Re: [ATM] Thermal mirror deformation -fan on both sides

["tony gondola" <acgna@comcast.net>]

----- Original Message ----- 
From: "Ric Rokosz" <radicell2@yahoo.com>
To: "tony gondola" <acgna@comcast.net>; <atm@atmlist.net>
Sent: Wednesday, August 30, 2006 6:04 AM
Subject: Re: [ATM] Thermal mirror deformation -fan on both sides


>
>
> --- tony gondola <acgna@comcast.net> wrote:
>
>> I don't think it's a matter of how important the
>> work is but is it a useful,
>> validated tool? It's interesting but I don't think
>> anyone really knows what
>> to do with it. Everyone knows that performance will
>> be degraded while the
>> mirror is equalizing to ambient. My personal feeling
>> is that actual field
>> measurements would be more useful.
>
> Perhaps you need to tell the pro's that,as it has been
> noted on the list over the years that from their
> studies blowing air across the front face and back
> does allow faster cool down .

Where did I say it didn't?

>>
>> I'm also not sure that I agree with conclusion on
>> fan placement. The most
>> common configuration is to blow air out from the
>> back of the tube or mirror
>> box. The fan isn't blowing directly on to the glass
>> but is rather setting up
>> a flow of air that surrounds the mirror, front back
>> and sides.
>
> Funny how once the idea of even having a fan of any
> type -blowing or sucking,was a very alien notion.
>
That's true, it's common now. I'll bet that doing so has a fairly 
complicated history in ATM circles though.
>
>
>> The actual
>> airflow is much more complicated then Jan's simple
>> infinite diameter disk
>> model suggests and is also subject to turbulence and
>> dead areas induced by
>> various structures in the flow path including the
>> mirror's edge. Even a full
>> CFD analysis wouldn't tell the whole story.
>
> Give us a break here,we're talking about the thermal
> mass of the glass and how to cool it,with low flow
> fans over atm constructed cells,not the dynamics of
> Mach 2 airfoils!

The paper talks about much more then just cooling a mirror faster with fans. 
I have no argument with that. The main point of the paper is how the mirror 
deforms when fan cooled on one side. When you start working at that level of 
detail, just how and where the air moves over the full surface of the mirror 
becomes important. Why not think a little bit about some of the issues I've 
raised rather then just having a reaction and missing my point. The 
originator of the work was able to make a respectful and civil reply that 
carries on the discussion. I don't see why you can't do the same.

Tony
 

_______________________________________________
ATM mailing list http://www.atmlist.net/