1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Turbine blades

  1. Jun 7, 2010 #1
    As an example what is the estimated distance between each blade of a Jet Turbine blade and how far would each rotary blade be from the other to compress the air within the turbine housing?

    My accomplishment would be to make a miniture sized electirc turbine, which i have made when i was 13 yrs old, but it was made from 9 computer fans, not sure if the blades were all the same angle or not and i know the placement wasnt right, but it then still scooted across the table top, not at a fast speed but maybe 12inches every 8 to 10 seconds consistant. This time instead of using a kool aid can im going to use a 9 inch long pill bottle that is 2 inches in diameter.

    The theory is to compress air as much as possible, using a electric DC motor with a multiple gear housing to pick up more speed to compress more air harder for maximum trust.
     
  2. jcsd
  3. Jun 7, 2010 #2

    minger

    User Avatar
    Science Advisor

    I think perhaps you have some nomenclature wrong. What I am assuming you had was a bunch of in-line computer fans that powered a miniature car.

    The purpose of a turbine is typically to extract energy from the flow to power the fan/compressor stages. I only say this because the design of turbines vs fans is quite different.

    I think an illustration of what you're trying to accomplish would be great.
     
  4. Jun 8, 2010 #3
    I so want electric to take over the world, i mean it just has to, fuel for turbines as it is today will come to and end anyway.

    An electric turbine would be
    awesome! Do not give up on this!, the best attempt at an electirc turbine i've seen so far is the DSM 94 HST fan by scheubler
    for modelers,a 12 bladed carbon fan,( i think it is 128 or 129mm in diameter) it sounds absolutely awesome, unlike the 3-4 bladed fans they use, this is an entirely different machine! and efficiency is increased by 30% over the conventional fans they use.

    It's quite a work of art visually and audibly! I've seen 2 Youtubes on it. (they are ducted fans, but i'm sure they can be of interest for
    they (for the first time) are able to be compared seriously to the fuel turbines in model flying.

    If you can create an electric turbine with actual turbine/compression stages that improves on existing tech, well, hats of to you my friend !!! You'll be my hero.
     
    Last edited: Jun 8, 2010
  5. Jun 8, 2010 #4
    well i was thinking of assembling a shaft with a bunch of blades that could be comupterized to feather out and what not and the turbine shaft would be on a gear system to pick up more torque or speed to make a heavier thrust within the turbine housing or chamber. Thus the air could be compressed faster and harder than a normal modern jet engine.

    For now i would have to stick it with simple basic items i would like to use computer blades with out the computer fan's casing that houses the computer fan, but then i would have to get around to making to the blades stick to the shaft and make a whole new magnetic setup so the shaft or the blades would rotate as power is amped to the turbine.

    Yes Axefly, thats my point is to create a greener power plant for our environment, as i am in the process of making a "perpetual motion machine" or in lamens terms a self suffecient power source, if such could be created, there are many things that that source could be plugged to. Like lets say cars, houses, airplanes and etc. This theory, idea, project would consume the thought of using fossil fuels to run our machines of present day. Thought it would considerably negetively throw out the electric companies around the world.

    Also as we have these computer components the rectify our electrical currents in our PC's and what not like Diodes, transistos, resistors, rectifiers, capacitors and what not's, then we man-kind can obtain a power plant to be such as a self suffecient power source. If scientist can make a computer chip with diodes and capacitors the size of the ink ball pen, then we should be able to do what we want scientifically. No matter if the Law of Conservation of Energy says its impossible, though anything that man makes is going to have resistance, heat, drag, and what ever else it may do, but the system still runs.

    Now back to the main subject here, if there was someone here that could give me the blue prints and math and materials that could be used to make a home made miniture model of a jet engine, i could make a similar one but only creates and compresses air for thrust with out the use of jet fuel or any other power source but a battery. I mean back in the day hydrogen the molicules of breaking down water (H2o) to a piston to run an engine. I do believe the first fuel powered engine came from the idea of the water pump, where there was a handle that was hooked up to a piston, and when that handle was going up and down so was the piston to pump the water from the ground below.
     
