A not for profit, pay-only-costs open results wind tunnel in a developing country?

[aerogreen]

I just realized aerodynamics design is my passion.

Along with a few other guys here, we are seriously planning to build a not for profit, wind tunnel in a developing country.

We already have a bunch of discarded (yet perfectly running) airplane engines and propellers, even some turboshafts.
They are in mint condition, but they must be retired from service after a set amount of flight hours for security, even if they still are almost like new.

We intend to get a free big landspace to use for free, from the local airspace authority, a university or even from the local gov't thru a technology-promoting entity.

We'll need to build the tunnel
What buildng materials can be curved? Drywall?
And some custom curved lexan windows?

For the flow conditioner to avoid turbulence maybe some plates curved to honeycomb or some thin wall tubes welded together.


More later...

[aerogreen]

While initially crude on instrumentation the airplane engines and propellers will make it big and powerful.
Will elaborate more on technical stuff later.

Even tough its a non-profit organization, a "business" plan is the first step.

Being non-profit the aim of the wind tunnel is to charge only running costs like engine fuel, smoke chemicals and lighting electricity bills.

All test data and results will be made public as a contribution to mankind.
Youtube videos come to mind to keep web hosting costs low.
Although if possible the tunnel may also charge extra dollars for closed doors testing where results are released only to the customers. For example small car racing teams may choose to use this private service as not to be copied and surpassed. This extra income must be reinvested in equipment and facilities.

Customers will need to send the model by UPS or some similar company, prepaying for return if they want their model sent back after testing.
Model mounts and attached points will need to be standarized.

Green research will be given the highest priority for example zero or low emission vehicles, solar concentrators, heliostats and solar panel arrays and green buidings.

The tunnel may charge some extra (small) fees for model building, placing tufts, oil or evaporating chemicals on the model surface.
Minimum wage in that country is a bit less than $300/month for a workweek of fourty-something hours. Minimum wage isn't defined by hour in that country.

The tunnel is open to donations and to keep them honest only low wages will be paid to its employees. Low wage employees will do easy repetitive labor like sanding and gluing models, attaching tufts, cleaning, maintenance.
At least one highly knowledgeable aerodynamicist/manager will need to be hired. It must be discussed if higher wages can be paid for the manager or if his salary must come from a separate donation.

[ksa8907]

Whew, good luck with it.

[aerogreen]

Now some technical stuff

The first thing to calculate is the size and power required.
Ideally the tunnel would accomodate a full scale car or small plane without having to have a tanker ship engine to power it.
Reportedly several "small" engines and propellers can be run parallel.
For wind flow and speed calculation ease all propellers will need to be identical. Do all propellers need to run at the same time? At the same rpm?
Some wind tunnels like A2 a2wt.com can operate them at different rpms. Why is that?

What ratios of propeller area to test section area can be used?
I heard that higher wind speeds can be achieved by constricting the tunnel I mean a narrower test section area than the propeller area by Venturi effect.

How much of the test section cross area can be used for the model?
Are there ways to increase this useful area?

[ksa8907]

I don't mean to be rude, but are you fully aware of the cost involved in building a wind tunnel for testing? The size of the project? I'm not exagerating at all, youre talkin millions.

Have you researched what kind of facilities car companies have?

[niky]

Originally Posted by aerogreen

Being non-profit the aim of the wind tunnel is to charge only running costs like engine fuel, smoke chemicals and lighting electricity bills.

A sustainable non-profit must factor in the costs of construction and amortization for that funding if it's to be a continuing operation. Otherwise, it'll fold after a few years, as you are not charging enough to maintain it or to save up for upgrading and eventual replacement.

[kennybobby]

You may want to have two test chambers--one for small models in addition to the full scale testing.

The inside wall shape will need to be designed by you using aerodynamics just as in wing and foil design. The inside wall could be built like an airplane--structural frame covered by thin sheetmetal skin with countersunk rivets, etc.

The range of speeds you want to test will help determine how much energy and power you need. Determine the volume of the chamber and consider the weight/ mass of this much air moving at your speed as the base, then add the aero drag of the walls and of the test article. That will get you in the ballpark and will be quite large for full scale--that's why folks use small tunnels and models.

