EP4680523A1

EP4680523A1 - A telescopic anti-roll system using the magnus effect

Info

Publication number: EP4680523A1
Application number: EP24775315.5A
Authority: EP
Inventors: Hakan AKYILDIZ; Ozgur Ustun
Original assignee: Istanbul Teknik Universitesi ITU
Current assignee: Istanbul Teknik Universitesi ITU
Priority date: 2023-03-17
Filing date: 2024-03-18
Publication date: 2026-01-21
Also published as: WO2024196330A1; TR2023002998A2

Abstract

The invention relates to a telescopic anti-roll system which operates on the principle of the Magnus effect and enables the Magnus force to be controlled and increased.

Description

A TELESCOPIC ANTI-ROLL SYSTEM USING THE MAGNUS EFFECT

Technical Field

Prior Art

As it is known, environmental effects (sea and weather conditions) and external forces act on boats and all kinds of floating platform-like floating structures. External forces can be caused by current, wave, wind force and floating structure movements. Hence, the floating structure is subjected to static and dynamic roll movements. These movements can be periodic or non-periodic. In order for the floating structures exposed to these movements to fulfil their functions in a healthy way, it is important to reduce the roll motion to acceptable levels (angles). There are different systems in the literature and in the market as roll damping systems. One of them is Magnus-effect roll damping systems that work according to the principle of lifting force generated as a result of rotational movement in the fluid. These systems are mostly cylindrical and driven by an electric motor. Magnus force is a force proportional to the specific gravity of water, cylinder diameter, cylinder length, current velocity coming into the cylinder and angular rotational velocity. In order to dampen the roll motion, these cylindrical structures are rotated at different speeds and the Magnus effect is adjusted.

In the cylindrical roll prevention systems with Magnus effect used in the art, only rotational motion is utilised. The force generated in systems with Magnus effect varies in direct proportion to the square of the cylinder diameter and the length itself. Since there is no function of elongation and shortening of the cylinder length in the previous systems, both the cylinder takes up too much space and the Magnus effect cannot be controlled with elongation. In the Chinese patent document numbered CN104890831A, in the state of the art, retractable and collapsible hydrofoils of ships and specifically a stabilising apparatus combined with T-shaped hydrofoils and rotor foils is disclosed. The telescopic cylinders described in the document operate in an on-off manner and are not used for adjusting and increasing the Magnus force.

In Chinese patent document numbered CN108860500A, in the state of the art, a new ship stabiliser wing is disclosed. The new ship stabiliser wing comprises a stabiliser wing body, a rotating body, a first motor and a speed reducer. The stabiliser wing body is fixed to the rotating body. The stabiliser wing body comprises a telescopic wing plate and a hydraulic oil cylinder. The stabiliser wing body is provided with a storage cavity and a first mounting cavity. It is not about the Magnus effect, but an improvement of the force-developing area is mentioned.

In the Chinese patent document numbered CN111204432A, in the state of the art, a propulsion device that increases stability for the ship, which belongs to the technical field of seaside propulsion equipment, is mentioned. The device is placed under the hull of a ship and comprises a telescopic rod, a shape protection plate.

In the Korean patent document numbered KR20110001209 A, in the state of the art, a folding wing for optimising the stability and operability of a ship is disclosed, since the area, cross-sectional shape and aspect ratio of the wing are variably controlled according to the navigation state of the ship.

In the Korean patent document numbered KR20120105303A, in the state of the art, there is mention of a foldable wing stabiliser which aims to save horsepower and minimise the deterioration of resistance and rudder performances by implementing a reasonable surface area of a wet wing stabiliser according to the speed of a ship.

In the Chinese patent document numbered CN110615076A in the state of the art, a separate cylindrical stabiliser based on the Magnus effect in the field of ship stabilisation is mentioned. The separated cylindrical stabiliser comprises a motor, a motor bearing, a universal joint, a linear bearing, two semi-cylinders and an end plate. When the existing works in the art were examined, the need to realise a telescopic anti-roll system that enables the Magnus effect to be controlled and increased was felt.

Objects of the Invention

The object of the present invention is to realise a telescopic anti -roll system that allows the Magnus effect to be controlled and enhanced.

Another object of the present invention is to realise a telescopic anti -roll system which has faster and more effective control capability than conventional systems and which can adapt to sea and environmental conditions by taking up less space in terms of volume.

Another object of the present invention to realise, if necessary, a telescopic anti-roll system, different from the present systems, in which the appropriate stabilising force is provided by axial movement.

Another object of the present invention is to realise a direct-drive, compact, inwater telescopic anti-roll system which is easy to install and easy to remove.

Detailed Description of the Invention

The telescopic anti-roll system realised to achieve the object of the present invention is shown in the accompanying figures.

These figures are;

Figure 1: Schematic representation of the Magnus effect.

Figure 2: Schematic representation of the forces generated by the Magnus effect in the system according to the invention.

Figure 3: General schematic view of the telescopic anti-roll system according to the invention in an exemplary embodiment. Figure 4: Schematic view of the telescopic cylinder in the telescopic anti-roll system according to the invention.

Figure 5: Schematic view of the telescopic anti-roll system according to the invention.

The parts in the figures are numbered individually, and the corresponding descriptions are given below.

1. Boat hull

2. Rotary electric motor I

3. Rotary electric motor II

4. Linear electric motor

5. Distance sensor

6. Telescopic cylinder

7. Smart control system

8. Power and control signal connections

The invention relates to a telescopic anti-roll system for controlling and enhancing the Magnus effect, comprising the parts

- boat hull (1),

- a telescopic cylinder (6) consisting of nested rotating cylinders with different radii, which provides generation of the Magnus effect,

- a rotary electric motor I (2) connected to the boat hull (1) and providing horizontal rotational movement by adjusting the horizontal angle of the telescopic cylinder (6) with respect to the boat,

- a rotary electric motor II (3), which generates the Magnus effect by rotating the telescopic cylinder (6) around its centre,

- a linear electric motor (4) for lengthening and shortening of the telescopic cylinder (6),

- a smart control system (7) connected to the linear electric motor (4), controlling the horizontal angle, lengthening, shortening and rotation of the telescopic cylinder (6) with respect to the boat, and providing coordinated control of the rotary electric motor I (2), the rotary electric motor II (3) and the linear electric motor (4), having a boat rolling motion detection system.

When rolling from the port side to the starboard side in the case of a boat moving forward, the anti-roll moment must be opposed to the tilting (rolling) moment in order to reduce the rolling motion of the boat hull (1). While the port side of the boat hull (1) lifts up, the lift on the starboard side rotor must be downwards. In other words, the starboard rotor rotates anti -clockwise, while the port rotates clockwise when looking from starboard to port. The combined force produced on both rotors with respect to the longitudinal axis generates the required straightening moment. Similarly, if the ship rolls from starboard to port, the starboard rotor rotates clockwise with a downward lift and the port rotates anti-clockwise with an upward lift to reduce the roll motion of the ship.

The vertical component of the fluid flow caused by the roll motion of the ship cannot be ignored in the lift calculation. The lift taken into account by the controller must include both vertical and horizontal components of the flow. Assuming that a vessel incorporating the system of the invention rolls from starboard side to port side in the case of progression, the directions of the fluid flow, the rotation and the force of the port rotor when viewed from starboard to port are shown in figure 1.

Vhor = V is the horizontal velocity due to ship velocity.

V_ver ^{= r}ra>⁽P is the vertical velocity caused by the roll motion of the ship. ^rra> ^{= r}M ^{cos E} is the length of the Magnus rotor’s rotation arm. nu represents the distance between the hydrodynamic centre of pressure and the centre of gravity of the boat. a, is the angle between rM and the horizontal baseline. , is the rolling angular velocity.

VM, the resultant velocity of the velocities Vhor and Vver. L and D are the lifting and resistance components due to VM. m is the angular velocity of the rotor.

