CN115071939B - Follow-up symmetrical front wing sail - Google Patents

Abstract

The invention is a following symmetrical flap sail, which belongs to the field of ships and ocean engineering. It includes a main sail assembly, a flap and a transmission mechanism. Two symmetrically arranged flaps are connected to the main sail assembly through the transmission mechanism. The main sail assembly includes a main sail assembly. The main sail is connected to the drive module in the hull through the main sail shaft; the two flaps are symmetrical to the plane of the main sail's chord and are embedded in the grooves on both sides of the main sail; the two flaps are controlled by the transmission mechanism The retracting and unfolding action of the wing; when the main sail angle is 0, the two flaps are retracted in the grooves on both sides of the main sail to form an integral airfoil sail; when the main sail rotates, one side flap in the direction of movement of the tail of the main sail Turn in the same direction to the trailing edge of the mainsail, and retract the other flap into the mainsail groove. The invention pushes out the flap to increase the area of the sail. When the main sail rotates and the flap is pushed out, a gap is generated between the leading edge of the flap and the main sail, allowing part of the airflow to flow through the windward side of the main sail through the gap to the leeward side of the sail. Blowing away the trailing edge vortices greatly increases lift.

Description

A kind of following symmetrical flap sail

Technical field

The invention belongs to the field of ships and ocean engineering, and specifically relates to a following symmetrical flap sail.

Background technique

Due to the rise in fuel prices in recent years and the International Maritime Organization's strict requirements for ship energy conservation and emission reduction, major international shipping companies are actively looking for new methods of ship energy conservation and emission reduction, and have increased their efforts in the development of new energy sources. Invest. Wind energy, as a clean natural energy source, has been favored by people. Therefore, sails, as an application for ship navigation, have become a hot research topic in the shipping industry around the world. On the other hand, due to its low energy consumption and ultra-long range characteristics, unmanned sailboats have also become popular in the field of maritime unmanned systems in various countries in recent years. The working principle of a sail is to use the pressure difference formed by the airflow around the sail to generate lift, thereby generating power. Therefore, under the same area, the higher the efficiency of the sail, the lower the energy consumption of the ship and the lower the emissions.

Sail can be divided into soft sail and wing sail (i.e. hard airfoil sail). Because wing sail is relatively simple to operate and can provide relatively large lift, it is widely used in unmanned sailboats and navigation aids of large ships. The current focus of research in this field is to change the structure of the sail to increase the lift of the sail. One way is to add flaps to the end of the sail. Most flap sails today use simple flaps or slotted flaps. Simple flaps have a simple structure and are easy to install and operate. However, this structure basically does not change the area of the sail, so the increase in lift is small; the slotted flap improves lift more significantly, but according to the current design, this kind of flap The left and right asymmetry during deployment makes the sail's aerodynamic performance inconsistent when it rotates to both sides, which is not conducive to control (such as a new high-lift sail equipped with movable flaps proposed by Denmark's Rosander M and Bloch JOV in 2000). Moreover, the design of the slotted flap places a large number of flap slider mechanisms outside the sail, and external interference will reduce the reliability of this mechanism (see patent authorization announcement number CN104925241B).

Contents of the invention

Technical issues to be resolved:

In order to avoid the shortcomings of the prior art, the present invention provides a following symmetrical flap sail based on the structural characteristics of the Fuller flap. A pair of flaps of the same size are symmetrically installed on the trailing edge of the wing sail, and the The mechanical powerless transmission mechanism realizes the retracting and retracting action of the flaps. When the wing sail is turned, the flaps are released, which increases the surface area and section curvature of the sail, greatly increasing the lift of the sail; and because the Fuller flap is a retreating flap, the airflow blows away the trailing edge vortex through the gap, making the lift increase effect very great. obvious.

The technical solution of the present invention is: a following symmetrical flap sail, which includes a main sail assembly, a flap and a transmission mechanism, and two symmetrically arranged flaps are connected to the main sail assembly through the transmission mechanism;

The main sail assembly includes a main sail and a main sail shaft. The main sail is connected to a drive module in the hull through the main sail shaft, and the rotation of the main sail is controlled by the drive module;

The two flaps are symmetrical to the plane where the chord of the main sail lies, and are embedded in the grooves on both sides of the main sail;

The retracting and unfolding action of the two flaps is controlled by the transmission mechanism; when the main sail angle is 0, the two flaps are retracted in the grooves on both sides of the main sail to form an integral airfoil sail; when the main sail rotates, the main sail One flap in the direction of movement of the tail of the sail is turned in the same direction to the trailing edge of the mainsail, and the other flap is retracted into the mainsail groove.

