EP2977311A1 - Oszillierendes Dualmodus-Folienantriebssystem und Verfahren für die Oszillation mindestens einer beweglichen Folie - Google Patents
Oszillierendes Dualmodus-Folienantriebssystem und Verfahren für die Oszillation mindestens einer beweglichen Folie Download PDFInfo
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- EP2977311A1 EP2977311A1 EP14178280.5A EP14178280A EP2977311A1 EP 2977311 A1 EP2977311 A1 EP 2977311A1 EP 14178280 A EP14178280 A EP 14178280A EP 2977311 A1 EP2977311 A1 EP 2977311A1
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- European Patent Office
- Prior art keywords
- foil
- heave
- movable
- during
- downstroke
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63H—MARINE PROPULSION OR STEERING
- B63H1/00—Propulsive elements directly acting on water
- B63H1/30—Propulsive elements directly acting on water of non-rotary type
- B63H1/37—Moving-wave propellers, i.e. wherein the propelling means comprise a flexible undulating structure
Definitions
- the present invention relates to a marine propulsion system, in particular to an oscillating foil propulsion system including at least one movable foil.
- the invention further relates to a method for oscillating at least one movable foil in a fluid.
- the invention relates to a computer readable medium having stored thereon a set of computer implementable instructions. Additionally, the invention relates to a computer program.
- Different marine propulsion devices for use in a fluid are known, by means of which a vessel can be propelled.
- vessels are equipped with at least one screw propeller for propulsion.
- the efficiency of the propeller is typically about 60 % to 70 %. In other words, 30 % to 40 % of the provided energy is lost.
- Further optimization of conventional screw propellers has become more difficult and therefore new propulsive devices are needed, which, for example, produce thrust by a movement of an oscillating fin, which mimics the manner in which whales or other animals swim.
- the efficiency of whales has been estimated to be about 80 % to 90 %.
- New fin propulsion systems may, for example, lead to achievement of a greater propulsor efficiency compared to a conventional screw propeller.
- the document GB 1,092,839 discloses a steering and/or propelling means, which comprises a blade carrier pivotally secured to the stem of a boat above the water line and carrying a blade adapted to extend in its operative position below the water line, means by which the blade may be secured in a raised position, and means by which the blade may be oscillated from within the boat.
- the blade carrier may comprise an aft port hinged to a fore port which is pivotally secured to the stern of the boat and has a tiller attached thereto.
- the fore port has a vertical slot therein into which the blade is placed for use as a rudder and the aft port has a slot for the blade when it is desired to move it like a fish's tail by oscillating the tiller to propel the boat.
- An object of certain embodiments of the present invention is to provide an oscillating foil propulsion system.
- a further object of certain embodiments of the present invention is to provide a method for oscillating at least one movable foil of a marine propulsion system.
- an object of certain embodiments of the present invention is to provide a computer readable medium having stored thereon a set of computer implementable instructions.
- an oscillating foil propulsion system comprising at least one movable foil, at least one pitch mechanism connected to the at least one movable foil and configured to control a pitch motion of the at least one movable foil, at least one heave mechanism connected to the at least one movable foil and configured to control a downstroke heave motion and an upstroke heave motion of the at least one movable foil, and wherein the at least one pitch mechanism is configured to control a pitch angle of the at least one foil such that a thrust force and a drag force are obtained during the downstroke heave motion, and the at least one pitch mechanism is configured to control a pitch angle of the at least one foil such that an induced drag force during the upstroke heave motion is substantially smaller than the drag force during the downstroke heave motion.
- the at least one pitch mechanism is self-adjusting or actively controllable.
- the at least one self-adjusting pitch mechanism comprises at least one damper.
- the at least one actively controllable pitch mechanism comprises at least one hydraulic cylinder or at least one crank mechanism.
- the system includes at least one connector, which is pivotally connected to a hinge mechanism and rotatably connected to the at least one movable foil.
- the at least one heave mechanism includes at least one of the group: a hydraulic cylinder, rack and pinions, a worm screw, or swiveling joints.
