Ships – Torpedo launching
Reexamination Certificate
2001-02-13
2003-07-01
Carone, Michael J. (Department: 3641)
Ships
Torpedo launching
C114S021200, C114S316000, C114S317000, C114S318000, C114S319000, C114S320000, C114S313000, C102S399000, C244S199100, C244S204000, C089S001809, C089S001810
Reexamination Certificate
active
06584924
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention generally relates to an apparatus for controlling pressure recovery. More particularly, the invention relates to an apparatus for controlling pressure recovery in a submarine cylindrical shutter way/guide-can recess.
(2) Description of the Prior Art
The current art and known construction of a submarine torpedo launchway causes a substantial recovery of dynamic pressure in a cylindrical shutterway/guide-can recess (SGR).
Referring to the conventional art of
FIG. 1
, the known SGR is illustrated therein. Specifically, the portion of the submarine showing the launchway location of a torpedo T prior to launch is depicted in general by reference number
10
. The launchway
10
includes a shutterway
12
, and a guide-can recess
14
in longitudinal alignment with the shutterway
12
. An entering flow of sea water
16
passes into a first end
12
a
of the shutterway
12
and enters the guide-can
14
at a passage opening
18
at a second end
12
b
of the shutterway
12
and a first end
14
a
of the guide-can
14
. The guide-can
14
and shutterway
12
are those portion of the launchway
10
through which the torpedo T passes upon firing the torpedo from the submarine.
The second end
14
b
of the guide-can
14
terminates in an opening, thereby defining an open area
20
between the guide-can
14
and a launch tube
22
of the submarine. The entering flow
16
becomes either stagnation flow
24
or redirected flow
26
as explained in the following.
Just prior to launch, when a muzzle door (not shown) of the torpedo launch tube
22
has opened, the pressure head of water that has built up at the entrance to the launch tube
22
, or otherwise termed “recovered pressure”, induces an adverse pressure gradient along a length of the torpedo T while the torpedo is in the tube
22
. An adverse pressure gradient means that the pressure is higher at the nose of the torpedo compared to the pressure at its tail end. This condition energizes a breechward movement of the torpedo T that could result in structural damage to the weapon if this condition becomes excessive. Furthermore, fluid flow from the torpedo tube
22
to the turbine pump is reversed, thereby causing an undue stress on the turbine pump of the torpedo at start-up. Over time, this undue stress may structurally fatigue a turbine pump clutch of the torpedo.
An inspection of the submarine launchway reveals the probable cause for the adverse pressure gradient along the torpedo while in the tube
22
. Specifically, the large separation between the second end
14
b
of the guide-can
14
and the torpedo tube
22
permits flow through the SGR and into a free-flood region
28
of the submarine. This separation is necessary to allow opening of the torpedo tube muzzle door just prior to launch of the torpedo. Note that the free flood region
28
of the submarine is formed to be outwardly concentrical with the shutterway
12
/guide-can
14
portion, and receives the redirected flow
26
from the guide-can
14
. It is also revealed that the free-flood region
28
is not isolated from the flow dynamics external to the hull of the shutterway
12
and guide-can
14
. In particular, the sides and rear of doors to the shutterway
12
do not seat tightly against the external hull in their closed position. Large gaps which frame the shutter doors permit low-velocity flow, indicted at
28
a,
through the free-flood region that eventually leads to the flow dynamics external to the submarine hull. The high-momentum/low-volume flow through the SGR is supported by a low-momentum/high-volume flow through the free-flood region. The high-momentum flow through the SGR stagnates locally at the torpedo tube muzzle door as shown by
24
, thereby recovering the full dynamic pressure of the flow through the SGR.
The ensuing event of the above flow path centers on flow stagnation
24
at the torpedo nose just prior to launch. Complete conversion of the dynamic pressure to static pressure gives a much higher static pressure at the torpedo nose compared to the pressure at its tail. A simple, but synonymous example, is a jet flow impinging on a flat plate where the recovered pressure is directly attributed to a quick termination of stream wise flow momentum due to the presence of the solid wall at the entrance to the torpedo tube
22
. At the wall, the flow stagnates (
24
) and recovers its entire dynamic head. In this example, the flow redirects at
26
laterally along solid end walls
30
of the launch tube
22
. Translated into submarine geometry, the flow redirects to the free-flood region
28
.
Possible corrections for reducing the stagnation pressure
24
at the muzzle door/end walls
30
center on preventing any external flow from entering the SGR. Geometric modifications to the launchway include sealing the gaps between the shutter doors and the submarine hull, or enclosing the open zone
20
between the guide-can
14
and the torpedo tube
22
. Although these changes address the symptoms of the recovered pressure problem, their functionality may not be one hundred percent assured. In particular, other access ports from the free-flood region
28
to the hull also generate external flow dynamics, but more importantly, fluid entrainment or its associated mass exchange entering the SGR can not be fully prevented due to the large characteristic length of the shutterway
12
. These geometric fixes simply translate the recovered dynamic pressure zone to within the SGR itself. The stagnation pressure
24
at the torpedo nose may remain unchanged.
Thus, a problem exists in the art whereby there is a need to reduce or eliminate the stagnation flow or pressure head build up at the door of the launch tube
22
. This should be done in a retrofit manner to accommodate existing submarine launch apparatus without undue expense or modification of the existing structure.
The following patents, for example, disclose various types of pressure recovery devices, but do not disclose an apparatus for controlling pressure recovery utilizing a plurality of retrofit circumferential chokes as occurs in the present invention.
U.S. Pat. No. 4,383,552 to Baker;
U.S. Pat. No. 5,020,943 to Filipelli; and
U.S. Pat. No. 5,521,340 to Thawani et al.
Specifically, the patent to Baker discloses an adjustable choke for automatically regulating high velocity flow through a pipe line. The choke comprises a generally cylindrical elongated body including an axially-directed inlet port at one end, means for selectively controlling flow though the regulator at the other end, and a radially-directed outlet port intermediate of the body. A pair of slidable, annular rings contained in the body adjacent the inlet port comprise an upstream ring and a downstream ring. Each of the rings are spring biased from the other. The upstream ring includes a flow passageway and a flow obstructing portion. The downstream ring includes a plurality of flow passageways, at least one of the downstream ring flow passageways being disposed out of communicable flow alignment with the upstream ring flow passageway. Upon impingement of sufficient flow against the obstructing portion of the upstream ring, the upstream ring is slid into abutment with the downstream ring for closing the one downstream ring flow passageway and for limiting fluid flow through the choke. Upon dissipation of the sufficient flow, the upstream ring is spring biased away from the downstream ring. The means for selectively controlling the flow is selectively, operatively engaged to the downstream ring whereby the downstream ring may be selectively slid into abutment with the upstream ring for closing the one downstream ring flow passageway. The means for selectively controlling also includes a selectively advanceable valve stem for closing the downstream ring flow passageways other than the one downstream ring flow passageway. It should be noted that the primary function of Baker s invention is limiting high velocity, which only indirectly limits high pressure. The proposed invention
Carone Michael J.
Kasischke James M.
McGowan Michael J.
Oglo Michael F.
Richardson John
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