A further technical solution of the present invention is that the drive module is a motor, the output shaft of the motor is coaxially connected to the main sail shaft, and the motor controls the rotation of the main sail shaft.

A further technical solution of the present invention is: the transmission mechanism includes a main sail shaft gear, a transmission shaft bottom gear, a transmission shaft main gear, a transmission shaft, a double gear, a rack, and a push rod assembly;

The main sail has a through hole along the span direction, and the through hole is located near the leading edge of the main sail; the drive shaft is arranged in the through hole, and is capable of relative rotation due to a clearance fit;

The bottom gear of the transmission shaft is fixed on the bottom end of the transmission shaft and meshes with the main sail shaft gear fixed on the main sail shaft; the power of the drive module is transmitted to the transmission shaft through gear transmission;

The main gear of the drive shaft, the double gear and the rack are located in the main sail. The main gear of the drive shaft is coaxially mounted on the drive shaft. The two racks are arranged side by side with the tooth surfaces facing both sides; the two double gears are opposite to each other. Inverted, the pinion ends are meshed with the main gear of the transmission shaft, and the large gear end is meshed with two racks respectively;

Guide holes are respectively opened between the rack and the grooves on both sides of the main sail, and the flaps on both sides are connected to the rack through push rod assemblies passing through the guide holes; the drive shaft drives the drive shaft main gear, double The coupling gear rotates, which in turn drives the rack and push rod components to control the retraction and expansion of the flaps.

A further technical solution of the present invention is that the push rod assembly includes an intermediate push rod and a secondary power push rod, one end of the intermediate push rod is hinged to the rack, and the other end is hinged to the fixed end of the secondary power push rod; The free end of the secondary power push rod is articulated with the leading edge of the flap.

A further technical solution of the present invention is that the secondary power push rod has a telescopic structure, and a spring limiting structure is provided inside it.

A further technical solution of the present invention is that fixing pieces are respectively installed at both ends of the transmission shaft to limit its axial displacement.

A further technical solution of the present invention is that the cross section of the flap is a variable curvature airfoil.

A further technical solution of the present invention is: the groove profile of the main sail is consistent with the front end of the flap variable curvature airfoil, ensuring that the retracted flap completely fits within the groove of the main sail;

The front end of the groove of the main sail has a rounded structure, so that the airflow will not generate turbulence when passing by, and can flow smoothly to the flaps.

A further technical solution of the present invention is: the upper and lower ends of the flaps are respectively slidingly connected to the upper and lower groove walls in the main sail groove through the main sail fixing three-level sliding rod; the main sail fixing three-level sliding rod is a telescopic rod, Its fixed end is rotatably connected to the groove wall, and its free end is rotatably connected to the flap end face; when the flap is retracted and retracted under the control of the transmission mechanism, the mainsail fixed three-stage sliding rod located at the upper and lower ends of the flap ensures the movement of the flap through telescopic motion. trajectory.

A further technical solution of the present invention is that the main gear of the transmission shaft of the transmission mechanism is located in the middle position of the main sail in the spanwise direction, and is combined with the main sail fixed three-stage sliding rods at the upper and lower ends to achieve smooth retraction and expansion of the flaps.

A further technical solution of the present invention is: the fixed end of the secondary power push rod is located in front of the fixed end of the main sail fixed third-stage slide rod, closer to the main sail leading edge and wing chord;

The angle between the extension line of the secondary power pushrod and the mainsail chord is θ ₁ , so that when the flap is pushed out, a gap is created between its leading edge and the inside of the flap on the other side, and the airflow blows away the trailing edge vortex through the gap and increases the vortex. Lift effect; the angle between the fixed three-stage slide rod of the main sail and the main sail chord is θ ₂ , θ ₂ > θ ₁ , so that the lateral movement distance of the trailing edge of the flap is greater than that of the leading edge. The longer the push-out distance, the greater the rotation angle. The greater the effect.

