Wind-assisted propulsion system and vessels equipped with such a system

Abstract

The present invention relates to a method for controlling the incidence angle (A1) of an aerofoil (100) of a wind-assisted propulsion system (1), the method comprising the steps of: measuring a parameter representative of the separation state of an airflow (F1) incident on the aerofoil (100) as a function of the incidence angle (A1) of the aerofoil (100), determining an incidence angle value (A1D_t2) of the aerofoil (100) corresponding to a stall; determining a safety incidence angle value (A1SD1_t2) of the aerofoil that is lower than the stall angle value as a function of the stall angle value (A1D_t2); and controlling the orientation of the aerofoil at an incidence angle set value equal to the safety incidence angle value (A1SD1_t2). The present invention also relates to a system and a corresponding vessel.

Description

[Technical Field]

[0001] The present invention relates generally to wind-assisted propulsion systems for marine vessels, also known as wind-assisted propellers. [Background technology]

[0002] From the state of the art, in particular from DE 10 200 04 14 A1, there is known a wind-assisted propeller which comprises an elongated hollow body, a suction area provided along the circumferential wall of the hollow body and suction means making it possible to generate an air flow inside the hollow body. The suction at the circumferential wall of the propeller makes it possible to limit the separation of the air flow from the wall of the propeller.

[0003] The lift profile, also called wing, makes it possible to generate lift in the aerodynamic sense, i.e. a force perpendicular to the direction of the flow in which the wing is arranged, thereby making it possible to realize a wind-assisted propulsion system for ships, for example cargo ships.

[0004] For a given configuration of the wing, the lift generated depends primarily on the wing's angle of incidence, i.e., the angle between the chord line of the wing's profile and the direction of the incoming airflow. In the case of a wind-assisted propulsion system mounted on a vessel, the flow incident on the wing is the apparent wind seen by the wing, which is the result of the wind seen by an observer on board the vessel and stationary relative to the vessel, and the wind generated by the vessel's displacement (velocity).

[0005] Lift increases steadily with incidence angle up to a maximum value, beyond which there is a more or less abrupt decrease in lift, which corresponds to a stall.

[0006] Before using a wing, it is possible to estimate the angle of incidence at which a stall may occur, i.e., the stall angle, depending on the wing's profile, and this allows defining an allowable range of incidence angles for controlling the wing's rotation. However, stall angle estimation is unreliable and remains variable depending on environmental conditions, so it is necessary to define a sufficient safety margin between the maximum allowable incidence angle and the estimated stall angle to prevent the wing from inadvertently stalling.

[0007] Patent document 2 describes a machine for harvesting wind energy that uses self-adjusting aerodynamic blades and rollers, with sensors monitoring the operating conditions.

[0008] Patent Document 3 describes a variable geometry wing that is stepwise movable between a neutral configuration and a deformed configuration, in which the wing assumes a cambered airfoil cross-section.

[0009] The object of the present invention is to propose a novel wind-assisted propulsion system and a corresponding method making it possible to overcome all or part of the problems disclosed above. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] French Patent Publication No. 2503286 [Patent Document 2] U.S. Patent No. 4,582,013 [Patent Document 3] International Publication No. 2014 / 085835 Summary of the Invention

[0011] To this end, the subject of the present invention is a method for controlling the angle of incidence of a lift-generating device, called an aerofoil, of a wind-assisted propulsion system relative to the apparent wind direction, the aerofoil comprising a hollow body, the aerofoil being located in an outer airflow incident on the aerofoil, the wind-assisted propulsion system comprising: a suction device in fluid communication with the hollow body; at least one suction opening in the peripheral wall of the hollow body that receives the external airflow that is incident on the wing, the suction device generating an airflow from the at least one suction opening into the interior of the hollow body; - a device for measuring a parameter representative of the separation of the airflow incident on the wing; a power system for pivoting the blades about a vertical pivot axis parallel to the longitudinal axis of the hollow body; -Drive unit and A method comprising: a) measuring the apparent wind direction by a device for measuring the apparent wind direction; b) using a power system for rotating the wing to rotate the wing about a vertical axis of rotation, so that the chord line of the wing profile can assume different angles of incidence relative to the apparent wind direction; c) measuring, during the pivotal displacement of the blade, by means of said device for measuring a parameter representative of the state of separation, said parameter representative of the state of separation of the airflow incident on the blade as a function of the value of the angle of incidence of the blade, and determining, by means of a drive unit, from the measured values ​​of said parameter representative of the state of separation of the airflow incident on the blade, a value of the angle of incidence of the blade corresponding to a stall, called a stall angle value; d) determining, by a drive unit, a safety angle of incidence value of the blade in response to the stall angle value, the safety angle of incidence being lower than the stall angle value in absolute value; e) controlling the orientation of the blades by the drive unit at an incidence angle set value equal to the incidence angle safety value; The method is characterized by comprising:

[0012] Such a wind-assisted propulsion system design allows for reliable detection of the stall angle and reduces the safety margin between the maximum allowable angle of incidence and the stall angle, thereby limiting the risk of stall while still benefiting from lift close to maximum lift.

[0013] Depending on this measured stall angle, the drive unit can define a maximum allowable angle of incidence as a value equal to this stall angle value (in absolute value) minus a safety value, this safety value being smaller than the value that would be used if the stall angle were simply estimated depending on the shape of the wing. The system can then provide a lift close to the maximum lift by measuring the stall angle, thereby adapting the allowable range of incidence angles to the measured stall angle, bringing it closer to the stall angle, thereby benefiting from a large lift while limiting the risk of unintended stall.

[0014] Thus, measuring or learning the stall angle allows the location and extent of the wing's incident operating region to be adjusted depending on the stability of the operating conditions. Measuring or learning the stall angle, rather than simply estimating it, also allows the angle of incidence to be reduced if it is determined that the wing is experiencing premature stall.

