Aerodynamic Tunnel

For Reynolds Numbers less than 2000 (i.e. laminar flow, as requested) in a duct of that diameter, ambient air needs to be flowing at no more than 27mm/sec.

Some "wind tunnel".

What you want is impossible. Not doable. Won't work.

Rethink the requirements. Rephrase the question.

$$$$$$$$$$$$$!!!!!!!!!!!!!!!!!

<...fill the entire cross section of the inlet with with small, thin walled tubes...>

Straightened flow isn't laminar. Flow with a parabolic velocity profile is laminar (Reynolds Number less than 2000), and laminar is what the original poster asked for. Of course, it might not be exactly what the original poster wants or needs.

Perhaps the forum may never know.

"Absence makes the heart grow fonder" - Anon

To Kamil

Maybe I don't understand what the outcome should be, You want to build aerodynamic tunnel which will generate air flow and have some abblity to control the air speeds inside the catainment chamber.

I have some questions first does the air flow need to be a certian temp?

I have some knowledge of a way to get this done from a natural source with aid from man made thermal heat transfure systems in a cone shape structure that can mantaine airflow speeds. This is a renewable energy power source for the future energy needs that many only make fun of & think it's to SI-FI. fiction, Lack of everday things around us with a new approuch in today's technologies.

Check out the public awearness ED. site renewablethermalwindpower.com

I do travel giving speeking about this systems for a community size interest.

I would gang it and have an inlet fan as well as an exhaust fan. I use this method for cooling electronics in tight places. Push/pull.

i donno about the gas dynamics (but i'm up2 to model the "us wc superflow aided by 2lB" ^(*))

ok ()_() <- tube put fans like the jet ones on each end rotate from side mounted fixer gears (/!\ you have to precision design your fan blades -- separate for pull push 1-s /!\) -- you may need to add (turbulence kill el. -- i can't advice what it is)

// -- ^(*) by defining a "smart surface¹" - that-is

• clusterable/re-mergable
• inside (where required e.g. near edges-contact surfaces) pregressivly differentiable -- this eliminates to over iterate the structure¹
• allows to define/track internal the surface¹(s) gradient fields to track -- the setOf.surface¹ is basicly a water bubble or arbitary shape and size
• such an apoach is trainable¹ to become resembling the water -- by known features e.g. (the "Discovery" shown) parachute/exploding raindrops - , waterspheres on stickers'-back-paper , tap-stream splashing to sink e.c.
• i don't have 3-D game engine libs to visualise / make it interactive (for error discovery -- required in training¹)

if you cant program or have a programmer associate -- the preceeding is likely off the topic here

oh! i forgot another structure air² is required to interact with the already concepted "smart surface¹" -- i don't've a good idea for yet ... the solid mechanical parts dont require internal defines in flow pattern modelling

your task is that way easier you've 2 def. the air² only

this is what google found (general wind tunnels // none "do 1, do 2, .." to design 1)

• tunnel wall interaction (near Mach flow speeds) http://ftp.rta.nato.int/public//PubFulltext/AGARD/AG/AGARD-AG-336///11chap09.pdf
• "2.1 Description of the wind tunnel" http://www.dlr.de/at/en/Portaldata/20/Resources/dokumente/tu/meastech-firenze-SEG.pdf
• 2D-probe http://www.acme.pwr.wroc.pl/repository/333/online.pdf
• "4.3.6.4 Wall Functions" http://etheses.nottingham.ac.uk/110/1/MPS_thesis.pdf
• 3D probe http://www.ewp.rpi.edu/hartford/~ernesto/S2011/EP/MaterialsforStudents/Gawronski/Jiang2003.PDF

There are a couple of parameters to be respected in order to obtain a good result with the mentioned idea. I used it but not with tubes, I used honeycombs. The parameters are :

- length of honeycomb in flow direction > 20 hydraulic diameters ( dh= 4 *A/P A section P perimeter)

- for the maximal flow and the tubes or honeycomb the diamaters (dh) have to be such that Reynolds < 20

- the ratio of free are to total area as near as possible to 1

- using tubes is not optimal since between tubes sections are smaller and have a higher resistance to flow the global flow is NOT homogenuous

Agreed, I was presenting a quick and dirty idea, thank you for adding some detail

I am sorry to mention that in many cases as this details are important! If you consider the tubes as 3 in contact the hydraulic diameter of the area between the tubes is about 0.1 of the tube diameter. The friction for same pressure drop is a lot higher so that the flow through those sreas will be very small. The result is not an uniform velocity field but a bunch of high speed (relative) flows separated by zone where due to the speed difference turbulences can and will occur.

You are correct, thank you

I am surprized that you praized my answers and at same time did not consider them as good.

Apologies I was rushing