DE102023100314B4 - Device and method for increasing a buoyancy force on a ship's rudder by means of active flow control, and ship's rudder - Google Patents

Abstract

The invention relates to a device, a method and a ship's rudder for increasing a buoyancy force on a ship's rudder by means of active flow control for use in shipping.
It is therefore an object of the invention to eliminate the disadvantages of the prior art and to provide a device and a method for increasing a lift force on a ship's rudder by means of active flow control, which make it possible to increase the (maximum) lift force, in particular by delaying the flow separation during large angles of attack on the rudder, and thus lead to improved maneuverability and/or reduced fuel consumption.
This problem is solved by the features listed in the claims.

Description

The present invention relates to a device and a method for increasing a buoyancy force on a ship's rudder by means of active flow control for use in shipping, as well as a ship's rudder.

In general, active flow control aims to change an existing flow state of a body using some form of local energy input into the boundary layer. In particular, it aims to reduce drag (e.g. blunt bodies), increase lift and/or maximum lift (e.g. aircraft) and thus increase the efficiency of the system. It also serves to reduce noise and vibrations.

In the context of wings, rudders and other control surfaces, the main application of active flow control is to delay, suppress and/or reverse stall in order to improve the lift and drag characteristics of aerodynamic and/or hydrodynamic surfaces.

Typical examples of active flow control are blowing out wall jets, generating longitudinal vortices using vortex generators or sucking out laminar or turbulent boundary layers.

Actuators are used to influence the flow. These are drive units that convert energy into mechanical movements or changes in physical quantities such as pressure or temperature.

For this purpose, fluidics uses fluid mechanical components using pneumatic (e.g. air) or hydraulic (e.g. water, oil) auxiliary energy.

An example of such a device is a fluidic oscillator, which generates an oscillating (temporally and spatially alternating) flow from a stationary inlet solely through the applied volume flow and pressure, and does not require any electrical or mechanical components, such as valves. This behavior is achieved through a diverging geometry with a bi-stable flow regime and an internal feedback mechanism that varies from device to device. The general principle of the fluidic oscillator is well known. In its original form, it was used for fluidic logic circuits as an alternative to electrical systems.

The general principle of active flow control with fluidic oscillators is known from aviation. A special version of the fluidic oscillator is the sweeping jet oscillator, which has been used at least experimentally on the wings and tail of aircraft to improve their aerodynamic properties.

A system for active flow control using fluidic oscillators for aircraft is in US 2020 / 0 017 199 A1 revealed.

A special version of a fluidic oscillator is a pulse-jet oscillator, which is able to switch the flow back and forth between two outlets. The flow is guided completely through one of the outlet openings at any given time, so that the oscillation behavior of the system corresponds to a rectangular function in a first approximation.

Similar to aviation, stalls also occur in shipping. When the rudder overshoots a ship-specific angle of attack, the rudder stalls. The stall results in a reduction in lift forces, resulting in reduced maneuverability while maximizing fuel consumption and greenhouse gas emissions. Typical rudders are only designed for loads that only occur for very short periods of time, e.g. during a harbor maneuver. Most of the time, a ship's rudder is only operated at small angles of attack. Nevertheless, the rudder generates resistance the entire time the ship is moving, which maximizes fuel consumption and greenhouse gas emissions.

A system for active flow control using fluidic oscillators for aircraft is in US 2020 / 0 017 199 A1 revealed.

EP 0 909 703 A2 discloses a system for active flow control of watercraft, in particular a rudder for watercraft with a rudder blade that has a leading edge and adjoining side surfaces spaced apart from one another, which are characterized in that they have outlet openings for a liquid and/or gaseous medium. The outlet openings arranged in the front third of the rudder blade are preferably supplied with liquid medium by means of a pump. The escaping fluid prevents flow separation at large rudder angles and minimizes the resistance component directed against the direction of travel.

US 8 382 043 B1 discloses a ship's rudder having a compact arrangement of a plurality of discrete fluid actuator oscillators in a two-dimensional array in either a planar or linear manner.

A disadvantage of the state of the art in terms of active flow control in aircraft is the high complexity of the system, consisting of a large number of actuators connected along a fluid channel, which prohibits commercial use to date.

A disadvantage of the state of the art in terms of active flow control in watercraft is the inefficient, energy-intensive continuous blowing out of the fluid.

Description of the invention

It is an object of the invention to eliminate the disadvantages of the prior art and to provide a device and a method for increasing a buoyancy force on a ship's rudder by means of active flow control, as well as a ship's rudder, which make it possible to increase the buoyancy force, in particular during large angles of attack on the rudder, and thus lead to improved maneuverability and/or reduced fuel consumption.

This problem is solved by the features listed in the claims.

The problem is solved by a device for increasing a buoyancy force on a ship's rudder with active flow control, wherein the device for increasing a buoyancy force on a ship's rudder has at least one fluidic oscillator. The fluidic oscillator causes a flow guide for the oscillating deflection of a fluid coming from an inlet opening towards a first or a second flow channel. The deflected fluid flows in an oscillating manner along the first or the second flow channel, which open into a plurality of first and a plurality of second outlets to the rudder surface. The plurality of first outlets and the plurality of second outlets are arranged alternately along a line parallel to a leading edge of a first side of the ship's rudder.

According to various embodiments, the plurality of first outlets of the first flow channel and the plurality of second outlets of the second flow channel are arranged along a span of the ship's rudder on the first side of the ship's rudder.

The positioning of the plurality of first outlets and the plurality of second outlets is preferably selected such that actuation occurs as close as possible to an expected position of the flow separation in order to operate as energy efficiently as possible.

According to various embodiments, the plurality of first outlets of the first flow channel and/or the plurality of outlets of the second flow channel are designed in the form of a slot. The slots can be oval or rectangular, for example. Other embodiments of the plurality of first outlets and/or the plurality of second outlets are conceivable, e.g. in the form of round and/or square recesses. Preferably, rectangular slots have an aspect ratio of approximately 1:30. For example, rectangular slots have a width of 1.1 mm and a length of 30 mm.

According to various embodiments, the outlets are formed with a constant and/or variable diameter (e.g. tapering). Preferably, an exit angle of the plurality of first outlets and/or the plurality of second outlets is 30° to the tangent of the rudder surface. Further embodiments with respect to the exit angle are conceivable.

According to various embodiments, the at least one fluidic oscillator is a pulse-jet oscillator.

According to various embodiments, the device for increasing a buoyancy force on a ship's rudder further comprises a pump system, a pipe system and/or a tank for receiving, storing and/or transporting the fluid. The pump system is preferably a submersible or centrifugal pump or another type of pump that is able to transport the fluid and provide the necessary operating pressure. The fluid is transported via the pipe system, which preferably consists of flexible hoses, from its origin to the at least one fluidic oscillator, wherein the fluid can originate from the seawater surrounding the ship and/or a process volume flow of the ship. According to one embodiment, the fluid is temporarily stored in a tank.

According to various embodiments, the device for increasing a buoyancy force on a ship's rudder further comprises a sensor unit, a control unit and/or a regulation unit.

Various measured values can be recorded using a sensor unit. The measured values can be evaluated using a control or evaluation unit. Using previously defined or known (for example stored) threshold values of the measured variables, the active flow control can be regulated based on the measured values, in particular the control of at least one fluidic oscillator. Examples of relevant measured variables that can be used for controlling and/or regulating the device according to the invention, the active flow control and/or the fluidic oscillator are a wall shear stress and/or a surface pressure on the ship's rudder. The use of alternative measured values from sensors is conceivable. According to one embodiment, the automated triggering of the actuation can alternatively or additionally take place using ship and rudder-specific model data when the ship's rudder exceeds a defined angle of attack. It is also conceivable that an actuation can also be carried out manually using an actuating device.

According to various embodiments, the at least one fluidic oscillator, the first flow channel, the second flow channel, the pump system, the pipe system, the tank, the sensor unit, the control unit and/or the regulation unit are arranged inside the ship's rudder.

According to various embodiments, the device for increasing a buoyancy force on a ship's rudder also has a suction device. The suction device acts as an antagonistic force to the actuation and increases its effect. Preferably, the suction takes place at the same time as the actuation, preferably on the same side. Furthermore, the suction preferably takes place by means of openings arranged in one or more rows parallel to the outlets, wherein an arrangement of these in the flow direction in front of and/or behind the outlets is conceivable. The suction device can be designed, for example, in the form of a submersible pump, wherein the suction device and the pump system can represent one and the same component.

