All of these cases have a big problem. Can you tell what it is? If you said the
intake fans are starving for air flow, give yourself a gold star. This was a
widespread problem in case design for years. But new airflow edition cases
have flooded the market, completely solving it. Or have they? See, there's
nothing that Lee and Lee or Fractal can do about users shoving their cases right
up against the wall or on top of a shag carpet. You could be totally killing
your gains, bro. >> Killing your gains. >> Killing your games.
>> But by how much? How much space does a
fan need before it gets starved for fresh air? To find out, we sent Adam all
the way to NASA's Langley Research Center in Virginia. Oh.
to work with some of the top scientists in America [music] to figure out just
how close is too close for good PC
cooling. And how close is too close for me to
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I know how I would try to answer our question, but where would NASA start
with a problem like this? >> Great question. We're at the hypersonic
test complex at the NASA Langley Research Center, and we're going to do
some super scientific stuff, and that means we're using this tape and this
string. I'm not even joking. This is called tufting and it is decidedly low
tech but it remains one of the most important forms of aerodynamic testing
that can be done and it's basically where NASA starts every single time. You
see air is difficult to study because it looks like this.
[screaming] >> So we rely on the way it affects other
things to understand its behavior. >> Wow. I wasn't that far off. What you're
looking at is a Noctua NFA12X25
with some acrylic acting as our airflow restrictor or our panel. With tufts or
little pieces of string on the back side of the fan, we can see how adjusting the
distance of our panel from 3 1/2 cm down to just.5 cm affects our air flow. We'll
put the specifics up on the screen and you can pause and read them.
>> Actually, we changed our minds. There's an article on the lab website. It's in
the description.
So, what did we find out? Well, a few things. As you'd expect, at an ample
distance from our panel, our fan performs admirably, sucking air in on
one side and blowing it out the other. What I didn't expect, though, was that
the toughs near the center only started to get a little floppy when the front
panel got really close, just 1 and 1/2 to 2 cm from the face of the fan.
Another thing I didn't expect [music] was that getting even closer caused the
fan to not only blow ineffectively, [music] but even start sucking the tufts
back into the blades, indicating reversed air flow. But it's a little
hard to see like this. Oh yeah, I forgot. These are strings. They glow in
the dark. We took this big ass NASA grade ultraviolet lamp to get maximum
glow from our tufts while we recorded on this beast, the Kronos 4K12 high-speed
camera. We're prepping our 1,00fps 4K
camera. That's about 11 GBs per second
of data, which means that recording on this for a minute is going to be bigger
than your Call of Duty install. And in slow motion, we can get a much closer
look. Note the increased tough movement in our close-up test condition,
indicating more turbulent flow. And you can even see some of the toughs dragging
into the middle of the fan where there's areas of low pressure. Pretty cool, huh?
>> Super cool, Adam. But we have Kronos camera at home. Why did we need NASA for
this? We didn't. But for what we're going to do next, we sure did. And
besides, if NASA invites you out, are you really going to say no? They were
even nice enough to give us a whole tour that included an incredible new maker
space that they use for rapid prototyping. Our supporters on Floatplane get exclusive access to that
and a ton of other content. So, if you want to check that out, head over to LMG.gg/flatlane.
For now, I'll just give you a TLDDR. The Langley Research Center is kind of the
OG NASA facility. In fact, it predates NASA itself. Founded in 1917 as part of
the NACA, which is the aeronautics organization that would eventually
become NASA, the Langley Research Facility was key to numerous discoveries
and improvements to early flying machines, creating the first hypersonic
jets and paving the way for space travel and would go on to play a key role in
the Apollo missions. Currently, one of the focuses of the research center is
assisting the Artemis campaign to get to the moon as a means to get to Mars.
Pretty cool. a little bit out of the scope that we're going to be working on today. So, we're going to steal a couple
of the 3,500 employees that come here every day to do some uh more down to
earth testing. We're inside of the hypersonic test complex at the NASA
Langley Research Center to answer that. Wait a second. This is the same lab.
>> Yep, same lab. >> I thought we were supposed to go somewhere that was like more high-tech.
>> Oh, it's more high-tech over there.
>> Oh, right. And this is uh Dr. Lewis Edelman. He's a researcher here at NASA
and he's helped design all of these experiments that we're going to be running today.
>> Hello. So, what the heck are we doing? >> So, we've moved on from tuing to
particle image symmetry or PIV. >> Oh, flashing lights and fancy cameras.
Sounds like my kind of deal.
First, we shine a bright light focused into a thin vertical sheet. Then, we
fill the air with, you guessed it, particles and start rapidly taking
pictures. [music] Now that might sound like video, but it's different in one
important way. Instead of taking images at a constant frame rate, we instead
take two samples just microsconds apart
followed by a short gap, then another two samples, and so on and so forth. We
can then use really clever math to determine the velocity of the particles.