[aerohead]

You might consider the book,'Low Speed Wind Tunnel Design,' by Alan Pope.It will walk you through all the different types,their merits and shortcomings.
Wolf Heinrich Hucho also covers various tunnels in his 'Aerodynamics of Road Vehicles.'
Conservatively speaking,GM,Lockheed Marietta,and NASA Ames are the only tunnels in North America with test sections large enough to satisfy full-scale model criteria.
The Pininfarina tunnel at Turin,Italy would be the absolute bare minimum.
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*You'll first need to select the 'type',then design from there.
*The test vehicle cannot occupy more than 5% of the test section cross-sectional area,so you largest vehicle will determine the test section size.
*A minimum airspeed of 20-mph is required to produce a turbulent boundary layer/proper Reynolds number .
*If say,you were going to test a full-size SUV of 36 sq-ft frontal projected area,your test section would need to be at least 720 sq-ft.
*At 20-mph,the test section airspeed would need to be a minimum of 1720 ft/min.
*And flow volume produced by the fans,1,267,200 CFM,and at a static pressure high enough to overcome all the surface friction losses from the ductwork,turning vanes,stator vanes,fan(s),radiators (if your recycling your air),turbulence screen,etc..
*And you'll need your force measuring equipment (Sting,load cells,knife-edge balance,with boundary layer control,with capability for maybe a minimum of 8-degrees of yaw.
*A moving floor has been deemed 'statistically insignificant' by some researchers who did back to back investigations.So you could probably skip that expense.
*You are looking at millions of dollars,even if it's measured in sweat equity.
*Hundreds of thousands in materials.
*"A trial by fire measured by any standard "says Ayla of the Clan of the Cave Bear.

[aerogreen]

Originally Posted by ksa8907

I don't mean to be rude, but are you fully aware of the cost involved in building a wind tunnel for testing? The size of the project? I'm not exagerating at all, youre talkin millions.

Have you researched what kind of facilities car companies have?

Professionally built wind tunnels cost a lot.
That's why I think there's some room for this amateur built yet pro sized tunnel.

Pros
Special variable RPM electric motors
Us
Discarded airplane engines

Pros
Custom built propellers
Us
Discarded airplane propellers

Pros
Designed by well paid engineers
Us
Designed at no cost by us

Pros
Built by well paid contractors
Us
Built by the local drywall and sheetmetal contractors

Pros
Curved walls and windows and their supporting ribs.
Us
Flat walls and windows
I'm thinking that while less efficient a rectangular section tunnel can be built to avoid the costs of round walls, windows and floor.

Pros
Custom made dual-curvature nozzles, diffusers, vanes and flow conditioners usually requiring custom molds.
Us
Simple flat or single curvature nozzles, diffusers, vanes and flow conditioners made from plain sheet metal or drywall.

Pros
Specially made to order flow straighteners
Us
simple straighteners made from sheet metal or thin wall tubes

and so on
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Originally Posted by niky

A sustainable non-profit must factor in the costs of construction and amortization for that funding if it's to be a continuing operation. Otherwise, it'll fold after a few years, as you are not charging enough to maintain it or to save up for upgrading and eventual replacement.

So true
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Originally Posted by kennybobby

You may want to have two test chambers--one for small models in addition to the full scale testing.

The inside wall shape will need to be designed by you using aerodynamics just as in wing and foil design. The inside wall could be built like an airplane--structural frame covered by thin sheetmetal skin with countersunk rivets, etc.

The range of speeds you want to test will help determine how much energy and power you need. Determine the volume of the chamber and consider the weight/ mass of this much air moving at your speed as the base, then add the aero drag of the walls and of the test article. That will get you in the ballpark and will be quite large for full scale--that's why folks use small tunnels and models.

Did you mean cocentric test sections one inside the other?
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[aerogreen]

An inspiration to us is the a2 wind tunnel
A2 Wind Tunnel

It's narrow yet full scale cars are tested there


I really wonder how they avoid interference from the closely placed walls. I read somewhere that they adjust the ceiling height or shape to the shape of the object to be tested.

It can run up to 85 mph and is powered by three 72-inch 200HP and one 42-inch diameter 40HP, electric fans.
We aim for higher speeds coming from more propellers and engines.