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Re: [PSUBS-MAILIST] dual hull??
Hi,
I think Ray gave a good answer to the multi layer pressure hull.
But, uou could always make the spacing bigger and fill it with
concrete...
Something similar that could work: coil high pressure
piping all the way along the inside of the hull cylinder, with
the pipe coils kind of acting like framing for the cylinder but
bunched up very close (touching even). Now if you pressuring
the high pressure piping it will provide support for the hull.
You could even exposed the inside of the piping to external
pressure. The idea being that the pressurized piping keeps
the hull under internal tension (kind of like the hull had been
pressurized). Carl T.F. Ross's book "Pressure Vessels: External
Pressure Technology" as a couple of paragraphs discussing this
idea/method.
Ian.
On Wed, 29 Jan 2003 17:59:11 -0700
jbarlow@bjservices.ca wrote:
> I sent to the wrong address before, but I'm still curious.
>
>
> ----- Forwarded by James Barlow/BJSCAN/BJSERVICES on 29/01/2003 05:54 PM
> -----
>
> James Barlow
> To: owner-personal_submersibles@psubs.org
> 29/01/2003 10:31 cc:
> AM Subject: Dual Hull Concept
>
>
>
>
>
> I'm just thinking out loud here..
>
> If you have a 36" [914.40 mm]OD x 0.500" [12.70 mm] WT outer hull and put
> inside a 34" [863.60 mm] OD x 0.500" [12.70 mm] WT inner hull. ( leaving an
> annulus of 0.500" per side) and fill that area with hydraulic oil that you
> pump up to some high pressure. The pressure is equal everywhere but the
> area on the outer hull is greater, resulting in a net force outward.
>
> 36 - 0.5 -0.5 = 35.000" ID [889.00 mm]
>
> 34 OD of inner hull = [863.60 mm]
>
> If the was 100 psi oil pressure in the annulus area then the force out
> would be:
> 100 psi x 355/113 (pi) x 35.000" x length = 3500 pi x L pounds
> [7.030696 kg/cm2 x 355/113 x 88.900 cm = 625.029 pi X L ]
>
> force on inside would be:
> 100 psi x 355/113 (pi) x 34.000" x L = 3400 pi x L pounds
> [7.030696 kg/cm2 x 355/113 x 86.360 cm = 607.171 pi X L]
>
> a direct ratio of diameters. (id outer / OD inner)
>
>
> If you are 100 psi deep (6.80 atm (217 feet [66 m])
> then the outer hull would see 2.8 psi differential. (ratio of 36" / 35")
> (OD/ID of outer hull)
>
>
>
> Negating yield of outer hull due to increasing inner (which you can't do
> but maybe you would want to fill with a compressible gas like nitrogen
> instead of oil) the inner hull sees the same 100 psi, but the outer sees
> outside pressure less roughly 100 psi.
>
> Did I miss something??
>
>
> Of course you essentially have a 33" [838.20 mm] ID Hull now... and one
> that weighs essentially the same as a 33" ID [838.20 mm] x 1" WT [12.70 mm]
> hull.
>
>
> The pressure rating of such a hull would be great anyway. However perhaps
> as the inner hull only sees 100 psi and is protected from mechanical
> damage, it could be made from fibreglass or some such material to save
> weight.
>
>
>
> All the numbers above are only just numbers I threw in for illustration.
> It wouldn't have to be a 1/2" wall thickness hull.
>
>
>
> Not to start any wars, I'm not advocating the use of dual hulls. Just
> curious...
> Comments?
>
> Jay.
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