Wind Tunnel Construction

[BillA]

at $40 + $19 shipping, buy another motor

[bigben2k]

Why didn't I think of that... it's got a standard 1/2" shaft.

[BillA]

because you always make things more difficult
??

[Etacovda]

Originally Posted by BillA

because you always make things more difficult
??

** Etacovda laughs

[bigben2k]

Originally Posted by BillA

bought a blower
http://cgi.ebay.com/Dayton-2C820-Rad...QQcmdZViewItem

BTW, there's a small discrepancy that you might want to be aware of:

The Grainger site lists the motor as 1/2 HP, and the eBay listing has the blower setup with a 1/3 HP motor. I don't think it'll make much difference, unless you plan to push the edge of the 5" wc pressure drop.

I should win a 2C820 too, unless someone outbids me on it. I'm finding a 120 Vac motor for it:
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7588113994
(might get another one than that, seller is fuzzy on the specs)
and controller:
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7589764727

[BillA]

yea, if the fan is operated at very low back-pressure it will burn up the motor - easily

that speed controller is for ceiling fans, will not work
get a 1 to 3 phase speed controller, $150 + and use the 3 phase motor with a blast gate

spent yesterday looking for a copy of AMCA 210-99, $90
tried an interlibrary loan but from OK is unlikely, probably a ref copy

the diffusers are screens with different gage wire and spacing
the 500 CFM unit from fantester uses a 16" tube, ~ok for 2 120mm fans in parallel; w/o the blower or gate $6900

a 32" dia concrete form tube is $116.80 for a 12' length
a 34" spiral formed steel duct 7' long is $129.00
either would need bulkheads, etc., etc., etc
am now thinking to go for 20 to 24" dia, looking for a surplus aluminum pipe now - easier to weld

awaiting a quote on the nozzles, not yet sourced the screens

[BillA]

nozzle prices from Helander

.687 $63.53
.750 $69.88
1.000 $76.23
1.250 $82.58
1.500 $88.94
1.600 $88.94
2.000 $101.64

adding taps in 1" and above about doubles the price
plugs are $10.50 ea

so ~$400 for 500 CFM worth

[bigben2k]

I was afraid of the Helander prices. I'm going to buzz Jon. Taps are out, but the plugs are a common hardware store (Lowe's) item, albeit maybe not in all sizes.

http://www.electricmotorwarehouse.co...e_inverter.htm
I'm thinking variac with the 1/2 HP 120v motor; think it'll work? I need a cheaper option than $150. Even a belt or chain drive with stepped wheel would be cheaper than that converter.

Keeping my fingers crossed on the blower; am being outbid. Hopefully the seller has more (been listing them for a while now).

Good find on the concrete former; local? Can we split one, or is 6' too short? Darn, it's a bit short... Really need 7 feet, at 32".

I could make bulkheads from commonly available plexiglass sheets, cutting and stacking multiple parts. A bit tricky, but cheapest of all. Thinking fiberglass & resin to seal the bulkhead to the tube. I'd have no problem using JB Weld on alu (the stuff is available in larger quantities).

I believe that standard/common screens are of the 75 or 67% opening, variety. Again, cheaper to stack them, and combine an egg crate. i.e. 2 stacked before the egg crate, then 3 stacked after. (duplicated on both sides of the nozzle wall). Any thoughts?


Am planning a stop for the phenolic this week, and possibly some surplus shops for the egg crate, time permitting. I believe that CDscrapmetal is closer to you.


Got a new toy: http://tasktoy.com

[BillA]

what size/thickness phenolic you need ?
I have a fair amount

would suggest 20 or 24" dia

run the blower flat out with a blast gate
you need to learn "simple"

[bigben2k]

3/8" preferably, but will settle for anything right now. Need a 3" wide strip, enough to construct a box.

I'm also leaning towards a smaller diameter; 32" is not handy (bordering on ludicrous), and would have wheels, like fantester's biggest unit. I have no problem/concerns/qualms exceeding the specifications, if testing an 8" by 6" core, on a 24" diameter tunnel.

Got a source for 24" concrete formers? At 24", we could split a 12' length.

Yeah, I'll get the motor first, then try it out. If I want to add motor control, I'll do it later. Lost the blower; better luck on the next one.

[BillA]

eh ?
3/8 x 3 x ?