[0015] The system can thus maximize the thrust generated by the ship over time, since measuring the stall angle allows updating the stall angle value to be taken into account, using an appropriate safety margin between the maximum allowable angle of incidence and the measured stall angle, thereby allowing the wing to best approach the maximum lift point while avoiding stall. This improves the efficiency of the system, since the aerodynamic operating point that maximizes thrust often constitutes the maximum lift point.

[0016] Thus, a wind-assisted propulsion system configured to detect blade stall and use the corresponding measured stall angle to reliably and efficiently define the maximum allowable angle of incidence, thereby improving the system's operating efficiency by enabling high lift values ​​to be achieved while reducing the risk of unintended stall. Taking the stall angle into account allows for an effective check on the system's drive.

[0017] The measurement of the apparent wind angle is preferably carried out in the vicinity of the system. An apparent wind direction sensor may be fixed to the system, for example in a wind vane located above the system.

[0018] Thus, the wind-assisted propulsion system and corresponding method allows for correction or elimination of the theoretical stall angle estimate, which is by definition an approximation, by actually testing the stall angle or determining the actual stall angle by considering a stall experienced at a given angle.

[0019] In other words, the control method and the corresponding system therefore make it possible to pivot the blade, measure the air separation during the blade pivot, and accurately and reliably determine the actual stall angle from the measurements made, thus reducing the safety margin between the maximum permissible angle of incidence and the stall angle.

[0020] Conversely, the state of the art only estimates the angle at which a stall may occur before the wing is used. However, the estimation of the angle at which a stall may occur is unreliable and remains variable depending on the environmental conditions, and therefore a sufficient safety margin must be defined between the maximum allowable angle of incidence and the estimated stall angle to prevent the wing from inadvertently stalling.

[0021] The control method and the corresponding system according to the invention eliminate the need for the user (navigator) to intervene in adjusting the wind-assisted propeller. It should be noted that in the state of the art, the user does not have data that would allow him to determine the stall of the wind-assisted propeller, especially when the wind-assisted propeller is installed on a cargo ship.

[0022] The system may also include one or more of the following features employed in any technically permissible combination.

[0023] According to one embodiment, after a first implementation process of steps a) to e) providing a first stall angle value and a first incidence angle safety value, steps a) to e) are repeated in a second implementation process to obtain a second stall angle value and a second incidence angle safety value corresponding to an updated incidence angle safety value. According to a particular aspect, the angular sectors through which the blades are pivotally displaced extend on either side of the stall angle value obtained during the first implementation process.

[0024] According to one embodiment, in step b) of the second implementation process the wings are displaced until a stall is detected and / or the angular sector in which the wings are pivoted extends on either side of the stall angle value obtained during the first implementation process, the pivoting of the wings is preferably performed so as to reach or exceed (i.e. pass through) the angle previously determined as the stall angle.

[0025] According to one embodiment, after the first implementation process of steps a) to e) of providing the first stall angle value and the first incidence angle safety value, the method is preferably implemented at a given frequency, for example 10 Hz; - determining the angular position of the blade corresponding to the blade incidence angle value and measuring said parameter representative of the separation of the airflow incident on the blade; - determining, by a drive unit, the stalled or non-stalled state of the wing depending on said measured parameters representative of the separation of the airflow incident on the wing; If a stall condition is detected, - repeating steps a) to e) in a second implementation process, or - assigning, by a drive unit, the determined incidence angle value of the blade to a stall angle value; determining, by a drive unit, a safety incidence angle value of the blade in response to the stall angle value, the safety incidence angle value being lower than the stall angle value in absolute value; controlling, by a drive unit, the orientation of the blades at an incidence angle setpoint equal to the incidence angle safety value; Includes.

[0026] According to one embodiment, an apparatus for measuring a parameter representative of the separation state of an airflow incident on an airfoil comprises a pressure sensor system configured to measure the pressure in the airflow inside a hollow body.

[0027] According to one embodiment, the pressure sensor system is configured to measure the pressure in the air flow inside the hollow body between said at least one suction opening and the suction device.

[0028] According to one embodiment, the pressure sensor system comprises a sensor of the differential pressure sensor type, which comprises a pressure tap located inside the hollow body.

[0029] According to one embodiment, the wing comprises a fairing coupled to a peripheral wall of the hollow body, and the differential pressure sensor comprises a reference pressure tap located within the fairing.

[0030] According to one embodiment, the incident angle safety value is denoted as A1SD1_t2 and is expressed by the formula ||A1SD1_t2||=||A1D_t2||-a s is calculated according to the formula: s is a strictly positive value called the interval value, and A1D_t2 is the stall angle value.

[0031] According to one embodiment, the interval value is a predetermined value.

[0032] According to one embodiment, the spacing value is a function of the apparent wind speed.

[0033] According to one embodiment, the stall angle value is determined as an incidence angle value at which a parameter representative of the separation state of the airflow incident on the wing exceeds a threshold value and / or has a gradient value exceeding a threshold value.

[0034] According to one embodiment, the apparent wind direction is measured using a wind vane positioned on the wing.

[0035] According to one embodiment, the device for measuring a parameter representative of the separation state of an airflow incident on a wing comprises a wall pressure sensor positioned on the wing in the incident airflow upstream of said at least one suction opening.

[0036] According to one embodiment, the device for measuring a parameter representative of the separation state of the airflow incident on the wing comprises a flexible strip assigned to electronic processing means, called an electronic indicator, positioned on the wing in the incident airflow upstream of said at least one suction opening.

[0037] According to one embodiment, the device for measuring a parameter representative of the separation state of the airflow incident on the wing comprises a device for analyzing the operating parameters of the suction device.

