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Vertical Wind Tunnels using green technology

  1. Apr 19, 2016 #1
    I wish to create a state-of-the-art vertical wind tunnel for indoor skydiving. By state-of-the-art I mean using green technology to create the power necessary to push air, and I would like to reclaim as much energy I can from the movement of air, drive shafts, and anything else I have not thought of but you may have knowledge of. Most tunnels require about 1000 hp to move enough air in a 3 metre wide tunnel. I want a 6 metre wide tunnel and that would require much more energy, and if I can exhibit how this can be done using minimal energy production through innovation and ingenuity then it would be a good example for others, and will of course reduce operating costs. Thank you.
     
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  3. Apr 19, 2016 #2

    berkeman

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    Welcome to the PF. :smile:

    Please tell us your thoughts on how you will accomplish this. Please include calculations for where you will be able to conserve energy.
     
  4. Apr 19, 2016 #3
    Thank you for taking the time to inquire about my post. I could detail my thoughts, certainly, but at this point I am not clear as to my direction but for the true starting point of such a project: energy, and how to make best use of the newest technology of which I don't think I am fully up to date on. I plan to read the suggested threads below before so as to potentially update my knowledge on the subject.
    I do know the conventional wisdom would state there's no free lunch concerning created energy and thereafter attempting to increase it. I'm thinking outside the box and though my lunch will not be free it will be substantially discounted.
    More information as I learn from the contributions made to this site. Have a nice day!
     
  5. Apr 19, 2016 #4

    Baluncore

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    Consider a solar updraft tower as part of the solution. https://en.wikipedia.org/wiki/Solar_updraft_tower

    Build your free-fall chamber near the base of the tower where you can gently pinch the section to increase the air velocity. It will only operate when the sun is out, but it might be used to generate an energy credit when not being used for free-fall.

    A wider skirt or taller chimney will gather more solar power. Area and height limitations will dictate the percentage of the required power may be generated by the tower. Even if additional power is required for a fan, the use of any updraft tower should improve the environmental bottom line.
     
  6. Apr 19, 2016 #5

    russ_watters

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    No offense, but an idea like that would be worth millions of dollars; Don't you think people who do know the physics/engineering have been working on such things, given that there would be a lot of money in it? And you want us to invent it for you here? Do you really think that is realistic?
     
  7. Apr 19, 2016 #6

    boneh3ad

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    I honesty don't think it would be worth millions. Vertical wind tunnels for this purpose are a very niche market. In trying to transfer the hypothetical concepts to a more conventional configuration, the high additional cost of such a system would price most users that could benefit out of the market (i.e. universities) and wouldn't be worth the additional cost to most of the rest (i.e. government) who can afford the power draw of a more conventional design.

    Still, even if it was a lucrative idea, I totally agree it would be silly to expect a bunch of us to basically invent it for someone else for them to benefit.
     
  8. Apr 19, 2016 #7

    Baluncore

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    I'm happy to throw in ideas because the OP will have to do all the work of selecting and integrating the collection of suggestions received. The idea is only 2% of the invention. Making the prototype is another 2%. I hope our suggestions make possible a successful business that employs many and earns it's investors a good financial return.

    I am often presented with challenging problems. I solve them using ideas I get from all over the place, including from OP's questions and member's replies here on PF. This is a two way exchange of ideas. It is a community.
     
  9. Apr 20, 2016 #8

    boneh3ad

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    I get it, and usually I'd agree. I happily throw out idea when it's an idea that is already well-thought-out and they are generally looking for help with a piece of it. This, though, feels like someone fishing for the answer to the entire project. Maybe I'm wrong, but that's just how it read to me.
     
  10. Apr 20, 2016 #9
    Ah, how interesting. The two gentlemen agree that knowledge should not be freely disseminated... a side note, would there ever be a situation where you would think knowledge should not have a pricetag?
    Now, on the topic before us, please, this is not quite rocket science. Vertical wind tunnels (VWT) are straightforward. Calculations indicate 925 bhp would generate enough air velocity for a 3 metre diameter flying chamber. One can, roughly speaking, take four V8 enginesrive sha that can develop 250 bhp, add a fan or propellor blade to each, run them at the correct and constant rpms necessary to combine their airflow through a vertical tunnel to achieve the desired velocity. Attach a generator to each drive shaft and reclaim some juice. Have your engines run biodiesels. Now that's about it for the conventional thinkers. No big deal. I have a few other ideas for green energy feeding machinery to move blades that push air. And the gentleman's comment about varying the diameter of the tube I understand and appreciate.
    The intellectual challenge is straightforward. Air is flowing in a closed loop system. The movement of air requires a push by power. The very fact that circulating air through the chamber is at a high velocity means at any point in the circulation chamber one may remove energy from the wind. But the 'no free lunch' principle means that what was removed is replaced by the powered machinery - call it an engine. But can one outthink conventional wisdom and have a system in which the use of the engine that results in moving air is arranged and augmented so lunch, if not free, is severely discounted -- and without using fossil fuels.
    One may decide on optimal engines and optimal blades to create the desired velocity. But a solution that harnesses the wind's power without the need to recreate that original wind velocity through the use of the engine is something that you cannot come up with whether you get money or not - it would violate a principle of physics. But there must be a way through technology and efficiency, through the manipulation of the tunnel diameter as suggested) and the use of outside green energy sources to augment the principle energy production that the end result would be an example of what can be done -- when there's a will there's a
     