Note that this is not speed, but velocity because we're talking about how
fast they're going and also their direction. Sounds simple, right? I mean,
not really. But for starters, the particles we're tracking are not air,
which means that they won't move exactly [music] like air. Second, to do this
right, we need the velocity of many particles. That [music] means thousands
of samples across thousands of images. And third, we need some pretty special
cameras. The Levision Flowmaster is a super high precision machine that uses a
double frame buffer to take photos just nanoseconds apart. All right, it's
finally time to test. Hit it.
>> So, this is [music] our first test result. That means there's no
obstruction on this fan. It's >> no obstruction, pure control. So, we've just we're doing the analysis now on one
image pair as a test for the processing stream. And we go, okay, that's uh not
very clean. Once we take an average of the 200 or 158 images we just took, this
will fill out, >> okay, >> to look like a fairly nice picture.
>> Importantly, that this is kind of the hub. Like we're really we're really only looking at the top half of the fan right
now. >> We're looking at the top half of the fan. >> Would it be fair to expect that there would be I mean it's a circle, so
there'd be symmetry on the bottom. >> I would expect radial symmetry in all
things you want to try and measure in as much detail as possible. So if we were
fully zoomed out and looking at the whole fan, we'd be wasting resolution
effectively. So this is it applying the scaling um from pixel space to physical
space from our calibration plate. Now it's starting to do the PIV and we can
see for our 158 frames that's probably
going to take about 20 minutes. >> What is this computer running on? >> Um this is a um i9 14900 [laughter] K
with 192 gigs of RAM.
>> So this just takes a long time is what you're telling me? >> Yes. After considerable number
crunching, we've got our results. And what you're looking at is a narrow slice
of air that is flowing out of the fan. The colors indicate the streamwise
velocity of the air. So, how fast it's going away from our fan blades. And then
the arrows are kind of just an easier way to visually process that same
information. Then, to make it even simpler, we added these dots. Without a
front panel, flow is smooth and fast moving. There's a small section where
you can see there's no flow, but if you look closely, that's right behind the
fan hub where there are no blades. Now, it is important to remember that this is
just a thin slice of the overall air flow in what is a 3D space. Our test
isn't going to capture the spiraling 3D vortex of [music] the air, but the
overall direction away from the fan is what's most important for cooling. So,
this is good enough for our purposes. Fun observation. By the way, Dr. Dr.
Edman noted that the way that Noctua's fans throw momentum inward more than a
typical fan contributes to reducing their overall noise. Good job, Noctua.
When we move the plate closer, we don't see much change. That is until, just
like in our tuft test, we get as close as about 15 mm. Take a look at how large
our dead zone has become. Now, we also noticed that the flow of air is starting
to curl outward rather than coming straight out of the fan. What that means
is lower streamwise momentum to blow air across your components or to pass
through a restrictive heat sink or radiator. But why? Well, it's due to the
difference in radial pressure. The air that passes through the tip of the
[music] fan blades is lower pressure and almost bounces off the stagnant and thus
higher pressure air that's right by the fan hub. This isn't optimal, but our
overall air flow is still pretty good. So, for a case fan, it's probably still
fine to have this much restriction. We will check on this test condition again
later once we add a radiator. For now, let's look at our worst case scenario in
open air. Imagine your case is right up against a wall or your power supply
intake is on the floor on a carpet. This
is what you're doing to your poor poor PC. Not only is the fan barely pulling
any air in at the edges, it is so starved for air that there's a reverse
flow that causes the air to curl into a vortex that isn't going to move heat
anywhere. And that's your best case scenario. What if we were trying to cool
something directly with our starved fan?
