A sailboat including an aerodynamic shape and a system for determining the characteristics of the incident airflow on its leading edge

Abstract

The present invention relates to a sailing boat comprising an aerodynamic profile and a system for determining the characteristics of the incident air flow on its leading edge. In order to be able to precisely determine the position of the stagnation point at different regions along the leading edge of the aerodynamic profile, a system comprises: rows (S1 to S5) of pressure sensors (16) distributed on either side of the leading edge (14) and virtually forming a pattern (M1 to M5) spaced apart from each other in the form of a simple broken line; and a computer (20) connected to the pressure sensors (16). The computer (20) determines the corresponding stagnation point position along each of the patterns (M1 to M5), the stagnation point position being defined by the abscissa of the curve (a1 to a5) and by the height (z1 to z5) evaluated based on the corresponding height data from the pressure sensors (16) in the corresponding rows (S1 to S5), for which the pressure P*, interpolated based on the pressure measurements provided by the pressure sensors (16) in the corresponding rows (S1 to S5), is at a maximum.

Description

Technical Field

[0001] The invention relates to a sailing vessel comprising an aerodynamic profile, and to a system for determining characteristics of an airflow incident on the leading edge of the aerodynamic profile. Background Art

[0002] Traditionally, the determination of the speed and orientation characteristics of the airflow incident on the leading edge of the sail of a sailboat is based on the use of wind indicators and anemometers and on the use of meteorological data.

[0003] These instruments and data only deliver general information and in particular do not allow the direction and speed of the airflow at individual points on the leading edge to be known.

[0004] However, such information would be useful for a detailed a posteriori analysis of the performance and behaviour of the sail on the one hand, and to allow the accuracy of automatic or assisted piloting devices to be improved on the other hand. Summary of the invention

[0005] The object of the invention is in particular to provide a simple, economical and effective solution to this problem.

[0006] To this end, the invention proposes a sailing vessel comprising an aerodynamic profile forming a sail of the sailing vessel, and a system for determining the characteristics of the airflow incident on the leading edge of the aerodynamic profile, the system comprising:

[0007] - a series of pressure sensors arranged on the surface of the aerodynamic profile, the pressure sensors in each series being distributed on either side of the leading edge of the aerodynamic profile, the series of pressure sensors virtually forming respective patterns spaced apart from one another, each of the patterns being a simple broken line; and

[0008] - a computer connected to the pressure sensors in order to receive the local pressure values ​​respectively originating from the pressure sensors.

[0009] The computer is configured to determine, along each of the patterns, a respective stagnation point position, the stagnation point position being defined by a curve abscissa defined along the pattern in question and by a height evaluated from respective height data of a pressure sensor in the corresponding series, for which the pressure P* interpolated from the pressure measurements transmitted by the pressure sensor in the corresponding series is maximum along the pattern in question.

[0010] The respective altitude data of the pressure sensors are determined from the respective altitudes of the pressure sensors in a reference frame fixed relative to the sailing vessel and from a variable component determined for each of the pressure sensors from the measurements of the orientation of the sailing vessel.

[0011] The system allows the location of stagnation points in various regions along the leading edge of the aerodynamic profile to be accurately determined.

[0012] Knowledge of the location of the stagnation point is particularly advantageous in that it allows the modulus of the velocity of the incident flow and its direction at various points along the leading edge to be determined, as will become more apparent below.

[0013] In a preferred embodiment of the invention, the patterns are in respective pattern planes that are different from each other and such that each of the pattern planes is orthogonal to the osculating plane at the intersection of the leading edge and the pattern plane in question.

[0014] Preferably, the pattern planes are parallel to each other.

[0015] In a preferred embodiment of the invention, the system further comprises a memory containing a map relating the stagnation point positions and the operating parameters of the aerodynamic profile respectively determined along each of said patterns to the directional distribution of the airflow.

[0016] In a preferred embodiment of the invention, the computer is further configured to determine, along each of said patterns, a respective stagnation pressure defined as the value of the pressure P* at the corresponding stagnation point location.

[0017] Preferably, the system also includes a reference pressure sensor, which is placed in a shielded area away from the aerodynamic shape and connected to the computer, and the computer is also configured to determine the velocity distribution of the airflow based on the reference pressure transmitted by the reference pressure sensor and based on the stagnation pressure determined along each of the patterns.

[0018] As a variant, the system also includes an anemometer connected to the computer, and the computer is also configured to determine the velocity distribution of the airflow by equating the airflow velocity value transmitted by the anemometer with the velocity value of the airflow incident on one of the patterns and according to the stagnation pressure determined respectively along each of the patterns.

[0019] In a preferred embodiment of the invention, the sailing vessel comprises automatic or assisted piloting means configured to control at least one operating parameter of the aerodynamic profile based on the stagnation point positions respectively determined along each of said patterns. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The invention will be better understood and other details, advantages and characteristics of the invention will become apparent on reading the following description, given by way of non-limiting example with reference to the accompanying drawings, in which:

[0021] Figure 1is a schematic perspective view of a sailing vessel, in this case a sailing yacht, comprising an aerodynamic profile and a system for determining characteristics of an airflow incident on a leading edge of the aerodynamic profile according to a preferred embodiment of the invention;

[0022] Figure 2 is similar to Figure 1 And shows the front of the rigid sail of the sail yacht Figure 1 A larger scale view of the sailing yacht in;

[0023] Figure 3 It is a schematic diagram of a cross (i.e. horizontal) section of the aerodynamic shape;

[0024] Figure 4 is a graph showing the quantity P*=pgz+P (ordinate axis) as a function of position along a normalized curve of a pattern formed by a series of pressure sensors placed on either side of the leading edge (abscissa axis);

[0025] Figure 5 is a graph showing the position of the stagnation-point along the pattern Figure 3 A larger scale view of the detail V in ;

[0026] Figure 6 is a graph showing the position of the stagnation point (abscissa axis) at various heights (ordinate axis);

[0027] Figure 7 is a graph showing the distribution of airflow along the direction of the leading edge;

[0028] Figure 8 is a graph showing stagnation pressure (abscissa axis) at various heights (ordinate axis);

[0029] Fig. 9 is a graph showing the velocity distribution of the airflow along the leading edge. DETAILED DESCRIPTION

[0030] The present invention generally relates to a sailboat 10 including a sail 12 forming an aerodynamic profile of the sailboat, and a system for determining characteristics of an airflow incident on a leading edge of the aerodynamic profile.

[0031] The described examples relate more particularly to sailing yachts with rigid sails (sometimes referred to as "rigid wings"). Rigid sails usually replace the mainsail of a conventional sailing yacht and generally consist of a front element 12A forming a contoured leading edge 14, and a rear element 12B, called a "flap", forming a contoured trailing edge 15 and forming an adjustable angle θ relative to the front element 12A, the angle sometimes referred to as the camber angle ( Figure 3). The front element 12A generally comprises a structural front part that acts as a mast, since the sail is rotatably mounted on the yacht via the front part. The front element 12A generally comprises a bottom plate 12AA and a top plate 12AB ( Figure 1 ).

[0032] In a sailing yacht in this specification, the longitudinal direction X is defined as the general direction of travel of the sailing yacht or even as a direction extending from the stern to the bow, the transverse direction Y is a direction orthogonal to the longitudinal direction X, i.e. a direction extending from the starboard side to the port side, and the vertical direction Z is a direction orthogonal to the directions X and Y.

[0033] The system for determining the characteristics of the incident air flow comprises a pressure sensor 16 ( Figure 4 These sensors are usually formed into series S1 to S5 ( Figure 2 ), for example, the series S1 to S5 are five in number and are physically or non-physically defined so that the sensors in each series are distributed on either side of the leading edge 14 of the aerodynamic profile 12 and so that the sensors in each series virtually form a corresponding pattern M1 to M5 spaced apart from one another. Each of the patterns M1 to M5 is defined by virtually connecting the sensors in a given series in pairs to form a simple broken line, that is, a geometric figure formed by a sequence of straight line segments connecting a sequence of points corresponding to the sensors, in which the intersection point of two different segments belonging to the broken line is empty in the case of two consecutive segments or is reduced to their common vertex. The fact that the patterns are spaced apart from one another means in particular that the patterns do not intersect one another.

[0034] Thus, the series S1 to S5 of pressure sensors are distributed along the front edge 14 .

[0035] In a preferred embodiment of the invention, the series S1 to S5 of pressure sensors are arranged so that the patterns M1 to M5 are in respective pattern planes P1 to P5 that are different from one another and so that each of the pattern planes is orthogonal to an osculating plane O1 to O5 at the intersection point I1 to I5 of the leading edge 14 and the pattern plane in question. Figure 2 ).

[0036] Furthermore, the series S1 to S5 of pressure sensors are advantageously arranged such that the pattern planes P1 to P5 are locally orthogonal to the leading edge 14 .

[0037] In general, the arrangement of the pressure sensors is preferably designed to minimize the angle between each pattern plane and the standard or average airflow for the type of application envisioned.

