Wanted to try some push/pull testing.
Special thanks to Masika for sponsoring the Noctuas, and Hondacity of the GT. Thanks guys..
I struggled trying to think of the proper scenario here, so I just went with some random ideas and figured I'd see how they turn out. In the end, I'm not completely satisfied... I think I need to build some sort of flow spreader between the radiator and anemometer vane for the CFM values to be more accurate. Oh well, the tests should provide some value and were a good draft run.
Noctua Push vs Pull vs Push Pull Test 1 (ALL PUSHING INTO FLOW METER)
http://www.youtube.com/watch?v=VHhKyViTSqE
First I ran the Noctua with both fans mounted and switched around which fan was turned on, push then pull then push/pull. Obviously push+pull will be stronger, but I'm not believing it's THAT much stronger. Both fans were run in parallel for power, except the second fan had the RPM readout on the second controller. It appears there is either a small amount of Vdroop, or you can simply expect the pull fan to run higher RPMs...because that's what happened. It's probably better to run each set on a different controller so you can intentionally match up the RPM levels. I didn't do that here, I purposely ran them parallel so I could see what would happen.
Gentle Typhoon Push vs Pull Test 2 (PUSH INTO FLOW METER & PULL)
http://www.youtube.com/watch?v=wXk0pfzC3Co
Second was just an arbitrary GT ran in push, then flipped the fanaround and tried pull and covered the microphone with a little wind deflector. I don't think my anemometer is particularly mounted such that it can test equally in each direction. I've also got all sorts of wind noise in the pull scenario. I guess it does at least give you some idea...the pull condition seems to have less harmonic issues than push.
CONCLUSION
I'm not quite sure yet...need to review the videos a bit. I do like the push/pull power and sound qualities at the lower RPMs, but not sure about the slight pulsing you get at higher RPM...but I suppose some of that could be tuned out if you had a controller on each channel.
Regarding push vs pull...not sure. I know in radiator thermal based testing that I ended up with some varied results (pull being better in low speed, push being better in high speed). I suspect it depends on each fan to some degree. Noise wise, I think the deeper you can bury the fan the better but either way works fine. Right now it's looking like push is slightly better for decreasing noise but it's also not performing quite as well.
Feel free to post your own experiences...I'm on the fence. I may consider some shroud based testing next.
Cheers!
Martin
All of these are ran with the radiator now filled with water..and include the spectrum recording in the corner for a view at frequency spikes...
Oh and a quick setup picture of the noctua test 1. The GT was similar except I had to pull everything apart and reset so you should not compare the two videos...they are intended to be stand alone tests.
The second picture is a concept of a new flow chamber I'm thinking about that's really needed to do this sort of testing. What I have now doesn't seem to work very well.
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