WO2023177379A1

WO2023177379A1 - A cavitation controlled rudderless propulsion system

Info

Publication number: WO2023177379A1
Application number: PCT/TR2023/050254
Authority: WO
Inventors: Guven GONCA
Original assignee: Yildiz Teknik Universitesi
Priority date: 2022-03-16
Filing date: 2023-03-15
Publication date: 2023-09-21

Abstract

The invention relates to a rudderless propulsion system with cavitation control that has been developed for use in sea vehicles, performs the propulsion and manoeuvring of the vehicle without the need for a rudder, and comprises main propulsion propeller, starboard auxiliary propeller, port auxiliary propeller, upper auxiliary propeller, lower auxiliary propeller, starboard auxiliary propeller connection, port auxiliary propeller connection, upper auxiliary propeller connection, lower auxiliary propeller connection, propeller shaft, angle adjustment mechanism, pressure sensor and electronic control unit.

Description

A CAVITATION CONTROLLED RUDDERLESS PROPULSION SYSTEM

Technical field of the invention

State of the Art

The rudders are the dynamic parts of air and sea vehicles that serve to steer the vehicle. They are elements made of steel sheet, which are used to change the course of the ship while cruising and to facilitate the movements of the manoeuvring ship. When the rudder is directed to starboard or port, it tries to turn the ship with a water force depending on the cruising speed of the ship. If the rudder is turned at a low angle, the boat turns slowly. If the boat is desired to turn quickly or strongly, the rudder angle should be enlarged. The ship's rudder is turned by an electrical and hydraulic system called rudder gear.

The current rudder system used in vessels today causes additional resistance at the rear of the vessel. In addition, the initial installation cost of these rudder systems is high. The total production and propulsion cost of the ship increases due to the rudder systems. In addition, in existing vessels, the probability of sinking is high when the vessel receives a major injury. In the studies carried out, it is tried to reduce the appendage resistance of the ship by lightening the rudder system and using the rudder form that causes less resistance. Although the total resistance is tried to be reduced by arranging the rudder form and propeller track, the rudder system itself always causes some resistance. In order to eliminate this resistance, a more efficient manoeuvring propulsion system should be put in place of the rudder.

During the rotation of the ship's propellers, a vacuum is created. This vacuum falls under the evaporation pressure of sea water and initiates the formation of vapour. This fact causes the formation of bubbles filled with water vapour. When the bubbles hit the impeller surface, they burst and cause damage to the material forming the propeller. This situation, which is stated as one of the biggest problems seen in ship propellers, is the formation of cavitation due to the decrease in pressure.

Vibrations caused by cavitation are felt more especially when there is no load on the ship. Vibrations felt may negatively affect the comfort of the ship's personnel, as well as cause deterioration of electronic equipment. Another undesirable result of cavitation in the propeller is the uneven force applied to the shaft to which the propeller is attached. This creates capillary cracks in the shaft and can create problems that are difficult to repair over time. In addition, cavitation is one of the most important factors affecting the life of the propeller. When cavitation progresses, unusual sounds can be heard from the stern of the ship. In particular, the periodic change in the size of the layer cavitation on the propeller blades causes non-constant propeller forces and vibration, and noise generation under water and within the ship.

The invention that is the subject of the patent no "TR 2017/18567" in the state of the art is related to a propeller system that enables ships and similar vessels to manoeuvre without using a rudder. In particular, the invention relates to a propeller system developed for use in vessels, which eliminates the need for a rudder, as it contains one main propeller that provides the propulsion of the vessel and four auxiliary propellers that provide manoeuvring. However, in this propeller system, there is no improvement in preventing abnormal sounds from the stem of the ship, non-continuous propeller forces and vibration, and noise that may occur underwater and within the ship.

The invention that is the subject of the patent no "JPS5747295A" in the state of the art relates to an apparatus developed to prevent cavitation wear. This structure has an air injection port near the rear end of a ring-like structure in front of a spiral propeller at the stern of a ship. The ring-like structure is mounted on the front of the propeller. A side surface of the structure takes the shape where the length of the upper part is longer and narrows towards the lower part. A plurality of air ducts are arranged in an upper part of the ring-shaped structure, and the injection zones at the end parts open towards the impeller.

The invention that is the subject of the patent no "CN1440346A" in the state of the art relates to a marine propeller, particularly to a cavitation prevention device that can increase the efficiency of the marine propeller. The rear edge of this device may preferably have a series of continuously curved rearward projections. The anti-cavitation tube may include fins located in a region of the outer cover and may also include a transition region between the rear edge and the upper bracket. However, there is no sufficient development in said cavitation preventive device to prevent vibrations caused by cavitation, and thereby the negative effects on the comfort of the personnel, by preventing the deterioration of electronic devices. It is also clear that the tube will cause additional resistance and negatively affect the ship's propulsion performance.

Considering the advantages and disadvantages of a rudderless propulsion system in the art, there is a need for a new rudderless propulsion system that can be cavitation controlled and affects the total resistance of the ship as little as possible.

Brief Description and Aims of the Invention

The invention relates to a cavitation controlled rudderless propulsion system developed for use in marine vessels, meets the above-mentioned requirements, eliminates all disadvantages and brings some additional advantages.

The most important aim of the invention is to prevent the formation of cavitation in the propeller and its shafts. In the present invention, the angle of the shaft and the immersion level of the propellers are adjusted with the existing angle adjustment mechanism. Since the tilt of the propeller shaft can be adjusted, the ship's stem trim angle can be reduced and the overall ship resistance can be reduced.

Another aim of the invention is to prevent the bubbles formed due to the vacuum created by the rotation of the ship's propellers, falling under the evaporation pressure of the sea water and initiating the formation of vapour. By preventing the formation of these bubbles, the bubbles are prevented from bursting when they hit the impeller surface and damage to the material forming the propeller is prevented.

Another aim of the invention is to prevent the vibrations caused by cavitation and negative effects on the comfort of the personnel by preventing the deterioration of electronic devices.

Another aim of the invention is to prevent the force applied to the shaft to which the propeller is connected by preventing cavitation. Because, the irregular force applied to the shaft to which the propeller is connected creates capillary cracks in the shaft and creates problems that are difficult to repair over time.

Another aim of the invention is to prevent abnormal sounds coming from the stem of the ship, non-continuous propeller forces and vibration, and noise that may occur underwater and within the ship. With the invention, it can be prevented that the layer cavitation size formed on the propeller blades changes periodically.

Another aim of the invention is to enable the vessel to manoeuvre without the need for a rudder system and to prevent cavitation.

Description of Figures:

FIGURE-1; is the figure showing the first and second methods in the cavitation controlled rudderless propulsion system that is the subject of the invention.

FIGURE-2; is the figure showing the first and second methods in the cavitation controlled rudderless propulsion system that is the subject of the invention.

FIGURE-3; is the figure showing the first and second methods in the cavitation controlled rudderless propulsion system that is the subject of the invention.

FIGURE-4; is the figure showing the third method in the cavitation controlled rudderless propulsion system that is the subject of the invention.

FIGURE-5; is the figure showing the third method in the cavitation controlled rudderless propulsion system that is the subject of the invention. FIGURE-6; is the figure showing the third method in the cavitation controlled rudderless propulsion system that is the subject of the invention.

FIGURE-7; is the drawing showing the working principle of the angle adjustment mechanism in the cavitation controlled rudderless propulsion system that is the subject of the invention.

Definition of Elements/Parts Composing the Invention

In order to better explain the cavitation controlled rudderless propulsion system developed with this invention, the parts and elements in the figures are numbered, and the equivalent of each number is given below:

1. Main propeller

2. Starboard auxiliary propeller

3. Port auxiliary propeller

4. Upper auxiliary propeller

5. Lower auxiliary propeller

6. Starboard auxiliary propeller connection

7. Port auxiliary propeller connection

8. Upper auxiliary propeller connection

9. Lower auxiliary propeller connection

10. Propeller shaft

10a. Fixed shaft

10b. Rotary shaft

10c. Connection shaft

11 . Angle adjustment mechanism

12. Pressure Sensor

13. Electric control unit

14. Starboard auxiliary propeller reducer

15. Port auxiliary propeller reducer

16. Upper auxiliary propeller reducer

17. Lower auxiliary propeller reducer M. Motor side

P. Propeller side

Detailed Description of the Invention

The invention relates to a rudderless propulsion system with cavitation control that has been developed for use in sea vehicles, performs the propulsion and manoeuvring of the vehicle without the need for a rudder, and comprises main propulsion propeller (1 ), starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4), lower auxiliary propeller (5), starboard auxiliary propeller connection (6), port auxiliary propeller connection (7), upper auxiliary propeller connection (8), lower auxiliary propeller connection (9), and propeller shaft (10).

One of the biggest problems seen in ship propellers is the formation of cavitation. Cavitation stems from bubble formation due to pressure drop. To prevent this, the pressure of the flow on the propeller must be increased. In order to achieve this, the propeller shaft is designed with a downward tilt or the ship is floated with a stem trim. In the system developed with the invention, the angle of the shaft and the submersion level of the propellers are adjusted by the angle adjustment mechanism.

In the system developed with the invention, the proposed shaft adjustment mechanism and the electronic control unit (13), which adjusts the angle according to the pressure, are provided to get rid of the cavitation of the propeller without trimming the ship to the stem. Since reducing the trim level and wet surface area on the ship will also reduce the ship's resistance due to the wet surface, it will make a positive contribution to fuel consumption and the performance of the ship.

With the invention, it is possible to manoeuvre the vessel without the need for a rudder system. While manoeuvring in the port-starboard direction with the aid of the starboard auxiliary propeller (2) and the port auxiliary propeller (3), it is ensured that, with the help of the upper auxiliary propeller (4) and the lower auxiliary propellers (5), the vessel floats close to the surface in case of a damage. This system is connected to the ship with the propeller shaft (10). In the centre of a cavitation controlled rudderless propulsion system, there is the main propulsion propeller (1 ) and it provides the propulsion of the vessel.

On the starboard side of the ship, there is a starboard auxiliary propeller (2) and a starboard auxiliary propeller connection (6). On the port side, there is the port auxiliary propeller (3) and the port auxiliary propeller connection (7). On the upper part of the main propeller (1), there is the upper auxiliary propeller (4) and the upper auxiliary propeller connection (8). At the bottom of the main propeller (1), there is the lower auxiliary propeller (5) and the lower auxiliary propeller connection (9). The purpose of the mentioned connections is to connect the starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4) and lower auxiliary propeller (5) to the propeller shaft (10).

The normal propulsion of the starboard auxiliary propeller (2) and the operation of the port auxiliary propeller (3) in the stern-way (reverse direction of the propeller) enables the vessel to manoeuvre in the port direction. The normal propulsion of the port auxiliary propeller (3) and the operation of the starboard auxiliary propeller

(2) in the stern-way on the other hand enables the vessel to manoeuvre in the starboard direction. The normal propulsion of the operation of the lower auxiliary propeller (5) and the operation of the upper auxiliary propeller (4) in stern-way brings the hull of the vessel closer to the sea surface. This reduces the likelihood of a damaged vessel sinking. The normal propulsion of the upper auxiliary propeller (4) and the operation of the lower auxiliary propeller (5) in stern-way will move the hull of the vessel away from the sea surface and cause the hull of the vessel to submerse more. This manoeuvre feature helps to control the ballast as needed.

The main propeller (1 ), starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4) and lower auxiliary propeller (5) are connected to a single shaft, that is the propeller shaft (10). Thus, it is more advantageous than previous systems in terms of area and resistance.

The main propeller (1 ) and starboard auxiliary propeller (2), port auxiliary propeller

(3), upper auxiliary propeller (4), lower auxiliary propeller (5) differ in terms of their propulsion methods. In the first method, the main propeller is driven by an internal combustion engine (diesel or gasoline). Starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4) and lower auxiliary propeller (5) are electrically driven.

In the second method, main propeller (1 ) and starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4), lower auxiliary propeller (5) are electrically driven.

In the third method, the main propeller (1 ) and starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4), lower auxiliary propeller (5) are driven by an internal combustion engine (diesel or gasoline). The main propeller (1 ) is connected to the propeller shaft (10) that is connected to the internal combustion engine (diesel or gasoline), directly or by means of a reducer. Starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4) and lower auxiliary propeller (5) are connected to the propeller shaft (10) connected to the main propeller (1 ) with the help of starboard auxiliary propeller reducer (14), port auxiliary propeller reducer (15), upper auxiliary propeller reducer (16), and lower auxiliary propeller reducer (17) and are driven by the internal combustion engine. In this system, either electric or internal combustion engine drive should be selected. With three different methods, different drive combinations can be selected. These combinations vary according to the ship's design and operating characteristics and requirements.

Propeller dimensions are designed in relation to ship dimensions, and the engine may be more than one. The engine is also referred to as a ship engine in the literature.

The ratio of the maximum torque produced by any of the starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4), and lower auxiliary propeller (5) to the maximum torque produced by the main propeller (1 ) varies according to the design and operating characteristics and requirements of the ship.

In the cavitation controlled rudderless propulsion system developed with the invention, there is an angle adjustment mechanism (11) between the propeller and the stem. The angle adjustment mechanism (11 ) provides the downward rotation of the propeller shaft (10) up to a maximum of 30 degrees from the horizontal axis. It is shown in the lower right image in Figure-7.

When the angle is 0 degrees, the propeller shaft (10) is perfectly straight. As the angle increases, the propeller shaft (10) moves from the sea surface to the sea bottom and the water pressure on the propellers increases. Increasing pressure and speed of water are signalled to the electronic control unit (13) from the sensor to determine whether cavitation has occurred, and if there is cavitation, the angle is increased. Cavitation is controlled by increasing angle. Increasing the angle in the absence of cavitation is projected to adversely affect the propulsion performance of the ship.

