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Re: shock wave as pressure builds in a vacuum?



This is worked problem 12-12 in compressible flow:

"Atmospheric air is allowed to fill an initially evacuated
insulated bottle. What is the temperature of the air in
the bottle when it is full?
Assume air is at 70degF and gamma equals 1.4"
(Answer: 282 degF)

from p707- Fluid Mechanics
REA Problem Solvers "A Complete Solution Guide"
Fogiel/Cimbala ISBN 0-87891-547-8 LOC 95-70958

I'll try to put some flesh on this note later this evening....

Brian Whatcott Altus OK

At 09:10 AM 5/29/2003 -0700, you wrote:
Brian,
Could you give a brief overview of the rapid
inrush of air into a vacuum that gives the
temperature of 100K. ( I assume this is 100
degrees kelvin rather than 100,000 degrees) At
first thought I do not see why it would happen.

I have broken a beryllium window on an x-ray
Si-Li detector when venting the chamber to which
it was connected. I do not think a rise of 100K
would weaken beryllium very much.

Thanks
Roger Haar


Brian Whatcott wrote:
>
> At 03:52 PM 5/28/2003 -0400, Stefan Jeglinski , you wrote:
>
> Likening Stefan's situation to the classical problem of rapid inrush of
> room temperature air into an insulated vacuum bottle, where a temperature
> rise of more than 100K is expected, the thin polymer membrane will
> possibly not have been selected for strength at elevated temperature,
> and so may be weakened to its yield point locally. If that were the
case,
> a high temperature film might suit the purpose.
> (Inveterate list members may recall that a certain UBC Emeritus posed a
> contrasting problem: if a tubeless tire leaks at some rate, what is the
> temperature rise? In that case it was negligible)
>
> Brian Whatcott Altus OK