[PSUBS-MAILIST] model testing

[Clifford Redus via Personal_Submersibles]

Fronde number for surface effects and Reynolds number for submerged drag, both form drag and viscous friction on a streamlined surface.  

Cliff

> On Dec 30, 2014, at 7:09 PM, Marc de Piolenc via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
> 
> I thought Froude number scaling only applied to wave drag, that is to surface running effects.
> 
> Marc
> 
>> On 12/30/2014 5:22 AM, Sean T. Stevenson via Personal_Submersibles wrote:
>> Reynolds number scaling only helps with viscous forces. Form drag
>> comparisons require scaling the Froude number.
>> 
>> Sean
>> 
>> 
>> 
>> On December 29, 2014 12:06:49 PM PST, Cliff Redus via
>> Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>> 
>>    Drag results between a model and full scale does not scale
>>    geometrically.  You have to scale model and full scale off the
>>    dimensionless  Reynolds number.   Reynolds number scaling enables
>>    you to scale results between model and full scale using either a
>>    water tunnel or air tunnel.
>> 
>>    Cliff
>> 
>> 
>> 
>>    *From:* Alan James via Personal_Submersibles
>>    <personal_submersibles at psubs.org>
>>    *To:* Personal Submersibles General Discussion
>>    <personal_submersibles at psubs.org>
>>    *Sent:* Monday, December 29, 2014 1:55 PM
>>    *Subject:* Re: [PSUBS-MAILIST] model testing
>> 
>>    Hank,
>>    I just ran a test on my pressure program & you get the same crush depth
>>    on a sphere of A516-70 steel that is 1000mm diameter & 10mm thick as you
>>    do on a sphere 100mm diameter & 1mm thick.
>>    What I am not sure of is if you can scale up the drag results on a
>>    model.
>>    If you have a scale model that is 1/50th & it takes X amount of
>>    force to push it
>>    at 3 knots, can you multiply X by 50 to get the required thrust?
>>    Alan
>> 
>> 
>> 
>>    *From:* Brian Cox via Personal_Submersibles
>>    <personal_submersibles at psubs.org>
>>    *To:* Personal Submersibles General Discussion
>>    <personal_submersibles at psubs.org>
>>    *Sent:* Tuesday, December 30, 2014 8:43 AM
>>    *Subject:* Re: [PSUBS-MAILIST] model testing
>> 
>>    Hank,
>>           I would say no.  It would have to be so exact that it would
>>    be virtually impossible to extrapolate from the small model, and
>>    aside from that I think there are other engineering principles
>>    involved that would come into play , Sean would be the person to ask
>>    !  I know that it is done in wave tanks and wind tunnels, but in
>>    those you are looking at laminar flow and such things, not
>>    structural strength so much.  You might be able to get a rough idea
>>    of how it would start to collapse maybe.  The larger the model the
>>    better I would think.
>> 
>>    Brian
>> 
>>    --- personal_submersibles at psubs.org
>>    <mailto:personal_submersibles at psubs.org> wrote:
>> 
>>    From: hank pronk via Personal_Submersibles
>>    <personal_submersibles at psubs.org
>>    <mailto:personal_submersibles at psubs.org>>
>>    To: personal_submersibles at psubs.org
>>    <mailto:personal_submersibles at psubs.org>
>>    Subject: [PSUBS-MAILIST] model testing
>>    Date: Mon, 29 Dec 2014 10:52:46 -0800
>> 
>>    Hi all
>>    If you make a scale model of a submarine in complete detail.  Scale
>>    the size and metal thickness, is it a reasonable representation of
>>    depth capabilities when pressure tested?
>>    Hank
>>    _______________________________________________
>>    Personal_Submersibles mailing list
>>    Personal_Submersibles at psubs.org <mailto:Personal_Submersibles at psubs.org>
>>    http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>> 
>> 
>>    _______________________________________________
>>    Personal_Submersibles mailing list
>>    Personal_Submersibles at psubs.org <mailto:Personal_Submersibles at psubs.org>
>>    http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>> 
>> 
>> 
>>    _______________________________________________
>>    Personal_Submers! ibles mailing list
>>    Personal_Submersibles at psubs.org <mailto:Personal_Submersibles at psubs.org>
>>    http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>> 
>> 
>>    ------------------------------------------------------------------------
>> 
>>    Personal_Submersibles mailing list
>>    Personal_Submersibles at psubs.org
>>    http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
>> 
>> 
>> 
>> _______________________________________________
>> Personal_Submersibles mailing list
>> Personal_Submersibles at psubs.org
>> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles
> 
> -- 
> Archivale catalog: http://www.archivale.com/catalog
> Polymath weblog: http://www.archivale.com/weblog
> Translations (ProZ profile): http://www.proz.com/profile/639380
> Translations (BeWords profile): http://www.bewords.com/Marc-dePiolenc
> Ducted fans: http://massflow.archivale.com/
> _______________________________________________
> Personal_Submersibles mailing list
> Personal_Submersibles at psubs.org
> http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles