<VV> fanz - SPAL #30102113

Thu Aug 4 00:53:47 EDT 2005

Choke flow is the very last thing we need to be concerned about here, forget 
it.
RonH

----- Original Message ----- 
From: "AKG" <hdflstf at earthlink.net>
To: "Roger Gault" <r.gault at sbcglobal.net>; "Corvair List" 
<virtualvairs at corvair.org>
Sent: Wednesday, August 03, 2005 9:10 PM
Subject: Re: <VV> fanz - SPAL #30102113

> The one thing now addressed about the orifice (which likely does not apply
> in this case is there is a point where no matter how much pressure you add
> the flow does not increase - choked flow.
> Reynolds numbers - I need to get out the books but given the speed of the
> airflow I would expect the number to be on the low side.  Given the 
> surface
> finish and the turbulence I would not be surprised to see turbulent flow.
> On the plus side the surface roughness, turbulence, and fin spacing would
> all but eliminate and possibility of detached flow.
>
> The Artful Dodger
>
>> From: "Roger Gault" <r.gault at sbcglobal.net>
>> Date: Wed, 3 Aug 2005 22:56:25 -0500
>> To: "Corvair List" <virtualvairs at corvair.org>
>> Subject: Re: <VV> fanz - SPAL #30102113
>>
>> Under no circumstances will higher pressure across the fins result in 
>> lower
>> flow.
>> Even if a transition between laminar and turbulent flow was taking place 
>> as
>> the pressure goes up, the slope of the mass flow vs pressure curve will
>> never go negative.  In our case, with less than 1/8" fin spacing, I
>> seriously doubt the flow between the fins is anything but essentially
>> laminar.  The air can't get far enough from the surface for the flow to
>> break up.  I'll admit I could be wrong here, I haven't calculated 
>> Reynolds
>> Number since 1968.  AERONED!  WHERE ARE YOU?
>>
>> An interesting paper can be found at:
>> http://naca.larc.nasa.gov/reports/1937/naca-tn-621/
>> It takes some study to understand the graphs and nomenclature, but the
>> general info is easy to see.
>>
>> One of the things that interests me most about it is the strong 
>> relationship
>> of pressure drop to fin spacing at a fixed mass flow rate.  It really
>> reinforces the need to adequately deflash our heads.  And, it argues for 
>> the
>> 1/8" drill method since that opens up the spacing considerably.
>>
>> I'd wager that the guys who have these electric fan cooled engines have 
>> done
>> everything they could think of to help them cool, including fanatically
>> deflashing the heads.  I'm also really curious how well deflashed the 
>> heads
>> were in the GM tests.
>>
>> By the way.  If you guys haven't looked at these reports, you've missed a
>> valuable resource.  Yes, they're old.  But air is still air, even if it 
>> does
>> have more junk in it these days.
>>
>> Roger
>>
>>
>> ----- Original Message -----
>> From: "Bill & Chris Strickland" <lechevrier at earthlink.net>
>> To: <virtualvairs at corvair.org>
>> Sent: Wednesday, August 03, 2005 4:16 PM
>> Subject: Re: <VV> fanz - SPAL #30102113
>>
>>
>>> ronh at owt.com wrote:
>>>>
>>>> that is the pressure needed to get enough air flow through the fins
>>>> to cool it adequately.
>>>
>>> Please cite the source of your data. We know there is a pressure
>>> build-up -- GM supplied the data -- does the same article address a
>>> 'need' for this pressure, or like you, is it just assumed?
>>>
>>> There is some evidence of wasted energy in the fan system -- could using
>>> a fan as an air compressor account for this waste? Ten inches of water
>>> is about 1/3 of a psi. This compressed air flow probably in itself
>>> produces a turbulence through the cooling fins which is not conducive to
>>> maximizing flow rates -- max flow occurs with a more laminar flow
>>> (example: polished intake ports), ie, if the fan wasn't trying to over
>>> blow the cooling air, would more air actually flow through the fins?
>>> Would more air mean a cooler engine? Or would it be cooler with a more
>>> turbulent flow? Did GM engineer it this way, or did they just settle for
>>> a system that sorta worked with the technology/money that was available?
>>> Their concept cammer engine had three vertically oriented axial fans --
>>> is there any data for this motor?
>>>
>>> These are just questions -- does anyone know of data in the literature
>>> to support or deny any of this?
>>>
>>> Is there any data for air flow out the bottom/back of the engine, either
>>> volume or temperature? Is it related to say rpm or horsepower or oil
>>> temp?
>>>
>>>> Since a fan [he means an electric, I presume] can only develop 10% of
>>>> the pressure of the Corvair blower at the required mass flow rate ...
>>>
>>> Again, where do you get the information about max pressure developed by
>>> an electric fan such as the ones under discussion? Did you find a
>>> definition of what Spal calls 'Static pressure' and their test method?
>>>
>>> I really think that there is a possibility that there are some
>>> unanswered questions concerning the Corvair cooling system that if we
>>> had answers for, we could perhaps prolong the life of these little cars
>>> that we so like to drive -- new heads are getting harder to find these
>>> days and if anyone starts up a reproduction run, would we be able to
>>> afford them if they did? We probably need to preserve what we've got,
>>> and any new information that may show a better way to operate our little
>>> cars should not just be dismissed because "we've always done it *this*
>>> way."
>>>
>>> Drive On!
>>>
>>> Bill Strickland
>>> _______________________________________________
>>> This message was sent by the VirtualVairs mailing list, all copyrights 
>>> are
>> the property
>>> of the writer, please attribute properly. For help,
>> mailto:vv-help at corvair.org
>>> This list sponsored by the Corvair Society of America,
>> http://www.corvair.org/
>>> Post messages to: VirtualVairs at corvair.org
>>> Change your options:
>> http://www.vv.corvair.org/mailman/options/virtualvairs
>>> _______________________________________________
>>
>> _______________________________________________
>> This message was sent by the VirtualVairs mailing list, all copyrights 
>> are the
>> property
>> of the writer, please attribute properly. For help, 
>> mailto:vv-help at corvair.org
>> This list sponsored by the Corvair Society of America, 
>> http://www.corvair.org/
>> Post messages to: VirtualVairs at corvair.org
>> Change your options: 
>> http://www.vv.corvair.org/mailman/options/virtualvairs
>> _______________________________________________
>
> _______________________________________________
> This message was sent by the VirtualVairs mailing list, all copyrights are 
> the property
> of the writer, please attribute properly. For help, 
> mailto:vv-help at corvair.org
> This list sponsored by the Corvair Society of America, 
> http://www.corvair.org/
> Post messages to: VirtualVairs at corvair.org
> Change your options: 
> http://www.vv.corvair.org/mailman/options/virtualvairs
> _______________________________________________
> 