Wind-assisted propulsion system and boat provided with such a system

Abstract

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

Description

[0001] Description

[0002] Title of the invention: WIND PROPULSION SYSTEM AND BOAT PROVIDED WITH SUCH A SYSTEM

[0003] [1] FIELD OF THE INVENTION

[0004] [2] The present invention relates generally to wind propulsion systems for boats, also called wind thrusters.

[0005] [3] PRIOR ART

[0006] [4] Known from the state of the art, and in particular from document FR2503286A2, are wind thrusters which comprise an elongated hollow body, suction zones arranged along the peripheral wall of the hollow body and suction means for generating an air flow inside the hollow body. The suction at the peripheral wall of the thruster makes it possible to limit the separation of the air flow from the wall of the thruster.

[0007] [5] A lifting profile, also called a wing, makes it possible to generate lift, in the aerodynamic sense, that is to say a force perpendicular to the direction of the flow in which the wing is placed, which makes it possible to create a wind propulsion system for a ship, such as a cargo ship.

[0008] [6] For a given wing configuration, the lift generated is mainly dependent on the wing's angle of incidence, i.e. the angle between the chord line of the wing profile and the direction of the incident airflow. For a wind propulsion system mounted on a boat, the incident airflow on the wing is the apparent wind perceived by the wing, which is the resultant of the wind perceived by an observer present on the boat and stationary relative to the boat, and the wind created by the movement (speed) of the boat.

[0009] [7] Lift increases regularly with the angle of incidence up to a maximum value. Beyond this point of maximum lift, lift decreases more or less abruptly, which corresponds to stalling. [8] Prior to using the wing, it is possible to estimate the angle of incidence from which stalling is likely to occur, i.e. the stall angle, based on the shape (profile) of the wing, in order to define a range of authorized angles of incidence for the wing pivot control. However, the estimation of the stall angle remains unreliable, variable according to environmental conditions, and it is then necessary to define a significant safety margin between the maximum authorized angle of incidence and the estimated stall angle so that the wing does not suffer an untimely stall.

[0010] [9] Document US4582013 A describes a machine for harvesting wind energy that uses a self-adjusting aerodynamic blade, and an aerodynamic roller. Sensors monitor operating conditions.

[0011]

[0010] Document WO2014085835 A describes a wing of variable shape, movable in increments between a neutral configuration and a deformed configuration. The wing takes a curved camber airfoil section shape in the deformed configuration.

[0012]

[0011] The aim of the present invention is to propose a new wind propulsion system and a corresponding method making it possible to overcome all or part of the problems set out above.

[0013]

[0012] SUMMARY OF THE INVENTION

[0014]

[0013] To this end, the invention relates to a method for controlling the angle of incidence of a lift-generating device, called a wing, of a wind propulsion system relative to the apparent wind direction, the wing comprising a hollow body, the wing being located in an external air flow incident on the wing; the wind propulsion system comprising:

[0015] - a suction device in fluid communication with the hollow body;

[0016] - at least one suction opening provided in a peripheral wall of the hollow body subjected to said flow of external air incident on the wing, the suction device generating a flow of air inside the hollow body from said at least one suction opening;

[0017] - a device for measuring a parameter representative of the state of separation of the air flow incident on the wing; - a motorized system for driving the wing to pivot around a vertical pivot axis parallel to the longitudinal axis of the hollow body;

[0018] - a piloting unit; characterized in that the method comprises the following steps: a) measuring the apparent wind direction by an apparent wind direction measuring device; b) pivoting movement of the wing about the vertical pivot axis by the motorized wing pivoting drive system, to allow the chord line of the wing profile to take different values ​​of angle of incidence relative to the apparent wind direction, and, c) during the pivoting movement of the wing, measuring, by said device for measuring a parameter representative of the separation state, said parameter representative of the separation state of the air flow incident on the wing as a function of the value of the angle of incidence of the wing;and, from the measurement of said parameter representative of the state of separation of the incident airflow on the wing, determination by the control unit of a value of angle of incidence of the wing corresponding to a stall, called stall angle value; d) determination by the control unit of a safety value of angle of incidence of the wing, as a function of said stall angle value, the safety value of angle of incidence of the wing being, in absolute value, less than said stall angle value; e) control by the control unit of the orientation of the wing with an angle of incidence setpoint equal to the safety value of angle of incidence.;

[0019]

[0014] Such a design of the wind propulsion system makes it possible to reliably detect the stall angle and to reduce the safety margin between the maximum permitted angle of incidence and the stall angle in order to be able to benefit from a lift force close to the maximum lift force, while limiting the risk of stalling.

[0020]

[0015] The pilot unit can define the maximum permitted angle of incidence as a function of this measured stall angle, as being equal to the value of this stall angle (in absolute value) reduced by a safety value which is smaller than that which would have to be used if the stall angle were simply estimated as a function of the shape of the wing. The system can then provide a lift force closer to the maximum lift force thanks to the measurement of the stall angle which makes it possible to adapt the permitted angle of incidence range to the measured stall angle in order to be able to approach the stall angle in order to benefit from significant lift, while limiting the risk of untimely stalling.

[0021]

[0016] Measuring or learning the stall angle thus makes it possible to adjust the position and extent of the wing's incidence operating zone as a function of the stability of the operational conditions. Measuring or learning the stall angle, and not simply estimating it, also makes it possible to reduce the angle of incidence when it turns out that a premature stall of the wing has occurred.

[0022]

[0017] The system can thus maximize over time the propulsive forces generated on the ship, because the measurement of the stall angle allows it to update the stall angle value to be taken into account and to use an appropriate safety margin between the maximum authorized angle of incidence and the measured stall angle, which allows the wing to best approach the point of maximum lift while avoiding stalling. The efficiency of the system is thus improved since the aerodynamic operating point which maximizes the propulsive force is frequently the point of maximum lift.

[0023]

[0018] The wind propulsion system is thus configured to detect the stall of the wing, and to use the corresponding measured stall angle to reliably and efficiently define a maximum permissible angle of incidence making it possible to improve the operating efficiency of the system by making it possible to achieve high lift values ​​while reducing the risk of untimely stall. Taking the stall angle into account makes it possible to effectively control the piloting of the system.

[0024]

[0019] The measurement of the apparent wind angle is preferably carried out in the vicinity of the system. The apparent wind direction sensor may be attached to the system, such as a weather vane located above the system.

[0025]

[0020] The wind propulsion system and the corresponding method thus make it possible to correct or avoid an estimation, by definition approximate, of the theoretical stall angle, by actually testing the stall angle or by taking into account a stall experienced at a given angle to determine the actual stall angle.

[0026]

[0021] In other words, the control method and the corresponding system thus make it possible to pivotally move the wing in order to measure the state of air separation during the pivoting of the wing and to determine precisely and reliably the actual stall angle from the measurements taken, and thus reduce the safety margin between the maximum permitted angle of incidence and the stall angle.

[0027]

[0022] Conversely, in the state of the art, only an estimation of the angle at which the stall is likely to occur is carried out, and this prior to the use of the wing. However, the estimation of the angle likely to stall remains unreliable, variable depending on the environmental conditions, and it is then necessary to define a significant safety margin between the maximum authorized angle of incidence and the estimated stall angle so that the wing does not suffer an untimely stall.

[0028]

[0023] Thanks to the control method and the corresponding system according to the invention, the user (navigator) does not need to intervene himself in the adjustment of the wind thruster. It should be noted that in the state of the art, the user does not have as such the data which would make it possible to judge the stall on a wind thruster, in particular when it equips a cargo ship.

[0029]

[0024] The system may also include one or more of the following features taken in any technically admissible combination.

[0030]

[0025] According to one embodiment, after a first process of executing steps a) to e) providing a first stall angle value and a first angle of incidence safety value, steps a) to e) are repeated in a second execution process so as to obtain a second stall angle value and a second angle of incidence safety value corresponding to an update of the angle of incidence safety value. According to a particular aspect, the angular sector in which the wing is pivotally displaced extends on either side of the stall angle value obtained during the first execution process.

[0026] According to one embodiment, in step b) of the second execution process, the wing is moved until a stall is detected and / or the angular sector in which the wing is pivotally moved extends on either side of the stall angle value obtained during the first execution process. The pivotal movement of the wing is preferably carried out so as to reach or exceed (i.e. pass through) the angle previously determined as being the stall angle.

[0031]

[0027] According to one embodiment, after the first process of performing steps a) to e) providing a first stall angle value and a first angle of incidence safety value, the method comprises the following steps preferably performed at a given frequency, for example 10 Hz:

[0032] - determination of the angular position where the wing is located, to which corresponds a value of angle of incidence of the wing, and measurement of said parameter representative of the state of separation of the air flow incident on the wing; and,

[0033] - determination by the control unit of the state of stall or not of the wing as a function of said measured parameter representative of the state of separation of the air flow incident on the wing; and, in the event of detection of a state of stall:

[0034] - either steps a) to e) are repeated in a second execution process;

[0035] - either, assignment to the stall angle value, by the control unit, of said determined wing angle of incidence value; determination by the control unit of a wing angle of incidence safety value as a function of said stall angle value, the angle of incidence safety value being, in absolute value, less than said stall angle value; control by the control unit of the orientation of the wing with an angle of incidence setpoint equal to the angle of incidence safety value.

[0036]

[0028] According to one embodiment, the device for measuring a parameter representative of the state of separation of the air flow incident on the wing comprises a pressure sensor system configured to measure the pressure in the air flow inside the hollow body.

[0029] 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.

[0037]

[0030] According to one embodiment, the pressure sensor system comprises a differential pressure sensor type sensor, the differential pressure sensor comprising a pressure tap which is located inside the hollow body.

[0038]

[0031] According to one embodiment, the wing comprising a fairing coupled to the peripheral wall of the hollow body, the differential pressure sensor comprises a reference pressure tap which is located in the fairing.

[0039]

[0032] According to one embodiment, the angle of incidence safety value, denoted A1SD1_t2, is calculated according to the formula:

[0040] Il A1SD1J2 II = Il A1 DJ2 II - as with as a value, called the spacing value, strictly positive, and A1 D_t2 being the stall angle value.

[0041]

[0033] According to one embodiment, said spacing value is a predefined value.

[0042]

[0034] According to one embodiment, said spacing value is a function of the apparent wind speed.

[0043]

[0035] According to one embodiment, said stall angle value is determined as being the angle of incidence value for which the parameter representative of the separation state of an air flow incident on the wing crosses a threshold value and / or has a slope value which crosses a threshold value.

[0044]

[0036] According to one embodiment, the apparent wind direction is measured using a weather vane positioned on the wing.

[0045]

[0037] According to one embodiment, the device for measuring a parameter representative of the state of separation of the air flow incident on the wing comprises a parietal pressure sensor, positioned on the wing in the incident air flow upstream of said at least one suction opening.

[0038] According to one embodiment, the device for measuring a parameter representative of the state of separation of the air flow incident on the wing comprises a flexible strip associated with electronic processing means, called an electronic pennon, positioned on the wing in the incident air flow upstream of said at least one suction opening.

[0046]

[0039] According to one embodiment, the device for measuring a parameter representative of the state of separation of the incident air flow on the wing comprises a device for analyzing operating parameter(s) of the suction device.

[0047]

[0040] The invention also relates to a wind propulsion system comprising:

[0048] - a lift-generating device, called a wing, the wing comprising a hollow body, the wing being intended to be located in an external air flow incident on the wing;

[0049] - a suction device in fluid communication with the hollow body;

[0050] - at least one suction opening provided in a peripheral wall of the hollow body capable of being subjected to said flow of external air incident on the wing, the suction device being configured to generate an air flow inside the hollow body from said at least one suction opening;

[0051] - a device for measuring a parameter representative of the state of separation of the incident air flow on the wing;

[0052] - a motorized system for driving the wing to pivot around a pivot axis parallel to the longitudinal axis of the hollow body;

[0053] - a control unit configured to perform the steps of a method for controlling the angle of incidence of the wing relative to the apparent wind direction, the method being in accordance with any one of the preceding embodiments.

[0054]

[0041] The invention also relates to a boat equipped with the wind propulsion system, the wind propulsion system being mounted on the deck of the boat.

[0055]

[0042] According to a preferred embodiment, the parameter relating to the state of the air flow which is measured is the pressure inside the hollow body. The pressure inside the hollow body in the air flow generated by the suction device and coming from the suction opening makes it possible to reliably detect an increase in internal pressure above a threshold value and / or according to a growth slope greater than a threshold value, which is characteristic of a state of separation of the air flow around the wing upstream of the suction zone on the peripheral wall, i.e. of a stall of the wing. It may be provided that the angle of incidence for which this pressure rises above a threshold value and / or has a growth slope greater than a threshold value is defined as being the stall angle.

[0056]

[0043] The invention also relates to a method for controlling the angle of incidence of a lift-generating device, called a wing, of a wind propulsion system relative to the apparent wind direction, the wing comprising a hollow body, the wing being located in an external air flow incident on the wing; the wind propulsion system comprising:

[0057] - a suction device in fluid communication with the hollow body;

[0058] - at least one suction opening provided in a peripheral wall of the hollow body subjected to said flow of external air incident on the wing, the suction device generating a flow of air inside the hollow body from said at least one suction opening;

[0059] - a device for measuring a parameter representative of the state of separation of the air flow incident on the wing; characterized in that the method comprises the following steps: a) measuring the direction of the apparent wind; b) pivoting movement of the wing around a vertical pivot axis, to allow the chord line of the wing profile to take different values ​​of angle of incidence relative to the direction of the apparent wind, and, c) during the pivoting movement of the wing, measuring said parameter representative of the state of separation of the air flow incident on the wing as a function of the value of angle of incidence of the wing; and, from the measurement of said parameter representative of the state of separation of the air flow incident on the wing, determining a value of angle of incidence of the wing corresponding to a stall, called stall angle value;d) determining a safety value of the angle of incidence of the wing, as a function of said stall angle value, the safety value of the angle of incidence of the wing being, in absolute value, less than said stall angle value; e) controlling the orientation of the wing with an angle of incidence setpoint equal to the safety value of the angle of incidence.;

[0060]

[0044] BRIEF DESCRIPTION OF THE DRAWINGS

[0061]

[0045] Other characteristics and advantages of the invention will emerge from the following description, which is purely illustrative and non-limiting and must be read in conjunction with the appended drawings, in which:

[0062]

[0046] - [Fig. 1] Figure 1 is a schematic cross-sectional view of a wind propulsion system according to one embodiment of the invention, the system being mounted on the deck of a boat;

[0063]

[0047] - [Fig. 2] Figure 2 is a schematic view of the wing of the system of Figure 1, with a representation of an authorized angular range of incidence, defined as a function of a first measured value of stall angle, the wing having an angle of incidence contained in the authorized angle range, and the wing not being subject to a stall;

[0064]

[0048] - [Fig. 3] Figure 3 is a schematic view of the wing of Figure 2 which has an angle of incidence, greater than that of Figure 2, for which a stall is detected while the angle of incidence is still within the authorized range;

[0065]

[0049] - [Fig. 4] Figure 4 is a schematic view of the wing of Figure 3 after redefinition (update) of the permitted angle of incidence range, as a function of a new stall angle value corresponding to the angle of incidence of Figure 3 for which the stall was detected;

[0066]

[0050] - [Fig. 5] Figure 5 is a schematic view of the wing of Figure 4 which has an angle of incidence included in the new permitted angle of incidence range;

[0067]

[0051] - [Fig. 6] Figure 6 is a curve giving the opposite of the pressure coefficient (-Cp) as a function of the angle of incidence measured during the pivoting movement of the wing to determine the actual stall angle;

[0052] - [Fig. 7] Figure 7 is a flowchart comprising steps of a method for controlling the incidence of the wing of a wind propulsion system according to an embodiment of the invention.

[0068]

[0053] DETAILED DESCRIPTION

[0069]

[0054] The inventive concept is described more fully below with reference to the accompanying drawings, in which embodiments of the inventive concept are shown. In the drawings, the size and relative sizes of elements may be exaggerated for clarity. Like numerals refer to like elements throughout the drawings. However, this inventive concept may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Instead, these embodiments are provided so that this description is complete, and communicates the scope of the inventive concept to those skilled in the art.

[0070]

[0055] A reference throughout the specification to "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the occurrence of the phrase "in an embodiment" at various locations throughout the specification does not necessarily refer to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0071]

[0056] With reference to the figures, a wind propulsion system 1, also called a wind thruster, is shown. As illustrated in Figure 1, the wind propulsion system 1 is located on the deck of a boat 1000.

[0072]

[0057] The wind propulsion system 1 is placed in a moving air flow F1 which makes it possible to produce a lift force. As detailed below, this system is controlled to optimize the lift force while limiting the risk of stalling, which makes it possible to improve the operating efficiency of the system.

[0073]

[0058] Wing

[0059] The wind propulsion system 1 includes a lift generating device, called a suction wing 100, which has an aerodynamic profile. The following description is made for one wing, but also applies to a plurality of wings.

[0074]

[0060] The wing 100 comprises a hollow body 10 elongated along an axis A10, with which a suction device 13 is in fluid communication as explained below. The axis A10 is orthogonal to the plane of the deck of the boat, i.e. substantially vertical, when the wing is in the use configuration. The hollow body is a rigid body unlike a sailboat sail for example.

[0075]

[0061] Preferably, the wing also comprises a fairing 110 (which delimits an enclosure devoid of air flow) attached to an outer part, called the front part, of the peripheral wall of the hollow body 10. 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 can be used. In the example illustrated in the figures, the profile of the wing is ovoid in shape. The profile of the wing corresponds to a cut (section) along a plane orthogonal to the axis A10 of the hollow body.

[0076]

[0062] The peripheral wall of the hollow body 10 of the wing has at least one opening 11, called a suction opening, capable of communicating with the interior of the hollow body 10 of the wing 100. According to one embodiment, the peripheral wall 10 has two suction openings, preferably distributed symmetrically with respect to an axis of symmetry of the profile of the wing.

[0077]

[0063] According to one embodiment, the hollow body 10 is provided with a movable flap 12. The flap makes it possible to modify the camber of the wing profile in order to increase the lift, whether the wind comes from one side or the other of the ship. The ship can sail on both tacks - port tack or starboard tack. According to one embodiment, it can be provided that the movement of the flap makes it possible to close one suction opening 11 and to free the other suction opening.

[0078]

[0064] Suction device

[0079]

[0065] The wind propulsion system comprises a suction device 13 in communication with the interior of the hollow body 10 of the wing 100 for sucking air through said at least one opening 11 formed in the peripheral wall of the wing.

[0066] It may be provided that each suction opening 11 has a variable opening size or porosity along the wing, for example to vary the quantity of air sucked depending on the position along the wing. Each opening 11 may be produced in the form of a grid.

[0080]

[0067] In the example illustrated in the figures, the suction device 13 is formed by a fan which is in fluid communication with the hollow body 10. The fan may be of the centrifugal or helico-centrifugal fan type. The fan may be located inside or outside the hollow body while being in fluid communication with the hollow body. The fan is configured to allow air circulation to be generated through the hollow body with suction at the suction opening 11 in order, at the area of ​​the suction opening 11, to promote the maintenance of the air layer of the external flow against the peripheral wall of the hollow body.

[0081]

[0068] As illustrated in Figure 1, the suction opening 11 allows an external air flow F1 which arrives at the suction opening 11 to be at least partly sucked into the hollow body 10 using the fan 13 and thus to form from the suction opening 11 an internal air flow F2 which passes through the fan 13. The fan 13 is configured to discharge the sucked air flow into the open air.

[0082]

[0069] Wing pivoting

[0083]

[0070] The wind propulsion system 1 comprises a support (not shown) on which and relative to which the wing 100 is pivotally mounted. Preferably, the wing is pivotally mounted on the support around an axis substantially parallel to the longitudinal axis A10 of the hollow body 10 of the wing 100. It is understood that the pivot axis PIV1 is preferably parallel to the axis A10, but that the pivot axis may have a slight angle of one or a few degrees relative to the axis A10, for example an angle of less than 5°.

[0084]

[0071] For this purpose, the wind propulsion system 1 comprises a motorized system 18 for driving the wing to pivot.

[0085]

[0072] Thus, in the mounted state of the system on the deck of the boat 1000, the wing 100 can rotate around the axis A10 (vertical) by being controlled by the motorized pivoting drive system 18, itself controllable by the control unit 180, so as to orient the wing relative to the direction of the apparent wind. As explained below, the orientation of the wing is controlled or regulated according to the desired lift and so as to reduce the risk of stalling.

[0086]

[0073] In the configuration of use of the system where the wing 100 is erected on the deck of the ship, such as a cargo ship, by means of its support, the support is fixed relative to the deck.

[0087]

[0074] The wing 100 is thus mounted to pivot relative to the boat around its vertical pivot axis PIV1, to allow the chord line D100 (also called the orientation direction) of the profile of the wing 100 to take different values ​​of angle of incidence A1 relative to the apparent wind direction V1.

[0088]

[0075] The chord line (or direction of orientation) D100 of the profile of the wing 100 can be defined as being the straight line which connects the leading edge of the wing to the trailing edge, in view of the wing according to a cutting plane (section) orthogonal to the longitudinal axis A10 of the hollow body.

[0089]

[0076] Preferably and as illustrated in Figure 1, the wing 100 is provided with a flap 12. The flap makes it possible to modify the camber of the wing profile in order to increase the lift, whether the wind comes from one side or the other of the ship. The ship can sail on both tacks - port tack or starboard tack. According to one embodiment, it can be provided that the movement of the flap makes it possible to close a suction opening and to free another suction opening when the wing has several suction openings.

[0090]

[0077] A system for measuring the direction of the apparent wind V1 is provided, such as a weather vane, which can be mounted on the wing 100 or on the boat 1000. The apparent wind can thus be measured at the level of the wing 100 or nearby, upstream or downstream, of the wing, for example on the front of the boat equipped with the wing.

[0091]

[0078] A method is proposed for controlling the angle of incidence A1 of the wing relative to the apparent wind direction V1, to enable the lift of the wing 100 and therefore the efficiency of the system 1 to be optimized, i.e. to maximize the lift reliably with a reduced risk of stalling.

[0092]

[0079] Apparent wind measurement

[0080] The apparent wind direction V1 is measured using a wind direction measuring device 15, such as a wind vane positioned on the wing. Alternatively and / or additionally: the measurement can be carried out using a wind vane located on a part of the boat fitted with the wing.

[0093]

[0081] The apparent wind direction serves as a reference for controlling the angle of incidence A1 of the wing relative to the apparent wind direction V1.

[0094]

[0082] According to one embodiment, the apparent wind speed (or force) is also measured by a wind speed measuring device 16, for example using an anemometer, which is preferably located in the same area or close to the wind direction device.

