Energy saving configuration for twin-screw vessels.
Patent Information
- Application Number
- JP2023548625
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2021-02-24
- Filing Date
- 2022-02-22
- Publication Date
- 2024-12-16
- Estimated Expiration
- 2042-02-22
AI Technical Summary
Existing solutions for twin-shaft ships fail to optimally reduce propulsion requirements due to non-uniform pre-turn of inflow into the propellers, which leads to inefficiencies and increased energy consumption.
The configuration includes guide devices with fins extending from the propeller shafts, positioned to generate targeted pre-swirl in areas with reduced pre-turn, ensuring uniform inflow into the propellers by interacting with the water flow to minimize turning losses.
This configuration reduces flow losses and minimizes power requirements by generating a zone-specific pre-swirl, resulting in improved energy efficiency and fuel savings for twin-shaft ships.
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Abstract
Description
[Technical field]
[0001] The present invention relates to an arrangement for reducing the propulsion requirements of a twin-screw ship, comprising a first propeller and a second propeller, a first guiding device and a second guiding device, the first guiding device being arranged forward of the first propeller and the second guiding device being arranged forward of the second propeller, as viewed along the forward movement of the ship.Furthermore, the present invention relates to a ship, in particular a twin-screw ship, comprising such an arrangement. [Background technology]
[0002] Various devices are already known for reducing the propulsion requirements of ships: for example, a ring nozzle upstream of the propeller in the direction of travel of the ship can optimise the inflow to the propeller and thus favourably influence the energy consumption of the ship.
[0003] Furthermore, active devices are known that reduce friction losses between the water and the hull or turning losses: such devices can generate air bubbles through nozzles distributed along the hull that reduce the friction of the hull, allowing further energy savings.
[0004] In ships with asymmetric skegs or sterns, such as twin-screw ships, a pre-rotation of the inflow to the propeller already occurs in some areas due to the asymmetry of the skeg. However, the pre-rotation is not uniformly formed in front of the propeller, which is arranged in the flow direction behind the skeg, meaning that a non-optimal inflow for the propeller may occur. However, known solutions for reducing the drive power requirements cannot be used for a targeted optimization of the pre-rotation.
[0005] The object of the present invention is to create an improved arrangement for reducing the propulsion requirements or for reducing the power consumption of a twin-screw vessel. Summary of the Invention
[0006] This problem is solved by the features set forth in claims 1 and 12. Further preferred embodiments of the invention are set forth in the dependent claims.
[0007] According to one aspect of the invention, an arrangement is provided for reducing the propulsion requirements of a twin-screw vessel.
[0008] The arrangement comprises a first propeller and a second propeller, and further comprises a first guiding device and a second guiding device, the first guiding device being disposed forward of the first propeller and the second guiding device being disposed forward of the second propeller when viewed along a forward direction of the vessel.
[0009] The first and second propellers are mounted on a first and second propeller shaft, the first propeller shaft defining a first propeller axis and the second propeller shaft defining a second propeller axis.
[0010] According to the present invention, each of the first guiding device and the second guiding device has at least one fin extending from the propeller shaft, and the fins of the first guiding device and the second guiding device extend outward toward the side of the vessel.
[0011] In particular, at least one fin of the first guiding device and of the second guiding device is arranged in a region with reduced pre-rotation.
[0012] Additionally, the at least one fin may, for example, extend radially or substantially radially from the propeller axis.
[0013] The fins of the first guiding device extend towards a first side of the vessel, while the fins of the second guiding device extend towards a second side of the vessel, in particular towards the side opposite the first side of the vessel. In particular, the fins of the first guiding device may extend towards the starboard side and the fins of the second guiding device towards the port side. The fins of the two guiding devices do not extend inward, i.e. into the area between the propellers. Thus, no fins are provided in the interior area between the propellers.
