RU2840558C1 - Propulsion complex of object in water environment - Google Patents

Abstract

FIELD: shipbuilding.

SUBSTANCE: invention relates to ship building, particularly, to propulsors, particularly, to screw-nozzle propulsion systems of objects moving in the water environment. Propulsion complex of object in water environment comprises screw propellers and nozzle. Screw propeller hub ends are located in one plane on one line, on curve. Screw propellers perform alternating right and left rotation with loop-shaped blades, form two disk spaces combined at the blade end with a bridge in the form of a nozzle part. Pair blades in their disk spaces are displaced relative to each other by half of blade width and have double-sided segment profile of blades, which is characterized with invariance of blade profile shape along the whole length of curved envelope of blade profile, symmetrical execution of blade width relative to blade mid line. Propeller nozzle is shifted and located between ship hull or underwater object aft end ahead of screw propeller loop blade first disc and comprises straightener blades and outlet cross-section does not extend beyond disc space of every screw.

EFFECT: increasing the thrust and propulsive efficiency of propellers with loop-shaped blades, increasing energy efficiency at all speeds.

2 cl, 2 dwg

Description

Field of technology

The invention relates to shipbuilding, namely to propulsion devices, in particular to propulsion systems of the screw-nozzle type for objects moving in an aquatic environment, and can be used as a propulsion device for a surface vessel or for moving underwater objects by forming a jet and creating a driving longitudinal force.

State of the art

There are known propulsion systems for ships that contain propellers installed with overlapping propeller disks, which makes it possible to increase the hydrodynamic efficiency of such systems.

However, such propulsion systems are not efficient enough at high values of the thrust load coefficient.

Also known is a propulsion system of the screw-in-nozzle type, comprising two or four propellers, with the stern of the vessel located between the propellers (patent No. 2101210, IPC B63G 8/00 (1995.01), B63G 8/08 (1995.01), Published: 10.01.1998) or (patent No. 2681415, IPC B63G 8/00 (2006.01), Published: 06.03.2019 Bulletin No. 7) in which the streamlined hull contains a group of three or four stern cruising reversible water-jet propulsors. The inlet and outlet pipes of the propulsors are rigidly fixed in the hull of the apparatus. In this case, the inlet openings of the inlet pipes of the cruise propulsors are made in the form of a single annular gap along the perimeter of the apparatus body in cross-section, and guide plates are installed in the outlet openings of the outlet pipes of the aft cruise water-jet propulsors.

However, such a design leads to an increase in the dimensions of the complex and a decrease in its efficiency due to the impossibility of reducing losses with circumferential induced speeds, but such a design allows for the creation of different thrust on the propeller disks and increases controllability. There is a need to additionally install a group of bow transverse thrusters to increase controllability.

The closest to the proposed invention, in its technical essence, is the propulsion system of a two-shaft vessel (USSR Author's Certificate No. 846395, published 1975), containing propellers, the disks of which are located in one plane and installed in a nozzle with overlapping propeller disks, due to which an increase in hydraulic efficiency and a decrease in the transverse dimensions of the prototype propulsion system are achieved.

The disadvantage of placing the propeller disks in the same plane with overlapping propeller disks with more than 2 propeller blades does not allow creating sufficient support under high loads at low propeller rotation speeds in the mode, for example, of economical running with high hydraulic efficiency.

The disadvantage of this design is the low value of thrust and propulsive efficiency, as well as the tendency to cavitation in the peripheral area of the blade. At high speed, the water flow, moved by centrifugal force at high speed, hits the inner wall of the annular nozzle and creates braking of the propeller torque.

Disclosure of the essence of the invention

The objective of the invention is to create a propeller-nozzle type propulsion system for an object located in a water environment with high hydraulic efficiency under high loads in all operating modes on straight courses, to ensure maximum thrust at all speeds of movement with minimum dimensions of the propulsion system.

The technical result of using the proposed invention is an increase in the thrust and propulsive efficiency of propellers with loop-shaped blades, and an increase in energy efficiency at all speeds.

The stated task is achieved by the fact that the propulsion system of an object located and moving in an aquatic environment, containing propellers and a nozzle, can have from 2 to 5 propellers, the hubs of which are located in the same plane on the same line, on a curve or at the vertices of a rectangle.

In the propulsion complex, the number of propellers can be from 2 to 5, the ends of the hubs of which are located in the same plane on the same line, on a curve, while the propellers are made alternately of right and left rotation, with loop-shaped blades, forming two disk spaces, united at the end of the blade by a bridge in the form of part of the nozzle, while the paired blades in their disk spaces are shifted relative to each other by half the width of the blade, and having a two-sided segmented blade profile characterized by the invariance of the geometry of the blade profile shape along the entire length of the curvilinear envelope of the blade profile, symmetrical execution of the blade width relative to the center line of the blade, the screw nozzle is shifted and is located between the hull of the vessel or underwater object in front of the first disk of the blades of the loop blades of the propeller, contains the blades of the straightening apparatus and in the outlet section does not extend beyond the boundaries of the disk space of each of the propellers, while the shafts of the propellers of the propulsion system of the underwater object can be located at different angles, while the axes of the shafts can intersect before and after the common disk space of the propellers.

The nozzle mounting posts have an installation angle to compensate for the flow twisting by the propellers, which is determined by calculation depending on the rotation speed of the propeller.

The blades of loop-shaped propellers have a double-sided segmented profile, which ensures that the geometry of the blade profile shape remains constant along the entire length of the curved envelope of the blade profile to create favorable conditions for flow around the profile and minimize cavitation and losses of the generated pressure.

The loop shape helps reduce cavitation phenomena during propeller operation, and the shape and location of the curvilinear envelope of the propeller blade profile reduces losses and helps improve hydrodynamic characteristics, and, as a result, increase thrust and propulsive efficiency.

The described complex screw surface with variable relative width and variable spacing of the front and rear parts of the blade along its height provides for improvement of the hydrodynamic characteristics of the propeller. Two suction and two pumping surfaces of one blade of the propeller provide for an increase in the thrust characteristics of the propeller.

It is possible to use propellers with the parameters given for the design described in patent No. 2780771 (IPC B63N 1/00, published 30.09.2022, bulletin No. 28).

The advantage of a fixed-pitch propeller is the highest efficiency for propellers of objects in the aquatic environment. Propellers have a relatively low manufacturing cost, they are easier to operate and maintain. Constant-pitch propellers are reliable and durable.

To create sufficient thrust of the propulsion system of an object in the water environment, for example, a shallow-draft vessel, a certain area of the propeller disk is required. With a small draft, this is possible only by increasing the number of propellers. But with an increase in the number of propellers, the width of the vessel increases. The intersection of the disk space of several propellers allows creating thrust with a small width of the vessel and increasing the hydraulic efficiency of the complex, consisting of several small-diameter propellers. The engine power is divided by the number of propellers.

For an object with a propulsion system immersed in water, when the propellers operate, in addition to twisting, there is a narrowing of the water flow, which leads to some decrease in the efficiency of the propeller. To eliminate this phenomenon, guide nozzles are used. The nozzle is a ring in which the propeller rotates. The nozzle cross-section has a wing profile with a convex surface facing the propeller.

The nozzle increases the propulsion coefficient of the propeller. Propellers with nozzles are successfully used when it is necessary to create additional thrust at low speeds.

In a propeller operating in a nozzle, the axial velocities of the water flow increase in the nozzle itself, due to which the flow velocity around the propeller with a nozzle is significantly higher than without it.

Since part of the thrust required from the propulsion system is created in the nozzle, and the speed of water flowing onto the propeller increases, the nozzle has an unloading effect on it. This leads to an increase in the efficiency of the propeller, due to which, with the same power of the ship's power plant, a greater thrust of the propeller is created.

The guide nozzle evens out the flow of water entering the propeller, eliminates oblique water flow around the propeller, and improves its operation in rough water.

With the opposite direction of rotation of the propellers and the convergence of the propeller shaft lines behind the disk space, the narrowing of the water flow occurs in opposite directions, while the flows are combined, which enhances the effect of increasing the thrust, since they are added together into a single flow.

In the event of convergence of the propeller shaft lines to the disk space, a divergence of the narrowing flows from each propeller occurs, which increases the thrust area of the propulsion system.

With 4 propellers in a line, the two middle propellers add flows and the two outer flows diverge, which increases the flow speed and thrust in the center of the propulsion system.

If there are 4 propellers in the nodes of a quadrangle at the aft end of a spindle-shaped underwater object, it is more advantageous to add the narrowing flows from the propellers.

The presence of a nozzle on vessels sailing in shallow water equalizes water loss behind the stern, which reduces the erosion of the bottom soil or the walls of the channel from the operation of the propeller.

When there are several propellers combined into a single disk space, there is a need for a nozzle that envelops the disk space of the propellers with the smallest possible gap - no more than 0.5% of the diameter of the propeller - between the ends of the blades and the body of the nozzle.

The minimum gap value is taken to be equal to 0.1% of the diameter D of the screw, due to the fact that with a smaller value, the value of hydraulic resistance increases, which leads to an increase in energy costs.

With its greater value, the value of hydraulic resistance increases due to the increase in friction in the gap, which also leads to an increase in energy costs, therefore, no more than 0.5% of the propeller diameter is accepted as the gap between the ends of the blades and the nozzle body. The size of the gap can be determined by the dimensions and design features of the propellers and nozzle.

The proposed propulsion system of the screw-nozzle type for an underwater object with a compact combined disk space of mutually intersecting propellers on parallel shafts with loop-shaped blades allows the creation of a propulsion system with high hydraulic efficiency under high loads in all operating modes on straight courses with maximum thrust at all speeds of movement.

The technical result of using the proposed invention is an increase in the thrust and propulsive efficiency of the propeller, and an increase in energy efficiency at all speeds.

Brief description of the drawings

To clarify the essence of the proposed invention

Fig. 1 shows a propulsion system whose propellers have loop-shaped blades.

Fig. 2 shows a side view of the propulsion system with loop-shaped propellers, where:

1 - loop propeller;

2 - blade;

3 - bushing;

4 - nozzle;

5 - stand;

6 - aft end; 7-shaft;

Implementation of the invention

Fig. 1 and 2 show an underwater object equipped with a propulsion system consisting of two loop-shaped propellers 1 on shafts 7 installed in a nozzle 4 with racks 5, in the aft end 6 of the underwater object with overlapping disks of loop-shaped blades 2. Loop-shaped propellers 1 are alternately made for right and left rotation and do not have the ability to change the pitch of the blades.

Loop-shaped propellers 1 with loop-shaped blades 2 form two disk spaces united at the end of the blade by a bridge in the form of part of the nozzle 4, wherein the paired blades 2 in their disk spaces are shifted relative to each other by half the width of the blade, and have a two-sided segment profile of the blades 2 characterized by the invariance of the geometry of the shape of the blade profile along the entire length of the curvilinear envelope of the profile of the blade 2, symmetrical execution of the width of the blade relative to the center line of the blade 2.

In the drawing Fig. 2, the nozzle 4 of the propeller 1 is offset and is located between the aft end 6 of the underwater object in front of the first disk of the loop blades of the propeller 1, contains posts 5 in the form of blades of a straightening apparatus compensating for the heeling moment arising on the hull of the underwater object during operation of the loop propeller 1. Each loop propeller 1 has a different angle of arrangement of posts 5 to compensate for the heeling moment during operation of the propeller 1 of right and left rotation. The nozzle 5 in the outlet section does not extend beyond the boundaries of the disk space of each of the propellers 1.

The struts 5 are installed with their inner ends on the casing, and the nozzle 4 is attached to their outer ends. The convex side of the struts 5 faces the direction of rotation of the propeller 1, and the flat or concave side forms a positive blade installation angle with the axial direction, measured from the direction of movement in the direction of rotation of the propeller 1. In this case, the angle of attack in each section of the blade and the profile shape are calculated in such a way that the flow swirl rate on the struts 5 is equal to the flow swirl rate in the corresponding sections of the propeller 1. However, in cases where the requirements for ease of manufacture are more significant than the requirements for the efficiency of the propeller, the swirling blades of the struts 5 can be installed at a constant installation angle and have a profile shape that is constant along the height of the strut 5. In this case, the installation angle of the struts 5 required to compensate for the moment of the propeller 1 is determined by calculation or selected experimentally.

The nozzle 4 is made in the form of an annular wing, facing with its convex side inward, and a device for its fastening on the body of the tapering stern end 6 of the underwater object, wherein the flow annular channel of the propeller is formed on the inner side by the tapering stern end 6 of the underwater object, and on the outer side by the convex part of the profile of the nozzle 4.

The cone angle of the outer surface of the nozzle 5 is less than the cone angle of the tapering stern end 6 of the underwater object.

The propeller shafts are driven by one drive motor through a gearbox (not shown) and shafts 2. When the loop-shaped propellers 1 rotate at equal angular velocities, the blades of one of the propellers 1 enter the gap between the blades of the other propeller 1. In this case, it is possible to reduce the dimensions of the propulsion system.

The location of the nozzle 4 in the zone of the narrowing flow along the narrowing aft end 6 of the underwater object and the selection of the optimal angle of its conicity ensure the occurrence of a useful thrust force on the nozzle 4 even at low values of the load of the loop-shaped propellers 1.

The use of the design elements of the attachment of the nozzle 4 in the form of posts 5, on the body, as a twisting device ensures the occurrence of a moment that compensates for the roll moment from the operation of the propeller 14, and also leads to an increase in the efficiency of the latter, which completely or partially compensates for the resistance of the twisting posts 5 of the attachment of the nozzle 4.

The presence of the end surface of the loop-shaped propellers 1 makes it possible to increase the propeller thrust without increasing its rotation frequency, which makes it possible to reduce the energy consumption for driving the loop-shaped propellers 1. The location of the loop-shaped propellers 1 in the outlet section of the nozzle 4 or beyond it does not cause acceleration of the flow on the elements of the propeller 1 and, therefore, does not worsen its cavitation characteristics.

In the presence of two loop-shaped propellers 1, there is a total increase in the efficiency of the proposed propulsion system compared to a single propeller under the same operating conditions at high loads on straight courses, to ensure maximum thrust at all speeds.

The interaction of intersecting propellers has been developed on a spatial model in a graphical editor, which allows the selection of optimal geometric characteristics of the propulsion system.

Claims (2)

1. A propulsion system for an object in an aquatic environment, comprising propellers and a nozzle, characterized in that the number of propellers can be from 2 to 5, the ends of which are located in the same plane on the same line, on a curve, and the propellers are made of alternately right and left rotation with loop-shaped blades, forming two disk spaces connected at the end of the blade by a bridge in the form of part of the nozzle, and the paired blades in their disk spaces are offset relative to each other by half the width of the blade and have a two-sided segmented blade profile, characterized by the invariance of the geometry of the blade profile shape along the entire length of the curvilinear envelope of the blade profile, symmetrical execution of the blade width relative to the center line of the blade, the nozzle of the propellers is offset and is located between the hull of the vessel or the aft end of the underwater object in front of the first disk of the loop blades propeller blades, contains the blades of the straightening apparatus and in the outlet section does not extend beyond the boundaries of the disk space of each of the propellers. 2. A propulsion system for an object in an aquatic environment according to paragraph 1, characterized in that the propeller shafts can be located at different angles, and the axes of the shafts can intersect before and after the common disk space of the propellers, the nozzle mounting posts have an installation angle to compensate for the swirling of the flow by the propellers.

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