  6. Jun 8, 2010 #5

    minger

    User Avatar
    Science Advisor

    You have several misunderstandings of physics and engineering.

    First of all, do not think that you're going to revolutionize the gas turbine industry.

    Second of all, talking about a PMM will get your thread locked incredibly fast.

    Lastly, what you want is a fan, not a turbine. Like I said, turbines extract energy from a moving fluid and turn it into kinetic energy to power the fan/compressor stages. You are looking for fan design, not turbines. There is a stark difference.
     
  7. Jun 9, 2010 #6
    Why not instead of fuel driving the turbine for compression use an electric motor?
    With high efficiency brushless motors, could this not be possible? I suppose you'll
    tell me that the losses would be greater than the gains, but improvement, innovation is key, then let's improve upon the idea.

    Why so much against trying to create an alternative to a fossil fuel turbine engine?

    Or use electricity instead of fuel, to create heat in some way injected into the turbine.

    If my ideas sound absurd, some alternatives would be great!

    Remember, we need to start and think small at first, even if it takes us
    a few steps backwards, doesn't matter if the first few concepts turns out to be much worse than fuel turbines,
    from there we can build and improve.

    A preview on minuture turbines:
    http://www.rchelicopterfun.com/model-turbine-engines.html

    The best electric fan in existence that i know of is the one i mentioned:

    This is a simple illustrative overview of the DS 94 HST fan:


    The fan in action:



    Just listen to it, you can tell by the sound it's meant for business :) !

    now the question is how can we improve upon it, can we use it as a start to create an electric turbine?

    Building instructions on a FD3/64 fuel turbine http://www.sfu.ca/~jst4/plans/docs/jetengine/FD3%20turbine.pdf [Broken]

    Then These people provide plans for fuel turbines, at what cost i'm not sure of:
    http://www.artesjet.com/ [Broken]
    www.gtba.co.uk[/URL]

    We need to keep on thinking doesn't matter what odds are against us!
     
    Last edited by a moderator: May 4, 2017
  8. Jun 9, 2010 #7
    i say the same Axefly " we do need to keep on thinking about the improvement of man-kinds living conditions, no matter what odds are against us"

    I have a theread about Perpetual motion machine and its been locked for a charge of "Crockpotting" which i dont know what that is, nor are the rules really all that specific in details.

    And Minger, were not talking about making the electric turbine a PMM, that idea of the project can come later when MAN KNOWS IT CAN BE DONE, by me of course. but im sure it can't be all that hard to turn the blue prints for a fueled jet turbine system into all electric with absolutly no fuel required. Heres an idea that should of been thought out in the 40's when boeing started flying commercial was to generate electric engines and cover the wings with light industrial solar panels, OH WAIT, solar panels wasn't even thought of back in the day, and prolly wouldn't be all the effecient neither are the ones in present day which suck, you can have 5 panels of solar panels and that would be just enough to warm your water in your house, couldn't do much with the solar panels unless you had some Diodes, capacitors and a battery so you can run more than 1 appliance on the 5 panels, IF YOUR LUCKY. out technology still sucks in the present day because no one is really trying for futuristic projects, if they are, then someone is shotting them down or the government is coming up with threats to black ball the person's theory because its not government funded or the government didn't know till last minute.

    I'm kinda getting sickened of people coming up with saying oh its not going to work because of this and this, well if you know about this and that, then why be negetive and help with the solution to improve the theory than being quite. People who are being quite upon helping with the idea, theory, or project don't need to say anything if their not going to help to improve the idea. serisously its sickning that 85% of man kind isnt wanting to help their own selves because either their too scared of the government or their greedy for the wealth and want to bask in their riches (gloat)/ their wating the physical attraction.
     
  9. Jun 9, 2010 #8
    You cannot produce something from nothing.
    Energy cannot be extracted from nothing.

    Of course we are all trying to find new sources of energy, help the environment, etc., but talking about impossibilities is not going to help.
     