[0095]

[0083] It is useful to measure the wind speed because the aerodynamic performance of the wind turbine can be affected in various ways. The stability of the atmospheric air can cause variations in the wind direction that are more or less marked and more or less rapid. The stability of the air also has an influence on the earlier or later onset of stall.

[0096]

[0084] Measurement of a parameter representative of the stall state of the wing

[0097]

[0085] The wind propulsion system 1 includes a device for measuring a parameter relating to the state of the air flow F1 incident on the wing at the suction opening 11 which is in fluid communication with the suction device. Said parameter is in particular a parameter representative of the stall state of the wing, in particular of the detachment state of the air flow incident on the wing, upstream of the suction opening 11 through which the air flow F2 is set in motion inside the hollow body 10 of the wing by the suction device.

[0098]

[0086] According to a preferred embodiment, said measured parameter is the pressure inside the hollow body, in particular the pressure inside the hollow body in the air flow F2, set in motion by the suction device 13, said measured pressure preferably being the pressure in the internal flow F2 between the suction opening 11 and the suction device 13.

[0099]

[0087] The air flow F2 is considered from said suction opening 11 (upstream of the fan), and this air flow exits downstream of the suction device 13 either through an outlet which can be provided in the hollow body 10 when the suction device 13 is located in the hollow body or through an outlet of the suction device 13 when the suction device 13 is located outside the hollow body but of course in fluid communication with the hollow body.

[0100]

[0088] According to a preferred embodiment, the device for measuring a parameter relating to the state of the incident air flow F1 comprises a pressure sensor system 14 configured to measure the pressure in 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.

[0101]

[0089] According to a particular aspect, the pressure sensor system 14 comprises a sensor of the differential pressure sensor type. As shown diagrammatically in Figure 1, the sensor comprises a pressure tap P141 in the hollow body. The sensor can be housed inside the hollow body 10 or, as in the case of Figure 1, outside the hollow body 10 but in fluid communication with the hollow body 10. For example, the sensor can be housed sheltered in the fairing 110 with a pressure tap P141 which opens into the hollow body to measure the pressure inside the hollow body in which the air flow F2 set in motion by the fan circulates. The differential sensor has another pressure tap P14ref which serves as a reference.The reference pressure tap P14ref is located in an area without air flow, for example in the space defined between the front fairing 110 and the hollow body 10, to measure the atmospheric pressure (static air pressure in the fairing). Alternatively, the reference pressure tap can be located at any other location in the system, outside the flows F1 and F2, where the flow velocity is zero.

[0102]

[0090] The description is given below in the case where the device for measuring a parameter relating to the state of the air flow F1 incident on the wing is an internal pressure measuring device which makes it possible to measure the pressure in the internal flow F2 inside the hollow body 10. As explained below, the measurement of this internal pressure, and in particular its variation as a function of the angle of incidence of the wing, makes it possible to reliably determine the state of separation of the air flow F1 incident on the wing, and therefore the state of stall of the wing, as a function of the angle of incidence of the wing.However, the description can be applied to other embodiments, which remain less advantageous than a pressure sensor measuring the pressure inside the hollow body through which the flow F2 is sucked, for which the device for measuring a parameter relating to the state of the air flow F1 incident on the wing can be a parietal pressure sensor, or an electronic pennon (i.e. a flexible strip associated with electronic processing means), positioned on the wing in the flow F1 or a device for analyzing operating parameter(s) of the fan, such as the intensity, the power consumed and / or the rotation speed.

[0103]

[0091] Steering unit

[0104]

[0092] The device comprises a control unit 180 which comprises a module 181 for controlling pivoting and recording the corresponding pressure. The module 181 is configured to control the pivoting of the wing 100 around its vertical pivot axis PIV1, which can coincide with the central axis A10 of the hollow body 10, in a given angular range to allow the (horizontal) orientation axis D100 of the wing 100 to take different values ​​of angle of incidence A1 relative to the apparent wind direction V1, and, during the pivoting movement of the wing 100, to control the recording of the pressure measurement inside the hollow body as a function of the value of angle of incidence A1 of the wing 100.

[0105]

[0093] The control unit 180 also comprises a stall determination module 182 configured to determine a value A1 D_t2 of the angle of incidence of the wing 100 corresponding to a stall, called the stall angle value. The module 182 is configured to detect a passage of a parameter relating to the pressure, such as the opposite of the pressure coefficient (-Cp), above or below (depending on the parameter used) a threshold value. It will be noted that a rise in pressure inside the hollow body in the flow F2 above a threshold value corresponds to a detached state of the air flow F1 around the wing at the suction opening 11. In particular, in the non-detached state of the wing subjected to an incident air flow, the pressure is negative inside the hollow body 10 in the flow F2.Then, when there is separation of the flow F1 upstream of the suction opening 11, the pressure inside the hollow body 10 in the flow F2 rises and the parameter -Cp falls.

[0094] The pressure coefficient Cp is calculated as a function of the measured apparent wind speed Vvl. The pressure coefficient Cp can be calculated by the formula.

[0106]

[0096] with P_i the internal pressure measured in the hollow body by the pressure sensor, and the density of the air.

[0107]

[0097] It should be noted that the lift of the wing is linked to the pressure coefficient itself calculated from the measured internal pressure.

[0108]

[0098] An example of the evolution of the opposite of the pressure coefficient -Cp, as a function of the angle of incidence A1 of the wing measured during said pivoting movement of the wing is proposed in Figure 6.

[0109]

[0099] It can thus be provided that the module determines the value A1 D_t2 of the angle of incidence of the wing 100 corresponding to a stall as being the angle of incidence of the wing for which the value of -Cp falls below a given threshold value and / or has a decrease slope greater than a given threshold value.

