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Old 10-06-2006, 07:10 AM
Timothy Daniels
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Default Re: turbulent flow not bad for cooling

Here are more examples of and advice regarding
turbulence and forced draft cooling:

http://www.overclockers.com/tips90/ -

"Turbulent air cools better. Say, for sake of argument,
you have a simple tube with a fan in the middle. The fan pulls
air from one side of the tube, and blows into the other. If you
have a hot component on the exhaust side of the fan, it will
be more efficiently cooled than on the intake side.

"This is because the air on the exhaust side of the fan
is more turbulent. For lack of a better explanation, the loops
and whorls of turbulent air moving across the surface pick
up more heat. The effective surface area of the object is
increased. (Actually, it was explained to me by saying the
effective surface area of the air is increased.) The total
volume of airflow remains the same, but turbulent air just
cools better."

http://www.begellhouse.com/books/497...32b58c789.html -

"Turbulent flow is the most common form of motion of liquids
and gases playing the role of the heat-transfer medium in thermal
systems. The complexity of turbulent flow and the importance of
hydrodynamics and heat transfer in practice inspired continuing
research for methods of efficient heat augmentation by the
Lithuanian Energy Institute. The solution of this problem was directly
linked with the determination of the reaction of flow in the boundary
layer to the effect of various factors and heat transfer rate under
given conditions. The investigated factors included elevated degree
of turbulence of the external flow as well as strong acceleration and
turbulization of flow near the wall by surface roughness. The material
in this volume shows that it is possible to control the efficiency of
turbulent transfer when the vortical structure of the turbulent flow is
known."

http://www.cougarlabs.com/cool2.html -

"For convective heat transfer to work well, we need to get the
heat energy out into the flowing coolant. Turbulence will do this
for us."

http://www.ceere.org/beep/docs/FY200..._Enclosure.pdf -

"Comparatively speaking, turbulent flows often lead to higher
transport rate of momentum, energy and mass than laminar flows.
These features are widely made use of in energy systems in industry.
For example, turbulence enhancers such as ribs are added to
cooling systems of turbine blades and microelectronic devices
to create more turbulent motions so that the overall heat transfer
efficiency can be improved."

*TimDaniels*

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