Surface roughness helps with heat transfer, because a turbulent boundary
layer transfers more heat than a laminar one, at least for fluids with low
thermal conductivity. However, it also increases pressure drop through the
cooling passages. The designer needs to find the appropriate balance
between pressure drop and heat transfer to meet requirements, which is a
non-trivial task.
The underlying problem is that every known technique for fabricating a
flight weight rocket engine chamber & nozzle with integrated cooling
passages is awful in its own special way. DMLS offers a way out, so I am
excited to see how it goes for them.
-p
On Wed, Sep 16, 2015 at 9:14 AM, Ed LeBouthillier <codemonky@xxxxxxxxxxxxx>
wrote:
The question was honestly asked .. I am not a liquid motor specialist …and
was genuinely curious about whether their approach of 3D printing themotor introduced even more risk.
Although 3D printing seems to simplify some things, I too wonder about
complications due to its use.
One issue that interests me is the effects of surface texture due to 3D
printing.
I know that different surface textures can affect the heat transfer rate.
My understanding is that surface texture affects boundary layer formation.
The surface texture from their 3D printing looks rough and I'm curious as
to whether that would be a help or hindrance. Perhaps it's just something
that has to be accommodated in the design.
Anyone else out there have any idea about the effects of surface roughness
on cooling in an application like this?
