GB2365462A

GB2365462A - Improvements relating to ice penetrating devices

Info

Publication number: GB2365462A
Application number: GB9109560A
Authority: GB
Inventors: Christopher John Collister
Original assignee: GEC Marconi Ltd; Marconi Co Ltd; Thales Underwater Systems Ltd
Current assignee: Thales Underwater Systems Ltd; BAE Systems Electronics Ltd
Priority date: 1990-06-19
Filing date: 1991-05-09
Publication date: 2002-02-20
Anticipated expiration: 2011-05-09
Also published as: GB2365462B; GB9109560D0; GB9013661D0

Abstract

An ice penetrating device, e.g. for use in radio or acoustic communication, comprises a thermo-chemical boiler for converting water into steam under pressure, and a probe 23 through which the pressurized steam is released in the region in which ice is to be penetrated. The probe may comprise a plurality of lengths telescopically received within one another, which are extended by the pressure of the steam and joined to allow leakage of steam therethrough. Upon initiation, a gas generator 19 is heated and a thermo-chemical furnace 15 is ignited; eventually wax bungs 13 melt to allow pressurised water and anti-freeze mixture 14 to enter a space between the furnace 15 and canister walls 11, where it is heated and vapourized. Emergent steam is directed axially and radially from a nozzle 35. Deployment of the probe unwinds a communication wire 24.

Description

<Desc/Clms Page number 1> Improvements Relating to Ice Penetrating Devices This invention relates to ice penetrating devices for achieving a rapid penetration of ice layers to facilitate, for example, the transmission and/or reception of information through the resultant opening in the ice.

The information concerned may be transmitted by radio communication or acoustically, for example, and may be transmitted to and/or from locations above or below the penetrated ice layer. It is especially envisaged that the resultant opening in the ice layer may be utlilised for the deployment through the opening of a suitable antenna or sensor for communications purposes.

According to the invention an ice penetrating device comprises a thermo-chemical boiler for converting water into steam under pressure, and a probe means from which the pressurized steam is to be released in the region in which the ice is to be penetrated.

Preferably the probe means comprises a plurality of telescopic sections arranged to be extended by the pressure of the steam. In such a case the joints between the

sections may be arranged to allow a leakage of steam therethrough to prevent the progressively widening probe from jamming within the hole created by the steam.

The thermo-chemical boiler preferably comprises a thermo-chemical furnace surrounded by a water jacket, and arranged so that the water is boiled at a predetermined rate. In a preferred embodiment the thermo-chemical furnace is contained within a canister immersed within the water jacket, the canister including a plurality of small holes by which the water can enter the canister at a predetermined rate under pressure to be boiled.

The remote end of the probe means preferably includes a nozzle arranged to direct steam both axially and radially outwardly of the probe means, and to accomplish this may include a plurality of circumferentially spaced apart castellations.

An embodiment of the invention will now be described by way of example with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a partly schematic longitudinal sectional view through a buoy incorporating a device according to the

invention, Figure 2 is a fragmentary view to an enlarged scale of part of the antenna assembly shown in the device of Figure 1; and Figure 3 is a perspective view from above of one of the components shown in Figure 2.

The ice penetrating device shown in Figure 1 is for use as a communications buoy to be launched from a submerged vessel such as a submarine and comprises an outermost generally cylindrical housing 1 at one end of which is attached a detachable hemi-sperical end cap 2 via a pressure resistant seal 3. A boiler or steam generator comprises a pressure resistant housing 4 including a lid 5 attached by bolts 6. A gasket seal 7 is present between the lid 5 and the housing 4. On the top of the lid 5, a cylindrical collar 8 is secured about a through hole 9 in the lid 5, and a rupturable disc pressure seal 10 extends across the outlet from the collar 8 to prevent the ingress of sea water into the boiler when the device has just been launched. An innermost cannister 11 depends from the underside of the lid 5. The innermost cannister 11 includes a plurality of small through holes 12 in the base which are sealed by wax bungs

13 so as to, initially, seal the container against the ingress of the water and anti-freeze mixture 14 within which it is immersed. A thermo-chemical furnace 15 is located within the innermost cannister 11 and spaced apart from the walls thereof by metal gauze padding 16. The chemicals used are selected to produce no gas whilst they are reacting and the furnace 15 includes an electric ignitor (not shown) connected by leads 17 to control circuitry 18. The metal gauze 16 provides an electrical return path between the furnace 15 and the cannister 11. A gas generator 19 is immersed within the water 14 and is connected by electrical leads 20 to the control circuitry 18 for the purpose of pressurizing the interior of the boiler housing 4, the reason for which will be explained later on. The gas generator 19 may comprise an electrically actuated gas bottle or a water activated chemical gas generator comprising, for example, a glass phial containing a pellet of active material in contact with a pyrotechnic protractor, or piercing device, of generally known type, and arranged so that detonation of the protractor causes the glass phial to shatter and the pellet to come into contact with the water and anti-freeze mixture 14. It has been found that if the thermo-chemical furnace is merely immersed within a water jacket, the water is heated so violently that a mixture of steam and water is ejected from the boiler and the ice is