FL is the force used to prevent the boat from rolling and can be calculated as in formula I:

F_L = L cosO + D sinO (Formula I)

In the formula;

9, is the angle between the velocity of the current, Vc, and the velocity of the boat, V and can be calculated by formula II: (Formula II)

The working principle of the system is that when a rotating cylinder (rotor) is held in a flowing liquid, a force perpendicular to the direction of the flowing liquid and the axis of rotation is generated, this is the Magnus effect. On the surface of the rotor, the fluid will rotate at the tangential velocity component of the outer radius of the cylinder due to the no-slip condition, and the effect of viscosity will transmit this rotation to adjacent fluid layers. This increases the velocity of the fluid flow in the direction of rotation and opposes the velocity in the opposite direction. The change in velocity leads to a pressure difference. This explains the Magnus lift force and the difference of the pressure of the upper flow surface and the lower flow surface leads to the formation of lifting.

The inventive system comprises a telescopic cylinder (6) structure which allows the cylinder length and diameter to be optimised. Thanks to the telescopic cylinder (6), the Magnus force will change in direct proportion to the changing cylinder length and the efficiency of the system will increase. The length of the linear translation generated by the linear motor is measured by the distance sensor (5) and sent as feedback to the smart control system (7). The distance sensor (5) is a sensing system that works with laser, magnetic, ultrasonic or other measuring principle that can determine the distance in incremental (counting) or absolute terms. In addition, in cases where a single cylindrical structure is used, it is inevitable that some structural problems will arise as the cylinder length and diameter increase, so the telescopic cylinder (6) structure will minimise structural problems.

In the system according to the invention, the movement in the axial direction, which enables the telescopic cylinder (6) to lengthen and shorten, is provided by a linear electric motor (4). The linear electric motor (4) is a motor that operates by electromagnetic, electrostatic, piezo-electric, thermo-electric and other electrical effects and performs translational movement. The linear electric motor (4) is controlled by means of a smart control system (7) and allows the cylinder translational speed and position as well as its length to be varied in order to provide the required Magnus effect force. The linear electric motor (4) consists of a fixed and a moving part, with the fixed part housing the feed and windings. The moving part transmits the movement by means of a bearing in the cylinder, which allows the cylinder to be lengthened or shortened.

The telescopic cylinder (6) is controlled by a smart control system (7). There are three different movements in the system according to the invention. These movements are the rotational movement obtained to generate the Magnus effect, the horizontal angular positioning movement that adjusts the cylinder angle according to the boat, and lastly the telescopic extension movement. The smart control system (7) in the Magnus effect setup can control these three movements both independently and in coordination, thus increasing the effectiveness of the anti-roll system with Magnus effect. The power and control signal connections (8) from the smart control system to the motors carry the electrical energy required for the operation of the motors in the system with appropriate voltage and current waveforms, and at the same time transmit information from the distance sensor (5) and motors to the smart control system (7). It is also able to intelligently damp low amplitude roll motions by changing only the cylinder length at a constant cylinder rotational speed and a constant horizontal angle with respect to the boat.

The control method used to prevent roll in the system according to the invention is described below. The system according to the invention is a system comprising a telescopically extending telescopic cylinder (6) consisting of nested cylinders, and it does not operate only in an open-close manner, but operates in such a way that a linear electric motor (4) provides a continuous lengthening-shortening control as desired.

The equation for the Magnus effect is given in formula III.

FM=2nr²pv )l (Formula 111)

The explanation of the terms in the formula is given below.

FM: Magnus force [N] r: cylinder radius [m] p'. fluid density [kg/m³] v. boat velocity (current velocity) [m/s] ar. cylinder angular velocity [rad/s]

/: cylinder length [m]

As can be understood from the equation, the Magnus force is directly proportional to the boat velocity (current velocity), cylinder angular velocity and cylinder length and squarely proportional to the cylinder diameter (radius). In classical cylindrical anti-roll systems, the cylinder structure is turned on and off by means of a driving system rotating around a centre perpendicular to the hull bottom and the Magnus force is adjusted by changing the cylinder velocity.

However, above a certain cylinder speed, the Magnus effect disappears according to the characteristics of the flow region around the cylinder. In other words, there is a velocity threshold (limit) value depending on the Reynolds number. Above this velocity, the Magnus effect cannot be increased even if desired. However, in the system according to the invention, both the magnitude of the Magnus force is increased and a more continuous and faster Magnus force control is provided. For example, if the limit velocity value is approached and the Magnus effect will be eliminated if higher velocity is desired, the Magnus force will be increased by increasing the cylinder length instead of the cylinder velocity, both depending on the changed radius (diameter) value and because the moment arm is extended due to the increase in the cylinder length, the Magnus force will increase. As a result, the straightening moment, which will prevent the roll effect, increases.