  10. Jun 10, 2010 #9
    Using an electric motor to turn the blades to compress air to drive a generator sounds good but the blades cnnot be made to function with zero losses. Then there is the motor which is no more than 90% efficient and then the generator which is also only 90% efficient at best. Add to that the heat losses in the compression of the air and you have a net loss of over 30% (it is actually a lot higher than that) - so you need to put over 30% more power in than you can get out.... not going to work.
     
  11. Jun 10, 2010 #10

    jack action

    User Avatar
    Science Advisor
    Gold Member

    Just so that we are all on the same page and that we are all using the same language, you cannot make an "electric turbine". What you want to built, is an "electric-powered propeller". Here what you should know to understand what a turbine does (the info comes from wikipedia):

    http://en.wikipedia.org/wiki/Jet_engine" [Broken]: It is a reaction engine that discharges a fast moving jet of fluid to generate thrust in accordance with Newton's laws of motion.

    In some common parlance, the term jet engine loosely refers to an internal combustion duct engine. These typically consist of an engine with a rotary (rotating) air compressor powered by a turbine ("Brayton cycle"), with the leftover power providing thrust via a propelling nozzle. ----> This is what most of us refer to as a "turbine" (the engine itself).

    http://en.wikipedia.org/wiki/Ramjet" [Broken]:

    472px-Ramjet_operation.svg.png

    A Ramjet is jet engine that does not have a compressor. The compression is done by vehicle speed (> Mach 3). Like all jet engines, the power comes from the thrust provided by the heated exhaust.

    http://en.wikipedia.org/wiki/Turbojet" [Broken]:

    Turbojet_operation-_centrifugal_flow.png

    The turbojet is a ramjet with a compressor, such that the compression doesn't rely as much on the vehicle speed (Mach 1 < v < Mach 3). That compressor is driven by a turbine (which take some energy from the heated exhaust) and the vehicle is still propelled by the thrust provided by the heated exhaust.

    http://en.wikipedia.org/wiki/Turbofan" [Broken]:

    800px-Turbofan_operation_lbp.svg.png

    The turbofan is a turbojet for vehicles with lower speed (< Mach 1.6). It has the same compressor and turbine as the turbojet, but it has an extra turbine that powers a fan. The fan contributes to compress the air for the jet engine but it also bypass some fresh air around the exit nozzle. The power source is still the thrust provided by the heated exhaust.

    http://en.wikipedia.org/wiki/Turboprop" [Broken]:

    800px-Turboprop_operation-en.svg.png

    The turboprop is not a jet engine, it is a propeller (or any other device) powered by a "turbine". In this case, there is still a compressor driven by a turbine, there is also another turbine that drives a propeller (similar to the turbofan) but this last turbine removes all energy (or as much as it can) from the heated exhaust gas such that there is none left to provide a forward thrust (hence, the reason why it is not a jet engine). The maximum speed of the vehicle must be < Mach 0.75 (see http://en.wikipedia.org/wiki/Propfan" [Broken]).

    In this case, you can replace the "turbine" by a typical 4-stroke engine or an electric engine if you want. But you still need a propeller or a fan, but not a "turbine".

    Commercial air carriers use turbofan as their speed are around Mach 0.8. Fighting jets use turbojet as their speed are supersonic. Ramjet principles are use with airplanes like the Blackbird SR-71 (http://en.wikipedia.org/wiki/Pratt_&_Whitney_J58#Turbo-ramjet_design").

    http://en.wikipedia.org/wiki/Motorjet" [Broken]:

    800px-WRDK.svg.png

    This is probably closer that what you want to do. An external motor replaces the turbines that drives the compressor (and fan) of a jet engine. In this case you can also use an electric motor to do the job. The question is: In an airplane, is the added fuel consumption for the weight of the electric motor and batteries vs the turbines is less than the fuel saved by the electric motor?
     
    Last edited by a moderator: May 4, 2017
  12. Jun 11, 2010 #11
    Thank you Jack, thats what i needed there, and yes an electric generated turbine engine can be built, with a gear system aswell. Instead of the fuel powering the turbine, you would have an electric motor either built on the outside of the casing and something i have thought about which is inside the turbine in a housing with a shaft hooked to the electric motor, which im sure that wouldnt work so the electric motor would have to be on the exterrior of the turbine casing or housing. I do greatly appreciate the diagrams you have shown here, it gives me a better idea of where the blade placement is and how i could build my theory.

    I think aslong as the air can be compressed and exhausted with great force creates thrust for the turbine. I was told you can hold back a F-16 turbine engine with your own hands, the turbine engine can spin all it wants, but it has no forward motion to create thrust, so when it start to get its forward motion thats when you need to get out the way.

    If a person can hold back a F-16 turbine engine from moving forward, then what makes a electric turbine so different. Its kinda retarded that scientist dont do enough to improve our global living, yea we have volcanologist, astrologist, meteorologist and etc. etc.

    Theres people building rockets in their own garages who are regular joes like me, they do alittle studying here and there and ask around for some ideal info and BOOM!!! their calling NASA for a contract to fly NASA's equipment to the ISS. so who ever says that something can't be done without testing the project themselves should just stop where their at and try it, then you can actually say "No it wont work" instead of taking one persons word for it because they can test it and make it work and tell others it cant be done so no one else can build it. screw that, if it sounds like it can work, im going to do.
     
  13. Jun 14, 2010 #12
    The burning fuel does all the work that you want an electric motor to do - some 10s of thousands of horsepower. The expanding gases from the burning of the fuel turn the turbine blades that turn the compressor blades to mix air and fuel together so it will burn fast enough to generate the power to turn the turbine.
    Now that we understand exactly what you are trying to do then all you have to do is find a motor with the kind of power you need and a battery big enough to keep it working long enough to overcome the size of the battery and its weight.
     
  14. Jun 14, 2010 #13

    mheslep

    User Avatar
    Gold Member

    I think that should be electric powered fan to compete with high speed aircraft.
     
  15. Jun 14, 2010 #14

    mheslep

    User Avatar
    Gold Member

    There has been significant recent research done on high performance (ie high power density) electric ducted fan engines for aviation


    Overview:
    http://www.drives.co.uk/fullstory.asp?id=2033 [Broken]

    In Applied Superconductivity, IEEE Transactions:
    http://ieeexplore.ieee.org/search/s...jrns&query=((masson)<in>au+)&pos=5&access=no"

    http://ieeexplore.ieee.org/search/s...jrns&query=((masson)<in>au+)&pos=6&access=no"

    Powerpoint overview from the authors, better graphics.
    http://www.masbret.com/asc08/ASC08_Tuesday_Plenary_Electric_Aircraft.ppt
     
    Last edited by a moderator: May 4, 2017
  16. Jun 14, 2010 #15
    What a pretty post!
     
    Last edited by a moderator: May 4, 2017
  17. Jun 15, 2010 #16
    yea sgvailbhav, were learning about jet propulsion ( not sure if i spelled that right but on that basis) not only does this post rock, but this forum site ROCKS aswell.
    With the info that mheslep has put in, im sure electric motors and power will over-come the way man-kind lives in present future no im not saying its within 50 yrs but so sooner. Just aslong as we can put our heads together and make things work and proove that it works with minimum break downs and work, than im sure the future is and will be upheld in full electriconics, just aslong as we can bust the solar electric pulse that the sun gives off (forgot what its called) but it kills all electronic machines, (seen it in the Discovery Channel) and it has to do with something of the solar panels which really doesnt do much on a mass scale, so thus is the reason why the ISS has such long and big solar panels just for a little bit of energy to power the ISS.

