RU2617866C1 - Ship hull - Google Patents

Abstract

FIELD: transportation.

SUBSTANCE: ship hull is designed in a form of an impermeable membrane, formed of the outer skin and the set of beams. Impermeable membrane is made in a form of two separate impermeable nose and stern parts connected by a nondetachable connection located on the housing nose side of a middle section. Nondetachable connection durability is selected such that it provides parts connection before achieving the bending moment M₀ affecting the nondetachable connection, of the limit value linked to the critical value of the hydrodynamic force P_cr which corresponds to the maximum permissible drop of a metacentric height for the vessel, by the following relation:

where M₀ is the limit value of the bending moment affecting the nondetachable connection, Hm⋅; P_cr is the critical value of the hydrodynamic force, N; L_N is the length of the nose impermeable part, m; ℓ is the distance from the prow to the point of the hydrodynamic forces resultant application while capturing of the prow by wave, m; C_r is the reserve coefficient.

EFFECT: higher safety of navigation.

1 dwg

Description

The invention relates to the field of shipbuilding, in particular to the design of hulls.

A known design of the displacement type part of the vessel (RF Patent for the invention No. 2374120, IPC ВВВ 1/06, publ. 11/27/2009) with transverse symmetry relative to the central axis, with the hull forming lines increasing in width from the baseline. The bottom is flat or has a pitch and goes into the bottom with a given radius of the bottom. From the bottom to a predetermined height, the generatrix lines are slightly inclined outward. At the level of the deck of the tank, the shape of the outward sloping line stops and passes upward in the form of a curved line back in the direction of the central axis.

This design has the following disadvantages:

- the ship has a large windage;

- the wheelhouse is removed from the engine room, which makes it difficult to lay cable routes;

- poor habitability;

- shock waves can knock out windows in the wheelhouse and lead to damage to navigation equipment;

- at a high wave height, they can overlap through the superstructure, while the flat deck surfaces will contribute to the capture of the bow of the vessel by the wave [Burakovsky EP, Burakovsky PE Some problems of ensuring the general strength of ships in emergency situations // Transactions of the Krylov State Scientific Center. - Vol. 82 (366), 2014. - S. 21-30];

- poor germination per wave, because due to the slenderness of the waterline, the ship crashes into a wave, and it twists above the bow and to the side, as a result of which the bow of the ship can be captured by the wave, which will lead to the death of the ship.

The hull of the vessel, which is an impenetrable shell consisting of thin sheets, which are supported by beams made of rolled or composite welded sections (Barabanov N.V. Design of the hull of marine vessels. L., Shipbuilding, 1981. - 552 s), was adopted as the closest analogue. ., p. 9-11, figure 1).

This design has a significant drawback consisting in the possibility of capturing the bow of the nose by the wave, due to the presence of flat deck surfaces and the superstructure of the tank, as a result of which a metacentric height may fall and the vessel will tip over [Burakovsky E.P., Burakovsky P.E. Some problems of ensuring the overall strength of ships in emergency situations // Transactions of the Krylov State Scientific Center - Issue. 82 (366), 2014 - S. 21-30]. Capture of the nasal tip by a wave means that when the deck is flooded heavily, it operates in a submerged position as a wing streamlined by a liquid stream, as a result of which pressure forces arise on flat surfaces, which is determined by the angle of attack and the speed of the incoming liquid. This flow is unstable, as a result of which the resultant can at any moment move away from the diametrical plane and cause a strong roll or tipping of the vessel. Under the action of the resultant hydrodynamic forces, the trim of the vessel increases, while there is a sharp decrease in the transverse metacentric height, which contributes to the capsizing of the vessel.

The invention solves the problem of improving the safety of navigation, excluding a catastrophic decrease in the stability of the vessel upon capture by the wave of the bow tip due to the limitation of the hydrodynamic force acting on the ship's hull.

To solve the problem in the hull, made in the form of an impenetrable shell formed from the outer skin and set beams, it is proposed that the impenetrable shell be made in the form of two separate impermeable parts - fore and aft, connected by an integral connection located on the fore side of the hull from the mid-frame. The strength of the permanent connection is proposed to be chosen so as to ensure the connection of the parts until the bending moment M ₀ acting on the permanent connection reaches the limit value associated with the critical value of the hydrodynamic force P _cr , which corresponds to the maximum allowable drop in the metacentric height for a given vessel, by the following ratio:

Where

M ₀ - the limit value of the bending moment, acting on an integral connection, Nm;

P _cr - the critical value of the hydrodynamic force, N;

L _H - the length of the nasal impermeable part, m;

- расстояние от носа судна до точки приложения равнодействующей гидродинамических сил при захвате волной носовой оконечности судна, м;

- distance from the bow of the vessel to the point of application of the resultant hydrodynamic forces when the wave captures the bow of the ship, m;

To _s - safety factor.

In the proposed technical solution, when the hydrodynamic force acting on the nasal extremity exceeds a critical value, the inextricable joint is destroyed, thereby preventing the ship from tipping over, and the fore and aft impermeable parts remain afloat.

The attached graphic materials depict a general view of the proposed hull.

The following notations are used on graphic materials:

1 - feed impermeable part;

2 - nasal impermeable part;

3 - one-piece connection;

L is the length of the vessel, m;

L _H - the length of the nasal impermeable part, m;

L _K - the length of the feed impermeable part, m;

P is the resultant of hydrodynamic forces when a wave captures the bow of the ship, N;

- расстояние от носа судна до точки приложения равнодействующей гидродинамических сил при захвате волной носовой оконечности судна, м.

- distance from the bow of the vessel to the point of application of the resultant hydrodynamic forces when the wave captures the bow of the ship, m

The hull structure consists of an outer skin and set beams forming a stern impermeable part 1 and a bow impermeable part 2, which are connected by an integral connection 3.

