R
Ricky
Guest
On Monday, April 18, 2022 at 8:14:36 PM UTC-4, Clifford Heath wrote:
https://youtu.be/ghrjJ1OL6jM?t=21
On 18/4/22 3:45 am, DecadentLinux...@decadence.org wrote:
jla...@highlandsniptechnology.com wrote in
news:thfo5ht952906bo98...@4ax.com:
On Sun, 17 Apr 2022 09:10:41 -0700,
jla...@highlandsniptechnology.com wrote:
On Sun, 17 Apr 2022 15:55:21 -0000 (UTC),
DecadentLinux...@decadence.org wrote:
Ricky <gnuarm.del...@gmail.com> wrote in
news:3f3e0e0f-175e-4d27...@googlegroups.com:
The large surface area of the long, skinny fins are perfect
coupling between the low thermal resistance of the heat sink
and the relatively high thermal conductivity of the fin/air
contact.
The word(s) for today is \"boundary layer\".
https://www.heatsinkcalculator.com/blog/wp-
content/uploads/2016/05/effect_of_boundary_laher_thickness.png
https://www.heatsinkcalculator.com/blog/top-3-mistakes-made-when-
selecting-a-heat-sink/
Slow air would pass right over a close fin spaced sink. High
speed
forced air is required when the fins get that closely spaced.
Right. Viscous drag will keep air from flowing between tall,
closely spaced fins. It will have to be ducted and forced, or it
will go around.
The limiting case, more and more denser and thinner fins,
volumetric air flow will approach zero.
My general rule is that a heat sink should reduce the native air
flow by about half. Neither zero nor 100% does any cooling.
And of course, the tips of tall thin fins have a high thermal
resistance to the baseplate, so run at about inlet air temp, so
restrict air flow without contributing much coolong. My 50% number
is useless if the air flow is restricted without corresponding
cooling.
There is no limit to how bad a heat sink you can design. A solid
aluminum brick is pretty bad.
I even saw some where they slice up each fin into little fingers
and the sink was \"bristling\" with them. Probably pretty good, but
again, the air movement over and through them is required. Air flow
means nothing if it does not intertwine with the heated elements to
get hot and then be carried off as more air is added to be heated and
moved. It\'s a bucket brigade.
I\'m surprised they don\'t skive using a wavy cutter. It seems you could
easily add turbulence to the air to get better cooling with bigger fin
spacing (fewer fins).
https://youtu.be/ghrjJ1OL6jM?t=21