Preferably, the plurality of first outlets and the plurality of second outlets are evenly distributed over the entire span of the rudder in order to delay and/or prevent flow separation over the entire rudder surface.

Each first outlet is assigned to the plurality of first outlets and each second outlet is assigned to the plurality of second outlets. Directly adjacent outlets, i.e. two outlets, one of which is assigned to the first outlets and the other to the second outlets, are referred to as a pair.

According to one embodiment, both sides of the rudder can be actuated. This requires the use of a plurality of at least one fluidic oscillator and the corresponding first and second flow channels. In particular, two fluidic oscillators can be used for this, which divert the fluid coming from an inlet opening to a total of four flow channels and at least four corresponding outlets. In this case, a fluidic oscillator supplies two flow channels and at least four corresponding outlets, which are arranged on one rudder side.

Rudders here do not only refer to vertically designed rudders on ships, but also explicitly to other designs, such as horizontal depth rudders and/or X-rudders on submarines. Actuation of ship stabilizers is also conceivable, which prevent or at least reduce the rolling motion of a ship. Ship stabilizers are, for example, bilge keels and/or fin stabilizers. Other types of stabilizers are conceivable.

The first flow channel and the second flow channel are preferably formed as separate hollow chambers within the rudder. The separate hollow chambers are each connected to one of the two outlets of the at least one fluidic oscillator. This guarantees that a given oscillation frequency remains the same across the entire rudder. Furthermore, this ensures that all pairs of the plurality of first outlets and the plurality of second outlets oscillate in the same phase.

Due to the maintenance-free nature of a fluidic oscillator compared to mechanical components, it is preferably arranged inside the ship's rudder. For this purpose, the rudder has additional hollow chambers to accommodate the at least one fluidic oscillator together with peripheral components, such as the pump and/or pipe system and/or other elements. According to one embodiment, the flow channels (hollow chambers) themselves serve to accommodate the at least one fluidic oscillator together with peripheral components, such as the pump and/or pipe system and/or other elements. Alternative positioning, such as in the keel, in the stern, in the bow and on deck, is conceivable.

The problem is further solved by a method for increasing a buoyancy force on a ship's rudder by means of active flow control trolls. By means of the device for increasing a buoyancy force on a ship's rudder, which has a fluidic oscillator, an energy-rich fluid is ejected on a first side of the ship's rudder alternately between several first outlets and several second outlets in such a way that a flow separation on the ship's rudder is delayed and/or prevented.

According to various embodiments, the high-energy fluid is ejected in pulses

According to various embodiments, in addition to the expulsion of the high-energy fluid, sea water is sucked off at an outer edge of the ship's rudder. The suction preferably takes place at the same time as the actuation on the identical side. Furthermore, the suction preferably takes place through openings arranged in one or more rows parallel to the outlets, whereby an arrangement of these in the flow direction in front of and/or behind the outlets is conceivable.

According to various embodiments, the energy-rich fluid is taken from a process volume flow of the ship and/or the seawater surrounding the ship.

According to various embodiments, the ejection of the high-energy fluid takes place using a sensor unit, a control unit and/or a regulating unit and/or by means of manual triggering.

The expulsion of the fluid along the rudder surface accelerates the aqueous boundary layer and thus prevents flow separation.

By ejecting the fluid in bursts along the rudder surface, in addition to the impulse input, vortices are generated in the aqueous boundary layer, which mix the boundary layer and thus introduce additional energy-rich fluid from the outer flow areas into the boundary layer. This increases the effect of the actuation. At the same time, this reduces the required actuation energy, since the ejection is not constant and the vortices bring an additional impulse into the boundary layer by mixing with the outer flow in addition to the impulse introduced through the slots. By changing the internal geometry of the fluidic oscillator, in particular by adapting a so-called feedback tube of the fluidic oscillator, whereby the feedback tube is a flow channel within the fluidic oscillator which, together with a splitter device, is responsible for the oscillating flow, the frequency of the alternation of the ejection through the several first outlets and the several second outlets can be adjusted and coordinated with instabilities already present in the flow.

