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Thread: How to calculate the pressure ratio of a fan ?

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  1. #1
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    Red face How to calculate the pressure ratio of a fan ?

    Hi everyone

    I am working on my graduation project which is hovercraft, and i am using integerated system. The fan i got is 80 cm dia. and has 5 blades and the available power is 13 hp @ 3600 rpm.

    I am sure that it is going to produce a good thrust, but here i am worried about the lift, i want a pressure of about 0.02 bar ( gauge ), and i dont know any data about this fan, so i was asking: how can i calculate the pressure ratio of this fan in terms of power, speed, blade cross section and diameter to know if the lift will be succsesful or not.

    I am also sure that it will produce the required flow rate, but here i am concern about the pressure.

    please need help .

  2. #2
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    Default Re: How to calculate the pressure ratio of a fan ?

    hi

    what size is your craft

    my single seater integrated craft is based on a skirt pressure of 600Pa (0.006 Bar) which is well below your estimation and i run 5 blades through a 90cm duct but with 50Hp

    there is software available to give pressure/flow rate of fans at various speeds/pitches but i don't have it sorry, other people who post here may be along to help you - good luck with your project

    tony

  3. #3
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    Default Re: How to calculate the pressure ratio of a fan ?

    Quote Originally Posted by broad5186 View Post
    hi

    what size is your craft

    my single seater integrated craft is based on a skirt pressure of 600Pa (0.006 Bar) which is well below your estimation and i run 5 blades through a 90cm duct but with 50Hp

    there is software available to give pressure/flow rate of fans at various speeds/pitches but i don't have it sorry, other people who post here may be along to help you - good luck with your project

    tony
    well, i calculated the pressure from this relation P=F/A

    - the area which the air is trapped in is 2.2 m2
    - and for 200 kg ( 2000 N ) weight
    it gives about 0.0091 bar ( i was wrong sorry )

    but i am using the closed type skirt, like this one http://amasci.com/amateur/hovercft.html

    but i am not going to make it circular, do you think this fan at this power will give the required pressure.

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