RE: [ATM] Temperature-changes

[Ross Sackett <rsackett00@yahoo.com>]

--- Arjan te Marvelde <arjan.te.marvelde@hetnet.nl>
wrote:

> In a simulation of convection cooling I did for a
> 250x19mm glassplate, the
> temp dsitribution roughly has a cosine profile, both
> in lateral and paraxial
> direction.
> 
> Mirror start temp is 293K, environment temp is 273K,
> results after an hour
> of cooling:
>   Mirror edge temp: 275.50K
>   Mirror center temp: 277.75K
>   Center-surface temp: 277.57K
> Note that the cooling is most effective at the
> edges. I leave it as an
> excercise to the reader to calculate the resulting
> deformation. Gut feeling
> tells me it's gonna be undercorrected.

Arjan,

Yeah, from that temp distribution I would guess it
would be undercorrected, too.  I was thinking of a fan
aimed at the back center of the mirror, guessing that
the velocity would be highest in a ring around a dead
zone in a center, dropping off to the edges.  However,
the additional heat loss on the sides of the mirror
would probably compensate for the lower air velocity. 
So maybe a temperature-induced TDE? <g>




		
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