- the at least one heave mechanism is connected to the at last one connector.
- the system is configured to move at least a portion of the at least one movable foil through a surface of a liquid during the downstroke heave motion and the upstroke heave motion.
- the at least one movable foil is at least partially flexible.
- the system includes a first connector, which is connected to a first movable foil, and a second connector, which is connected to a second movable foil.
- the first connector and the second connector are movable connected to each other by a sliding mechanism.
- the sliding mechanism includes a coupling which is movable along the first connector and the second connector.
- the heave mechanism is connected to the coupling and/or to at least one of the connectors.
- the invention also concerns a method for oscillating at least one movable foil of a marine propulsion system, comprising the steps of:
- the pitch angle is controlled during the upstroke heave motion such that an angle of attack between an unsteady oncoming local fluid flow and a chord line of the at least one movable foil is substantially smaller than the drag force during the downstroke heave motion.
- the angle of attack during the upstroke heave motion is less than 5 degrees, preferably less than 3 degrees, and even more preferably essentially zero degrees.
- the velocity of the downstroke heave motion of the at least one movable foil is greater than the velocity of the upstroke heave motion.
- At least a portion of the at least one movable foil is moved through a surface of a liquid during the downstroke and upstroke heave motion.
- a pitch motion and a heave motion of a first movable foil and a second movable foil are controlled simultaneously and/or independently.
- the pitch angle of a first movable foil is controlled during the downstroke heave motion and the pitch angle of a second movable foil is simultaneously controlled during the upstroke heave motion.
- aspects of the invention further concern a computer readable medium having stored thereon a set of computer implementable instructions capable of causing a computing device, in connection with a pitch mechanism capable of controlling a pitch motion of at least one movable foil and a heave mechanism capable of controlling a heave motion of the at least one movable foil, to vary a pitch angle of the at least one foil such that a thrust force and a drag force are obtained during a downstroke heave motion and that an induced drag force during an upstroke heave motion is substantially smaller than the drag force during the downstroke heave motion.
- An oscillating foil propulsion system which implements aspects of the movement of a whale. Additionally, a method for oscillating at least one movable foil of a marine propulsion system is provided.
- a vessel for example a cargo vessel or a passenger vessel, can be propelled by means of the propulsion system according to the embodiments of the present invention.
- the required motion of the at least one foil is natural, continuously controllable and adjustable by modification of parameters.
- the pitch angles of the at least one movable foil are adjusted in order to obtain optimum thrust forces during the downstroke heave motion.
- the pitch angles of the movable foil are furthermore adjusted such that induced drag forces of the movable foil are minimized during the upstroke heave motion, thus reducing the total ship resistance during operation of the propulsion system.
- the movable foil may be additionally at least partially flexible to improve efficiency further.
- the efficiency improvement of a flexible or partially flexible foil is typically in the range between 3 % and 8 % compared to a rigid foil.
- Model tests of a propulsion system according to an embodiment of the invention have indicated that a propulsor efficiency of 50 % - 70 % or greater can be achieved, which is in the range of or significantly greater than the efficiency of a conventional screw propeller.
- the efficiency of a conventional screw propeller is further more sensitive to a variation of the service speed and the sea margin than the efficiency of the oscillating foil.
- the wetted propulsion surface of the at least one foil can be additionally larger than the area of a conventional propeller which reduces the area load.
- the propulsion system is especially suited for so called horizontally positioned foils having a large aspect ratio in order to achieve advantageous lift and drag coefficients.
- the propulsion system according to the invention is suitable for vessels with limited draught, for example inland navigation vessels.
- the hydrofoil further reduces noise and vibrations.
- the system includes at least one horizontal, heaving, pitching and surface piercing foil.
- the surface piercing arrangement enables a lower draught. Additionally, by turning the at least one foil at the most top position in the air less drag is created than by turning the at least one foil in the liquid. The at least one foil can furthermore penetrate the fluid in the optimal angle of attack in the beginning of the downstroke heave motion.
