Free stream flow into a pipe

[xnh11]

I have a sense of how to do this calculation, but I'm looking for a book or journal article that addresses it. I want to be sure I understand the fundamentals.

Consider a straight pipe held up to the wind. What is the air velocity through the pipe? It obviously depends on the angle between the wind and the axis of the pipe.

Consider a tee held up to the wind. What is the air velocity in the tee? It obviously depends on whether the wind enters through the run or the branch of the tee as well as the angle with the wind.

Simple situations, but I'm not aware that any of the standard texts address this type of mixed internal-external flow.

I thought, perhaps, flow theory of isokinetic probes might yield something, but I didn't come across anything useful. I'm avoiding supersonic flows (there's lot of info on internal-external flows of ramjets). I also don't care right now about CFD modeling.

Thanks.

NH

 

[BigInch]

Not that I've done an extensive search specifically on that topic, but the only things I've seen have been flow around a square sheet, a sphere, a disc, wing sections and simple building-shaped objects, broken down to drag coefficients. Being that this is PIPING - which considers only internal flow, I'd suggest you post in the Aerodynamic forum, get proficient in CFD, or build yourself a wind tunnel.

From "BigInch's Extremely simple theory of everything."

 

[MikeHalloran]

I don't know of any data for a bare pipe or fitting in a free stream, and I can't imagine why anyone would care about flow within the lumen induced by the free stream flow.

People do care about flow into and out of an opening in a plane, or a planar surface of finite area, or the end of a pipe or fitting, for lumen flows not solely induced by the free stream flow.

The flows in and out of such an aperture are not symmetrical. Isobars for flows exiting the aperture will be roughly parabolic, whereas isobars for flows entering the aperture will be roughly spherical. This is important to all of us for the specific case where the apertures are our nares, and is the reason we don't inhale the exact same air that we exhaled.

I think some stuff has been published about liquid flows around the apertures used in particle counters based on the Coulter Principle(r).


Mike Halloran
Pembroke Pines, FL, USA

 

[btrueblood]

"This is important to all of us for the specific case where the apertures are our nares, and is the reason we don't inhale the exact same air that we exhaled."

love it, Mike. It's also why putt-putt steamboats work.

 

[xnh11]

Flow through a pipe in free stream is important in design of wind-driven eductor-type ventilators.

See, for example,

http://services.eng.uts.edu.au/~phuoc/docs/writings/AFMC00120.pdf.

 

[bimr]

Maybe you can find something here:

http://ateam.lbl.gov/Design-Guide/DGHtm/basicducthydraulics.htm

 

[786392]

Dear xnh11 Hello/Good evening,

I am not sure if this is going to be what you exactly asked for?
But if this relates to wind related issues then just a wild thought;

Probably the wind tunnels used for aerodynamics designing of Concord in early seventies and similar wind tunnels mostly used for fighter and/or other airplanes should be providing helping guidance in this context.


Best Regards
Qalander(Chem)