Burris Contractors Supply (281) 657-8900

[bigben2k]

3/8" x 3" x 3", 6 times.

[BillA]

1/4" ok ?
why so large ?
put the phenolic next to the slug (?) with an air gap

[bigben2k]

1/4 is perfect.

I got the heater inside the box, and doing a vacuum. It might end up being only 1" tall, not sure yet. I can PayPal you something.

[BillA]

I'll wack off a piece tomorrow, I'm in Shoreacres - want to pick up ?
no $, you owe me
lol

[bigben2k]

I'll save the meeting for another time. You have PM with my new address. Offer stands, at least for shipping.

[BillA]

why do you keep avoiding the titty bars ?
NO other reason to live in Houston
(I live in Shoreacres, lol)

[bigben2k]

Moral objection, being married notwithstanding. How about that bar in Kemah, the one with the 20 foot tall fishtank?

Am working on a PID setup for air temp. More when I have the controller in hand.

[BillA]

don't get too exicited, they make more than we do

ck your PM

[Brians256]

Darn straight they make more than we do. With strippers, you get screwed not laid.

Ben, how much do you know about tuning a PID system? This may get interesting when you actually try it....

[bigben2k]

The PID control is going to be another learning effort. I understand the general principle, and I downloaded the manual for the unit I spotted on eBay. It comes with a "pulsed voltage output SSR drive", forward and backward, and can be configured manually, or let the fuzzy logic circuit figure it out. The only part I'm not clear on, is how I'm going to integrate a heater to the whole thing, nor what kind of heater. The unit is spec'ed with a 1 second response time, minimum: I'm not even sure if it's going to be enough, or if I can somehow make it work with a slow response heater. Right now I'm still trying to figure out the details of the "pulsed voltage output SSR drive"; it'll pretty much make or break the idea.

Looking at it backwards, I'm targeting for it to maintain a 25 deg C air inlet temp, with minimal fluctuations. I have yet to define what "minimal" is, but I can figure it out, that's not a problem.

Interesting indeed; if this works out, the same effort could be used in a water cooling loop. The dynamics are a bit different, but the application is the same.

Temp probes gallore coming... and I haven't tested my GPIB network yet!

[bigben2k]

Went through the PID manual last night, got 2 pages of notes. Will know more when I have the unit in hand. Auto-tune is going to be limited (needs a 40 deg C span) , but fuzzy and PID will be available.

Stopped by Lowes today:
-egg crates available, ~1/2" squares, ~1/4" thick. 2' by 4' sheets, ~$10.

-screens available; door screen (reticular implant estimates 85% opening) and "dog-resistant" screen, reticules to ~67% (brick pattern). $5 to $10 for a roll. Manufactured by Phifer.

-picked up a "test plug", 1 1/2". Expands to 1 5/8", at best. No smaller sizes available there. $2.

Today I'm going to source an SSR, and continue to try to master the calculations.

Uncle Sam is blessing me with a fat return

[bigben2k]

Bought a 1" plug at a local auto parts store. $3. Other sizes available, but none smaller.

I should find out at the end of today wether or not I'll win the controller I've been eying.

This week; keeping on the flow calcs, and paying Bill a visit.


Sidenote: went through the Leybold vacuum primer (200 page, is there anything better to do on a Saturday night? ), for the heat die / test chamber. Most informative! Spent Sunday repairing my bumper.

[bigben2k]

Victory!

FUJI PYX-9 FUZZY CONTROLLER
http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7590593467

The manual
(PDF, 98 pages, 669kb)

More info

[bigben2k]

Just got back from visiting Bill; thank you Bill for a very informative learning session!

To update everyone else, since Bill is going to have access to a wind tunnel, I've bought the blower, blast gate, and hose that he had already acquired.

I'll be experimenting with the temperature controller that I just acquired, but after discussing it with Bill, it's now clear to me why it is going to be a problem. In short, Bill showed me his environmental chamber and the design of it. It is composed of a refrigeration unit and a heater unit. The air is recirculated in such a way that it is first cooled, then heated back up to the desired temperature. The reason for doing it that way (cool then heat) is to eliminate any fluctuations. The Haake chiller works the same way.

Thinking about it on my drive to work, the temperature controller probably won't be able to maintain a very steady temperature (which I've suspected). I'll test it out (in a small makeshift setup) and report results.

I have to make notes about everything Bill showed me today.