- a schematic view of a propulsion system 1 according to a first embodiment of the invention is illustrated, wherein a movable foil 2 is shown in a certain position during a downstroke heave motion h d (t).
- the system 1 includes a pitch mechanism and a heave mechanism which are not shown in Fig. 1 .
- the pitch mechanism is connected to the movable foil 2 and configured to control a pitch angle ⁇ d (t) of the movable foil 2.
- the pitch mechanism may be self-adjusting, i.e. passively controllable, or actively controllable.
- the heave mechanism is also connected to the movable foil 2 and configured to control a heave motion h d (t) of the movable foil 2 in a vertical direction.
- a connector 4 is pivotally secured to the stern 9 of a vessel 8 at one end by means of a hinge mechanism 6 and connected to the movable foil 2 at the other end.
- the pitch angle ⁇ d (t) of the movable foil 2 is adjusted such that optimum thrust forces T d (t) are obtained during the downstroke heave motion h d (t).
- the force on a foil section set at an angle of incident to the local fluid flow can be resolved into two components, i.e. the lift L and the drag D.
- the most important parameters for the lift coefficient C L of a foil are the angle of attack between the chord line of the foil and the direction of the oncoming local fluid flow in the foil working area as well as the aspect ratio of the foil.
- the lift force L can be effectively maximized by increasing the angle of attack and reaches a maximum at a critical angle of attack. Increasing the angle of attack beyond the critical angle of attack leads to stalling of the foil as well as a decrease of the lift force.
- the critical angle of attack is in particular depending on the aspect ratio of the foil.
- pitch angles ⁇ d (t) between the chord line c of the movable foil 2 and a horizontal plane H are provided during the downstroke heave motion h d (t) of the movable foil 2 in order to obtain sufficient angles of attack ß d (t) between the chord line c of the movable foil 2 and the oncoming local fluid flow 7 in the foil working area.
- the pitch angles ⁇ d (t) during the downstroke heave motion h d (t) are controlled such that the angles of attack ß d (t) are in the range of but less than the critical angle of attack of the movable foil 2, for example less than 20° or 15°.
- the oncoming local fluid flow 7 in the foil working area is changing with increasing service speed of the vessel 8 from a rather vertical direction to a more horizontal direction and therefore continuous or step-wise adjustment of the pitch angles ⁇ d (t) is advantageous in order to provide sufficient angles of attack ß d (t) during the downstroke heave motion h d (t) of the movable foil 2 and to obtain an optimal thrust T d (t) by maximizing the lift.
- the critical angle of attack may be further delayed.
- the aspect ratio of the movable foil 2 may be, for example, greater than 2, 3, 4, or 5 in order to provide advantageous lift coefficients.
- the movable foil 2 may be flexible, in particular at least a portion of the rear part of the movable foil 2 may be flexible.
- a flexible foil can be more efficient than a rigid foil because of the rotation of the force vector during the downstroke heave motion h d (t) into a direction which is more in-line with the direction of advance.
- Flexible foil means that at least a portion of the foil deforms during the downstroke heave motion h d (t).
- the trailing edge of the foil may be deformed, for instance.
- the deformation is typically at least 1 cm.
- the movable foil 2 is water thigh and light weight.
- the foil 2 may be, for example, made from aluminum.
- the deformation of the trailing edge of the foil may be, for example, 5 cm to 10 cm or more.
- the power to the heave mechanism may be, for example, provided by means of hydraulic cylinders which are connected to the stern 9 of the vessel 8 and the connector 4. According to other embodiments, the power to the heave mechanism may be provided by rack and pinions which are driven hydraulically or electrically. Otherwise, it is also possible to provide the power to the heave mechanism by means of a worm screw which is driven hydraulically or electrically or by means of any other mechanism, for example by a device configured to swivel joints and torque arms.
- Fig. 2 a schematic view of a propulsion system 1 according to a second embodiment of the invention is illustrated, wherein the movable foil 2 is shown in a certain position during an upstroke heave motion h u (t).