not melted efficiently. The boiler is thermally insulated by insulation 21. The base 22 of a telescopic probe or antenna assembly 23 is located above the disc pressure seal 10 over the outlet 9 of the boiler. The antenna assembly 23 comprises a plurality of tubular lengths or sections of GRP (glass fibre reinforced plastics) telescopically received within one another. A length of wire 24 used for radio transmission extends between the top of the innermost section 23a and a position underneath the base 22 of the assembly 23 where it is wound around a bobbin 25. The other end of the wire may extend outwardly of the buoy for attachment to a radio transmitter (not shown). A nozzle 35 is fixed to the remote end of the innermost antenna section 23a. The nozzle 35 is arranged to direct steam both axially and radially outwardly of the antenna by means of a plurality of upwardly standing circumferentially spaced castellations 36. Because steam is directed radially outwardly, any problems that can arise by the nozzle jamming and sealing against the ice surface are minimised. A rupturable pressure disc seal may be located within the nozzle to prevent the ingress of water during launch. The diameter of the nozzle 35 and/or the diameter of the innermost antenna section 23a are of preferably small size, eg a few mm, so as to restrict the flow and thereby pressurize the steam eg to about 10 5 NIM2 (1 bar) or more.

Referring to Figure 2, but not shown in Figure 1 for clarity, a tapered annular cap 26 is present about the end of each section of the antenna assembly 23. The cap 26 provides an annular exit 27 through which steam can escape, in use, in the region of the "steps" between each adjacent antenna length so as to cause the hole formed in the ice to enlarge and allow the progressively widening antenna to rise. In order to prevent the antenna from collapsing once it has been deployed, an annular ring 28 is present about the base portion of each antenna section length 23 and, beneath that, as best seen in Figure 3, a strip of sprung steel 29 bent into an annulus and having a plurality of circumferentially spaced apart outwardly extending springfingers 30. The springfingers 30 bear upon the opposing inner wall of an adjacent section length 23 to provide frictional grip to prevent the deployed antenna from collapsing, and also allow steam to pass through and exit past the annular cap 26. Referring back to Figure 1, a flotation collar 31 of generally toroidal shape is stored, in a deflated condition, within the heini-spherical cap 2, and is arranged to be inflated by a pressurized gas source 32 mounted beneath a transverse wall 33 located at one end of the container 1.

The pressurized gas source 32 is operatively connected to the control circuitry 18 by leads 34. A battery 37 is located within the base of the container for powering the control circuitry 18 and ignitors. A sensor 38 is mounted in the wall of the outermost housing 1 and is connected to the control circuitry 18 by leads 39. The sensor 38, comprising e.g. a polymeric force dependant resistor, is together with the control circuitry 18, operative to activate the various components of the device in the desired sequence. The sensor 38 incorporates a sea water switch to tell the device that it has been launched and is operative to provide an output signal proportional to the sensed pressure so that, for example, the device can be activated at a predetermined depth. In addition, or alternatively, the control circuitry 18 may be operative to monitor the rate of change of depth and activate the device when it has ceased to rise. This may be useful if, for example, the ice is substantially thicker than expected. In the absence of any suitable signal from the sensor 38, the control circuitry 18 may be arranged to activate the device after a predetermined period of time, eg ten minutes after launch. In use, a device as described may be launched from underneath a layer of ice from a submerged vessel such as a submarine. After launch the pressurized gas source 32

commences inflating the flotation collar 31 which urges the cap 2 from the housing 1. Upon reaching the underside of the ice, the control circuitry 18 and sensor 38 cause the furnace 15 to be ignited and the gas generator 19 to be activated. As the thermo-chemical material within the furnace 15 heats up, the wax bungs 13 melt and allow the, by now pressurized, water and anti-freeze mixture 14 to enter the small holes 12 at a predetermined or limited rate at the base of the innermost canister 11. The water 14 is heated and vaporized upon passage through the annular space between the furnace 15 and innermost cannister 11 walls and, at a predetermined pressure, ruptures the disc seal 10 on the collar 8. The pressurized steam bears upon the base 22 of the antenna assembly 23 and urges the section lengths upwardly so as to deploy the assembly 23. Steam emerging from the nozzle 35 is directed both axially and radially of the antenna to bore a hole in the ice. Because the steam contains a large amount of latent heat of vapourization, the ice is rapidly penetrated. The limited release of steam through each annular space 27 ensures that the antenna does not become jammed in its hole. As the antenna assembly 23 is deployed by the steam, the wire 24 is unwound from the bobbin 25. once the antenna has been deployed, the springfingers 30 prevent it from collapsing. The device may then be used as appropriate to transmit a radio signal using