Working principle: When the wing sail rotates, the greater the turning angle, the greater the lift generated. The flaps will rotate in the same direction toward the trailing edge of the wing sail, while the flaps on the other side are retracted to a fixed position. The flap rotation angle on the rotating side has a linear relationship with the sail angle of the main sail. The greater the wing sail rotation angle, the larger the flap release area and downward release angle, and the greater the lift generated. big. When the sail angle is zero, the flaps on both sides are retracted, and the shape is a complete wing sail, and the lift generated at this time is minimal. The flaps extend at the same angle and length when the wing sail turns to both sides, ensuring that under the same circumstances, the lift generated when the sail turns to both sides is consistent, thus solving the problem in the prior art that the flap sail turns to both sides. Aerodynamic inconsistency issues. The control part of the present invention is a purely mechanical design. There are no motors and hydraulic devices inside the sail. The power of the main sail and flaps only rely on the force of the hull to rotate the main sail. Except for the central shaft gear, there are no other exposed mechanical structures. When the sail angle is zero, all mechanical structures are inside the main sail, which avoids the core transmission mechanism from contacting the outside world and reduces environmental interference on the mechanism.

beneficial effects

The beneficial effects of the present invention are:

1. The flap sail designed by the present invention can not only push the flap backward to increase the area of the sail, but also install a transmission mechanism and a series of push rods with preset angles inside the existing wing sail body. When the main sail rotates, , when the flap is pushed out, due to the angle between the power push rod and the main sail chord, while the flap retreats and rotates, a gap can be created between the leading edge of the flap and the main sail, so that part of the airflow can By flowing the windward side of the main sail through this gap to the leeward side of the sail and blowing away the trailing edge vortex, the lift can be greatly increased. This flap sail design that combines receding flaps and slotted flaps achieves the effects of increasing the wing sail area, increasing camber, and controlling the boundary layer, that is, it achieves the effect of a Fuller flap. Referring to Figure 1, when turned at the same angle, the lift effect of a Fuller flap sail is better than that of a simple flap sail. Under the same energy conditions, this design can effectively increase the range of the aircraft.

2. Most of the current slotted flap sails and receding flap sails are not symmetrical, but the present invention can make the sail have consistent aerodynamic characteristics when it rotates to both sides, and it is easy to control when the main sail rotates to both sides at the same angle. When the power push rods on both sides push out the flaps on both sides, the distance the flaps deviate from the fore and aft lines of the mainsail, and the angle at which the flaps rotate outward are all the same, resulting in an increased area of the sail, increased camber and slits in the section. The sizes are all the same. Obviously, under the same angle of attack and air conditions, the aerodynamic characteristics of such a design are consistent when the sail is turned to the same angle on both sides, and the lift generated is also consistent. This symmetrical feature means that both sides of the sail have the same and complete aerodynamic characteristics, which eliminates the turbulence generated when the asymmetric flaps rotate to the side with incomplete aerodynamic characteristics, improves the efficiency of the sail, and saves more energy. And compared with the design of an asymmetric sail that has uneven force when rotating to both sides, the present invention reduces the difficulty of controlling the sail. Compared with an asymmetric sail, the use of this sail increases the sail's maneuverability, thereby increasing the sail's maneuverability. It improves the maneuverability of the ship, reduces the energy consumption of the asymmetric flap sail due to this part of the control, and further saves energy. This also reduces the complexity of the control system, thereby improving the robustness of the system.

3. The present invention can control the degree of flap push-out in proportion to the rotation angle of the main sail. The greater the sail angle, the greater the lift provided. When the sail angle is zero, the two flaps are fully retracted, and no unnecessary force will be generated. , Undesired resistance. Compared with traditional sails, this invention has a higher lift coefficient and lift-to-drag ratio, and can easily achieve variable angle control. The maximum flap rotation angle is 30°, making lift greater than drag.

4. In the present invention, the flap rotation angle and push-out area can change with the angle of the sail, which solves the problem that in some designs, the flaps only have two modes: deployment and retraction. As the deflection angle of the flap sail increases, the sail's deflection angle increases. The lift coefficient and lift-drag ratio increase accordingly, and the thrust coefficient of the sailboat increases, which has a better impact on improving the performance of the sailboat.

