeing it look for a place to go- then exhaust, the big finish were you make all that expanding air go somewere usefull. e-mail me for further help at mark_whitaker@hotmail.com BE SAFE !!!
Turbine engine boost pipe failure. Turbo based turbine.
this is just a feeling for you guys to see how dangerous this really is.