[0014] If the direction of rotation of the propeller is directed inwards, it is provided that the guide is arranged on the outside, in particular on the lateral skeg, as a result of which the guide is arranged on the strike side of the propeller where pre-rotation is reduced or absent.
[0015] In the remaining area of the inflow to the propeller, pre-rotation already occurs due to the asymmetry of the skeg around the propeller. The two guides can therefore only be arranged in the area of inflow without pre-rotation. By using the guides, pre-rotation can be generated section by section at the inflow to the propeller. This results in an inflow to the propeller that is practically completely impinged by the pre-rotation.
[0016] The generation of targeted or regional pre-swirl in the area of the water mass entering the propeller reduces flow losses. There is an interaction between the water flow and the guider in a designated area determined by the shape of the skeg.
[0017] The areas requiring the use of such guiding devices may be determined in the direction of travel of the vessel ahead of the propeller using a flow simulation, in particular such a flow simulation may be a CFD (Computational Fluid Dynamics) flow simulation.
[0018] Preferably, each of the first and second guiding devices comprises at least two fins.
[0019] In a preferred embodiment, the at least two fins of the first and second guiding device are angled relative to one another and the at least two fins of the guiding devices are mounted in the area of a shaft bearing, in particular towards the outer shell of a stern tube designed to support the first and second propeller shafts of the ship, or towards the hull of the ship in the area of the sternstock. The angle between the two fins of the respective guiding device can be defined as the axis of rotation of the fins starting from the bearing.
[0020] The angle between two fins of the guide device or multiple angles between at least three fins of the guide device can be selected to optimally apply pre-rotation to a corresponding water flow before that water flow hits the propeller by spreading the fins out over an area where pre-rotation is reduced.
[0021] The angles between the at least three fins may be selected to be the same or different such that a defined pre-swirl distribution can be generated for the inflow to the propeller, the pre-swirl distribution may generate a pre-swirl that varies along the cross-sectional area of the water mass flowing into the propeller.
[0022] According to a further embodiment, at least one fin of the guiding device is designed to generate a pre-rotation at the inflow to the first and second propellers, the pre-rotation being generated by the respective guiding device in the inflow area to the propellers where there is no or reduced pre-rotation generated by the at least one asymmetric skeg or stern. This measure results in a uniform or more uniform inflow to the propellers along the entire cross-sectional area as the inflow occurs.
[0023] The targeted influence of the water mass by the guiding device minimizes turning losses resulting in savings in the power requirements of the vessel.
[0024] The inflow to the propeller can be precisely adjusted if the fin has a length corresponding to 65%-110%, preferably 80%-110%, particularly preferably 90%-105%, most preferably 100% of the propeller radius of the propeller. In particular, this can reduce the resistance introduced by the guiding device in addition to the hull.
[0025] If at least two fins are provided per guiding device, in particular if the at least two fins of the first and second guiding device are connected by a connecting bar, the fins of the guiding devices can be structurally reinforced.
[0026] Furthermore, at least one actuatable connecting bar, for example in the form of a ring segment or a straight connection between at least two fins, can further influence the flow of the propeller, which can be achieved by profiling and / or distorting or twisting the connecting bar.
[0027] The connecting bars may support the fins particularly efficiently if, when viewed along the length of the fin, they are preferably located at between 30% and 70% of the length of the fin, particularly preferably between 45% and 55% of the length of the fin or at the center. A single connecting bar may link or connect several fins, for example three or more fins.
[0028] Additionally or alternatively, a connecting bar may connect the tips of two fins together or mechanically connect the tip of a first fin to a second fin.
[0029] Alternatively, multiple connecting bars may be provided, each positioned between two fins, the multiple connecting bars mechanically interlocking or connecting all the fins of the guiding device to each other forming a row.
[0030] Preferably, at least one connecting bar may create a statically fixed or rigid connection between at least two fins.
[0031] According to other exemplary embodiments, the connecting bars have a straight or curved formation along the length and / or width of the connecting bar. At least one connecting bar may be provided with a bearing surface profile through which the inflow or water flow can be differentially influenced.
[0032] Alternatively, the at least one connecting bar may have a profile that minimizes its drag on the inflow to the propeller.
[0033] The arrangement and the guiding devices can be technically particularly simple if the guiding devices each comprise only two fins.
[0034] Alternatively, each of the guides may include only three fins.
[0035] Alternatively, each of the guides may include only one fin.
[0036] According to a further embodiment, the propellers are designed as contra-rotating propellers, the first guiding device is arranged on the strike side of the first propeller and the second guiding device is arranged on the strike side of the second propeller. Due to the asymmetric shape of the skeg, a water inflow or water entry area with reduced pre-rotation is formed on the strike side of the propeller which can be amplified by the guiding device.
[0037] In particular, the two propellers are designed to rotate inwards at the top, i.e. towards the area between the propellers of the vessel, with the fins of the two guiding devices protruding outwards towards the side of the vessel.
[0038] The terms "inward rotating" and "outward rotating" refer to the direction of rotation of a propeller when the propeller is assumed to be at the top of the propeller (i.e., the 12 o'clock position) with respect to the propeller installed on a vessel. Thus, when a propeller rotates outward, the motion of the propeller at its top point of rotation is directed outward, towards the outside of the vessel. When a propeller rotates inward, the motion of the propeller at its top point of rotation is directed inward, towards the area between the two propellers.
[0039] The guiding devices can be positioned in the vessel particularly efficiently if they are positioned approximately mirror symmetrically with respect to one another with respect to a vertical plane of symmetry of the vessel, so that the rectilinear stability of the vessel can be maintained unimpaired by the guiding devices.
[0040] The inflow through the water to the propeller can be particularly precisely controlled using the guiding device and corresponding fins where the fins have a constant or varying profiling and / or position along their length.
[0041] According to another aspect of the invention, a ship, in particular a twin-screw ship, is provided. The ship has a configuration with a first guiding device and a second guiding device according to the invention. The two guiding devices are preferably mounted on a shaft bearing of the propeller shaft and extend in the direction of the ship's sides. In particular, the first guiding device may extend on the first ship's side, i.e. the starboard side, and the second guiding device may extend on the second ship's side, i.e. the port side. [Brief description of the drawings]
[0042] [Figure 1] 1 is an exemplary simulation of pre-rotation around a propeller of a twin-screw vessel. [Figure 2a] FIG. 1 is a perspective view of an arrangement according to the present invention according to a first embodiment. [Figure 2b] FIG. 2 is a perspective view of an arrangement according to the present invention according to a second embodiment. [Diagram 3] FIG. 11 is a rear view of an arrangement according to the present invention according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0043] In the following, a number of exemplary embodiments of the invention will be explained in more detail on the basis of the drawings.
[0044] Figure 1 shows an exemplary simulation of pre-rotation in the area of the propellers 20, 21 of a twin-screw ship 100, which is shown by way of example in Figures 2a and 3. The simulation shows the cross-sectional area of the inflow of running water with the corresponding pre-rotation distribution, i.e. in the direction of the propellers 20, 21. The pre-rotation around the first propeller shaft 22 and around the second propeller shaft 23 of the ship 100 designed as a twin-screw ship is shown.
[0045] The asymmetric shape of the skeg 110 of the vessel 100 creates an area of increased pre-turn 120 and an area of reduced or absent pre-turn 130. The lengths of the corresponding arrows indicate exemplary measurements of pre-turn, with lighter shaded areas corresponding to reduced pre-turn relative to the direction of propeller rotation and darker shaded areas corresponding to increased pre-turn relative to the direction of propeller rotation.
[0046] The arrangement 10 according to the invention shown in FIG. 2a comprises guiding devices 30, 31 arranged only in the area 130 where there is no pre-turn or where there is an unfavourable inflow.