- the system 1 is adapted to change from a first heave mode, i.e. the downstroke heave h d (t), to a second heave mode, i.e. the upstroke heave h u (t).
- the motion of the at least one movable foil features different characteristics during the upstroke heave motion than during the downstroke heave motion.
- the pitch angles ⁇ u (t) of the movable foil 2 are adjusted such that the induced drag forces D u (t) of the movable foil 2 are minimized or kept as small as possible during the upstroke heave motion h u (t). Creation of lift and thrust may take place but is not required during the upstroke heave motion.
- the total resistance of the system can be reduced by minimizing the drag forces D u (t) of the at least one movable foil 2, 3 during the upstroke heave motion h u (t).
- the drag coefficient C D of a foil is depending on the angle of attack between the chord line of the foil and the direction of the oncoming local fluid flow in the foil working area.
- the drag forces D u (t) of the movable foil 2 can be effectively reduced by minimizing the angles of attack ß u (t) during the upstroke heave motion h u (t).
- the direction and velocity of the local fluid flow 7 in the foil working area are typically non-constant during a single upstroke heave motion of the at least one movable foil 2.
- the pitch angles ⁇ u (t) during the upstroke heave motion h u (t) are preferably continuously or step-wise controlled such that the angles of attack ß u (t) are less than 5 degrees, preferably less than 3 or 2 degrees, and even more preferably essentially zero degrees.
- the pitch angles ⁇ u (t) during the upstroke heave motion h u (t) are also depending on the speed of the vessel 8.
- the drag forces D u (t) of the movable foil 2 can be also effectively reduced by means of consideration of the change of the direction and velocity of the local fluid flow 7 in the foil working area as well as continuous or step-wise controlled adjustment of the pitch angles ⁇ u (t).
- the velocity of the upstroke heave motion h u (t) of the at least one movable foil 2 may be further less than the velocity of the previous and/or subsequent downstroke heave motion h d (t) of the at least one movable foil 2.
- the drag forces D u (t) during the upstroke heave motion h u (t) are substantially smaller than the drag forces D d (t) during the downstroke heave motion h d (t).
- a schematic top view of a propulsion system 1 according to a third embodiment of the invention is illustrated.
- the system 1 is adapted to change from a first heave mode, i.e. the downstroke heave h d (t), to a second heave mode, i.e. the upstroke heave h u (t).
- the system 1 includes a pitch mechanism and a heave mechanism which are not shown in Fig. 3 .
- a connector 4 is pivotally secured to the stern 9 of a vessel 8 at one end by means of a hinge mechanism 6.
- a first movable foil 2 and a second movable foil 3 are rotatably connected to the connector 4 at the other end.
- the pitch angles ⁇ d (t) during the downstroke heave motion h d (t) and the pitch angles ⁇ u (t) during the upstroke heave motion h u (t) can be adjusted.
- the adjustment of the two movable foils 2, 3 may take place simultaneously or independently.
- the pitch angles ⁇ d (t), ⁇ u (t) of the first foil 2 and the second foil 3 may be further equal or different.
- the system 1 is configured to create thrust T d (t) during the downstroke heave motion h d (t) and to reduce drag D u (t) during the upstroke heave motion h u (t).
- the taper ratio of the first movable foil 2 and the second movable foil 3, i.e. the minimum chord length c min in relation to the maximum chord length c max may be according to certain embodiments in the range between 0.2 and 0.7 in order to avoid an increase in induced drag due to a non-optimum taper ratio. Other embodiments may have other taper ratios, for example 1.1 or 1.3. According to certain embodiments, the maximum chord length c max of the first movable foil 2 and the second movable foil is 2.5 m or less than 2.5 m, for example 1.4 m. Other embodiments may have a chord length greater than 2.5 m, for example 5.0 m or more.
- Fig. 4 a schematic top view of a propulsion system 1 according to a fourth embodiment of the invention is illustrated.
- the system 1 is adapted to change from a first heave mode, i.e. the downstroke heave h d (t), to a second heave mode, i.e. the upstroke heave h u (t).