If desired, the Magnus force can also be adjusted by length control using only the linear electric motor (4) at constant cylinder rotation velocity.

In an exemplary embodiment of the system according to the invention, if a telescopic cylinder (6) consisting of three cylinder segments is considered, the radius and length of each cylinder segment are taken as n, Li, n, L2, n, L3 respectively: n, Li for the 1st segment, n, L2 for the 2nd segment, n, L3 for the 3rd segment. If the Magnus forces of the three parts are calculated separately, they are calculated depending on the radius and length values given above. The amplitude and the point of action of the combined force (roll preventing force) are also variable. In this sense, the control speed increases much more and the control region expands. Especially in cases where the Magnus force can no longer increase with the rotation velocity or in situations requiring a sudden control response, a fast response is provided. It brings a much superior control capability compared to previous systems. (Figure 2)

In this example, the amplitude of the resultant force and the position of the point of action are variable according to the value of the forces of the three parts.

Therefore, the Magnus force in the system according to the invention can be expressed as follows depending on three variables during a control action:

F_M = 27rr(t)²jOvL(t)u)(t) (Formula IV) In the system existing in the state of the art (one-piece cylinder), the Magnus force is calculated based on the cylinder dimensions. The Magnus force cannot be increased after the upper limit velocity is reached and the point of action of the force is constant. In this case, the amplitude of the force depends only on the rotational speed of the one-piece cylinder and the point of application does not change. (Figure 3)

Therefore, the Magnus force that the system will generate during a control action is expressed as follows depending on a single variable.

F_M = 2nr² pvLa)(t) (Formula V)

Magnus effect systems used to prevent roll are fixed-length cylindrical systems that utilise the rotational velocity and current velocity to create a force perpendicular to the cylinder axis. This force, known as Magnus force, is used to reduce the roll effect. As it is known, roll motion reduces navigation performance and passenger comfort in cruising boats. It has a negative effect on the stability of the boat. In addition, the boat resistance increases due to the rolling motion and the propulsion performance of the boat is adversely affected.

It is envisaged that the results of the inventive system will form an important basis for future research on ship motions and hydrodynamic characteristics. In addition, it is evaluated that the rotor system can be adapted to different floating structures such as medium-sized yachts and cruising boats, research vessels and platform support vessels and work boats.

Cruising boats, which are one of the most important components of boating tourism, are watercraft in which a lot of time is spent and therefore have high living comfort requirements. For this reason, roll preventing/reducing systems in cruising boats are becoming more and more preferred today. It is anticipated that the system according to the invention will increase and accelerate the preference and commercialisation of such systems, since a direct-drive, compact, in-water, easy- to-install and easy-to-disassemble anti-roll system will be developed. Manufacturing, assembly and commissioning of the system will be much easier than similar systems. In addition, the Magnus effect is enhanced due to the linear telescopic movement, and when not in use, the effect on the dynamics of the boat is minimised by taking up very little space thanks to its extendable-collapsable structure.

The system according to the invention is a system applicable to the shipbuilding industry. It contributes to increase comfort and performance especially in cruising boats.

Claims

1. A telescopic anti-roll system for controlling and enhancing the Magnus effect, characterized by comprising the parts

- boat hull (1),

2. A telescopic anti-roll system according to claim 1, characterised in that the rotary electric motor I (2), the rotary electric motor II (3) and the linear electric motor (4) have a permanent magnet brushless electric motor or asynchronous motor or piezo-electric motor or electrostatic motor topology.

3. A telescopic anti-roll system according to claim 1, characterised in that it comprises two rotary electric motors (2), (3) for providing the horizontal angle-adjusting rotational movement and the rotational movement of the cylindrical structure as direct drive without mechanical conversion systems, and one linear electric motor (4) for providing the linear movement of the cylindrical structure as direct drive without mechanical conversion systems. A telescopic anti-roll system according to claim 1, characterised in that it comprises a learning smart control system (7) capable of analysing the dynamics of the roll motion to which the boat is subjected and of generating a strategy for automatic roll damping control.