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How to convert air flow into pressure?

  1. May 17, 2015 #1
    Let's say i have an air pump which produce plenty of air flow, but almost no pressure.
    Is there a simple way to turn this high flow, low pressure into high pressure, low flow?

    I'm thinking something akin to a gearbox turning fast spin, low torque of a motor into a high torque, slow spin output.
    Or basically something like a lever - a simple mechanical concentration of force.

    I tried putting a cone at the output, but it just reduces the amount of air going out without increasing the pressure.
     
  2. jcsd
  3. May 17, 2015 #2

    CWatters

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    Wind turbine -> electricity -> compressor -> any pressure you like.
     
  4. May 17, 2015 #3

    russ_watters

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    You describe it as a "pump", which implies that it is a high pressure, low flow device, but then say it is generating high flow and almost no pressure. That doesn't make a lot of sense, but if the flow is higher than you need, you can probably just put a valve on the system to reduce the flow, which will increase the pressure.

    But it would help a lot if you provided more details about the pump and the system it is connected to.
    When you say "output", do you mean output to the air? The output to the air always has to be equal to atmospheric pressure because there is nothing to constrain it.
     
  5. May 17, 2015 #4
    It's a centrifugal "pump" like the image below, used to fill up air mattresses.

    It produces a lot of air flow, but almost no pressure.
    That is, it can quickly inflate a garbage bag, but won't force any air into a regular party balloon.
    The latter is what i was thinking of using it for.

    61kzBSjkvFL._SY355_.jpg
     
  6. May 17, 2015 #5

    CWatters

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    You can buy electric balloon pumps. They do two balloons at once. Under $40. Perhaps cheaper, I didn't look hard.
     
  7. May 17, 2015 #6
    I know.
    But that is not what the question is about.
     
  8. May 17, 2015 #7

    russ_watters

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    Sorry, but there isn't much that can be done to increase the pressure: it is purposely designed for low pressure so it doesn't pop air mattresses.
     
  9. May 18, 2015 #8
    That is a centrifugal compressor if I'm not wrong. They CANNOT produce high pressure, especially with a gaseous medium.
     
  10. May 18, 2015 #9

    russ_watters

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    Centrifugal compressors can produce high pressure, but this one isn't designed to. It's more of a blower/fan than a compressor (though the difference is largely colloquia).

    Fans, blowers, pumps, compressors, whatever all have a characteristic performance curve whereby higher flow occurs at lower pressure and vice versa (shape is roughly like the upper right quarter of a circle). But there is a maximum pressure that they can achieve at zero flow. The performance curve for this one was purposely selected to provide a maximum pressure that won't pop an air mattress.
     
  11. May 18, 2015 #10
    Well I did not know that. Russ could you give me some examples of high pressure centrifugal compressors. I will appreciate it. Thanx
     
  12. May 18, 2015 #11

    cjl

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    A lot of turboshaft and turboprop jet engines use centrifugal compressors, which will typically give a pressure ratio of something like 5:1 per stage (so a 2 stage centrifugal compressor can give ~25:1, though this depends on the specifics of each design). Wiki actually has a pretty good article on this: http://en.wikipedia.org/wiki/Centrifugal_compressorhttp://en.wikipedia.org/wiki/Centrifugal_compressor [Broken]


    EDIT: actually, come to think of it, a high(ish) pressure centrifugal compressor you might be more familiar with also exists in many modern cars - specifically, a turbocharger. They all run centrifugal compressors as well.
     
    Last edited by a moderator: May 7, 2017
  13. May 18, 2015 #12

    russ_watters

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