- the system 1 is configured to create thrust T d (t) during the downstroke heave motion h d (t) and to reduce drag D u (t) during the upstroke heave motion h u (t).
- the first movable foil 2 and the second movable foil 3 each sweep backwards.
- the sweep back angles of the first and second movable foil 2, 3 are typically less than 45°, preferably between 10° and 30°, for example 15°. Depending on the sweep back angle an optimum taper ratio can be then determined. With increasing sweep back angle lower taper ratios can be chosen. Taper ratios lower than 0.2 are typically not recommended. Certain embodiments may have a taper ratio lower than 0.2.
- the first movable foil 2 and the second movable foil may be additionally equipped with so called end plates or winglets which are not shown in Fig. 4 . According to other embodiments of the invention the first movable foil 2 and the second movable foil 3 may form a continuous single foil to avoid a gap between the two movable foils 2, 3.
- a schematic top view of a propulsion system 1 according to a fifth embodiment of the invention is illustrated.
- the system 1 is adapted to change from a first heave mode, i.e. the downstroke heave h d (t), to a second heave mode, i.e. the upstroke heave h u (t).
- the system 1 is configured to create thrust T d (t) during the downstroke heave motion h d (t) and to reduce drag D u (t) during the upstroke heave motion h u (t).
- the movable foil 2 of the propulsion system 1 includes aspects of the shape of a fluke plan form of an animal.
- the system 1 further includes a computer readable medium having stored thereon a set of computer implementable instructions capable of causing a computing device 11, in connection with a pitch mechanism capable of controlling a pitch motion of at the least one movable foil and a heave mechanism capable of controlling a heave motion of the at least one movable foil, to vary a pitch angle ⁇ d (t), ⁇ u (t) of the at least one foil such that a thrust force (T d (t)) and a drag force D d (t) are obtained during a downstroke heave motion h d (t) and that a drag force D u (t) during an upstroke heave motion h u (t) is substantially smaller than the drag force D d (t) during the downstroke heave motion h d (t).
- the system 1 allows controlled adjustment of the downstroke heave h d (t), the upstroke heave h u (t), the frequency of the downstroke heave h d (t), the frequency of the upstroke heave h u (t), the amplitude of the downstroke heave h d (t), the amplitude of the upstroke heave h u (t), the pitch angle ⁇ d (t) during the downstroke heave h d (t), the pitch angle ⁇ u (t) during the upstroke heave h u (t), the frequency of the pitch angle ⁇ d (t) during the downstroke heave h d (t), the frequency of the pitch angle ⁇ u (t) during the upstroke heave h u (t), the amplitude of the pitch angle ⁇ d (t) during the downstroke heave h d (t), and the amplitude of the pitch angle ⁇
- the frequency of the sinusoidal like heave motion is typically less than 3 Hz.
- Maximum pitch angles ⁇ d (t) during the downstroke heave h d (t) and maximum pitch angles ⁇ u (t) during the upstroke heave h u (t) are typically in the range between 70° and 0°, 60° and 0°, 50° and 0°, 40° and 0°, 30° and 0°, 20° and 0°, or 10° and 0°.
- the fluke plan form may include aspects of the shape of a whale or any other animal, for example the shape of a white whale, a mink whale, or a fin whale.
- Fig. 6 a schematic time-vertical position-diagram of a propulsion system according to a sixth embodiment of the invention is illustrated.
- the system is adapted to change from a first heave mode, i.e. the downstroke heave h d (t), to a second heave mode, i.e. the upstroke heave h u (t).
- the motion of the at least one movable foil features different characteristics during the first mode and the second mode.
- the velocity of the downstroke heave h d (t) is significantly greater than the velocity of the upstroke heave h u (t) in order to obtain optimum thrust forces T d (t) during the downstroke heave h d (t) and minimized drag forces D u (t) during the upstroke heave h u (t).
- Fig. 7 a schematic time-angle of attack-diagram of a propulsion system according to a seventh embodiment of the invention is illustrated.