To find out, we whipped out a water cooling radiator to create a scenario
with much higher back pressure. You can think of back pressure as the friction
that a fluid experiences in movement. And as you can see, adding a ton of
friction to an already restricted fan results in a two-word review of my debut
rap album, zero flow. Now, naturally, backing this off to a 15 mm gap, yields
much better results. But it's still worth noting that this is a massive drop
in performance compared to our free air test, especially with respect to the
size of our dead zone over the fan hub. Practically speaking, we're only getting
flow on about the outer 50% of the fan
blades. Interestingly though, the radiator completely straightens out the
flow and we don't see that same outward curling, but the speed is cut about in
half. So, what does all of this mean? Well, we can't draw overly broad
conclusions. We only tested the NFA 1225 at full speed, but it seems like you can
get as close as about 15 mm or a little
over half an inch from your fan with reasonable performance. Any closer and
you are seriously harming its cooling ability. An obvious question would be,
why go to all this trouble? Couldn't you have just sent a piece of acrylic and a
fan to Cybernetics to put in front of their fan tester? Well, yes, but also
no. While a fan tester would tell us the performance of the fan under various
conditions, we were more interested in measuring the behavior of the air, which
tells us not only the answer, but it also lifts the veil on why the answer is
what it is. It also gave us an excuse to check out another really cool piece of
kit down in Virginia. If you thought air was complex, well, just wait till human
perception gets involved. Yeah, we're going to talk about sound. Now, we have
been hard at work improving our audio testing at LT [music] Labs. I mean, we even just built a home theater room to
test more speakers now. But what we don't have is a NASA grade audio
chamber. This is the [music] shack, and it's a little old place where we can do
some testing. The small hover anooic chamber was constructed in the late 80s
and it gets as quiet as 18 dB, which is
disconcertingly quiet. For our testing today, we're using two different arrays.
A linear one up there and a spiral one. Why are they different shapes? Well,
they have two different jobs. The linear array is a directivity array [music] that gives us a broad idea of where
sound ends up in the chamber. The spiral array, also called a phase array, is a
collection of 40 beam forming MEMS microphones. It allows us to get super
[music] detailed information about the source of a sound. These microphones are
so precise that we can map the location of the sound onto footage from the
camera that sits in the middle of the array. >> Essentially, you can define a region in
here and it will perform uh an integration. So, right, it's a little
hard to see, but right now it's just region 1, 2, and three. And then you can
basically go ahead and have it process it and give you a spectrum like this
with the different contributions of those regions to the total sound field
or at least what it what their array picked up. >> Why would folks at NASA need to know
this kind of stuff? Well, when they're testing the acoustic properties of something, they want to know where that
sound's going to be coming from. Like this, for example, they might want to understand if the sound is coming from
the tips of the blades or [music] if it's coming from the rotor itself.
There's only one way to find that out, and that's to use the phase array. I
mean, there's probably another way to find out, but the way we're going to do is the phase array. So, stop asking
questions. >> Well, you can ask one more question. If you noticed our fan is looking a little
pink. >> Why would folks at
>> That's because this apparatus was designed to test rotors for things like
drones. So, our NFA2X25 that we were
using before, it was a bit too quiet and we swapped it out for this industrial
version that runs considerably faster and considerably [music] louder. The
paint that's on it is this funky pressure sensitive paint that we were
going to use for another test, but we ran out of time because NASA has a lot
of important work to do. [music] Anyway, I bring up the paint because it might
make the fan perform a bit worse than what Noctua would ship from the factory.
But we aren't comparing it to other fans. We're only comparing the intake
clearance, so we're not worried about that. Again, because of time constraints, we decided to just test the
fan without the front plate and at [music] the 15 mm point. Now,
intuitively, you might think that covering a fan would decrease the amount
of noise that it makes, right? But if you've ever tried placing your hand in
front of your PC fan, you might have noticed that it often gets louder up
until the point where it becomes completely starved of air. And in
[music] our test conditions, that's true. You can see a broadspectctrum
increase in noise when the front panel's present. Why? Well, referring back to
our PIV results, remember the stalled flow in the middle? that causes the
overall air flow to be more unsteady, which makes it louder. Think of it like
roaring rapids versus the smooth flowing water in the Mississippi Delta. And this
increase in noise also shows up in our phase array results. Yet another reason
to not let your fans get too close to obstructions. Even if you have cutouts
in the side panels, those can still cause annoying resonances. Fractal Terra
owners will know this very well. In summary, then for performance, keep your
fans more than 15 mm away from any surfaces and [music] 20 mm or more if
you're going to be contending with other obstructions like a heat sink or a
radiator. As for noise, it seems like you can't have too much clearance from
the intake, but you can definitely have too little. There are hundred other
questions we would have loved to answer, but frankly, NASA was already extremely
generous with their time, and they are hard at work answering much larger
questions. This may not have been the beall and endall answer that you were
looking for, but that's just how science is. It's the accumulation of many tiny
discoveries, solving many tiny mysteries that build up to create a knowledge base
that allows us to have a greater depth of understanding of the world that we
live in. Before we go, I want to thank all the folks at NASA to help who helped
make this possible at Lewis, Britney, Nick, Jordan, so many more folks that I
haven't named uh helped make this trip possible. Thank you so much. Thank you
for watching. And of course, thanks for this segue to our sponsor
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Thanks for watching. If you like this video, why don't you watch another one of our videos where we tour some cool
place like uh how about um uh there's an internet exchange in Toronto. That was
pretty dang neat. Thanks again to NASA. Thanks for watching. Bye.