[0038] The present invention also provides a wind-assisted propulsion system, comprising: a lift-generating device called an aerofoil, the aerofoil comprising a hollow body, the aerofoil intended to be located in the outer airflow incident on the aerofoil; a suction device in fluid communication with the hollow body; at least one suction opening provided in the peripheral wall of the hollow body capable of receiving the external airflow incident on the wing, the suction device being configured to generate an airflow from the at least one suction opening into the interior of the hollow body; - a device for measuring a parameter representative of the separation of the airflow incident on the wing; a power system for pivoting the blades about a pivot axis parallel to the longitudinal axis of the hollow body; a drive unit configured to carry out the steps of the method according to any one of the previous embodiments for controlling the angle of incidence of the blade with respect to the apparent wind direction; The present invention relates to a wind-assisted propulsion system comprising:

[0039] The invention also relates to a vessel equipped with a wind-assisted propulsion system, the wind-assisted propulsion system being mounted on the deck of the vessel.

[0040] According to a preferred embodiment, the parameter related to the state of the airflow measured is the internal pressure of the hollow body. The internal pressure of the hollow body generated by the suction device in the airflow arriving from the suction opening makes it possible to reliably detect an internal pressure rise above a threshold value and / or with a growth gradient higher than the threshold value, which is characteristic of a state of separation of the airflow around the airfoil upstream of the suction area of ​​the peripheral wall, i.e., a stall of the airfoil. It may be expected that the angle of incidence at which this pressure rises above the threshold value and / or has a growth gradient higher than the threshold value is defined as the stall angle.

[0041] Another object of the present invention is to provide a method for controlling the angle of incidence of a lift-generating device, called an aerofoil, of a wind-assisted propulsion system relative to the apparent wind direction, the aerofoil comprising a hollow body, the aerofoil being located in an outer airflow incident on the aerofoil, the wind-assisted propulsion system comprising: a suction device in fluid communication with the hollow body; at least one suction opening in the peripheral wall of the hollow body that receives the external airflow that is incident on the wing, the suction device generating an airflow from the at least one suction opening into the interior of the hollow body; - a device for measuring parameters representative of the separation state of the airflow incident on the wing; A method comprising: a) measuring apparent wind direction; b) pivoting the wing about a vertical pivot axis to allow the chord line of the wing profile to assume different angles of incidence relative to the apparent wind direction; c) measuring said parameter representative of the separation of the airflow incident on the blade as a function of the blade incidence angle value during the blade's pivotal displacement, and determining a blade incidence angle value corresponding to a stall, called a stall angle value, from the measurements of said parameter representative of the separation of the airflow incident on the blade; d) determining a safety angle of incidence for the blade in response to the stall angle value, the safety angle of incidence being lower in absolute value than the stall angle value; e) controlling the orientation of the blades at an incidence angle set point equal to the incidence angle safety value; The method is characterized by comprising: [Brief explanation of the drawings]

[0042] Other features and advantages of the present invention will become apparent from the following description, which is given by way of example only and is not limiting, and which should be read in conjunction with the accompanying drawings, in which: [Figure 1] 1 is a schematic cross-sectional view of a wind-assisted propulsion system according to an embodiment of the present invention, the system being mounted on the deck of a vessel. [Figure 2] 2 is a schematic diagram of the wing of the system of FIG. 1 illustrating an allowable incidence angle range defined in response to a first measured stall angle value, where the wing has an incidence angle that falls within the allowable angle range and the wing is not subject to stall. [Figure 3] 3 is a schematic diagram of the wing of FIG. 2, where the wing has an angle of incidence greater than the angle of incidence of the wing of FIG. 2, and a stall is detected when the angle of incidence is still within an acceptable range. [Figure 4] 4 is a schematic diagram of the wing of FIG. 3 after redefining (updating) the allowable incidence angle range according to a new stall angle value corresponding to the incidence angle of FIG. 3 at which stall was detected. [Figure 5] FIG. 5 is a schematic diagram of the airfoil of FIG. 4 with an incidence angle that falls within the new range of acceptable incidence angles. [Figure 6] FIG. 1 is a diagram of a curve showing the reciprocal of the pressure coefficient (-Cp) as a function of the angle of incidence measured during a pivoting displacement of the blade to determine the actual stall angle. [Figure 7] 3 is a flowchart including steps of a method for controlling the incidence angle of the blades of a wind-assisted propulsion system according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0043] The inventive concepts will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the inventive concepts are shown. In the drawings, the size and relative sizes of the elements may be exaggerated for clarity. Like numbers refer to like elements throughout the drawings. However, the inventive concepts may be embodied in many different forms and should not be construed as limited to the embodiments disclosed herein. Rather, these embodiments are provided so that this description will be thorough and complete, and will convey the scope of the inventive concepts to those skilled in the art.

[0044] Throughout this specification, the reference to "one embodiment" means that a particular feature, structure, or characteristic described in connection with one embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrase "in one embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0045] Referring to the figure, there is shown a wind-assisted propulsion system 1, also called a wind-assisted propeller. As shown in Figure 1, the wind-assisted propulsion system 1 is located on the deck of a vessel 1000.

[0046] The wind-assisted propulsion system 1 is positioned in a moving airflow F1, which allows it to generate lift. As will be described in more detail below, the system is actuated to optimize lift while limiting the risk of stall, thereby improving the system's operating efficiency.

[0047] wings The wind-assisted propulsion system 1 includes an aerodynamically profiled lift-generating device called a suction vane 100. The following description is given for one vane, but also applies to multiple vanes.

[0048] The airfoil 100 comprises an elongated hollow body 10 along an axis A10, which is in fluid communication with a suction device 13 as described below. The axis A10 is perpendicular to the plane of the deck of the vessel when the airfoil is in its in-use configuration, i.e., is substantially vertical. The hollow body is rigid, unlike, for example, a sail on a sailing ship.

[0049] Preferably, the wing also comprises a fairing 110 (defining an airflow-free enclosure) attached to the outer part of the peripheral wall of the hollow body 10, called the forward part. The aerodynamic profile of the wing is defined by the outer profile of the fairing and the outer profile of the hollow body. Different profile shapes may be used. In the example shown in the figures, the wing profile is egg-shaped. The wing profile corresponds to a cut (section) along a plane perpendicular to the axis A10 of the hollow body.

[0050] The peripheral wall of the hollow body 10 of the airfoil has at least one opening 11, called a suction opening, which can communicate with the interior of the hollow body 10 of the airfoil 100. In one embodiment, the peripheral wall has two suction openings, preferably distributed symmetrically relative to the axis of symmetry of the airfoil profile.

[0051] In one embodiment, the hollow body 10 is provided with a movable flap 12. The flap makes it possible to change the camber of the wing profile to increase lift, regardless of whether the wind is blowing from one side of the ship or the other. The ship can be sailed on both port and starboard tacks. In one embodiment, it may be provided that the displacement of the flap makes it possible to close suction openings 11 and open other suction openings.

[0052] suction device The wind-assisted propulsion system comprises a suction device 13 communicating with the interior of the hollow body 10 of the wing 100, by means of which air is sucked in through said at least one opening 11 provided in the peripheral wall of the wing.

[0053] Each suction opening 11 may have a variable opening size or hole size along the wing, for example to provide for varying the amount of air sucked in depending on the position along the wing. Each opening 11 may be manufactured in the form of a grid.

[0054] In the illustrated example, the suction device 13 is formed by a fan in fluid communication with the hollow body 10. The fan may be of the centrifugal fan type or of the spiral centrifugal fan type. The fan may be in fluid communication with the hollow body while being located inside or outside the hollow body. The fan is configured in such a way that it is possible to generate air circulation through the hollow body by suction at the suction openings 11, which promotes the maintenance of an air layer in the outer flow against the peripheral wall of the hollow body in the region of the suction openings 11.

[0055] 1, the suction opening 11 allows the outside air flow F1 that reaches the suction opening 11 to be at least partially sucked into the hollow body 10 using the fan 13, thus forming an inside air flow F2 that passes from the suction opening 11 through the fan 13. The fan 13 is configured to exhaust the sucked air flow to the outside air.

[0056] Wing rotation The wind-assisted propulsion system 1 comprises a support (not shown) on which the aerofoil 100 is mounted so as to be pivotable relative to the support. Preferably, the aerofoil is mounted on the support so as to be pivotable about an axis that is substantially parallel to the longitudinal axis A10 of the hollow body 10 of the aerofoil 100. The pivot axis PIV1 is preferably parallel to the axis A10, although it will be understood that the pivot axis may have a small angle of 1° or a few degrees, for example an angle of less than 5°, relative to the axis A10.

[0057] For this purpose, the wind-assisted propulsion system 1 comprises a power system 18 for rotating the blades.

[0058] Thus, with the system mounted on the deck of the vessel 1000, the wing 100 can rotate about the (vertical) axis A10, controlled by the powered pivoting system 18, which itself can be controlled by the drive unit 180, to orient the wing relative to the apparent wind direction. As explained below, the orientation of the wing is controlled or adjusted according to the desired lift, thereby reducing the risk of stall.

[0059] In a use configuration of the system, the wing 100 is raised on the deck of a ship, for example a cargo ship, via a support for the wing 100, the support being stationary relative to the deck.

[0060] Therefore, the wing 100 is mounted so as to be rotatable relative to the vessel about the vertical rotation axis PIV1 of the wing 100, which allows the chord line D100 of the profile of the wing 100 (also called the direction of orientation) to take on different values ​​for the angle of incidence A1 relative to the apparent wind direction V1.

[0061] The chord line (or direction of orientation) D100 of the profile of the wing 100 may be defined as the straight line connecting the leading edge and trailing edge of the wing when viewed from the wing along a cross-section plane (cutting surface) perpendicular to the longitudinal axis A10 of the hollow body.

[0062] Preferably, as shown in Figure 1, the wing 100 is provided with flaps 12. The flaps make it possible to change the camber of the wing profile to increase lift, regardless of whether the wind is blowing from one side of the ship or the other. The ship can be sailed on both port and starboard tacks. According to one embodiment, if the wing has several suction openings, it may be provided that the displacement of the flaps makes it possible to close one suction opening and open another.

[0063] A system for measuring the apparent wind direction V1, e.g. a wind vane, is provided and may be mounted on the wing 100 or on the vessel 1000. The apparent wind may therefore be measured at or near the wing 100, e.g. upstream or downstream of the leading wing of a vessel equipped with a wing.

[0064] A method is proposed that makes it possible to control the wing's angle of incidence A1 relative to the apparent wind direction V1, thereby optimizing the lift of the wing 100 and thus the efficiency of the system 1, i.e., ensuring maximum lift with reduced risk of stall.

[0065] Apparent wind measurements The apparent wind direction V1 is measured using a device 15 for measuring wind direction, for example a wind vane positioned on the wing. Alternatively and / or additionally, the measurement may be carried out using a wind vane located on the part of the vessel on which the wing is provided.

[0066] The apparent wind direction serves as a reference for controlling the blade incidence angle A1 relative to the apparent wind direction V1.

[0067] According to one embodiment, the apparent wind speed (or wind force) is also measured by a device 16 for measuring wind speed, for example using an anemometer, which device 16 is preferably located in the same area or nearby as the wind direction device.

[0068] Measuring wind speed is useful because it can affect the aerodynamic performance of a wind-assisted propeller in various ways. Atmospheric stability can make wind direction changes more or less noticeable, more or less abrupt. Air stability can also affect the early onset of stall more or less.