- the system is adapted to change from a first heave mode, i.e. the downstroke heave h d (t), to a second heave mode, i.e. the upstroke heave h u (t).
- the motion of the at least one movable foil features different characteristics during the first mode and the second mode.
- Sufficient pitch angles ⁇ d (t) between the chord line c of the movable foil 2 and a horizontal plane H are provided during the downstroke heave motion h d (t) of the movable foil 2 in order to obtain sufficient angles of attack ß d (t) between the chord line c of the movable foil 2 and the oncoming local fluid flow 7 in the foil working area.
- the pitch angles ⁇ d (t) during the downstroke heave motion h d (t) are controlled such that the angles of attack ß d (t) are in the range of but less than the critical angle of attack ß crit of the movable foil 2, for example, less than 20° or 15°.
- Optimum thrust T d (t) is created during the downstroke heave motion h d (t).
- the angles of attack ß d (t) during the downstroke heave motion h d (t) can be greater than the critical angle of attack ß crit of the movable foil 2.
- the pitch angles ⁇ u (t) during the upstroke heave motion h u (t) are continuously or step-wise controlled such that the angles of attack ß u (t) are less than 5 degrees, preferably less than 3 or 2 degrees, and more preferably essentially zero degrees. Due to the unsteady local fluid flow 7 in the foil working area the angles of attack ß u (t) oscillate within a certain range, for example between +1° and -1°, during the upstroke heave h u (t).
- the work done by the drag force D d (t) during the downstroke heave motion h d (t) is significantly greater than the work done by the induced drag force D u (t) during the upstroke heave motion h u (t).
- Fig. 8 a schematic view of a propulsion system 1 according to an eighth embodiment of the invention is illustrated.
- the system 1 includes a first movable foil 2 and a second movable foil 3 which are pivotally secured to the stern 9 of a vessel 8 via a first connector 4 and a second connector 5, respectively.
- the first connector 4 and the second connector 5 are movable connected to each other by a sliding mechanism.
- the sliding mechanism includes a coupling 10 which is movable along the first connector 4 and the second connector 5.
- the system 1 further includes at least one heave mechanism which is connected to at least one of the two connectors 4, 5 or to the coupling 10 of the sliding mechanism.
- a linear movement of the coupling 10 along the first connector 4 and the second connector 5 leads to the downstroke heave motion h d (t) of the first movable foil 2 and to a simultaneous upstroke heave motion h u (t) of the second movable foil 3.
- the pitch angles ⁇ d (t) of the first movable foil 2 are adjusted to obtain optimum thrust forces T d (t) during the downstroke heave motion h d (t).
- the pitch angles ⁇ u (t) of the second movable foil 3 are adjusted such that minimum drag forces D u (t) of the second movable foil 3 are induced during the upstroke heave motion h u (t).
- the system 1 includes two pitch mechanisms which are connected to the movable foils 2, 3 and configured to control a pitch motion of the respective movable foil 2, 3.
- the pitch mechanisms and the heave mechanism are not shown in Fig. 8 .
- the first movable foil 2 and the second movable foil 3 are not connected by a sliding means and move simultaneously in the same direction.
- the first movable foil 2 and the second movable foil 3 are then arranged in vertical direction one above the other. There may be even more than two foils arranged in vertical direction.
- Fig. 9 illustrates a schematic view of a propulsion system 1 according to a ninth embodiment of the invention, wherein the system 1 includes a horizontal, heaving, pitching and surface piercing foil.
- the system 1 includes a first movable foil 2 and a second movable foil 3 and two pitch mechanisms which are connected to the respective movable foils 2, 3 and configured to control a pitch angle ⁇ d (t), ⁇ u (t) during a downstroke heave motion h d (t) and an upstroke heave motion h u (t).
- the system 1 further includes a first connector 4, which is connected to the first movable foil 2, and a second connector 5, which is connected to the second movable foil 3.
- the first connector 4 and the second connector 5 are each pivotally connected to a hinge mechanism 6 at one end.
- the hinge mechanisms 6 are connected to a stern 9 of a vessel 8.