5. The structure of the invention is simple. The core transmission mechanism inside the main sail only has three gears, two racks and two sets of push rods. It does not require additional motors or hydraulic devices to provide thrust, and the main mechanisms are all inside the main sail, making the system More simple and reliable, less likely to be interfered by external factors. When unfolded, it can increase the stress-bearing area of the sail and greatly improve the utilization rate of wind energy. It is beneficial to the stability of the ship and facilitates maintenance and repair. Using wind energy to sail greatly extends its working time.

Description of the drawings

Figure 1 is a comparison chart of lift coefficient curves;

Figure 2 is an overall isometric view of a following symmetrical flap sail based on the Fuller flap structure of the present invention when the flaps on both sides are retracted.

Figure 3 shows the overall isometric view of the right flap when it is pushed out;

Figure 4 is a front view when the flaps on both sides of the flap sail are retracted;

Figure 5 is the front view of the flap on the right side of the flap sail when it is pushed out;

Figure 6 is a top view when the flaps on both sides of the flap sail are retracted;

Figure 7 is a top view of the flap sail when the left flap is retracted and the right flap is pushed out;

Figure 8 is a schematic diagram of the connection between the internal transmission mechanism of the main sail and the flap. The transmission mechanism is connected to the flap, and the three-stage sliding rod fixed to the main sail is also connected to the flap. This is the state when both flaps are retracted;

Figure 9 is a schematic diagram of the connection between the internal transmission mechanism of the main sail and the flap. The transmission mechanism is connected to the flap, and the three-stage slide rod fixed to the main sail is also connected to the flap. This is the state when the right flap is pushed out;

Figure 10 is a partial enlarged view of Figure 8, highlighting the meshing and connection between the main gear of the transmission shaft and the double gear, rack, intermediate push rod, and power push rod;

Figure 11 is a partial enlarged view of Figure 9, highlighting the meshing and connection between the main gear of the transmission shaft and the double gear, rack, intermediate push rod, and power push rod;

Figure 12 is a schematic diagram of the appearance of the upper left side of the trailing edge of the wing sail when the flaps on both sides are retracted;

Figure 13 is a perspective view of the connection between the mainsail fixed three-stage slide rod and the flaps above the left side of the wing sail trailing edge when the flaps on both sides are retracted;

Figure 14 is a schematic diagram of the appearance of the upper left side of the trailing edge of the wing sail when the right flap is pushed out;

Figure 15 is a perspective view of the connection between the mainsail fixed three-stage slide rod and the flap above the left side of the wing sail trailing edge when the right flap is pushed out;

Figure 16 is a partially enlarged schematic diagram of the connection between the power push rod and the left flap when the right flap is pushed out;

Explanation of reference signs: 1-mainsail; 2-mainsail shaft; 3-mainsail shaft gear; 4-mainsail fixed three-stage slider; 5-flaps; 6-flap shaft 7-flap leading edge fixed Pin; 8-drive shaft bottom gear; 9-drive shaft main gear; 10-double gear; 11-rack; 12-rack track constrainer; 13-intermediate push rod; 14-secondary power push rod; 15 -Fixing piece; 16-Drive shaft.

Detailed ways

The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention and are not to be construed as limiting the present invention.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " The directions indicated by "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" etc. or The positional relationship is based on the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, Therefore, it should not be construed as a limitation of the present invention.

Referring to Figures 2, 3, 4 and 5, a following symmetrical flap sail in this embodiment is composed of a main sail assembly, a flap and a transmission mechanism. Two symmetrically arranged flaps 5 are connected to the mainsail assembly through a transmission mechanism; the mainsail assembly includes a mainsail 1 and a mainsail shaft 2. The mainsail 1 is connected to the driving module in the hull through the mainsail shaft 2, and through the driving module Control the rotation of the main sail; the two flaps are symmetrical to the plane where the chord of the main sail 1 is located, and are embedded in the grooves on both sides of the main sail 1;

The retracting and unfolding action of the two flaps is controlled by the transmission mechanism; when the main sail angle is 0, the two flaps are retracted in the grooves on both sides of the main sail to form an integral airfoil sail; when the main sail rotates, the main sail One flap in the direction of movement of the tail of the sail is turned in the same direction to the trailing edge of the mainsail, and the other flap is retracted into the mainsail groove.

