Re: [ATM] Forced Ventilation

["Bill Kelley" <flex@commspeed.net>]

Doug et al,
Breaking up the turbulence works well when the mirror temp is not close to 
ambient. I didn't dispute the desireability of having a mirror at ambient 
temperature. I thought I made it clear that cooling the mirror is a moving 
target when the evening is cooling. The intent of my post was to refocus 
attention
on stabilizing the image as being the purpose of fans, and cross draft does 
this.
Bill

----- Original Message ----- 
From: "Doug Williams" <salguod@minbaritm.com>
To: <atm@atmlist.net>
Sent: Tuesday, February 01, 2005 8:23 AM
Subject: RE: [ATM] Forced Ventilation


> Bill,
>
> I think that we are quite properly fixated on cooling the mirror!  Cooling
> the mirror to ambient is still the ultimate goal, and Alan Adler clearly
> stated so in his article.  Breaking up the turbulence works only when the
> mirror is close to ambient anyway.  Alan Adler's methods are designed to
> break up the boundary layer WHILE cooling the mirror.  I don't think that 
> we
> can just ignore the mirror cooling issue because we blew the boundary 
> layer
> away.  Remember that if the mirror is at ambient temperature, there is no
> boundary layer in the first place!  Nothing Adler wrote disputes this 
> basic
> fact.
>
> Doug
>
> -----Original Message-----
> From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On Behalf 
> Of
> Bill Kelley
> Sent: Monday, January 31, 2005 4:38 PM
> To: Don Clement; atm@atmlist.net
> Subject: Re: [ATM] Forced Ventilation
>
>
> This was the thrust of Alan Adler's S&T article. Break up the turbulence 
> and
>
> it doesn't matter. Surprising how many are still fixated on cooling the
> mirror. The evening temperature can always drop faster than mirrror 
> cooling
> can keep up.
> Bill Kelley
>
> ----- Original Message ----- 
> From: "Don Clement" <clement.focuser@verizon.net>
> To: <atm@atmlist.net>
> Sent: Monday, January 31, 2005 9:12 AM
> Subject: Re: [ATM] Forced Ventilation
>
>
>> What about the idea of homogenizing thermal layers in front of the mirror
>> by
>> forcing air across the front of the primary mirror in an open or closed
>> support structure?
>>
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