Building a Flow bench

[Greg Hermann]

At 2:32 PM 1/31/02, Eric Fahlgren wrote:
>944Technologist wrote:
>>
>> I have been thinking about this project for years and always intended to use
>> a leaf blower. I still need a meter. I looked up the specs on the leaf
>> blower that I have and it draws twice the air that I will require. A
>
>Ah, but you are forgetting the other important variable, the
>pressure ratio at which this flow occurs.  The leaf blower specs
>are for free air on both sides of the turbine, which is probably
>a pressure ratio of 1.2:1 or something really low.  When you
>go to put it on a flow bench you want (iirc from a previous
>post on this thread) about 25 in/Hg, or about 17 kPa absolute,
>giving a pressure ratio across the turbine of about 6:1 or
>higher; it just ain't gonna happen.

It was 25 or 28 inches of H2O, not Hg, but _BINGO_. Not gonna happen with
any standard fan or blower wheel !!

If you want to do "off-standard" testing, fine. I was just outlining what
would be needed to do _repeatable_ work, on standard.

No "over-engineering" here, just facts as to what it would take to do the
job the way commercially available flow benches do it.

Greg
>
>--
>Eric Fahlgren                            Mechanical Dynamics, Inc
>efahl at adams.com                          Ann Arbor, Michigan, USA


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