[0069] Measurement of parameters indicative of the stall state of an airfoil. The wind-assisted propulsion system 1 comprises a device for measuring a parameter related to the state of the airflow F1 entering the blade at a suction opening 11 in fluid communication with a suction device, said parameter being in particular a parameter representative of the stall state of the blade, in particular the state of separation of the airflow entering the blade upstream of the suction opening 11, by means of which an airflow F2 is moved inside the hollow body 10 of the blade by the suction device.

[0070] According to a preferred embodiment, the measured parameter is the internal pressure of the hollow body, in particular the internal pressure of the hollow body in the air flow F2 driven by the suction device 13, and the measured pressure is preferably the pressure of the internal flow F2 between the suction opening 11 and the suction device 13.

[0071] The air flow F2 is considered to originate from said suction opening 11 (upstream of the fan) and this air flow emerges downstream of the suction device 13 by means of an outlet which may be provided in the hollow body 10 if the suction device 13 is located inside the hollow body, or by means of an outlet from the suction device 13 if the suction device 13 is located outside the hollow body but is of course in fluid communication with the hollow body.

[0072] According to a preferred embodiment, the device for measuring a parameter related to the state of the incoming air flow F1 comprises a pressure sensor system 14 configured to measure the pressure of the flow F2 inside the hollow body between the suction opening 11 and the fan 13. The pressure sensor system may comprise one or more sensors.

[0073] According to a particular embodiment, the pressure sensor system 14 includes a differential pressure sensor type sensor. As shown schematically in FIG. 1 , the sensor includes a pressure tap P141 inside the hollow body 10. The sensor may be housed inside the hollow body 10, or, as in FIG. 1 , it may be external to the hollow body 10 but in fluid communication with it. For example, the sensor may be housed under a cover in the fairing 110, with the pressure tap P141 exiting into the hollow body to measure the internal pressure of the hollow body through which the airflow F2 driven by the fan circulates. The differential pressure sensor has another pressure tap P14ref that serves as a reference. The reference pressure tap P14ref is located in an area without airflow, for example, in the gap defined between the forward fairing 110 and the hollow body 10, and measures atmospheric pressure (static pressure inside the fairing). Alternatively, the reference pressure tap may be located at any other location in the system away from flows F1 and F2 where the flow velocity is zero.

[0074] In the following, the case will be described where the device for measuring a parameter related to the state of the airflow F1 entering the blade is an internal pressure measuring device capable of measuring the pressure of the internal flow F2 inside the hollow body 10. As will be explained below, measuring this internal pressure and in particular its variation as a function of the angle of incidence of the blade makes it possible to reliably determine the separation state of the airflow F1 entering the blade and therefore the stall state of the blade as a function of the angle of incidence of the blade. However, this description can also be applied to other embodiments that remain less advantageous than a pressure sensor measuring the internal pressure of the hollow body into which the flow F2 is aspirated, and the device for measuring a parameter related to the state of the airflow F1 entering the blade can be a wall pressure sensor positioned on the blade in the flow F1, or an electronic display (i.e. a flexible strip assigned to electronic processing means), or a device for analyzing the operating parameters of the fan, such as its strength, power consumption and / or rotational speed.

[0075] Drive unit The device comprises a drive unit 180, which in turn comprises a module 181 for controlling the rotation and recording the corresponding pressure. The module 181 is configured to control the rotation of the wing 100 about a vertical rotation axis PIV1, which may coincide with the central axis A10 of the hollow body 10, within a given angular range, thereby allowing the (horizontal) axis D100 of the orientation of the wing 100 to take on different values ​​of the angle of incidence A1 relative to the apparent wind direction V1, and controls the recording of measured values ​​of the internal pressure of the hollow body during the rotational displacement of the wing 100 depending on the angle of incidence A1 of the wing 100.

[0076] The drive unit 180 also includes a stall determination module 182 configured to determine an incidence angle value A1D_t2 of the airfoil 100 corresponding to a stall, referred to as a stall angle value. The module 182 is configured to detect when a pressure-related parameter, such as the inverse of the pressure coefficient (-Cp), passes above or below a threshold value (depending on the parameter used). Note that an increase in the internal pressure of the hollow body 10 in the flow F2 above the threshold value corresponds to a separation of the airflow F1 around the airfoil at the suction opening 11. In particular, in the non-stalled state of the airfoil receiving the incoming airflow, the internal pressure of the hollow body 10 in the flow F2 is negative. If the flow F1 subsequently separates upstream of the suction opening 11, the internal pressure of the hollow body 10 in the flow F2 increases, and the parameter -Cp decreases.

[0077] The pressure coefficient Cp is calculated according to the measured apparent wind speed Vv1. The pressure coefficient Cp is calculated using the formula Cp=P_i / (1 / 2ρVv1 2 ) where P_i is the internal pressure measured inside the hollow body by the pressure sensor and ρ is the density of air.

[0078] Note that the lift of the wing is related to the pressure coefficient itself, calculated from the measured internal pressure.

[0079] An example of the evolution of the reciprocal of the pressure coefficient -Cp is proposed in FIG. 6 as a function of the angle of incidence A1 of the blade measured during said pivotal displacement of the blade.

[0080] It may therefore be provided that the module determines the angle of incidence value A1D_t2 of the wing 100 corresponding to the stall as the angle of incidence of the wing at which the value of -Cp passes below a given threshold and / or the angle of incidence of the wing having a damping slope greater than a given threshold.

[0081] The drive unit 180 also comprises a safety module 183 configured to determine a safety angle of incidence A1SD1_t2 of the wing depending on the stall angle value A1D_t2, the safety angle of incidence being lower in absolute value than the stall angle value. The safety angle of incidence may correspond to the determined stall angle value minus a given value, called an interval value, as described below. Using a safety angle of incidence that is lower in absolute value than the actually measured stall angle makes it possible to keep the maximum angle of incidence of the wing away from the stall angle, thereby limiting the risk of unintended stall.

