Noise suppression in ductwork? Minimum segment length?

Posted by on October 29, 2009, 8:48 pm

>>> You're think that an EE would realize velocity <> airflow
>>> VOLUME.

>> I admit that my skills in fluid dynamics are weak.
>> I'd been working with the assumption that I could get a
>> reasonable first-order approximation to airflow by multiplying
>> the average velocity across the duct times the area of the duct.
>> Given that the duct size didn't change, the relative volumes
>> should be the same as the relative velocities...to first order
>> for small changes. I assumed I could ignore the small changes in
>> air density due to the small change in pressure within the duct.
>> Please disclose the additional math required to determine the
>> airflow volume with sufficient accuracy to solve the noise problem
>> described.
>> Thank you for your willingness to educate.
>> mike

>HINT:
>LOOK UP REYNALD'S NUMBER.

I just talked to him the other day. Watcha need ?

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Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
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Posted by on October 29, 2009, 10:14 pm

>>>>> You're think that an EE would realize velocity <> airflow
>>>>> VOLUME.
>>>> I admit that my skills in fluid dynamics are weak.
>>>> I'd been working with the assumption that I could get a
>>>> reasonable first-order approximation to airflow by multiplying
>>>> the average velocity across the duct times the area of the duct.
>>>> Given that the duct size didn't change, the relative volumes
>>>> should be the same as the relative velocities...to first order
>>>> for small changes. I assumed I could ignore the small changes in
>>>> air density due to the small change in pressure within the duct.
>>>> Please disclose the additional math required to determine the
>>>> airflow volume with sufficient accuracy to solve the noise problem
>>>> described.
>>>> Thank you for your willingness to educate.
>>>> mike
>>>HINT:
>>>LOOK UP REYNALD'S NUMBER.

>> I just talked to him the other day. Watcha need ?

>I want to talk to his wife Flo.

I hear she really rates.

--
Click here every day to feed an animal that needs you today !!!
www.theanimalrescuesite.com/

Paul ( pjm @ pobox . com ) - remove spaces to email me
'Some days, it's just not worth chewing through the restraints.'
'With sufficient thrust, pigs fly just fine.'
HVAC/R program for Palm PDA's
Free demo online at www.pmilligan.net/palm/
Free 'People finder' program now at www.pmilligan.net/finder.htm

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Noise suppression in ductwork? Minimum segment length? - Page 4