    Back to the main subject of this thread. If a regular house fan can keep you cool thru out the night, well just imagion a bunch of those with compressed blades put one behind the other, It would act like a jet turbine just with no fuel and of course not the power, Yes because their isn't that much power going to the fan blades to compress enough air to create enough thrust to do anything, but just think, if one can put enough power into that idea, then that idea would throw the present day fuel turbines to exstincion and would be obsolete. I think, aslong as the air can be compressed with enough power will create the thrust needed, even if the system had gears like a car transmission, or even like a bicycle. Each gear gives more power than the other.
     
  18. Jun 16, 2010 #17

    minger

    User Avatar
    Science Advisor

    OK, I just have to chime in again.

    Realizing of course that your fan is adding energy to the room. It, like any other electrical device gives off heat. The cooling effect you feel is a temporary byproduct.

    No fuel? Where does the electricity come from? I bet your parents don't think you running the fan is free.

    Again, you really have very limited understanding of how gas turbine engines work. The turbine is a stage. Let's walk through the engine, hopefully you'll get a better understanding and use some better vocabulary in your posts.

    The fan stage's purpose is to move air through the engine. Typical thrust producing jet engines work by conservation of momentum. By accelerating the fluid through the engine, we can create a net force. As a result, fans typically have very low pressure ratios.

    Next is the compressor and combustor stages. These act very similarly to your car. The idea is that we are going to compress the air, add fuel and ignite it. This is adding energy to the flow.

    Next is the turbine stage. It's purpose is to extract the energy that we just put into the flow. Recall, we never mentioned how the fan actually turns. The fan is connected to the turbine by a shaft. After the combustor section, we have very high temperature, high velocity fluid. The turbine extracts that energy in order to turn the fan.

    The remaining fluid flow goes through a nozzle to increase it's velocity.

    This is for a typical turbojet. A turbofan simply has a bypass duct, which can help with efficiency.

    If you are using electricity as the energy source, then there is no turbine stage. As a result, you don't have a gas turbine engine. I'm really unsure of what you're trying to even think of to be honest.

    Lastly,
    No they don't.
    [tex]
    P = T\omega
    [/tex]
    The increase in speed of a higher gear is linearly proportional to its decrease in torque. There is no change in "power".
     
  19. Jun 22, 2010 #18
    1st off, sorry if my vocabulary is incorrect whoopty, secondly, i pay my own bills so the electricity is unlimited to my use aslong as i pay my bills. Oh and thanks for the input of better understanding. My idea can be made better with better info and what not, don't have much time because im at work. (Zappos.com is da hizzle) but thank you anyways.
     
  20. Jun 26, 2010 #19
    I can't speak to aero engines, but the idea of using electric motors to power compressors on land based applications is quite common. Depending on the plant, compressors are powered by either a steam turbine, a gas turbine, an electric motor, a gas expander, or perhaps a combination of two. There are advantages and disadvantages to each driver type, for instance, if a plant has waste heat from a process, a boiler can feed a steam turbine to recover that energy. Large synchronous motors (20-40 MW) do not require a steam system, but need additional hardware if you need to vary the speed. In a typical catalytic cracking gasoline refinery, an axial air compressor is power by a hot gas expander driven by the flue gas exhausted by a process. Gas turbines generally have a high power to weight ratio considering that the entire cycle is contained within the unit.

    The point is, you have to look closely at the particular application before you can say that one power source is "better" across the board. You don't see any gasoline power ceiling fans for the same reason you don't see electric powered commercial airplanes.

    I'm not trying to discourage new ideas, just be aware of the obstacles involved.
     
  21. Jun 29, 2010 #20
    There actually is a way to make a true electric turbine. I don't know if anyone has bothered to construct one in real life as it's currently not practical, but it is basically a standard jet engine with the fuel combustors removed and an electric arc heater is put in its place. The arc heater adds heat to the incoming compressed air which expands and runs the turbine.

    I suspect that an electrically driven fan using electric motors would be more efficient than an electric arc turbine or any other kind of "electric" + "turbine".

    Marlin
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook