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The perspex and frame just lifts off. So I can test with or without it. I have a wind speed meter (anemometer) and the twin fans blow about 35mph after the flow straightening straws.

Nice project so far, i love the lego parts in it!

Once you start the first runs i think you should measure the distribution of the speed of the air entering the test section right after the flow straightener.
Is it the same for the whole cross section, is it higher in the center than in the corners?

Next thing i would compare is how much do the numbers you get differ if you use the perspex hood or not for the same model.

Some critics:
The frame holding the perspex should be on the outside, the tyre pads should be in the same plane as the ground.

Hi, thanks for the comment. The tunnel roof is on the inside of the frame, its 4mm perspex. The sides however are inside, due to it only being 2mm thixk I decided it needed to be on the outside to be able to fix it to the frame better for rigidity. I was hoping the frame wouldnt interfere much as the back of the frame is well past the test bed and the front just blocks off some of the flow on the outer edge of the tunnel. As for the blocks that the car sits on, I will be changing the for some thinner ones (currently 12mm MDF, for something 6mm. Plus mak8ng the fit alot more snugly in the holes they fill. Hopefully meaning I can experiment with ground effects.

Love that there's Legos in it

Absolutelee wrote:Love that there's Legos in it

Everyyhing I make always seems to end up with a little lego in it

as previously mentioned, your car is blocking way, way too much of the tunnel cross section to get any meaningful results.

flyboy2160 wrote:as previously mentioned, your car is blocking way, way too much of the tunnel cross section to get any meaningful results.

I will give the same car a run at the same speed tonight, with and without the tunnel. Then will post the results on here. As you say, I too think it way be too small.

Would the fans be more effective if they were positioned in ducts?

seventhsin wrote:Would the fans be more effective if they were positioned in ducts?

I have no idea, its my first ever wind tunnel, and i have no background in anything aero. So its pretty much trial and error. I can add these things no problem, so its just a case of updating my wind tunnel, who knows this time next year I may need some down time to upscale to 60% like Mercedes have just done

Im pretty sure it would benefit from ducting, I dont know alot of aero either but I'd imagine you would be losing flow around the tips of the blades.

Plus every wind tunnel picture I can think of is ducted.




Impressive

NathanOlder wrote:

flyboy2160 wrote:as previously mentioned, your car is blocking way, way too much of the tunnel cross section to get any meaningful results.

I will give the same car a run at the same speed tonight, with and without the tunnel. Then will post the results on here. As you say, I too think it way be too small.

the fan area is also much too small in relation to the size of the car. you will have mixing flow with the stagnant air.

if you could control the room you test in it might be better to leave the system open no edge effects this way.

Well I think he has done a great job, might build one myself.

So far it will be good for model work to find basic effects from changes on the cars.
He should be able to improve the tunnel as he goes.
Great job.

Very cool project, looking forward to seeing testing results and further development of the design!

Autogyro, Paul
Thanks guys. I will spend some serious hours at the weekend testing. I have made a floor and rear diffuser for the car. First I will adjust the height of the wheel pads. I also will be testing with and withought the perspex tunnel. All results and findings will be posted for you guys to see. Thanks everyone for your input, much appreciated