[0047] Figure 2a shows a perspective view of an arrangement 10 according to the invention according to a first embodiment. The arrangement 10 serves to reduce the propulsion requirements of a twin-screw vessel or ship 100. For clarity, only the second, i.e. port, side of the aft section of the vessel 100 is shown. In Figure 3 the aft view of the vessel 100 is shown, showing both sides. Figure 2a will be explained with reference to Figure 3.
[0048] The arrangement 10 comprises a first propeller 20 and a second propeller 21. Furthermore, the arrangement 10 comprises a first guiding device 30 and a second guiding device 31.
[0049] When viewed along the forward direction F of the vessel 100, the first guiding device 30 is disposed in front of the first propeller 20, and the second guiding device 31 is disposed in front of the second propeller 21.
[0050] The first propeller 20 and the second propeller 21 are mounted on a first propeller shaft (not shown) and a second propeller shaft (not shown), the first propeller shaft defining a first propeller axis 22 and the second propeller shaft defining a second propeller axis 23.
[0051] In the illustrated exemplary embodiment, the first guiding device 30 and the second guiding device 31 each comprise two fins 32, 33 extending radially from the propeller shafts 22, 23. The fins 32, 33 of the first guiding device 30 and the second guiding device 31 extend outwardly towards the sides 101, 102 of the vessel.
[0052] In particular, the first guiding device 30 extends on a first, or starboard, side 101 of the vessel and the second guiding device 31 extends on a second, or port, side 102 of the vessel, respectively.
[0053] The two fins 32, 33 of the first and second guiding devices 30, 31 are at an angle A to one another. The two fins 32, 33 of the guiding devices 30, 31 are, by way of example, mounted in the area of the shaft bearing 40, in particular on the shell of a stern tube designed to support the first and second propeller shafts of the ship 100.
[0054] With reference to figure 2b, a perspective view of an arrangement 10 according to the invention according to a second embodiment is shown. In particular, figure 2b shows a side view of a vessel 100 similar to figure 2a. In contrast to the embodiments already described, the arrangement 10 comprises a connecting bar 50 arranged radially centrally between the fins 32, 33.
[0055] The fins 32,33 have a length L which corresponds to 100% of the propeller radius of the propellers 20,21.
[0056] The two radially protruding fins 32, 33 are provided with a connecting bar 50 located approximately in the radial center. The connecting bar 50 can structurally reinforce the fins 32, 33. In particular, the fins 32, 33 are mechanically connected to each other by the connecting bar 50.
[0057] In Fig. 3, a stern view of the ship 100 is shown, thereby illustrating the entire arrangement 10. The first and second guiding devices 30, 31 respectively extend from the shell of the stern tube and shaft bearing 40 towards the first and second sides 101, 102 of the ship. The direction of rotation of the two propellers is indicated by two arrows R arranged inwards at the upper point of rotation, i.e. at the 12 o'clock position.
[0058] In the case of the propellers 20, 21 rotating inwards in the direction of the arrow R, the two guiding devices 30, 31 are arranged on the outer or strike side of the propellers 20, 21. Based on a rear view, the guiding devices 30, 31 are therefore in the 3:00 am position and the 9:00 am position. In forming such an arrangement 10, the guiding devices 30, 31 are preferably arranged symmetrically with respect to one another with respect to the vertical symmetry plane S of the vessel 100.
[0059] Such an arrangement of guiding devices 30, 31 can be used to achieve particularly high energy savings or fuel reductions, especially in the case of twin-screw vessels.
[0060] Preferably, the guiding devices 30, 31 as well as other energy saving devices comprising fins or nozzles on the vessel are not arranged in the area of the propellers 20, 21, nor on the rudders.