[0038] In practice, the series S1 to S5 of pressure sensors are thus preferably arranged so that the pattern planes P1 to P5 are substantially parallel to the incident wind. Near sea level, the wind generally blows substantially parallel to the horizontal. Therefore, when the yacht adopts an orientation without lists and spacings, the pattern planes P1 to P5 are advantageously substantially horizontal.

[0039] Furthermore, within each series S1 to S5 , the sensors 16 are paired equidistantly along the corresponding pattern M1 to M5 .

[0040] In a preferred embodiment of the invention, the series S1 to S5 of pressure sensors are physically defined. In particular, the series of sensors is preferably a band B1 to B5 fastened to the surface of the aerodynamic profile 12. Documents WO2015091994A1, WO2015091996A1 and EP3144684A1 describe examples of bands of MEMS (micro-electromechanical systems) sensors that can be used in the context of the present invention. Such a band of sensors makes it possible in particular to obtain high-density sensors, enabling high spatial sampling rates. MEMS sensors can be internally clocked at high speed, for example at a frequency of 64Hz, and can therefore transmit data in real time at a rate suitable for processing operations performed on the data downstream, for example at a frequency of 16Hz.

[0041] The pressure sensors 16 are configured to measure the static pressure of the laminar airflow moving through the aerodynamic profile. To this end, these sensors 16 have respective sensing surfaces which are locally parallel to the surface of the aerodynamic profile 12 and thus locally parallel to the airflow in the vicinity of the closest aerodynamic profile.

[0042] The system further comprises a computer 20 connected to the pressure sensors 16 in order to receive the local pressure values ​​respectively originating from these pressure sensors.

[0043] The computer is configured to determine along each of the patterns M1 to M5 a corresponding stagnation point position defined by a pair of coordinates (ai, zi) comprising a curve abscissa a1 to a5 and a height z1 to z5 defined along the pattern M1 to M5 in question.

[0044] The curve abscissas a1 to a5 are determined so as to define the points on the pattern in question for which the pressure P* interpolated from the pressure measurements delivered by the pressure sensors in the corresponding series S1 to S5 is a maximum.

[0045] The heights z1 to z5 are the heights of the above-mentioned points of the pattern, which are evaluated from the corresponding height data of the pressure sensors 16 in the corresponding series S1 to S5.

[0046] Each stagnation point location thus defines the location of the stagnation point of the incident airflow in the corresponding pattern plane P1 to P5 , ie the location of the point where the incident airflow splits into two flows moving past the aerodynamic profile 12 on either side of the aerodynamic profile 12 .

[0047] The stagnation point is located at Figure 2 Indicated by PT1 to PT5.

[0048] To a first approximation, the altitude data may simply consist of the corresponding altitude of the pressure sensor 16 in a reference frame fixed relative to the yacht. These corresponding altitude data relative to the yacht are fixed preset data associated with the arrangement of the sensor 16.

[0049] Preferably, the altitude data also comprise a variable component determined for each of the sensors 16 from measurements of the yacht's orientation (height, trim), these measurements being delivered, for example, by gyroscopic sensors.

[0050] Thereby, the stagnation point position is determined with optimum accuracy.

[0051] The system further comprises a memory 22 containing a mapping relating the stagnation point positions and the operating parameters of the aerodynamic profile respectively determined along each of the patterns M1 to M5 to the directional distribution of the airflow. Such mapping is previously established according to an aerodynamic model of the aerodynamic profile.

[0052] In the described example, the operating parameters of the aerodynamic profile preferably include the rotation angle of the mast and the camber and twist angles of the aerodynamic profile.

[0053] In a preferred embodiment of the invention, the computer 20 is further configured to determine, along each of the patterns M1 to M5, a respective stagnation pressure PS1 , PS5 defined as the value of the pressure at the corresponding stagnation point location.

[0054] The system also includes a reference pressure sensor 24 placed in a shielded area away from the aerodynamic profile 12. It must be understood that the reference pressure sensor 24 is positioned in an area that is not normally subject to airflow. ref is equal to the height z of the sensor 24 to be measured ref Atmospheric pressure at .

[0055] A reference pressure sensor 24 is connected to the computer 20 .

[0056] The computer 20 is also configured to determine the pressure according to the reference pressure P transmitted by the reference pressure sensor 24. ref , and determining a velocity distribution of the airflow according to the stagnation pressures PS1 to PS5 respectively determined along each of the patterns M1 to M5.

[0057] In a preferred embodiment of the invention, the determination of the velocity profile is based on the application of Bernoulli's theorem, the following being considered true for each pattern Mi (in the example shown, i comprised between 1 and 5):

[0058] -The total pressure at the stagnation point is equal to the stagnation pressure PSi;

[0059] - This total pressure is also equal to in:

[0060] -vi is the velocity of the airflow incident on pattern Mi,

[0061] -zi is the height corresponding to the stagnation point position,

[0062] -ρ is the air density, which is considered constant and calculated at the reference point,

[0063] -g is the acceleration due to gravity.