[0110]

[0100] The control unit 180 also comprises a safety module 183 configured to determine a safety value of angle of incidence A1 SD1_t2 of the wing, as a function of the stall angle value A1 D_t2, which is, in absolute value, less than said stall angle value. The safety value of angle of incidence may correspond to the determined stall angle value reduced by a given value, called the separation value, as explained below. The use of a safety value of angle of incidence lower, in absolute value, than the stall angle actually measured, makes it possible to maintain the maximum angle of incidence of the wing separated from the stall angle to limit the risk of untimely stalling.

[0111]

[0101] The control unit 180 also comprises a wing orientation control module 184 which makes it possible to control the orientation of the wing via the motorized system 18 according to the desired lift. The wing orientation control module 184 thus makes it possible to control the orientation of the wing with an angle of incidence setpoint equal to the angle of incidence safety value A1SD1_t2 to obtain maximum lift in a safe manner. The wing orientation control module 183 also makes it possible to control the orientation of the wing with an angle of incidence setpoint lower than the angle of incidence safety value A1SD1_t2, in particular between 0° and A1SD1_t2 in given conditions where less lift is desired, for example for slowing down or stopping the boat.

[0112]

[0102] Spacing value

[0113]

[0103] According to one embodiment, the angle of incidence safety value A1SD1_t2 is calculated according to the formula:

[0114]

[0104] Il A1SD1J2 II = Il A1 DJ2 II - a s

[0115]

[0105] With a s a value, called the spacing value, strictly positive.

[0116]

[0106] The spacing value a s can be a predefined value, such as a value between 2° and 8°, for example 3°.

[0117]

[0107] According to one embodiment, the spacing value a s is defined based on a parameter of the device's environment, such as apparent wind speed.

[0118]

[0108] Update of the angle of incidence safety value

[0119]

[0109] After a first cycle of execution of the steps which make it possible to obtain a first stall angle value and a first angle of incidence safety value, the control unit 180 is configured to repeat the steps in a second execution cycle so as to obtain a second stall angle value and a second angle of incidence safety value to update the angle of incidence safety value. It is understood that the second angle of incidence safety value obtained, which corresponds to the update of the angle of incidence safety value, may be greater or less than the first angle of incidence safety value.

[0120]

[0110] For at least one or each cycle (execution process), it may be provided that the wing is moved until (i.e., stopping the movement when) a stall is detected. Alternatively or in combination, it may also be provided that the angular sector in which the wing is pivotally moved extends on either side of the stall angle value obtained during a previous execution process.

[0121]

[0111] Repeating the steps makes it possible to update the angle of incidence safety value by replacing the old determined value with the new value for the wing orientation control setpoint.

[0122]

[0112] It may be provided that the steps are repeated periodically to obtain a stall angle measurement and therefore a safety angle of incidence value setpoint which is appropriate depending on the navigation conditions. It may also be provided that the repetition of the steps is triggered depending on one or more environmental parameters, such as the direction and / or speed of the wind, the weather conditions, or operating conditions of the device, such as the rotation speed of the fan.

[0123]

[0113] It may be provided that the second stall angle value determined and the resulting angle of incidence safety value automatically replace the previous values. Alternatively, it may also be provided to compare one of the second determined values ​​with the corresponding first value or values ​​and to update one or more of said determined values ​​when the difference between the compared values ​​is greater than a threshold value.

[0124]

[0114] The angle of incidence of the wing can thus be regulated so as to maximize the propulsive force delivered to the boat by the wind propulsion system when conditions permit or so as to reduce or minimize the effect of the wind on the vessel when necessary.

[0125]

[0115] The regulation of the angle of incidence of the wing can be controlled by the control unit either in open loop or in closed loop. In open loop, the instructions delivered to the operating parameters are calculated explicitly from the available information and the actual state of the quantity associated with the instruction is not compared with this instruction. In closed loop, the quantity associated with a instruction is measured. The difference between the current value and the instruction for this quantity is taken into account and modifies the behavior of the regulation system.

[0116] Method

[0126]

[0117] The wind propulsion system presented above allows the implementation of a method for controlling the angle of incidence A1 of the wing so as to optimize the lift force while limiting the risk of untimely stalling. An embodiment of such a method is proposed below in connection with Figure 7.

[0127]

[0118] The suction device 13 operates so that an air flow F2 circulates through the hollow body from the suction opening 11. In particular, it can be provided that the control unit controls the rotation of the fan at a given speed.

[0128]

[0119] 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.

[0129]

[0120] As illustrated in Figure 2, the angle of incidence A1 of the wing 100 is in an authorized angular sector of incidence SF1 whose maximum value (in absolute value) is A1SD1_t1. The prohibited complementary sector is referenced SD1.

[0130]

[0121] In step 720, the control unit 180 controls the pivoting movement of the wing 100 around its vertical pivot axis PIV1, to allow the chord line D100 of the wing profile to take different values ​​of angle of incidence A1 relative to the apparent wind direction V1. The control unit controls the recording of the internal pressure values ​​measured by the sensor 14 as a function of the angle of incidence value A1 taken by the wing during the pivoting movement of the wing 100. The wing is moved over an angular range suitable for a stall to occur.

[0131]

[0122] In step 730, from the internal pressure measurements measured by the sensor 14, the control unit determines a value A1 D_t2 of the angle of incidence of the wing corresponding to a stall, called the stall angle value. This value A1 D_t2 of the angle of incidence of the wing is illustrated in Figure 3 with the flow separation referenced DF1. The recorded pressure measurements can be used to calculate values ​​of a parameter, such as the opposite of the pressure coefficient (-Cp), as a function of the measured angle of incidence, as illustrated in Figure 6, and thus make it possible to determine a corresponding stall angle by analyzing the evolution of this parameter as a function of the angle of incidence A1.