The cross-section of the main sail 1 is a NACA0415 airfoil, which can ensure that the lift force is greater than the drag force under conventional aerodynamic characteristics. The groove on the trailing edge of the main sail 1 is a variable curvature concave arc surface that is concave toward the center line of the main sail. The front side of the flap 5 is a variable curvature airfoil surface with the same curvature as the variable curvature concave arc surface on the main sail. In the retracted state, the flap 5 closely fits the variable curvature concave arc surface on the main sail 1 through its variable curvature airfoil surface. The front end of the slot is curved so that the airflow will not produce turbulence when passing by and can flow smoothly to the flaps.

The transmission mechanism includes a main sail shaft gear 3, a drive shaft bottom gear 8, a drive shaft main gear 9, a drive shaft 16, a double gear 10, a rack 11, and a push rod assembly; the main sail 1 has a Through hole, and the through hole is located near the leading edge of the main sail 1; the transmission shaft 16 is provided in the through hole, and can rotate relatively with a clearance fit, and fixed pieces are installed on the upper and lower ends respectively to limit its axial displacement. The transmission shaft bottom gear 8 is fixed on the bottom end of the transmission shaft 16 and meshes with the main sail shaft gear 3 fixed on the main sail shaft 2; the power of the drive module is transmitted to the transmission shaft 16 through gear transmission; the transmission shaft The main gear 9, the double gear 10 and the rack 11 are located in the main sail 1. The main gear 9 of the transmission shaft is coaxially mounted on the transmission shaft 16. The two racks 11 are arranged side by side with the tooth surfaces facing both sides. The trajectory restrainer 12 limits its offset to ensure the movement trajectory; the two double gears 10 are inverted with each other, and their pinion ends are meshed with the main gear of the transmission shaft, and the large gear end is meshed with two racks respectively; the rack 11 and There are guide holes respectively between the grooves on both sides of the main sail 1, and the flaps 5 on both sides are respectively connected to the rack 11 through push rod assemblies passing through the guide holes; the transmission shaft 16 drives the transmission shaft main gear 9, double The coupling gear 10 rotates, thereby driving the rack 11 and the push rod assembly to control the retracting and unfolding of the flaps.

The middle part of the flap 5 is connected to the main sail 1 through a push rod assembly. The push rod assembly includes an intermediate push rod 13 and a secondary power push rod 14. One end of the intermediate push rod 13 is articulated with the rack 11 , the other end is hinged with the fixed end of the secondary power push rod 14; the free end of the secondary power push rod 14 is hinged with the leading edge of the flap 5. The movement of flap 5 is mainly powered by the secondary power push rod 14.

The upper and lower ends of the flap 5 are respectively slidingly connected to the upper and lower groove walls in the groove of the main sail 1 through the main sail fixing three-level sliding rod 4; the main sail fixing three-level sliding rod 4 is a telescopic rod, and its fixed end is connected to the upper and lower groove walls of the main sail 1 groove. The groove wall is rotatably connected, and the free end is rotatably connected to the protruding shaft provided on the end face of the flap 5 through a bearing; when the flap 5 is controlled by the transmission mechanism to retract and unfold, the main sail fixed three-stage slide rod 4 located at the upper and lower ends of the flap 5 telescopically The movement ensures the movement trajectory of the flap.

Referring to Figures 6, 7, and Figures 12 to 16, when the flaps 5 on both sides retract the mainsail 1, the cross-section view is that of a complete, ordinary airfoil sail. At this time, the resistance of the entire sail is minimal. . When the main sail 1 turns to a certain angle, the flap 5 will be pushed out accordingly. Since this embodiment is based on the structure of a retreating flap such as Fuller flap, from the cross-sectional view, when the flap 5 is pushed backward, the clamp between the main sail fixed three-stage slide rod 4 and the fore and aft line of the main sail 1 The angle is greater than the angle between the secondary power pushrod 14 and the fore and aft line of the mainsail 1, and the connection point between the secondary power pushrod 14 and the flap 5 is located in front of the mainsail fixed third-stage slider 4 and the flap 5. This will The trailing edge of the flap 5 will move away from the fore and aft line of the main sail 1, which not only increases the air flow area, but also increases the cross-sectional curvature, thereby increasing the area of the negative pressure zone on the other side of the main sail 1. Moreover, a gap will be generated between the pushed-out flap 5 and the un-pushed flap 5 on the other side, allowing the airflow to blow away the trailing edge vortex through the gap to increase the lift effect.

