Wind Tunnel Construction

[BillA]

This will be a joint blog (biblog ?) by Ben and self describing our progress towards the construction of our respective wind tunnels. Contributions, comments, and criticism solicited as always.

This post will be an updated index/reference list of the source materials. (material from later posts will be moved or copied here)

Stds and Specs:
http://www.amca.org/crp/fans.asp (anyone have links to the docs themselves ?)
AMCA 210 - Laboratory Methods of Testing Fans for Rating Purposes.
AMCA 300 - Test Code for Sound Rating Air Moving Devices.
AMCA 301 - Method of Calculating Fan Sound Ratings from Laboratory Test Data.
http://www.iso.org/iso/en/CatalogueL...&scopelist=ALL
http://cart.amca.org/estore/download/amca_211.pdf

A ready-made guide:
http://www.me.pdx.edu/~gerry/epub/pd...enchManual.pdf

General wind tunnel references:
http://hightech.lbl.gov/Documents/CL...tProc_v1.3.pdf has dwg of wind tunnel

Specific equipment references:
wind tunnel
http://www.fantester.com this is my target, ~250CFM leaves some headroom
http://www.fantester.com/man16.htm the actual manual
http://www.overclockers.com/articles750/ JoeC's use of a wind tunnel
http://www.climatictesting.com/Air%2...st%20Stand.htm new
nozzles
http://www.helandermetal.com/air-flow-nozzle.htm other source ? (must be to spec, only)
fan
http://www.surplussales.com/Fans-Blo...ansBlow-1.html assorted
heat exchanger
http://www.lytron.com/reg/files/Lytr...alog_hx_AL.pdf ES7070
blast gate
http://cgi.ebay.com/8-CAST-ALUM-BLAS...QQcmdZViewItem

Other air measurement stuff:
http://www.ddc-online.org/inout/inou...na_06flow.aspx
http://www.ebtron.com/pdf/white_pape...son_052603.pdf
http://www.magnetrol.com/us/html/vie...sp?pdf=mii\552
http://www.ashrae.org/template/Asset...?assetID=22561
http://www.pdhonline.org/courses/m19...sourcebook.pdf

[BillA]

recommended minimum and maximum flows:

NOZZLE DIA ./ CFM @ 0.1 INCH W.G./ CFM @ 4.0 INCH W.G.
0.7 “ . . . . . . . 3.5 . . . . . . . . . . . . . . . 21.0
1.0“ . . . . . . . 6.7 . . . . . . . . . . . . . . . 42.0
1.6“ . . . . . . . 17.0 . . . . . . . . . . . . . . 110.0
2.0“ . . . . . . . 28.0 . . . . . . . . . . . . . . 172.0

max flow best @75% (3"WG)

[bigben2k]

[edited out link]

I'll be concentrating on the 16 inch'er, not for higher flow, but for the larger mounting area.

[BillA]

read the links Ben
the tunnel sectional area is 16x (min) the opening area
what size opening do you want ?

[BillA]

bought a -53VDC NMB blower for $20 as the air source ( http://www.surpluscenter.com/item.as...tname=electric ),
when I recognized that I could easily 'control' the air temp with parts on hand, the best kind

from a Lytron surplus MCS cooling unit I salvaged a ES0707 rad with a Comair Tarzan fan (yea, you can hear the scream)
fan http://www.comairrotron.com/ac_family.asp?FamilyID=66
ES7070 rad http://www.lytron.com/reg/files/Lytr...alog_hx_AL.pdf - nice to have rad specs, eh ?
the first (center) graph indicates, among other things, that an air flow rate of ~220CFM can be expected using this fan/rad combo
- I believe this is sufficient, with a Variac I can push it a bit

also added a link to an 8" blast gate I bought

would like a 5x5" opening, this means a 24" tube or a 20" sq duct
- am thinking that insulated duct may be the cheapest ?? (lg plastic pipe is pricey, got a source Ben ?)