[0064] Therefore, the corresponding speed value is:

[0065] As a variant, instead of using the reference pressure transmitted by the reference sensor 24, the computer can be configured to determine the velocity distribution of the air flow based on a reference velocity transmitted by an anemometer, the anemometer being arranged sufficiently close to one of the patterns Mj (in the example described, j is comprised between 1 and 5) and the leading edge so that the velocity of the air flow incident on said pattern Mj may be equal to the reference velocity.

[0066] The pressure in the airflow incident on pattern Mj can then be determined by means of Bernoulli's theorem by again equating the total pressure at the stagnation point with the stagnation pressure PSj. The velocity of the airflow incident on other patterns can then be derived in a manner similar to that described above, where P ref and z ref Replaced by PSj and zj.

[0067] Obviously, the system can combine these two techniques for respectively determining the velocity profile, namely the reference pressure measurement and the correlation, in order to deliver, for example, a velocity value obtained by averaging the results delivered by these two determination techniques.

[0068] Finally, the sailing yacht 10 also comprises an automatic or assisted piloting device 26 configured to control at least one operating parameter of the aerodynamic profile based on the stagnation point position determined along each of the patterns M1 to M5 , respectively.

[0069] The operating parameters controlled by device 26 include camber angle and pitch angle.

[0070] The operation of a sailboat such as sailboat 10 according to the present invention will now be described with reference to Figures 3 to 9 describe.

[0071] Figure 3 A cross section of the aerodynamic profile 12 is shown, for example, in the plane P1 of the sensor series S1 .

[0072] Figure 3 In particular, the airflow F incident on the leading edge 14 is shown, which becomes split into two flows FA and FB, which flow FA and FB move through the aerodynamic profile 12 on each side of the aerodynamic profile 12. The flows FA and FB are separated from each other by a stagnation line FS that meets the leading edge at a respective stagnation point PS1. The angle of incidence of the flow F on the leading edge 14 and therefore the position of the stagnation point is susceptible to change along the leading edge 14 (i.e., as a function of altitude).

[0073] The computer 20 receives local values ​​of pressure P* at a high frequency (for example 64 Hz), which respectively originate from the pressure sensor 16. The computer preferably performs a temporal filtering of these local pressure values ​​in order to remove insignificant fluctuations.

[0074] Figure 4 is a graph showing in the form of points the local value of the pressure P* in Pascals (ordinate axis) for each sensor 16 of one of the series, for example the series S1. The abscissa axis corresponds to the abscissa of the curve of the sensor along the corresponding pattern M1, which for simplicity has been normalized by the chord of the aerodynamic profile.

[0075] For each sensor series S1 to S5, the computer performs an interpolation of the local values ​​of the pressure P*, thereby generating the connection Figure 4 then, the computer determines the position of the maximum value of the pressure P* on the curve, which defines the abscissa a1 to a5 corresponding to the position of the stagnation point.

[0076] The computer also determines the altitudes z1 to z5 corresponding to the stagnation point positions, preferably by interpolation of the altitude data associated with the pressure sensor 16. These data are determined from the position of each of the sensors on the aerodynamic profile, which position is recorded in the memory 22, and in a preferred embodiment of the invention, these data are defined by means of measurements of the orientation of the yacht, which are transmitted to the computer, for example, at a relatively low frequency (for example 10 Hz).

[0077] Figure 5 yes Figure 3 1 is a larger scale view of a portion V of the pattern M1, in which the thickness of the strip of sensors B1 and the size of each sensor 16 have been exaggerated and the number of sensors shown has been greatly reduced for the sake of clarity. The figure shows the abscissa a1 of the position of the stagnation point along the pattern M1, which substantially coincides with the position of the sensor 16, for example.

[0078] Figure 6 is a graph showing stagnation point positions ( a1 ; z1 ) to ( a5 ; z5 ) determined for the respective sensor series S1 to S5 . The abscissa axis indicates the abscissa of the curve normalized by the chord of the aerodynamic profile, and the ordinate axis indicates the height in millimeters.

[0079] From the position of the stagnation point and from the map stored in the memory 22, the computer determines the distribution of the airflow along the direction of the leading edge 14, which is given by Figure 7 Graph 1 shows an example of a flow chart of FIG. 5 , wherein the axis of abscissa indicates the orientation of the airflow in degrees and the axis of ordinate indicates the height in millimeters.