[0082] The drive unit 180 also comprises a module 184 for controlling the orientation of the blades, which makes it possible to control the orientation of the blades via the power system 18 according to the desired lift. The module 184 for controlling the orientation of the blades therefore makes it possible to control the orientation of the blades at an incidence angle setpoint equal to the incidence angle safety value A1SD1_t2, thereby safely achieving the maximum lift. The module 184 for controlling the orientation of the blades also makes it possible to control the orientation of the blades at an incidence angle setpoint lower than the incidence angle safety value A1SD1_t2, in particular comprised between 0° and A1SD1_t2, in certain situations where a lower lift is desired, such as for example slowing down or stopping the vessel.

[0083] Interval Value According to one embodiment, the incident angle safety value A1SD1_t2 is calculated by the formula ||A1SD1_t2||=||A1D_t2||-a s is calculated according to the formula: s is a strictly positive value called the interval value.

[0084] Interval value a s may be a predetermined value including a value between 2° and 8°, for example 3°.

[0085] According to one embodiment, the interval value a s is defined as a function of the parameters of the environment of the device, for example the apparent wind speed.

[0086] Updated safe angle of incidence After a first implementation cycle of the steps enabling obtaining a first stall angle value and a first incidence angle safety value, the drive unit 180 is configured to repeat the steps in a second implementation cycle, thereby obtaining a second stall angle value and a second incidence angle safety value for updating the incidence angle safety value. It will be understood that the obtained second incidence angle safety value corresponding to the update of the incidence angle safety value may be greater or less than the first incidence angle safety value.

[0087] It may be provided that for at least one or each cycle (implementation process), the wings are displaced until a stall is detected (i.e., until the displacement is stopped when a stall is detected). Alternatively or in combination, it may be provided that the angular sector in which the wings are pivotally displaced extends on either side of the stall angle value obtained during the previous implementation process.

[0088] Repeating the steps allows the incidence angle safety value to be updated by replacing the old determined value of the set point controlling the orientation of the blades with a new value.

[0089] It may be provided that the steps are repeated periodically to obtain a stall angle measurement and thus an appropriate incidence angle safety set point depending on the navigation situation, and that the repetition of the steps is triggered depending on one or more environmental parameters, such as wind direction and / or wind speed, weather conditions, or device operation, such as fan rotation speed.

[0090] It may be provided that the determined second stall angle value and the resulting incidence angle safety value automatically replace the previous values. Alternatively, it may be provided that one second value of the determined second values ​​is compared with the corresponding first value, and if the difference between the compared values ​​is greater than a threshold, one or more of the determined values ​​is updated.

[0091] The blade incidence angle may therefore be adjusted, if conditions permit, to maximize the propulsive force transmitted to the vessel by the wind-assisted propulsion system, or to reduce or minimize the effect of the wind on the vessel, if desired.

[0092] The adjustment of the blade incidence angle may be driven by the drive unit either in an open loop or in a closed loop. In an open loop, the setpoint transferred to the operating parameter is explicitly calculated from available information and the actual state of the quantity assigned to the setpoint is not compared to this setpoint. In a closed loop, the quantity assigned to the setpoint is measured. The difference between the current value of this quantity and the setpoint is taken into account, thereby modifying the operation of the adjustment system.

[0093] method The wind-assisted propulsion system described above allows for the implementation of a method for controlling the wing incidence angle A1, thereby optimizing lift while limiting the risk of unintended stall. One embodiment of such a method is proposed below in connection with Figure 7.

[0094] The suction device 13 operates such that an air flow F2 circulates through the hollow body from the suction opening 11. In particular, a drive unit may be provided which controls the rotation of the fan at a given speed.

[0095] In step 710, the apparent wind direction V1 is measured using the measuring device 15. Advantageously, the wind speed is also measured using the measuring device 16.

[0096] 2, the incidence angle A1 of the wing 100 is within the allowed incidence angle sector SF1, which has a maximum value (in absolute value) of A1SD1_t1. The prohibited complementary sector is labeled SD1.

[0097] In step 720, the drive unit 180 controls the pivotal displacement of the wing 100 about its vertical pivot axis PIV1, allowing the chord line D100 of the wing profile to assume different values ​​of the incidence angle A1 relative to the apparent wind direction V1. The drive unit controls the recording of the internal pressure values ​​measured by the sensor 14 as a function of the incidence angle value A1 assumed by the wing during the pivotal displacement of the wing 100. The wing is displaced over a range of angles suitable for stall to occur.

[0098] In step 730, from the internal pressure measurements measured by the sensor 14, the drive unit determines the blade incidence angle value A1D_t2 corresponding to the stall, called the stall angle value. This blade incidence angle value A1D_t2 is shown in Figure 3 together with the flow separation marked with reference DF1. Using the recorded pressure measurements, it is possible to calculate the value of a parameter, for example the reciprocal of the pressure coefficient (-Cp), as a function of the measured incidence angle, as shown in Figure 6, and thus to determine the corresponding stall angle by analyzing the evolution of this parameter as a function of the incidence angle A1.

[0099] In step 740, the driving unit determines the wing incidence angle safety value A1SD1_t2 according to the stall angle value A1D_t2, and the incidence angle safety value A1SD1_t2 is lower than the stall angle value. Thus, the allowable incidence angle sector is updated, and a sector SF1' is obtained, as shown in Figure 4, where the sector SF1' may decrease compared with the previous allowable sector, but the updated prohibited sector SD1' is increased.

[0100] In step 750, the drive unit controls the orientation of the blade at an incidence angle setpoint equal to or lower than the incidence angle safety value A1SD1_t2, as shown in FIG.