The hull operates as follows. When the vessel is moving in strong oncoming waves, the bow tip may periodically immerse in water, which leads to the appearance of a complex mode of flow around the deck. Under such conditions, significant loads may occur, acting on the bow of the hull, caused by the flow around the submerged deck, which can be considered as a wing of complex shape, located at an angle of attack to the incoming liquid flow. Under the influence of hydrodynamic force, the trim of the vessel will increase, and its stability parameters will sharply decrease [Burakovsky EP, Burakovsky P.E. Some problems of ensuring the overall strength of ships in emergency situations // Transactions of the Krylov State Scientific Center - Issue. 82 (366), 2014 - S. 21-30]. When the hydrodynamic force reaches a critical value in the proposed design, the permanent connection 3 will be destroyed, as a result of which the feed impermeable part 1 and the bow impermeable part 2 are disconnected. Their waterproof design will prevent flooding of both parts. With the bow of the impermeable part 2 disconnected, the hydrodynamic loads acting on the stern impermeable part 1 will decrease, which will ensure the safety of the crew, who will have time to make decisions on choosing the optimal mode of movement of the vessel and measures to improve its stability, or to evacuate in case of adverse development of the situation. The construction of the closest analogue in a storm with strong oncoming waves is characterized by the fact that when the wave captures the bow of the tip due to an increase in hydrodynamic force and a drop in metacentric height, the ship capsizes, and this process develops so quickly that the crew does not have time to take any action.

могут быть оценены для каждого конкретного судна с использованием аппарата теории корабля в соответствии с [Бураковский Е.П., Бураковский П.Е. Некоторые проблемы обеспечения общей прочности судов в чрезвычайных ситуациях // Труды Крыловского государственного научного центра - Вып. 82(366), 2014 - С. 21-30].To ensure timely disconnection of the bow of the impermeable part 2 from the feed of the impermeable part 1, the destruction of the inseparable compound 3 should occur when the value of the hydrodynamic force reaches a certain critical value P _cr corresponding to the maximum permissible drop in the metacentric height for this vessel. Its size and distance of the point of application from the bow of the vessel

can be estimated for each specific vessel using the apparatus of the theory of the ship in accordance with [Burakovsky EP, Burakovsky PE Some problems of ensuring the overall strength of ships in emergency situations // Transactions of the Krylov State Scientific Center - Issue. 82 (366), 2014 - S. 21-30].

To ensure the effectiveness of the proposed design, it is necessary that when approaching the value of the hydrodynamic force to P _cr, the bending moment acting in one-piece joint 3 is equal to the ultimate moment M ₀ at which the one-piece compound 3 is destroyed, taking into account the safety factor K _s . From this condition, it is possible to determine the required ultimate moment for the integral connection 3, at which it will be destroyed

where M ₀ - the limit value of the bending moment, acting on one-piece connection, Nm;

P _cr - the critical value of the hydrodynamic force, N;

L _H - the length of the nasal impermeable part, m;

- расстояние от носа судна до точки приложения равнодействующей гидродинамических сил при захвате волной носовой оконечности судна, м;

- distance from the bow of the vessel to the point of application of the resultant hydrodynamic forces when the wave captures the bow of the ship, m;

To _s - safety factor.

To ensure the unsinkability of the bow of the impermeable part 2 and the feed of the impermeable part 1 in the area of the permanent connection 3, the installation of two waterproof bulkheads is necessary. Their strength should satisfy the requirements for the side ceilings of the vessel in question, since after separation of the bow impermeable part 2, these bulkheads will be exposed to loads comparable to those acting on the side ceilings. Ensuring the destruction of the permanent connection 3 when the bending moment reaches the desired value of M ₀ can be achieved by using sheets of the outer skin of a smaller thickness between these bulkheads than for neighboring areas of the housing, or by grooving grooves, providing local weakening of the skin. In addition, it is possible to use bolt and rivet joints of sheets in the area of permanent connection 3, while bolts or rivets must be cut off by the force arising when the bending moment in the cross section of the body reaches M ₀ . It is also possible to use welds, the strength of which should be lower than the strength of the sheathing plates. These methods can be applied to connect the beams of the longitudinal set of the housing in the area of permanent connection 3.

It should be noted that an excessive decrease in the value of M ₀ can lead to an unacceptable decrease in the strength of the hull and its destruction during normal operation, not associated with the action of extreme loads in the process of capture by the wave of the bow tip. To prevent such a situation, it may be necessary to implement measures that increase the values of P _cr , i.e. increasing the stability of the vessel, for example, by laying solid ballast. This will ensure sufficient strength of the hull and the effectiveness of the proposed design solutions.

Thus, the proposed design eliminates the loss of stability of the vessel during movement on oncoming waves in stormy conditions, which contributes to increased safety of navigation.

Claims (8)

The hull of the vessel, made in the form of an impermeable shell formed from the outer skin and beams of the set, characterized in that the impermeable shell is made in the form of two separate impermeable parts - fore and stern, connected by a permanent connection located on the fore side of the hull from the mid-frame, the strength of which chosen so that it ensures the connection of the parts until the bending moment M ₀ acting on the permanent connection reaches the limit value associated with the critical value of the hydrodynamic force P _kp , which corresponds to the maximum allowable drop in metacentric height for a given vessel, by the following ratio:

Where M ₀ is the limiting value of the bending moment acting on the permanent connection, Nm; P _cr - the critical value of the hydrodynamic force, N; L _H - the length of the nasal impermeable part, m; l is the distance from the bow of the vessel to the point of application of the resultant hydrodynamic forces when the wave captures the bow of the ship, m; To _s - safety factor.

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