Referring to Figures 8 to 11, the connection between the transmission mechanism and the flap 5 is shown, the flaps on both sides retract the main sail 1, and the flap 5 on one side is pushed out. The driving mechanism includes a transmission shaft 16, two double gears 10, two racks 11, two intermediate push rods 13, and two secondary power push rods 14. A transmission shaft main gear 9 is fixed at the center of the transmission shaft 16, and meshes with a mutually inverted double gear 10 at the rearward positions on both sides of the transmission shaft 16. The double gear 10 is a small gear meshing with the main gear 9 of the transmission shaft, and a large gear meshing with the rack 11 . The large gears of the two double gears 10 are staggered up and down to leave space for the rack 11. The rack track restrictor 12 is sleeved on the transmission shaft 16 in one section, and has two bearings arranged in one section. Its function is to constrain the rack 11 to only move forward and backward horizontally. The end of the rack 11 pointing to the trailing edge of the main sail has a fixed pin covered with a bearing and is connected to the middle push rod 13. The middle push rod 13 is connected to the secondary power push rod 14, and the secondary power push rod 14 passes through the main sail. The fixing hole is connected to the flap 5. A spring is installed between the inner and outer layers of the secondary power push rod 14. If it is pulled, it will receive force, thereby fixing the flap 5 in the slot at the rear end of the main sail 1. When the mainsail 1 rotates, for example, when the sail turns to the right, the mainsail shaft gear 3 rotates clockwise, which drives the transmission shaft bottom gear 8 to rotate counterclockwise, causing the transmission shaft main gear 9 to also move counterclockwise, and then drives the double gear 10 Rotate clockwise, causing the right rack 11 to push out the right flap 5 backward. The greater the rotation angle of the sail, the more the flap 5 is pushed out; the left rack 11 moves forward, and due to the secondary power push rod 14 There is a spring in the middle, so that when the push rod moves forward of the main sail 1, the flap 5 can be pulled and fixed in the groove on the trailing edge of the main sail 1.

Judging from the cross-sectional view of the flap, the fixed point of the secondary power push rod is in front of the main sail fixed third-stage slide rod and is closer to the bow and stern line of the main sail. The extension line of the secondary power pushrod has a small angle with the bow and tail line of the main sail, so that when the flap is pushed out, a gap is created between its leading edge and the inside of the flap on the other side. The airflow blows away the trailing edge vortex through the gap to increase lift. Effect. The angle between the fixed pushrod of the mainsail and the fore and aft line of the mainsail is slightly larger than that of the power pushrod. This allows the trailing edge of the flap to move laterally farther than the leading edge, achieving the effect that the longer the pushout distance, the greater the rotation angle. For example, when the present invention is designed, the included angle of the power push rod is 5°, and the included angle of the main sail fixed push rod is 10°. The action points of the two sets of rods on the flap section form a moment. For example, when the left flap is pushed out, the two action points form a clockwise rotation moment, and the flap will rotate outward at a certain angle with the action point of the push rod as the axis. This angle is linearly related to the distance of the power push rod. The final effect is that the greater the main sail rotation angle, the greater the flap rotation angle. Since the drag force will be greater than the lift when the flap rotation angle is too large, the maximum flap rotation angle designed in this invention is 30° during modeling.

Although the embodiments of the present invention have been shown and described above, it can be understood that the above-mentioned embodiments are illustrative and should not be construed as limitations of the present invention. Those of ordinary skill in the art will not deviate from the principles and purposes of the present invention. Under the circumstances, the above-described embodiments can be changed, modified, replaced and modified within the scope of the present invention.

Claims (10)