[0101] In step 760, the previous steps are repeated to obtain a new incidence angle safety value, in other words, the incidence angle safety value corresponding to the maximum allowable incidence angle in absolute value is updated, thus replacing the old incidence angle safety value determined to generate the set point that controls the orientation of the blades.

[0102] After performing steps 710-750, also referred to as steps a)-e), the stall angle value and the incidence angle safety value are provided, preferably in real time and at a given frequency, for example 10 Hz: - determining the angular position at which the blade 100 is located, corresponding to a value of the angle of incidence A1 of the blade 100, and measuring said parameter representative of the separation of the airflow F1 incident on the blade; determining, by the drive unit 180, the stalled or non-stalled state of the wing depending on said measured parameters representative of the separation state of the airflow F1 incident on the wing; may be performed.

[0103] If a stall condition is detected, steps 710 to 750 are repeated with additional execution processes, or the drive unit 180 assigns the determined incidence angle A1 value of the wing 100 (the incidence angle A1 value taken into account during the measurement that makes it possible to detect the stall condition) to a stall angle value, and then the drive unit 180 determines an incidence angle safety value of the wing according to the stall angle value, where the incidence angle safety value is lower in absolute value than the stall angle value. The drive unit 180 can then control the orientation of the wing at an incidence angle setting value equal to the incidence angle safety value.

[0104] If no stall is detected, the drive unit may be configured to wait for the next iteration of steps 710 to 750. Step 720 of the implementation process may provide that the angular sectors in which the wings are displaced and / or the wings are pivotally displaced extend from either side of the stall angle value obtained during the previous implementation process until a stall is detected.

[0105] Thus, the incidence angle safety value may be temporarily or continuously modified depending on the conditions encountered, thereby improving the performance of the system.

[0106] In case of an unintended stall, i.e. outside the learning phase, it may be provided that the system reduces the incidence until the flow is restored and thus the aerodynamic performance of the profile is restored or to an even lower incidence value, and then restarts the learning process to control the orientation of the wing according to the set incidence angle corresponding to the new value of the maximum allowable incidence angle. Alternatively, it may be provided that the observed stall value is used in the same way as in step 730, i.e. the cycle is restarted in step 740 using the stall angle value observed as a result of step 730, thus not necessarily restarting the full learning cycle.

[0107] The drive unit is, for example, in the form of a processor and a data memory in which computer instructions executable by said processor are stored, or even in the form of a microcontroller.

[0108] In other words, the described functions and steps may be implemented in the form of a computer program or via hardware components (e.g., programmable gate arrays). In particular, the functions and steps operated by the drive unit or its modules may be performed by an instruction set or computer module implemented in a processor or controller, or may be performed by dedicated electronic components or programmable logic circuit type components (or FPGA) or application specific integrated circuit type components (or ASIC). A combination of computer and electronic components is also possible.

[0109] The drive unit is therefore an electronic and / or computer unit. If it is specified that said unit is configured to perform a given operation, this means that the unit comprises computer instructions and corresponding implementation means that allow said operation to be performed and / or that the unit comprises corresponding electronic components.

[0110] Other Aspects It may be provided that the system 1 comprises a tilting mechanism making it possible to tilt the wing and possibly the support of the wing about a horizontal axis.

[0111] The tilting system allows the wing, and possibly the wing support, to be displaced between an upright position in which the wing extends perpendicular to the vessel deck when the system is mounted on the vessel deck, and a tilted position in which the wing extends substantially parallel to the vessel deck when the system is mounted on the vessel deck.

[0112] When the wing extends vertically and pivots about an axis substantially parallel to the axis of the wing, i.e. when the wing is operating in its vertical position, the support remains stationary relative to the deck of the ship, except for possible tilting movement of the support about an axis perpendicular to the axis of the wing.

[0113] In general, the system may be provided to adopt all or some of the features of the lift generating system described in international application PCT / FR2022 / 050268 and published in WO 2022 / 175622, or of the system described in patent application EP 17165662 and published in EP 3235719, by adding the above-mentioned additional elements, such as in particular the above-mentioned pressure measuring device and drive unit.

[0114] The invention is not limited to the embodiments shown in the drawings.

[0115] Furthermore, the term "comprising" does not exclude other elements or steps. Furthermore, features or steps described with reference to one of the above-disclosed embodiments may also be used in combination with other features or steps of other above-disclosed embodiments.

Claims

1. 1. A method for controlling the angle of incidence (A1) of a lift-generating device, called an aerofoil (100), of a wind-assisted propulsion system (1) with respect to an apparent wind direction (V1), said aerofoil comprising a hollow body (10), said aerofoil (100) being located in an outer airflow (F1) incident on said aerofoil, The wind-assisted propulsion system (1) comprises: a suction device (13) in fluid communication with said hollow body (10); at least one suction opening (11) in the peripheral wall of the hollow body (10) receiving the external airflow (F1) incident on the blade, the suction device (13) generating an airflow (F2) from the at least one suction opening (11) into the interior of the hollow body (10); - a device for measuring a parameter representative of the separation of said airflow (F1) incident on said wing; a power system (18) for pivoting said blade (100) about a vertical pivot axis (PIV1) parallel to the longitudinal axis (A10) of said hollow body (10); - a drive unit (180) and A method comprising: a) measuring (710) the direction of the apparent wind (V1) by means of a device (15) for measuring the direction of the apparent wind; b) a step (720) of rotating the wing (100) about the vertical pivot axis (PIV1) by the power system (18) for rotating the wing (100) so that the chord line (D100) of the profile of the wing (100) can take different values ​​for the angle of incidence (A1) with respect to the wind direction (V1) of the apparent wind; c) measuring (730) during the pivotal displacement of the wing (100) by the device for measuring the parameter representative of the separation state, depending on the value of the angle of incidence (A1) of the wing (100), the parameter representative of the separation state of the airflow (F1) incident on the wing (100), and determining by the drive unit (180) from the measured value of the parameter representative of the separation state of the airflow (F1) incident on the wing (100) an angle of incidence value (A1D_t2) of the wing (100) corresponding to a stall, called a stall angle value; d) determining (740) by the drive unit (180) a safety angle of incidence value (A1SD1_t2) of the blade depending on the stall angle value (A1D_t2), the safety angle of incidence being lower than the stall angle value in absolute value; e) controlling (750) the orientation of the blades by the drive unit (180) at an incidence angle set value equal to the incidence angle safety value (A1SD1_t2); A method comprising:

