flow performance test

[rookie37]

At work we have a metal shed that sits in full sun. We cut windows (no glass just open holes about 1 x 1 meter) in it to improve ventilation. However the holes had to have louvers in order to keep the rain out. Vermin was also a problem. wire mesh had to cover the 1x1 meter hole. The louvers also reinforced this mesh from wobbling as it is too frail to span 1 meter.

I think the design of these louvers is an overkill. While they do a wonderful gob keeping the rain out, they reduce the ventilation. I would like to remove every 2nd louver. This would increase ventilation but still be adequate to keep the rain out. I can model it in Inventor or 3d Autocad. How do I test the flow? I'd like a before my proposed modifications and after.

 

[dbill74]

Going back to your concern about the "Keep rain out aspect" of the vent design. The vent's design to keep rain out is not overkill, it is designed to keep rain out up to a certain free area velocity, usually (not always) 500 FPM.
Aside from the free area velocity, the shape of the blades are designed to change the direction of the air and "extract" rain via centrifugal forces.
By removing blades, you reduce the reduce the free velocity needed to keep rain out from 500 FPM to 250 FPM or less. (I'm guessing what the new rain penetration will be, but you get the idea anyway I hope.)
Also the straighter path means easier for rain to get through.
So unless you reduce the amount of air going through the louver (not your stated intent) to keep the free area velocity below the penetration velocity, removing louvers is a bad idea. To add louver area without going below the rain penetration velocity you will need more louvers.

 

[MisterE2]

What's the temperature at night? you could just add some thermal capacitance, i.e. a fishtank full of water, that or make it more reflective as its key source of heat is just going to be the sun.

 

[MisterE2]

also, you won't be able to check the flow rate, you have natural convection which is being interfered with on a minute by minute basis by heat loss by natural convection... well not won't be able to but it would take at least a month to run a CFD simulation, converge it and then calculate the heat loss, calculate a new flow rate, then calculate the new heat loss, you kindof get the picture.

 

[macmet]

You may be able to use assumptions to get a range of flows. Find a best and worse case. Did you say earlier that you had louvres at the top and the bottom of the space?

 

[Wilbur55]

What he said earlier is still on this page. Where do you find the word "top" used?

 

[macmet]

I guess I could have just a search... anyway, I did one now and the message I was thinking of was not from the OP, who seems to have lost interest already.

 

[rookie37]

I didn't really lose interest. I just see that my question has been answered (sort of) I can't conduct a physical test. (smoke, differential pressure....) From the answers that I got I conclude that it cannot be tested as a computer simulation without spending a great deal of money.

It was not made by a manufacturer that I can ask questions from. The 'water keep out' properties is such an overkill that little or no thought was put into the design. I can't even see through the window. I can only see reflected light. I can't see outside at all. However this is no problem. Ventilation is the ONLY reason why the window was put in in the first place. I think they over did it a bit on the rain protection. I would like to propose an alteration that cost little or no money at all.

http://content.screencast.com/users...-5619-4cba-9f50-a0035ad6802a/shed louvers.jpg