1. A following symmetrical flap sail, which is characterized in that: it includes a main sail assembly, a flap and a transmission mechanism, and two symmetrically arranged flaps are connected to the main sail assembly through the transmission mechanism; The main sail assembly includes a main sail and a main sail shaft. The main sail is connected to a drive module in the hull through the main sail shaft, and the rotation of the main sail is controlled by the drive module; The two flaps are symmetrical to the plane where the chord of the main sail lies, and are embedded in the grooves on both sides of the main sail; The retracting and unfolding action of the two flaps is controlled by the transmission mechanism; when the main sail angle is 0, the two flaps are retracted in the grooves on both sides of the main sail to form an integral airfoil sail; when the main sail rotates, the main sail One flap in the direction of movement of the tail of the sail is turned in the same direction to the trailing edge of the mainsail, and the other flap is retracted into the mainsail groove. 2. The following symmetrical flap sail according to claim 1, characterized in that: the transmission mechanism includes a main sail shaft gear, a transmission shaft bottom gear, a transmission shaft main gear, a transmission shaft, a double gear, a rack, and a pusher. rod assembly; The main sail has a through hole along the span direction, and the through hole is located near the leading edge of the main sail; the drive shaft is arranged in the through hole, and is capable of relative rotation due to a clearance fit; The bottom gear of the transmission shaft is fixed on the bottom end of the transmission shaft and meshes with the main sail shaft gear fixed on the main sail shaft; the power of the drive module is transmitted to the transmission shaft through gear transmission; The main gear of the drive shaft, the double gear and the rack are located in the main sail. The main gear of the drive shaft is coaxially mounted on the drive shaft. The two racks are arranged side by side with the tooth surfaces facing both sides; the two double gears are opposite to each other. Inverted, the pinion ends are meshed with the main gear of the transmission shaft, and the large gear end is meshed with two racks respectively; Guide holes are respectively opened between the rack and the grooves on both sides of the main sail, and the flaps on both sides are connected to the rack through push rod assemblies passing through the guide holes; the drive shaft drives the drive shaft main gear, double The coupling gear rotates, which in turn drives the rack and push rod components to control the retraction and expansion of the flaps. 3. The following symmetrical flap sail according to claim 2, characterized in that: the push rod assembly includes an intermediate push rod and a secondary power push rod, one end of the intermediate push rod is hinged with the rack, and the other end is articulated with the rack. The fixed end of the secondary power push rod is hinged; the free end of the secondary power push rod is hinged with the leading edge of the flap. 4. The following symmetrical flap sail according to claim 3, characterized in that: the secondary power push rod has a telescopic structure and a spring limiting structure is provided inside it. 5. The following symmetrical flap sail according to claim 4, characterized in that: both ends of the transmission shaft are respectively equipped with fixed pieces for limiting its axial displacement. 6. The following symmetrical flap sail according to claim 5, characterized in that: the cross section of the flap is a variable curvature airfoil. 7. The following symmetrical flap sail according to claim 6, characterized in that: the groove profile of the main sail is consistent with the front end of the flap variable curvature airfoil, ensuring that the flap after retracting completely fits the in the groove of the mainsail; The front end of the groove of the main sail has a rounded structure, so that the airflow will not generate turbulence when passing by, and can flow smoothly to the flaps. 8. The following symmetrical flap sail according to claim 7, characterized in that: the upper and lower ends of the flap are slidingly connected to the upper and lower groove walls in the main sail groove through the main sail fixed three-level sliding rod respectively; The main sail fixed three-stage sliding rod is a telescopic rod, its fixed end is rotationally connected to the groove wall, and the free end is rotationally connected to the flap end face; when the flap is controlled by the transmission mechanism to retract and expand, the main sail is fixed to the three-stage main sail at the upper and lower ends of the flap. The stage slide rod ensures the motion trajectory of the flap through telescopic movement. 9. The following symmetrical flap sail according to claim 8, characterized in that: the main gear of the transmission shaft of the transmission mechanism is located at the middle position of the main sail in the span direction, and is combined with the main sail at the upper and lower ends to fix the three-stage slide rod to achieve flap. Smooth retracting and retracting action of the wings. 10. The following symmetrical flap sail according to claim 9, characterized in that: the fixed end of the secondary power push rod is located in front of the fixed end of the main sail fixed third-stage slide rod, closer to the leading edge of the main sail and the wing chord. ; The angle between the extension line of the secondary power pushrod and the mainsail chord is θ ₁ , so that when the flap is pushed out, a gap is created between its leading edge and the inside of the flap on the other side, and the airflow blows away the trailing edge vortex through the gap and increases the vortex. Lift effect; the angle between the fixed three-stage slide rod of the main sail and the main sail chord is θ ₂ , θ ₂ > θ ₁ , so that the lateral movement distance of the trailing edge of the flap is greater than that of the leading edge. The longer the push-out distance, the greater the rotation angle. The greater the effect.