The device according to the invention and the method according to the invention for increasing a buoyancy force on a ship's rudder by means of active flow control lead to an improvement in maneuverability by increasing the applicable rudder forces, e.g. during harbor maneuvers, in emergency situations, on pleasure boats and/or in inland navigation.

While maintaining identical rudder forces, the device according to the invention and the method according to the invention for increasing a buoyancy force on a ship's rudder by means of active flow control enable a downsizing of the ship's rudder and an associated reduction in costs. Furthermore, the downsizing reduces the flow resistance when traveling straight ahead and saves the required propulsion energy. This results in both a reduction in fuel consumption and a reduction in the emission of greenhouse gases and the associated costs.

When travelling straight ahead, e.g. crossing the Atlantic, the device and method according to the invention for increasing a lift force on a ship's rudder by means of active flow control can enable latent manoeuvring, e.g. compensating for drift caused by crosswinds, without using the rudder. This reduces wear on the rudder and its mounting on the ship and the associated costs, among other things by minimising downtime during maintenance and repair work.

The device according to the invention using only one or two actuators represents a system with reduced complexity and reduces the number of components required and the associated costs for acquisition, operation and maintenance. Furthermore, it is characterized by a low susceptibility to failure, resulting from, for example, suspended matter in the water, and works with minimal energy consumption by means of intermittent actuation.

Implementation of the invention

• 1 eine schematische Darstellung der Vorrichtung zur Erhöhung einer Auftriebskraft an einem Schiffsruder.

The invention is explained in more detail using one or more embodiments.

• 1 a schematic representation of the device for increasing the buoyancy force on a ship's rudder.

In the description, reference is made to the accompanying drawings in which specific embodiments are shown by way of illustration are shown in which the arrangement according to the invention can be practiced. In this regard, directional terminology such as "above", "below", etc. is used with reference to the orientation of the drawings described. The directional terminology is for illustrative purposes and is not limiting in any way.

It is to be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present invention. It is to be understood that the features of the various exemplary embodiments described herein may be combined with one another unless specifically stated otherwise. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims.

In the figures, identical or similar elements are provided with identical reference symbols wherever appropriate.

The device according to the invention for increasing a buoyancy force on a ship’s rudder by means of active flow control is described in 1 The device for increasing a buoyancy force on a ship's rudder 1 has at least one fluidic oscillator 2. The fluidic oscillator 2 causes a flow guide for the oscillating deflection of a fluid coming from an inlet opening. The deflected fluid flows in an oscillating manner along a first flow channel 3 or a second flow channel 4, which open into a plurality of first outlets 31 and a plurality of second outlets 41. The plurality of outlets 31 and the plurality of outlets 41 are arranged alternately along a line parallel to a leading edge 12 on a first side 11 of the ship's rudder 1.

1 shows the arrangement of six first outlets 31 and six second outlets 41.

According to various embodiments, the plurality of outlets 31 of the first flow channel 3 and the plurality of outlets 41 of the second flow channel 4 are arranged along a span of the ship's rudder 1 of the first side 11 of the ship's rudder 1.

According to various embodiments, the plurality of first outlets 31 of the first flow channel 3 and/or the plurality of first outlets 41 of the second flow channel 4 are designed in the form of a slot. Alternative designs of the outlets are conceivable.

According to various embodiments, the at least one fluidic oscillator 2 is a pulse-jet oscillator.

According to various embodiments, the device for increasing a buoyancy force on a ship's rudder 1 further comprises a pump system 5, a pipe system 6 and/or a tank 7 for receiving, storing and/or transporting the fluid. The fluid is conveyed by the pump 5 via the pipe system 6 to the at least one fluidic oscillator 2, wherein the fluid can originate from the sea water surrounding the ship and/or a process volume flow of the ship. According to one embodiment, the fluid is temporarily stored in a tank 7.

According to various embodiments, the device for increasing a buoyancy force on a ship's rudder 1 further comprises a sensor unit 8, a control unit 9 and/or a regulation unit 10.

According to various embodiments, the at least one fluidic oscillator 2, the first flow channel 3, the second flow channel 4, the pump system 5, the pipe system 6, the tank 7, the sensor unit 8, the control unit 9 and/or the regulation unit 10 are arranged inside the ship's rudder. Alternative positioning outside the ship's rudder 1, such as in the keel, in the stern, in the bow and on deck, are conceivable and in 1 shown schematically.

