We will probably switch to stainless then. Al was chosen for its
lightweight and high thermal conductivity which now that I look back on it
are both relatively minor concerns. I really didn't have a good idea about
the design philosophy for film cooling to start. Using stainless should
give us much more margin and knowing that the design has been used multiple
times successfully gives me more confidence in it. Based on a theoretical
approach it makes alot more sense too as the higher allowed wall
temperatures will make the radiation heat transfer much higher from the
wall. Also the temperature difference between the film and the wall will
increase the convective heat transfer to the film. I am going to still
attempt to calculate the heat flux to the walls and get some estimated
temperatures but I am not sure how successful I will be with this. If
anyone has done this and predicted accurate chamber wall temperatures I
would still be very interested in how you did it.
Thank you,
Zachary Martinez
Aerospace & Mechanical Engineering
Missouri S&T
On Tue, Jun 27, 2017 at 10:50 PM, David Weinshenker <daze39@xxxxxxxxxxxxx>
wrote:
On 06/27/2017 08:46 PM, Ben Brockert wrote:
Stainless is most practical for a hobby or school project; machinable
and relatively cheap. Even mild steel will allow higher temperatures
and would be really cheap to make.
Type 316 stainless seems to be a pretty decent choice for strength at
moderately high temperatures - some of the inconels etc. hold more
strength up to a certain point, but then lose it more rapidly with
increasing temperatures. Uncooled 316 works reasonably well for
H2O2 monoprop chambers.
-dave w