[0080] Furthermore, the computer determines along each of the patterns M1 to M5 a respective stagnation pressure PS1 to PS5 which, as explained above, is defined as the value of the pressure at the corresponding stagnation point location.

[0081] Figure 8 Graph showing the stagnation pressures PS1 to PS5 in Pascals (axis of abscissa) determined for each sensor series S1 to S5 respectively identified by the height of the respective stagnation point position in millimeters (axis of ordinate).

[0082] Furthermore, the computer 20 determines the velocity distribution of the airflow using at least one of the above methods. Fig. 9 An example of the speed distribution thus obtained is shown. The axis of abscissa indicates speed in km / h, and the axis of ordinate indicates height in millimeters.

[0083] As a variant, the invention can also be applied to a flexible sail, in which case the aerodynamic profile on which the series of pressure sensors is placed comprises a rigid profile mast arranged at the front end of the sail.

[0084] References cited in the description:

[0085] WO 2015091994 A1, corresponding to document US 2016313150;

[0086] WO 2015091996 A1, corresponding to document US 20170079152;

[0087] EP 3144684 A1, corresponding to document US 20170074750.

Claims

1. A sailboat, the sailboat include: forming an aerodynamic shape (12) of the sail of the sailboat; and a system for determining the characteristics of the airflow (F) by determining the position of the stagnation point of the airflow (F) incident on the leading edge (14) of the aerodynamic profile, wherein the system comprises: a series (S1 to S5) of pressure sensors (16) arranged on the surface of the aerodynamic profile (12), the pressure sensors (16) in each series being distributed on either side of the leading edge (14) of the aerodynamic profile, the series (S1 to S5) of pressure sensors virtually forming respective patterns (M1 to M5) spaced apart from one another, each of the patterns being a simple broken line; and a computer (20) connected to the pressure sensors (16) so as to receive local pressure values ​​respectively originating from the pressure sensors; wherein the computer (20) is configured to determine, along each of the patterns (M1 to M5), a respective stagnation point position defined by a curvilinear abscissa (a1 to a5) defined along the pattern (M1 to M5) in question and by a height (z1 to z5) evaluated from respective height data of a pressure sensor (16) in the corresponding series (S1 to S5), for which the pressure P* interpolated from the pressure measurements transmitted by the pressure sensor (16) in the corresponding series (S1 to S5) is maximum along the pattern in question, And wherein the respective altitude data of the pressure sensors (16) are determined based on the respective altitudes of the pressure sensors (16) in a reference frame fixed relative to the sailboat and based on a variable component determined for each of the pressure sensors (16) based on the measurement results of the orientation of the sailboat.

2. The sailboat according to claim 1, in, The patterns (M1 to M5) are in respective pattern planes (P1 to P5) different from each other and such that each of the pattern planes is orthogonal to an osculating plane (O1 to O5) at the intersection of the leading edge (14) and the pattern plane (P1 to P5) in question.

3. The sailboat according to claim 2, in, The pattern planes (P1 to P5) are parallel to each other.

4. The sailboat according to claim 1, in, The system also includes a memory (22) containing a mapping associating the stagnation point positions and operating parameters of the aerodynamic profile (12) respectively determined along each of the patterns (M1 to M5) with the directional distribution of the airflow (F).

5. A sailing boat according to any one of claims 1 to 4, in, The computer (20) is further configured to determine, along each of the patterns (M1 to M5), a respective stagnation pressure (PS1 to PS5) defined as the value of the pressure P* at the corresponding stagnation point location.

6. The sailboat according to claim 5, in, The system further comprises a reference pressure sensor (24) placed in a shielded area away from the aerodynamic profile (12) and connected to the computer (20), and wherein the computer (20) is further configured to generate a reference pressure signal based on a reference pressure signal P transmitted by the reference pressure sensor (24). ref , and determining a velocity distribution of the airflow (F) according to the stagnation pressures (PS1 to PS5) respectively determined along each of the patterns (M1 to M5).

7. The sailboat according to claim 5, in, The system also includes an anemometer connected to the computer (20), and wherein the computer is further configured to determine the velocity distribution of the airflow (F) by equating the airflow velocity value transmitted by the anemometer with the velocity value of the airflow incident on one of the patterns (M1 to M5) and based on the stagnation pressure (PS1 to PS5) determined along each of the patterns (M1 to M5), respectively.

8. A sailboat according to any one of claims 1 to 4, comprising an automatic or assisted pilot device (26), which is configured to control at least one operating parameter of the aerodynamic profile (12) based on the position of the stagnation point determined along each of the patterns (M1 to M5).

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