  11. Apr 20, 2016 #10

    Baluncore

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    No. That would be very inefficient. It smells of an attempt at perpetual motion.
     
  12. Apr 20, 2016 #11
    How did you arrive at that conclusion of inefficiency?With a stationary conventional internal combustion engine, the driveshaft would spin to revolve the blades for air velocity, a belt attached -- in a similar fashion as one's automobile's fan belt -- and that belt turning a generator.... It would seem a waste NOT to do that, sir.
     
  13. Apr 20, 2016 #12

    russ_watters

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    That bears no relationship to what we said. It isn't just knowledge you are asking for, it is an invention. Inventions have value. You want to make money off of something we invent for you! Will you send us a check for a fair piece of our contribution? We'll happily provide knowledge for free, though:
    That would violate conservation of energy if it provided a benefit. Every HP of generator added would necessitate adding a HP to the engines to maintain the energy balance.
     
    Last edited: Apr 20, 2016
  14. Apr 20, 2016 #13

    Baluncore

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    Then you do not understand efficiency. Each time energy is converted there is loss.
    The motors are run to turn the blades. Why take some of that energy away from where it is needed ?
     
  15. Apr 20, 2016 #14

    russ_watters

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    The OP is trying to save 200 hp. At 1200 hours per year and 12cents per kWh, that's $215,000/year per installation.

    [Late edit]
    Beyond that, depending on the specifics, it could have implications in other industries, such as mine; HVAC. Saving fan poser is a significant fraction of what I do for a living. That also means that a lot of people have put a lot of thought into this already, so easy answers will be tough to come by.
     
    Last edited: Apr 20, 2016
  16. Apr 20, 2016 #15
    I believe the forum is a platform for the exchange of ideas and knowledge. I do not ask anyone to make calculations, or make any inventions. I merely ask for the dissemination of wisdom and perhaps all parties learn something of interest.
    As for efficiency, I agree in a system solely designed for moving air generating electricity off a drive shaft will entail energy. But perhaps I was not clear as there would be the entire facility containing the tunnel that would require power.
    Please make no calculations that may or may not prove that energy would be better used off a commercial grid!
    The ideas and rapport, sir, and/or sirs, is greatly appreciated, thank you kindly.
     
  17. Apr 20, 2016 #16

    Nidum

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    First generation vertical wind tunnels just used aircraft propellers . More recent ones have shown some advances in fan technology but not really very much . Use of gas turbine ducted fan technology could possibly give significant improvements in running efficiency but it would come at very high cost .
     
  18. Apr 20, 2016 #17
    Actually, regarding saving HP, which you've equated into money, my actual intent is to NOT use fossil fuels and showcase alternative solutions. My rough calculations show with conventional internal combustion engines, the size of the tunnel I envision may require up to 2000 HP to move the air at the velocity I desire. If I had diesel engines, and used bio-diesel, it would cost a bit more than the current price at the local station.
    Of course any business must concern themselves with the bottom line, but this project is about alternatives, the future, and how best to go about thinking 'outside the box' to achieve such a goal.
     
  19. Apr 20, 2016 #18

    Nidum

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    More like 4000 HP .

    It doesn't matter how the air moving system is driven - you still need a high power air moving system and nothing will change that fact .

    All that input power has to come from somewhere .
     
  20. Apr 20, 2016 #19
    I'll have to look into gas turbine fan technology. I have been considering aircraft engines. I recall KLM flew using alcohol for fuel, but my research is incomplete in this area. RollsRoyce has some interesting engines developed but I haven't all the details to accurately describe herein what they've managed to do.
     
  21. Apr 20, 2016 #20

    russ_watters

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    It is more than just an efficiency issue, it is the useful energy itself that is the problem. I'm not sure the OP got that from my previous post, so I'll try again, with an example:

    If you are spinning a fan that requires 1000hp, you use a 1000hp motor or engine. Then you decide you want to "recover" 500hp of that, so you attach a 500hp generator to the system. But oops, now you need an input of 1500hp instead of 1000 and you therefore haven't gained anything.
     
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