RU2807134C1 - Method for breaking ice cover - Google Patents

Abstract

FIELD: navigation in ice conditions.

SUBSTANCE: method for the destruction of the ice cover is proposed, which consists in excitation by underwater multi-hull vessel 1 in the ice cover of resonant bending-gravity waves. Two underwater hulls of multihull vessel 1 are interconnected and configured for changing the distance between them. During the movement of vessel 1, hydrodynamic curtain 8 is periodically formed at their bow extremities at the frequency of resonant flexural-gravity waves for a time equal to half their period.

EFFECT: periodic increase in the height of the excited flexural-gravity waves, i.e. their ice-breaking ability.

1 cl, 3 dwg

Description

The invention relates to navigation in ice conditions, in particular to underwater vessels sailing in ice conditions and destroying ice cover by the resonance method (1. V. M. Kozin. Resonance method of destroying ice cover. Inventions and experiments. M.: Academy of Natural Sciences. 2007 355 pp. ISBN 978-5-91327-017-7, see pp. 5-9).

The prior art is known from a method for destroying ice cover by the resonance method, implemented by a multi-hull vessel consisting of two underwater hulls, which are interconnected with the possibility of changing the distance between their bow and stern ends. While the vessel is moving, a hydrodynamic curtain is formed between the hulls at their bow ends (2. RU 2784537 C1 - adopted as a prototype).

The disadvantage of the solution is its limited ice-breaking ability.

The objective of the invention is to increase the height of flexural-gravity waves (IGW) excited by a ship.

The technical result is to increase the thickness of the destroyed ice cover.

Essential features characterizing the invention.

Restrictive: a method of destroying the ice cover by the resonant method, implemented by a multi-hull vessel consisting of two underwater hulls, which are connected to each other with the possibility of changing the distance between their bow and stern ends, while a hydrodynamic curtain is formed between the hulls at their bow ends.

Distinctive: during the movement of the vessel, a hydrodynamic curtain is formed periodically with the frequency of resonant IGWs for a time equal to half of their period.

From [2] it is known that an increase in the efficiency of ice destruction occurs due to an increase in pressure in the bow end of a multihull vessel due to the formation of a hydrodynamic curtain in this place.

It is also known (3. D.E. Kheisin. Dynamics of the ice cover. - L.: Gidrometeoizdat. 1967. - 218 p., see p. 136) that periodic application of a load to the ice cover with the frequency of resonant IGWs significantly increases its deformation along compared with a load of the same intensity, but applied stationary. This is explained by the fact that under such influences resonant IGVs arise. Thus, if the pressure between the ship’s hulls is periodically increased at the frequency of resonant IGWs, this will lead to the excitation in the ice cover of additional resonant IGWs (from the forward motion of the ship) in the ice cover. It is obvious that for their favorable interference with the main IGVs, i.e. To achieve the maximum periodic increase in the height of the total IGWs, it is necessary that the time of action of forces (areas with increased pressure) exciting additional IGWs is equal to half the period T of the main resonant IGWs, the value of which can be determined from the dependence [3]:

,

where: D is the cylindrical stiffness of the ice plate; ρ _l - ice density; h is the thickness of the ice cover; g is the acceleration due to gravity.

As a result, the most effective unique rocking of the ice cover, additional to the main IGW, will arise, which will lead to an increase in bending stresses in the ice cover.

The invention is illustrated graphically, where: FIG. 1 shows a top view of a multihull vessel in the stowed (initial) position; in fig. 2 - multihull vessel in operational (ice-breaking) mode; in fig. 3 - section along A-A in Fig. 2 (section along the plane of pump installation).

The invention is carried out as follows.

First, under the ice cover, the underwater multihull vessel 1 begins to move at a resonant speed with its hulls parallel to each other (Fig. 1). If ice destruction does not occur, then with the help of drives 2 (Fig. 1, Fig. 2) the aft ends of the underwater hulls are moved apart, and the bow ends are shifted in the horizontal plane. In accordance with the theorem on the lifting force of a wing, as well as according to the solution [2], a region of low pressure 3 will appear between the underwater hulls (Fig. 2). As a result, the wave load on the ice cover from the IGW will be added to the load from this area, which contributes to a decrease in the buoyancy force of the ice and, as a consequence, the appearance of additional bending stresses in the ice. If this is not enough to destroy the ice cover, then while the vessel is moving, pumps 4 are turned on, pre-installed in the bow ends of the underwater hulls in planes perpendicular to their diametrical planes and capable of pumping overboard the water located in the space between the light and strong hulls of the vessel ( Fig. 3). The suction 5 and discharge 6 openings of the pumps located in different housings are oriented towards each other at opposite inclination angles α, which will ensure the circulation movement of water 7 between them (Fig. 3), while the inclination angles are the most effective for creating more powerful water circulation determined in advance either experimentally or theoretically. As a result, a hydrodynamic curtain or hydrodynamic “wall” 8 will be formed at the bow end of the multihull vessel, which will lead to the emergence of areas of increased (in front of it) 9 and decreased 10 (behind it) pressures (Fig. 2). In turn, this will lead to the excitation of IGV of greater intensity. If this does not lead to destruction of the ice, then the hydrodynamic curtain 8 is formed periodically with the frequency of resonant IGWs for a time equal to half their period. As a result, additional resonant IGWs will appear in the ice cover, which, in phase superimposing on the main ones (from the movement of the vessel), will cause their favorable interference, from the point of view of an increase in wave height. This will lead to periodic excitation of IGWs of greater intensity (an increase in the total height of IGWs), i.e. to increase the efficiency of destruction of the ice cover (increase in the thickness of the destroyed ice) - achieving the stated technical result.

Claims (1)

A method for destroying ice cover by a resonant method, implemented by a multi-hull vessel consisting of two underwater hulls, which are interconnected with the possibility of changing the distance between their bow and stern ends, while a hydrodynamic curtain is formed between the hulls at their bow ends, characterized in that during motion of the vessel, a hydrodynamic curtain is formed periodically with the frequency of resonant flexural-gravity waves for a time equal to half of their period.

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