[0132]

[0123] In step 740, the control unit determines a safety value of angle of incidence A1SD1_t2 of the wing, as a function of said stall angle value A1 D_t2, lower than said stall angle value. The authorized angle of incidence sector can thus be updated so that as illustrated in Figure 4, a sector SF1 ' is obtained, which can be reduced compared to the previous authorized sector, while the updated prohibited sector SD1 ' has increased.

[0133]

[0124] In step 750, the control unit controls the orientation of the wing with an angle of incidence setpoint equal to or less than the angle of incidence safety value A1SD1_t2, as illustrated in Figure 5.

[0134]

[0125] In step 760, the preceding steps are repeated to obtain a new angle of incidence safety value. In other words, the angle of incidence safety value, corresponding, in absolute value, to the maximum authorized angle of incidence is updated and thus replaces the old determined angle of incidence safety value used to generate the wing orientation control instruction.

[0135]

[0126] After executing steps 710 to 750, also called steps a) to e), providing a stall angle value and a safety angle of incidence value, the following steps may preferably be performed in real time, for example at a given frequency, such as 10 Hz:

[0136] - determination of the angular position where the wing 100 is located, to which corresponds a value of angle of incidence A1 of the wing 100, and measurement of said parameter representative of the state of separation of the air flow F1 incident on the wing; and,

[0137] - determination by the control unit 180 of the state of stall or not of the wing as a function of said measured parameter representative of the state of separation of the air flow F1 incident on the wing.

[0138]

[0127] In the event of detection of a stall state, it can be provided that: either steps 710 to 750 are repeated in an additional execution process; or, the control unit 180 assigns to the stall angle value, said angle of incidence value A1 of the wing 100 determined (angle of incidence value A1 considered at the time of the measurement which made it possible to detect the stall state), then the control unit 180 determines a safety value of angle of incidence of the wing as a function of said stall angle value, the safety value of angle of incidence being, in absolute value, less than said stall angle value. The control unit 180 can then control the orientation of the wing with an angle of incidence setpoint equal to the safety value of angle of incidence.

[0139]

[0128] In the absence of stall detection, the control unit may be configured to wait for the repetition of steps 710 to 750 at the following time. It may be provided that in step 720 of the execution process, the wing is moved until a stall is detected and / or that the angular sector in which the wing is pivotally moved extends on either side of the stall angle value obtained during the previous execution process.

[0140]

[0129] The angle of incidence safety value can thus be modified, temporarily or not, for the conditions encountered, so as to improve the performance of the system.

[0141]

[0130] In the event of an untimely stall, i.e. outside the learning phase, it may be provided that the system reduces the incidence until the flow re-attaches and therefore until the aerodynamic performance of the profile is restored or to an even lower incidence value, then restarts a learning process to then be able to control the orientation of the wing according to a set angle of incidence corresponding to the new maximum authorized angle of incidence value. Alternatively, it may be provided that the observed value of the stall is used in the same way as in step 730, i.e. by resuming the cycle at step 740 using the value of the stall angle observed as resulting from step 730, and therefore without necessarily restarting a complete learning cycle.

[0142]

[0131] The control unit is presented for example in the form of a processor and a data memory in which computer instructions executable by said processor are stored, or in the form of a microcontroller.

[0143]

[0132] In other words, the functions and steps described can 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 control unit or its modules can be performed by instruction sets or computer modules implemented in a processor or controller or be performed by dedicated electronic components or components of the programmable logic circuit type (or FPGA which is the acronym for field-programmable gate array, which literally corresponds to in-situ programmable gate array) or of the application-specific integrated circuit type (or ASIC which is the acronym for application-specific integrated circuit, which literally corresponds to application-specific integrated circuit). It is also possible to combine computer parts and electronic parts.

[0144]

[0133] The control unit is thus an electronic and / or computer unit. When it is specified that said unit is configured to carry out a given operation, this means that the unit comprises computer instructions and the corresponding execution means which make it possible to carry out said operation and / or that the unit comprises corresponding electronic components.

[0145]

[0134] Other aspects

[0146]

[0135] It can be provided that the system 1 comprises a tilting mechanism which allows the wing, and possibly its support, to be tilted around a horizontal axis.

[0147]

[0136] The tilting system allows the wing, and possibly its support, to be moved between an upright position, in which, in the mounted state of the system on the deck of the boat, it extends perpendicular to the deck of the boat, and a tilted position, in which, in the mounted state of the system on the deck of the boat, the wing extends substantially parallel to the deck of the boat.

[0148]

[0137] When the wing extends vertically and pivots about an axis substantially parallel to the axis of the wing, that is to say during operation of the wing - in the vertical state of the wing - and apart from the possible tilting mobility of the support about an axis orthogonal to the axis of the wing, the support remains fixed relative to the deck of the boat.

[0149]

[0138] Generally speaking, it can be provided that the system takes up all or part of the characteristics of the lift generating system described in the international application PCT / FR2022 / 050268 published under the number WO / 2022 / 175622, or of the system described in the patent filed under the number EP17165662 and published under the number EP3235719, by adding the additional elements presented above, with in particular the pressure measuring device and the control unit as presented above.

[0139] The invention is not limited to the embodiments illustrated in the drawings.

[0150]

[0140] Furthermore, the term "comprising" does not exclude other elements or steps. Furthermore, features or steps that have been described with reference to one of the embodiments set forth above may also be used in combination with other features or steps of other embodiments set forth above.