2. 2. The method of claim 1, wherein after a first implementation process of steps a) through e) that provides a first stall angle value and a first incidence angle safety value, steps a) through e) are repeated (760) in a second implementation process to obtain a second stall angle value and a second incidence angle safety value that corresponds to an update of the incidence angle safety value.

3. 3. The method of claim 2, wherein the wing (100) is displaced until a stall is detected and / or the angular sector in which the wing (100) is pivotally displaced in step b) of the second implementation process spans both sides of the stall angle value obtained during the first implementation process.

4. After said first implementation process of steps a) to e) providing a first stall angle value and a first incidence angle safety value, The method is preferably carried out at a given frequency, for example 10 Hz. - determining the angular position at which said blade (100) is located corresponding to said value of the angle of incidence (A1) of said blade (100) and measuring said parameter representative of the separation of said airflow (F1) incident on said blade; - determining (730) by said drive unit (180) the stalled or non-stalled state of said wing depending on said measured parameters representative of said separation state of said airflow (F1) incident on said wing; If a stall condition is detected, - repeating steps a) to e) in a second implementation process (760), or - assigning, by the drive unit (180), the determined incidence angle (A1) value of the blade (100) to the stall angle value, and determining, by the drive unit (180), the safety incidence angle value of the blade depending on the stall angle value, the safety incidence angle value being lower in absolute value than the stall angle value; controlling, by the drive unit (180), the orientation of the blades at the incidence angle set point equal to the incidence angle safety value; 4. The method of claim 1, comprising:

5. 5. The method according to claim 1, wherein the device for measuring a parameter representative of the separation state of the air flow (F1) incident on the wing comprises a pressure sensor system (14) configured to measure the pressure in the air flow (F2) inside the hollow body.

6. 6. The method according to claim 5, wherein the pressure sensor system (14) is configured to measure the pressure in the air flow (F2) inside the hollow body between the at least one suction opening (11) and the suction device (13).

7. 7. The method according to claim 5 or 6, wherein the pressure sensor system (14) comprises a sensor of the differential pressure sensor type, the differential pressure sensor comprising a pressure tap (P141) located inside the hollow body.

8. The method of claim 7, wherein the wing (100) comprises a fairing (110) coupled to the peripheral wall of the hollow body (10), and the differential pressure sensor comprises a reference pressure tap (P14ref) located in the fairing (110).

9. The incident angle safety value is expressed as A1SD1_t2, and is expressed by the formula ||A1SD1_t2||=||A1D_t2||-a ｓ where a ｓ 9. The method of claim 1, wherein A1D_t2 is a strictly positive value called an interval value, and A1D_t2 is the stall angle value.

10. The method of claim 9 , wherein the interval value is a predetermined value.

11. The method of claim 9 , wherein the spacing value is a function of the apparent wind speed.

12. 12. The method according to claim 1, wherein the stall angle value (A1D_t2) is determined as an incidence angle value at which the parameter representative of the separation state of the airflow (F1) entering the wing exceeds a threshold value and / or has a gradient value exceeding a threshold value.

13. 13. The method according to any one of claims 1 to 12, wherein the direction (V1) of the apparent wind is measured using a wind vane positioned on the wing.

14. 14. The method according to claim 1, wherein the device for measuring a parameter representative of the separation state of the air flow (F1) incident on the airfoil comprises a wall pressure sensor positioned on the airfoil in the incident air flow (F1) upstream of the at least one suction opening (11).

15. 15. Method according to any one of claims 1 to 14, characterized in that the device for measuring a parameter representative of the separation state of the air flow (F1) incident on the wing comprises a flexible strip assigned to electronic processing means called an electronic indicator positioned on the wing in the incident air flow (F1) upstream of the at least one suction opening (11).

16. 16. The method according to any one of claims 1 to 15, wherein the device for measuring a parameter representative of the separation state of the air flow (F1) incident on the airfoil comprises a device for analyzing operating parameters of the suction device (13).

17. A wind-assisted propulsion system (1), comprising: a lift-generating device called an aerofoil (100), said aerofoil comprising a hollow body (10), said aerofoil (100) intended to be located in an external airflow (F1) incident on said aerofoil; a suction device (13) in fluid communication with said hollow body (10); at least one suction opening (11) in the peripheral wall of the hollow body (10) capable of receiving the external airflow (F1) incident on the wing, the suction device (13) being configured to generate an airflow (F2) from the at least one suction opening (11) into the interior of the hollow body (10); - a device for measuring a parameter representative of the separation of said airflow (F1) incident on said wing; a power system (18) for rotating said blade (100) about a rotation axis (PIV1) parallel to the longitudinal axis (A10) of said hollow body (10); a drive unit (180) adapted to implement the steps of the method according to any one of claims 1 to 16 for controlling the angle of incidence (A1) of the blade with respect to the apparent wind direction (V1); A wind-assisted propulsion system (1) comprising:

18. 18. A watercraft comprising a wind-assisted propulsion system according to claim 17, wherein the wind-assisted propulsion system is mounted on a deck of the watercraft.

Images