the length of wire 24. Once the device has been used it can be discarded because it can be relatively cheap to manufacture. It has been found that using a furnace of energy 0.4 MJ immersed in about 300 ml of water and anti-freeze mixture 14, a depth of ice of 3 metres can be penetrated in less than a minute, at a rate of about 80 mm per second. The amount of energy and the volume of water 14 is selected so that a depth of ice of 3 metres can be quickly penetrated, but for use in cases where the ice is substantially thinner than that, the device may incorporate a shut off valve, (not shown), e.g. in the nozzle, for preventing any further release of steam once the ice has been penetrated to prevent the release of a tell-tale infra-red emitting plume of steam. In such a case the device may incorporate further valve means (not shown) for transferring the excess steam from within the boiler housing 4 to a relatively cooler place, eg the space adjacent the walls of the outermost housing 1, where it can condense. Although in the embodiment described with reference to the drawings the device is embodied in a communication buoy releasable from a submerged vessel to penetrate a ice layer from below, it will of course be appreciated that the device

could be located on the top of the ice layer to be penetrated, as by being dropped as part of a pod, and then activated to bore an opening through the ice layer from above to allow the lowering of a hydrophone, for example, into the water below the ice.

Claims

CLAIMS 1. An ice penetrating device comprising a thermo-chemical boiler for converting water into steam under pressure, and a probe means through which the pressurized steam is to be released in the region in which the ice is to be penetrated.
2. An ice penetrating device according to Claim 1, in which the probe means comprises a plurality of telescopic sections which are arranged to be extended by the pressure of the steam.
3. An ice penetrating device according to claim 2, in which the joints between the sections are arranged to allow a leakage of steam therethrough.
4. An ice penetrating device according to Claim 2 or claim 3, comprising means for preventing the probe means from collapsing once it has been extended.
5. An ice penetrating device according to claim 4, in which the probe means includes at least one strip of sprung steel or like resilient material extending about a probe

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section and arranged to bear upon the inner most wall of an adjacent probe section.
6. An ice penetrating device according to any preceding claim, in which the probe means incorporates a restriction to pressurize the steam.
7. An ice penetrating device according to any preceding claim, in which the thermo-chemical boiler comprises a thermo-chemical furnace surrounded by a water jacket, and arranged so that the water is boiled at a predetermined rate.
8. An ice penetrating device according to Claim 7, in which the thermo-chemical furnace is contained within a cannister immersed within the water jacket, the canister including a plurality of small holes by which the water can enter the canister at a predetermined rate under pressure to be boiled.
9. An ice penetrating device according to any preceding claim comprising a seal disposed between the boiler and the probe means and arranged to be broken when the pressure within the boiler reaches a predetermined value.

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10. An ice penetrating device according to any preceding claim, in which the remote end of the probe means includes a nozzle arranged to direct steam both axially and radially outwardly of the probe means. 11. An ice penetrating device according to Claim 10, in which the nozzle includes a plurality of circumferentially spaced apart castellations. 12. An ice penetrating device as claimed in any preceding claim, in which the device comprises part of a communications buoy releasable from a submerged vessel. 13. An ice penetrating device substantially as hereinbefore described with reference to the accompanying drawings.

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Amendments to the claims have been filed as follows

1. An ice penetrating device comprising; j] boiler including a furnace containing t--hermo-chemical material-; means for igniting the material within t-he f urnace, the boiler being arranged such t , r1a t water is suppiied at a predetermined rate to 4 L he oIt_Side of the furnace to be converted into steam under pressure,- and a probe means t--hrough which the pressurized steam is to be released in the region in which the ice -is to be penetrated-

2. An ice penetrating device according to Claim 1, in which the probe means comprises a plurall,-y of telescopIc sections which, are arranged to he ext-ended by Li'le pressure of the steam.

3. An ice penetrating device according to Claim 2, in which the joints between the sections are arranged to al-low a leakage of steam theret-hrough.

4. An ice penetrating device according to Claim 2 or claim 3, comprising means for preventing the probe means from collapsing once it has been extended.

5. An ice Penetrating device according to Claim 4, in which the probe means includes at least one strip of sprung steel or like resilient material extending about a probe

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section and arranged to bear upon the inner most wall of an adjacent probe section. 6. An ice penetrating device according to any preceding claim, in which the probe means incorporates a restriction to pressurize the steam. 7. An ice penetrating device according to any preceding claim in which the thermo-chemical furnace is contained within a water jacket. 8. An ice penetrating device according to Claim 7, in which the thermo-chemical furnace is contained within a cannister immersed within the water jacket, the canister including a plurality of small holes by which the water can enter the canister at a predetermined rate under pressure to be boiled. 9. An ice penetrating device according to any preceding claim comprising a seal disposed between the boiler and the probe means and arranged to be broken when the pressure within the boiler reaches a predetermined value. 10. An ice penetrating device according to any preceding claim, in which the remote end of the probe means includes a nozzle arranged to direct steam both axially and radially outwardly of the probe means.

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11. An ice penetrating device according to Claim 10, in which the nozzle includes a plurality of circumferentially spaced apart castellanions. 12# An ice penetrating device as claimed in any preceding claim, in which the device comprises part of a communications buoy releasable from a submerqed vessel. 13. An ice penetrating device substantially as hereinbefore described with reference to the accompanying drawings.