According to various embodiments, the device for increasing a buoyancy force on a ship's rudder 1 further comprises a suction device (not shown).

Preferably, the plurality of first outlets 31 of the first flow channel 3 and the plurality of outlets 41 of the second flow channel 4 are arranged according to various embodiments along the expected position of the flow separation on the first side 11 of the ship's rudder 1 in the front area of the ship's rudder 1 in the direction of travel. The first flow channel 3 and the second flow channel 4 are preferably formed as separate hollow chambers within the ship's rudder 1. The separate hollow chambers are each connected to one of the two outlets of the at least one fluidic oscillator 2. The fluidic oscillator 2 is preferably arranged inside the ship's rudder 1. Alternative positioning outside the ship's rudder 1, such as in the keel, in the stern, in the bow and on deck, are conceivable and in 1 shown schematically.

Reference symbol

1

Ship's rudder

11

first page

12

Leading edge

2

fluidic oscillator

3

first flow channel

31

first outlet

4

second flow channel

41

second outlet

5

Pump system

6

Pipe system

7

tank

8

Sensor unit

9

Control unit

10

Control unit

Claims (15)

Device for increasing a buoyancy force on a ship's rudder (1) with active flow control, comprising at least one fluidic oscillator (2) having a flow guide for the oscillating deflection of a fluid coming from an inlet opening to a first or a second flow channel (3, 4), wherein the first flow channel (3) has a plurality of first outlets (31) and the second flow channel (4) has a plurality of second outlets (41), wherein these are arranged alternately along a line parallel to a leading edge (12) of a first side (11) of the ship's rudder (1). Device according to Claim 1 , characterized in that the plurality of first outlets (31) of the first flow channel (3) and the plurality of second outlets (41) of the second flow channel (4) are arranged along a span of the ship's rudder on the first side (11) of the ship's rudder (1). Device according to one of the preceding claims, characterized in that the plurality of first outlets (31) of the first flow channel (3) and the plurality of second outlets (41) of the second flow channel (4) are arranged along an expected position of a flow separation on the first side (11) of the ship's rudder (1). Device according to one of the preceding claims, characterized in that the plurality of first outlets (31) of the first flow channel (3) and/or the plurality of second outlets (41) of the second flow channel (4) are designed in the form of a slot. Device according to one of the preceding claims, characterized in that the at least one fluidic oscillator (2) is a pulse-jet oscillator. Device according to one of the preceding claims, further comprising a pump system (5), a pipe system (6) and/or a tank (7) for receiving, storing and/or transporting the fluid. Device according to one of the preceding claims, further comprising a sensor unit (8), control unit (9) and/or regulating unit (10). Device according to Claims 6 and 7 , characterized in that the at least one fluidic oscillator (2), the first flow channel (3), the second flow channel (4), the pump system (5), the pipe system (6), the tank (7), the sensor unit (8), the control unit (9) and/or the regulating unit (10) is/are arranged in the interior of the ship's rudder (1). Device according to one of the preceding claims, further comprising a suction device. Method for increasing a buoyancy force on a ship's rudder by means of active flow control, characterized in that by means of a device for increasing a buoyancy force on a ship's rudder (1) having a fluidic oscillator (2), an energy-rich fluid is ejected on a first side of the ship's rudder (1) alternately between a plurality of first outlets (31) and a plurality of second outlets (42) in such a way that a flow separation on the ship's rudder (1) is delayed and/or prevented. Procedure according to Claim 10 , characterized in that the ejection of the energy-rich fluid takes place in pulses. Procedure according to one of the Claims 10 or 11 , characterized in that in addition to the ejection of the energy-rich fluid, sea water is sucked off at an outer edge of the ship's rudder. Procedure according to one of the Claims 10 , 11 , or 12, characterized in that the energy-rich fluid is taken from a process volume flow of the ship and/or the sea water surrounding the ship. Procedure according to one of the Claims 10 until 13 , characterized in that the ejection of the energy-rich fluid takes place using a sensor unit (8), a control unit (9) and/or a regulating unit (10) and/or by means of manual triggering. Ship rudder comprising a device for increasing a buoyancy force on a ship rudder (1) with active flow control according to Claim 1 .