EDIT
all these fans are far too small

[bigben2k]

I was looking at being able to test heatercores, and I have one that's 6" by 8" (a bit larger than most). That puts the diameter of my wind tunnel at 32". That's more along the lines of what I expected.

I stopped by the local hardware store last night, and found a 12" concrete former: $9. Waxed cardboard. anything bigger would be harder to find.

Reviewing the documentation last night, I'm realizing how critical it is that everything is properly sealed (for the pressure drop measurements). Then I pondered about how good a cardboard tube would be, and concluded that waxing ought to do well, but that if there's a way to apply a better kind of coating instead, it wouldn't hurt.

I also gave some thought on maintaining a seal at the nozzle plate. If the nozzle plate needs to be interchangeable (I haven't determined that yet), then it would be best to cut the tube in two and put a flange, so that I can bolt the nozzle plate. The flange would also act as a support (on a small diameter setup).

Today I'm going to try to sum up the requirements (from all the links above) in a simpler list, and source a 32" diameter tube.


Did you get a quote from helandermetal yet?

[BillA]

no hurry on that quote, what sizes you thinking of ?
look at the stuff Ben, copy it
the nozzle plate is fixed, nozzles bolted into it; accessed through a port
the 2 ends are identical, push or pull

[bigben2k]

I haven't sized the nozzles yet, but I'm looking at the same flow rates as you; so the same.

[BillA]

I just had a conversation about a 2500CFM app. !
?
what are you going to use as the air pump ?

[bigben2k]

A DC blower, probably automotive, with controls.

I'm looking at the blast plate, and wondering if I could do an iris instead (complicated and time consuming, I'll probably pass). Been watching Stargate too much.
http://www.turbosquid.com/FullPrevie....cfm/ID/256262

edit: nope it won't do, since it can't be sealed.

[BillA]

some where on the site is a link to a surplus place from which I bought a huge one (at Swiftech), think it was from a Ford truck
this would be better than the Tarzan I think, I'll hunt
bingo
http://www.surpluscenter.com/item.as...tname=electric
$50 it is a beauty

[BillA]

another approach
http://cgi.ebay.com/ws/eBayISAPI.dll...MakeTrack=true
lower resolution

[bigben2k]

Can't find (readily) a 32" diameter tube. A 55 gallon drum would be ~22 inches:
http://www.zorinmaterial.com/product...cfm?product=77

Estimating length to be 3X the diameter; I need a salvage yard, and a trailer! (have hitch, can rent trailer)

[BillA]

lets think on this a bit
got a torch, grinder, welder. etc ?

[bigben2k]

I'll sleep on it.

I was going to pick up a grinder anyways...

[bigben2k]

[edit: removed off topic ramblings]

Today I'm going to put the nozzle (dP) calculations in an Excel spreadsheet, and continue to try to source a tube.

[BillA]

bummer
look for plastic too in 24 -32" dia (I may go 32 w/you, but not a steel drum)

[bigben2k]

Thanks.
Agreed. The only way I see steel working, is if I can get both halves in the right size, and use JB Weld to put on a flange; not likely, and not practical.

I also prefer plastic. I'm leaving an option open for cardboard, but I don't think that'll be anywhere near as easy to find (nor practical) as plastic.

[BillA]

settling vanes/egg crate ?

[bigben2k]

settling vanes?!? You mean the flow straightener?

[BillA]

yea

[bigben2k]

If you mean this:

then yes, was thinking the same, with a preference for thin alu. Definitely not a DIY item (you reading this Brian? )

[BillA]

actually rather easy if you have a source of al flatstock
stack and cut on a bandsaw all at once, interlock together
(I have a bandsaw)
1 1/2 x 1/16" strip ?

[bigben2k]

Seems reasonable, but they make these (shapes) for office fluorescent lighting too (plastic or "chromed" plastic).

At 32", might be easier to make oneself, rather than try to find one big enough, or try to patch a couple together. Dunno.

[BillA]

I'd patch if cheap
?