Claims

Claims

1. Method for controlling the angle of incidence (A1) of a lift generating device, called a wing (100), of a wind propulsion system (1) relative to the apparent wind direction (V1), the wing comprising a hollow body (10), the wing (100) being located in an external air flow (F1) incident on the wing; the wind propulsion system (1) comprising: - a suction device (13) in fluid communication with the hollow body (10); - at least one suction opening (11) provided in a peripheral wall of the hollow body (10) subjected to said external air flow (F1) incident on the wing, the suction device (13) generating an air flow (F2) inside the hollow body (10) from said at least one suction opening (11); - a device for measuring a parameter representative of the state of separation of the air flow (F1) incident on the wing; - a motorized system (18) for driving the wing (100) to pivot around a vertical pivot axis (PIV1) parallel to the longitudinal axis (A10) of the hollow body (10); - a control unit (180); characterized in that the method comprises the following steps: a) measurement (710) of the apparent wind direction (V1) by a device (15) for measuring the apparent wind direction; b) pivoting movement (720) of the wing (100) around the vertical pivot axis (PIV1) by the motorized system (18) for pivoting the wing (100), to allow the chord line (D100) of the profile of the wing (100) to take different values ​​of angle of incidence (A1) relative to the direction of the apparent wind (V1), and, c) during the pivoting movement of the wing (100), measurement, by said device for measuring parameters representative of the state of separation, of said parameter representative of the state of separation of the air flow (F1) incident on the wing as a function of the value of angle of incidence (A1) of the wing (100); and, from the measurement of said parameter representative of the state of Tl separation of the air flow (F1) incident on the wing, determination (730) by the control unit (180) of a value (A1 D_t2) of angle of incidence of the wing (100) corresponding to a stall, called stall angle value; d) determination (740) by the control unit (180) of a safety value of angle of incidence (A1 SD1_t2) of the wing as a function of said value (A1 D_t2) of angle of stall, the safety value of angle of incidence being, in absolute value, less than said value of angle of stall; e) control (750) by the control unit (180) of the orientation of the wing with an angle of incidence setpoint equal to the safety value of angle of incidence (A1SD1_t2).

2. The method of claim 1, wherein after a first process of performing steps a) to e) providing a first stall angle value and a first angle of attack safety value, steps a) to e) are repeated (760) in a second process of performing so as to obtain a second stall angle value and a second angle of attack safety value corresponding to an update of the angle of attack safety value.

3. A method according to claim 2, wherein in step b) of the second execution process the wing (100) is moved until a stall is detected and / or the angular sector in which the wing (100) is pivotally moved extends on either side of the stall angle value obtained during the first execution process.

4. Method according to one of claims 1 to 3, wherein, after the first process of performing steps a) to e) providing a first stall angle value and a first angle of attack safety value, the method comprises the following steps preferably performed at a given frequency, for example 10 Hz: - determination of the angular position where the wing (100) is located, to which corresponds an angle of incidence value (A1) of the wing (100), and measurement of said parameter representative of the state of separation of the air flow (F1) incident on the wing; and, - determination (730) by the control unit (180) of the state of stall or not of the wing as a function of said measured parameter representative of the state of separation of the airflow (F1) incident on the wing; and, in the event of detection of a stall condition: - either steps a) to e) are repeated (760) in a second execution process; - either, assignment to the stall angle value, by the control unit (180), of said determined angle of incidence value (A1) of the wing (100), determination by the control unit (180) of a safety value of angle of incidence of the wing as a function of said stall angle value, the safety value of angle of incidence being, in absolute value, less than said stall angle value; control by the control unit (180) of the orientation of the wing with an angle of incidence setpoint equal to the safety value of angle of incidence.

5. Method according to any one of the preceding claims, in which the device for measuring a parameter representative of the state of separation 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. 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 said at least one suction opening (11) and the suction device (13).

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

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

9. Method according to any one of the preceding claims, in which the angle of incidence safety value, denoted A1 SD1_t2, is calculated according to the formula: He A1SD1J2 II = He A1 DJ2 II - a s with a s a value, called the gap value, strictly positive, and A1 D_t2 being the stall angle value.

10. The method of claim 9, wherein said spacing value is a predefined value.

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

12. Method according to any one of the preceding claims, in which said stall angle value (A1 D_t2) is determined as being the angle of incidence value for which the parameter representative of the separation state of an air flow (F1) incident on the wing crosses a threshold value and / or has a slope value which crosses a threshold value.

13. A method according to any preceding claim, wherein the apparent wind direction (V1) is measured using a wind vane positioned on the wing.

14. Method according to any one of the preceding claims, in which the device for measuring a parameter representative of the state of separation of the air flow (F1) incident on the wing comprises a parietal pressure sensor, positioned on the wing in the air flow (F1) incident upstream of said at least one suction opening (11).

15. Method according to any one of the preceding claims, in which the device for measuring a parameter representative of the state of separation of the air flow (F1) incident on the wing comprises a flexible strip associated with electronic processing means, called an electronic pennon, positioned on the wing in the air flow (F1) incident upstream of said at least one suction opening (11).

16. Method according to any one of the preceding claims, in which the device for measuring a parameter representative of the state of separation of the air flow (F1) incident on the wing comprises a device for analyzing operating parameter(s) of the suction device (13).

17. Wind propulsion system (1) comprising: - a lift generating device, called a wing (100), the wing comprising a hollow body (10), the wing (100) being intended to be located in a flow outside air (F1) incident on the wing; - a suction device (13) in fluid communication with the hollow body (10); - at least one suction opening (11) provided in a peripheral wall of the hollow body (10) capable of being subjected to said external air flow (F1) incident on the wing, the suction device (13) being configured to generate an air flow (F2) inside the hollow body (10) from said at least one suction opening (11); - a device for measuring a parameter representative of the state of separation of the air flow (F1) incident on the wing; - a motorized system (18) for driving the wing (100) to pivot around a pivot axis (PIV1) parallel to the longitudinal axis (A10) of the hollow body (10); - a control unit (180) configured to execute the steps of a method for controlling the angle of incidence (A1) of the wing relative to the direction of the apparent wind (V1), the method being in accordance with any one of the preceding claims.

18. A boat equipped with a wind propulsion system according to claim 17, the wind propulsion system being mounted on the deck of the boat.

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