- the first connector and the second connector are furthermore connected to each other by a sliding mechanism, which includes a coupling 10, which is movable along the first connector 4 and the second connector 5.
- the coupling 10 is connected to a heave mechanism which is configured to control a downstroke heave motion h d (t) and an upstroke heave motion h u (t) of the movable foils 2, 3.
- at least one hydraulic cylinder is connected to the coupling 10 at one end. The at least one hydraulic cylinder is then connected to one of the connectors 4, 5 or to the vessel 8.
- a linear movement of the coupling 10 along the first connector 4 and the second connector 5 leads to the downstroke heave motion h d (t) of one of the movable foils 2, 3 and to a simultaneous upstroke heave h u (t) motion of the other movable foil 2, 3 and vice versa.
- the heave motion of each movable foil 2, 3 is preferably sinusoidal like.
- the amplitudes of the heave motion of the first movable foil 2 and the second movable foil 3 are at the system's maximum.
- the first movable foil 2 is partially arranged above the waterline W.
- the first movable foil 2 represents a horizontal, heaving, pitching and surface piercing foil.
- the pitch mechanisms are configured to control the pitch angles ⁇ d (t) of the first movable foil 2 and the second movable foil 3 in order to obtain a thrust force T d (t) during the downstroke heave motion h d (t). Additionally, there are obtained drag forces D d (t) during the downstroke heave h d (t).
- the pitch mechanisms are further configured to control the pitch angles ⁇ u (t) of the first movable foil 2 and the second movable foil 3 in order to minimize an induced drag force D u (t) during the upstroke heave motion h u (t).
- the pitch angles ⁇ u (t) of the movable foils 2, 3 are controlled during the upstroke heave motion h u (t) such that an angle of attack ß u (t) between an oncoming local fluid flow 7 in the foil working area and a chord line c of the respective foils 2, 3 is reduced.
- the angle of attack ß u (t) is during the upstroke heave motion h u (t) typically less than 5°, preferably less than 3°, and more preferably essentially zero degrees.
- the system 1 is configured to move at least a portion of the first foil 2 through the waterline W during the downstroke heave motion h d (t) and the upstroke heave motion h u (t).
- the first movable foil 2 and the second movable foil 3 may be partially flexible in order to rotate the resultant force vector during the downstroke heave motion h d (t) into a direction more in-line with the direction of advance.
- the disclosed embodiments are not limited to controlling the pitch angle of the at least one foil such that a thrust force is obtained during the downstroke heave motion. Thrust may be also created during the upstroke heave motion of the at least one movable foil and drag may be minimized during the downstroke heave motion.
- the drag force D d (t) during the downstroke heave, the drag force D u (t) during the upstroke heave, the thrust force T d (t) during the downstroke heave, the downstroke heave h d (t), the upstroke heave h u (t), the pitch angle ⁇ d (t) during the downstroke heave, the pitch angle ⁇ u (t) during the upstroke heave, the angle of attack ⁇ d (t) during the downstroke heave, and the angle of attack ⁇ u (t) during the upstroke heave are functions of time.
- the vertical direction is defined as being perpendicular to the horizontal direction and the transversal direction.
- the horizontal direction is further defined as being perpendicular to the transversal direction.
- the horizontal direction and the transversal direction form a horizontal plane.
- a rotation of one of the aforementioned directions about at least one axis of rotation leads to a rotation of the other two directions as well as to a rotation of the horizontal plane about the at least one axis of rotation within the meaning of the detailed description of embodiments.