[0061] Figure 3 also shows the symmetrical construction of the arrangement 10 and the guiding devices 30, 31. It can also be seen that the connecting piece or bar 50 is attached approximately midway between the fins 32, 33 when viewed along the length L of the fins 32, 33. [Explanation of symbols]
[0062] 100 Ships (2-axle ships) 101 First side (starboard side) of a vessel 102 Second side (port side) of a vessel 110 Ship Skeg 120 Pre-turn increase area 130 Pre-rotation reduction area 10 Configuration 20 First Propeller 21 Second Propeller 22 First propeller shaft 23 Second Propeller Shaft 30 First guide device 31 Second guide device 32 Fin of first guide device 33 Fin of second guide device 40 Shaft bearing 50 Connection Bar A is the angle between the two fins F Forward direction L Fin length S Vertical plane of symmetry of the vessel R Rotation direction
Claims
1. An arrangement (10) for reducing the propulsion requirements of a twin-shaft ship, comprising a first propeller (20) and a second propeller (21), a first guiding device (30) and a second guiding device (31), in a forward direction (F) of the ship (100), the first guiding device (30) is arranged forward of the first propeller (20) and the second guiding device (31) is arranged forward of the second propeller (21), the first propeller (20) and the second propeller (21) are mounted on a first propeller shaft and a second propeller shaft, the first propeller shaft defining a first propeller axis (22) and the second propeller shaft defining a second propeller axis (23), each of the first guiding device (30) and the second guiding device (31) comprises at least one fin (32, 33) extending from the propeller shaft (22, 23), the fins (32, 33) of the first guiding device (30) and the second guiding device (31) respectively extending outwardly towards the side (101, 102) of the vessel; each of the first guiding device (30) and the second guiding device (31) comprises only two of the fins (32, 33); each of the two fins (32, 33) of the first and second guiding devices (30, 31) is connected to each other by a connecting bar (50); the connecting bar (50) is disposed relative to the length (L) of the fins (32, 33) at a position between 30% and 70% of the length of the fins; The connecting bar (50) extends only between the two fins (32, 33) (10).
2. 2. The arrangement according to claim 1, wherein the two fins (32, 33) of the first and second guiding devices (30, 31) are at an angle (A) to one another and the two fins (32, 33) of the guiding devices (30, 31) are mounted in the area of a shaft bearing (40) designed to support the first and second propeller shafts of the ship (100) or are mounted on the hull of the ship.
3. 3. The arrangement according to claim 1 or 2, wherein the fins (32, 33) of at least one of the guiding devices (30, 31) are set to generate a pre-rotation when the first and second propellers (20, 21) are operated, the pre-rotation being generated by the respective guiding device (30, 31) in an inflow range (130) of the propellers (20, 21) where there is no or reduced pre-rotation generated by at least one asymmetric skeg (110).
4. The arrangement according to any one of claims 1 to 3, wherein the fins (32, 33) have a length (L), the length (L) of the fins (32, 33) corresponding to 65% to 110% of a propeller radius of the propellers (20, 21).
5. 5. The arrangement according to claim 1, wherein the connecting bar (50) is arranged relative to the length (L) of the fins (32, 33) at a position between 45% and 55% of the length (L) of the fins (32, 33).
6. 6. An arrangement according to any one of claims 1 to 5, wherein the connecting bar (50) is formed straight or curved along the length or width of the connecting bar (50).
7. 7. The arrangement according to claim 1, wherein the propellers (20, 21) are designed as contra-rotating propellers (20, 21), the first guiding device (30) being arranged on the strike side of the first propeller (20) and the second guiding device (31) being arranged on the strike side of the second propeller (21).
8. An arrangement according to any one of the preceding claims, wherein the guiding devices (30, 31) are positioned approximately mirror symmetrically to one another with respect to a vertical plane of symmetry (S) of the ship (100).
9. An arrangement as claimed in any one of claims 1 to 8, wherein at least one of the fins (32, 33) has a constant or varying profiling or position along its length (L).
10. A ship (100) comprising an arrangement (10) according to any one of claims 1 to 9, i.e. a twin-screw ship.