The working principle of the angle adjustment mechanism (11 ) is shown in figure 7. As can be seen in Figure-7, the connection shaft (10c) provides the connection between the rotary shaft (10b) and the fixed shaft (10a). There is a rotary shaft (10b) on the propeller side (P) and a fixed shaft (10a) on the motor side (M).

With the angle adjustment mechanism (11 ), whether cavitation has occurred or not can be calculated by using the pressure and the ship speed sensed by the pressure sensor (12). As the angle is increased, it submerses more into the water and the pressure on the propeller increases. In addition, with the electronic control unit (13), whether the angle is sufficient or not is controlled by the continuous feedback method and cavitation is controlled momentarily.

The angle of the propeller shaft (10) and the submersion level of the main propeller (1), starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4), and lower auxiliary propeller (5) are adjusted with the angle adjustment mechanism (11).

The cavitation formation, which is one of the biggest problems in ship propellers due to the decrease in pressure, has been solved by increasing the pressure of the flow on the propeller. Increasing the pressure on the propeller is achieved by designing the propeller shaft inclined downwards in the state of the art or by floating the ship with stern trim. The angle adjustment mechanism (11 ) and the electronic control unit (13) that adjusts the angle according to the pressure that are proposed in the present invention provide the propeller to get rid of cavitation without the need to trim the ship astern. The pressure sensor (12) located on the upper auxiliary propeller (4) sheet transfers the pressure data to the electronic control unit (13) and the electronic control unit (13) controls the angle adjustment mechanism (11 ), taking into account the ship and water speed, in a way that prevents cavitation, and ensures that the propeller shaft (10) comes to the appropriate angle. Reducing the trim level and wet surface area on the ship will also reduce the ship's resistance due to the wet surface, thus making a positive contribution to fuel consumption and the performance of the ship.

In the electronic control unit (13), pressure measurement, propeller properties, flow velocity calculation and cavitation control are performed to prevent cavitation, It also ensures that the angle is sufficient to be controlled by the continuous feedback method and the cavitation is taken under control instantly.

By means of the angle adjustment mechanism (11 ) and the multi-propeller structure in the system developed with the invention, if the ship is damaged from the stern and is sinking towards there, the angle can be maximized to prevent the ship from sinking according to its structure and characteristics. The electronic control unit (13) can also keep the ship on the water surface by increasing the angle, independent of the cavitation control, in case of an emergency where the ship is damaged from the stem.

Claims

1. A cavitation controlled rudderless propulsion system that has been developed for use in sea vehicles, performs the propulsion and manoeuvring of the vehicle without the need for a rudder, and comprises main propulsion propeller (1 ), starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4), lower auxiliary propeller (5), starboard auxiliary propeller connection (6), port auxiliary propeller connection (7), upper auxiliary propeller connection (8), lower auxiliary propeller connection (9), and propeller shaft (10), comprising;

• the angle adjustment mechanism (11 ) that is positioned between the entire propeller system and the stern, allows the propeller to get rid of cavitation by adjusting the angle of the propeller shaft (10) and the immersion level of the main propeller (1 ), starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4), and lower auxiliary propeller (5) and calculates whether cavitation occurs or not by using the pressure and ship speed information received from the pressure sensor (12),

• pressure sensor (12) that is located on the upper auxiliary propeller (4) sheet and transfers the pressure data to the electronic control unit (13), and transfers the pressure and ship speed it senses to the angle adjustment mechanism (11 ),

• electronic control unit (13) that controls the angle adjustment mechanism (11 ) to prevent cavitation, ensures that the propeller shaft (10) reaches the appropriate angle, constantly checks whether the angle is sufficient and adjusts the angle according to the pressure, and

• and engine driven starboard auxiliary propeller reducer (14), port auxiliary propeller reducer (15), upper auxiliary propeller reducer (16) and lower auxiliary propeller reducer (17) that connect the starboard auxiliary propeller (2), port auxiliary propeller (3), upper auxiliary propeller (4) and lower auxiliary propeller (5) to the propeller shaft (10) connected to the main propeller (1).

2. A cavitation controlled rudderless propulsion system according to Claim 1 , comprising the angle adjustment mechanism (11 ) that provides downward rotation of the propeller shaft (10) up to 30 degrees from the horizontal axis to prevent cavitation.

3. A cavitation controlled rudderless propulsion system according to Claim 1 , comprising electronic control unit (13) that enables the ship to be kept on the sea surface by increasing the angle in an emergency in which the ship is damaged in the stern.

4. A cavitation controlled rudderless propulsion system according to Claim 1 , comprising the angle adjustment mechanism (11 ) that ensures that the angle is maximized, and the ship is prevented from sinking if the ship is damaged from the stem and is sinking towards the stem.