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Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
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EP14178280.5A EP2977311A1 (de) | 2014-07-24 | 2014-07-24 | Oszillierendes Dualmodus-Folienantriebssystem und Verfahren für die Oszillation mindestens einer beweglichen Folie |
PCT/FI2015/050507 WO2016012656A1 (en) | 2014-07-24 | 2015-07-21 | Dual mode oscillating foil propulsion system and method for oscillating at least one movable foil |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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EP14178280.5A EP2977311A1 (de) | 2014-07-24 | 2014-07-24 | Oszillierendes Dualmodus-Folienantriebssystem und Verfahren für die Oszillation mindestens einer beweglichen Folie |
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EP2977311A1 true EP2977311A1 (de) | 2016-01-27 |
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EP14178280.5A Withdrawn EP2977311A1 (de) | 2014-07-24 | 2014-07-24 | Oszillierendes Dualmodus-Folienantriebssystem und Verfahren für die Oszillation mindestens einer beweglichen Folie |
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EP (1) | EP2977311A1 (de) |
WO (1) | WO2016012656A1 (de) |
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CN109835455A (zh) * | 2019-01-21 | 2019-06-04 | 西安交通大学 | 一种连杆机构驱动柔性仿尾鳍推进器 |
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CN114104236A (zh) * | 2021-11-30 | 2022-03-01 | 中国船舶科学研究中心 | 一种新型仿生振荡翼的组合运动方式 |
Citations (3)
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GB1092839A (en) | 1965-10-21 | 1967-11-29 | Victor Norman Davies | Improvements in or relating to the steering and propulsion of watercraft |
WO2002055381A2 (en) * | 2000-11-08 | 2002-07-18 | Cid, Inc. | Personal watercraft |
EP2470781A2 (de) * | 2009-08-24 | 2012-07-04 | Oscillating Foil Development B.V. | Verfahren und vorrichtung zur oszillation eines flügels in einer flüssigkeit |
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US5401196A (en) * | 1993-11-18 | 1995-03-28 | Massachusetts Institute Of Technology | Propulsion mechanism employing flapping foils |
US6877692B2 (en) * | 2003-03-05 | 2005-04-12 | National Research Council Of Canada | Oscillating foil propulsion system |
US20110255971A1 (en) * | 2008-08-18 | 2011-10-20 | Bas Goris DBA Oscillating Foul Development | Apparatus for oscillating a foil in a fluid |
-
2014
- 2014-07-24 EP EP14178280.5A patent/EP2977311A1/de not_active Withdrawn
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2015
- 2015-07-21 WO PCT/FI2015/050507 patent/WO2016012656A1/en active Application Filing
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
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GB1092839A (en) | 1965-10-21 | 1967-11-29 | Victor Norman Davies | Improvements in or relating to the steering and propulsion of watercraft |
WO2002055381A2 (en) * | 2000-11-08 | 2002-07-18 | Cid, Inc. | Personal watercraft |
EP2470781A2 (de) * | 2009-08-24 | 2012-07-04 | Oscillating Foil Development B.V. | Verfahren und vorrichtung zur oszillation eines flügels in einer flüssigkeit |
Non-Patent Citations (4)
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H. YAMAGUCHI; N. BOSE: "Oscillating Foils for Marine Propulsion", THE INTERNATIONAL SOCIETY OF OFFSHORE AND POLAR ENGINEERS, 1994 |
J. MATTHEIJSSENS; J.-P. MARCEL; W. BOSSCHAERTS; D. LEFEBER: "Oscillating foils for ship propulsion", NATIONAL CONGRESS ON THEORETICAL AND APPLIED MECHANICS; BRUSSELS, 9 May 2012 (2012-05-09) |
L SCHOUVEILER ET AL: "PERFORMANCE OF FLAPPING FOIL PROPULSION", JOURNAL OF FLUIDS AND STRUCTURES, vol. 20, no. 2005, 5 May 2005 (2005-05-05), pages 949 - 959, XP055162078 * |
YONGHUI HU YONGHUI HU ET AL: "Development and control of dolphin-like underwater vehicle", 2013 AMERICAN CONTROL CONFERENCE, 13 June 2008 (2008-06-13), pages 2858 - 2863, XP055151631, ISSN: 0743-1619, ISBN: 978-1-47-990177-7, DOI: 10.1109/ACC.2008.4586927 * |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN109835455A (zh) * | 2019-01-21 | 2019-06-04 | 西安交通大学 | 一种连杆机构驱动柔性仿尾鳍推进器 |
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