Shape-maintaining foldable propeller matched with water-drop-shaped nacelle and design method of shape-maintaining foldable propeller

Abstract

The invention provides a shape-preserving foldable propeller matched with a water-drop-shaped nacelle and a design method of the shape-preserving foldable propeller, and relates to the field of aeronautical technical equipment.The shape-preserving foldable propeller comprises a nacelle body in a water-drop shape and propeller blades. A geometric parameterization model of the nacelle body, a geometric parameterization model of the rotor wing type and a geometric parameterization model of the rotor wing type family; performing aerodynamic performance analysis modeling: performing rotor wing performance analysis model modeling, airfoil profile performance analysis model modeling and airfoil profile preprocessing by using a strip theory; and optimizing the outer arc airfoil family. The outer arc airfoil family optimization comprises outer arc airfoil family optimization, optimization condition setting and pneumatic database establishment. The problem that the resistance of the unmanned aerial vehicle is large in the cruising state is solved.

Description

Technical Field

[0001] One or more embodiments of the present specification relate to the field of aviation technology equipment, specifically a conformal foldable propeller matching a teardrop-shaped nacelle and a design method thereof. Background Art

[0002] Tilt-wing UAVs (UAVs) are currently attracting significant attention in the aviation industry, combining the advantages of both fixed-wing and rotary-wing UAVs to achieve vertical takeoff and landing (VTOL) and efficient cruising. With the development of distributed propulsion technology, which has shown the potential to increase power safety margins and improve air propulsion efficiency, researchers are attempting to apply the distributed propulsion concept to these UAVs, creating distributed propulsion tilt-wing UAVs.

[0003] As one of the most critical power components of a distributed propulsion tilt-wing UAV, the rotor's operating efficiency plays a crucial role in the UAV's overall performance. For tilt-wing configurations, rotor thrust requirements vary significantly across different flight modes: in vertical and transition modes, the thrust must balance the overall weight of the aircraft, while in cruise mode, the thrust only needs to balance overall drag. Consequently, the rotor itself presents complex design conditions and high overall parameter sensitivity. The use of advanced propulsion methods, such as distributed propulsion, further complicates the constraints involved in the design process. Furthermore, to reduce cruise drag and improve cruise efficiency, these UAVs partially fold their rotors during cruise. While the rotors and their nacelles are optimized to reduce drag, the shape of the rotors folded outside the nacelle significantly impacts the nacelle's aerodynamic characteristics, significantly increasing the nacelle's drag and negating the advantages of the aerodynamic design. This loss of cruise efficiency caused by the independent design of the power cabin and the nacelle continues to increase as the proportion of the cruise process in the entire mission profile increases. Therefore, it is very necessary to develop a conformal foldable propeller design that matches the teardrop-shaped nacelle to improve the overall performance of the rotor of this type of UAV. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to propose a conformal foldable propeller matching a teardrop-shaped nacelle and a design method thereof, so as to solve the problem that the rotor and its power nacelle proposed in the above-mentioned background technology respectively adopt optimized designs to reduce resistance, but the shape of the rotor after being folded outside the nacelle significantly affects the aerodynamic characteristics of the nacelle, causing the resistance of the power nacelle to increase sharply and failing to exert the advantages of the aerodynamic design.

[0005] This application adopts the following scheme

[0006] A conformal folding propeller matching a teardrop-shaped nacelle, the teardrop-shaped nacelle comprising

[0007] The nacelle body is teardrop-shaped and formed by rotating a given nacelle busbar around an axis. Frames 1, 2, 3, 4, and 5 are sequentially arranged inside the nacelle body from front to back. These frames are connected by longitudinal beams. Frame 1 has lightening holes, which facilitate wiring. Frame 2 serves as a structural reinforcement. Frame 3 has lightening holes. Frame 5 also serves as a structural reinforcement.

[0008] An electric adjustment mounting plate, the electric adjustment mounting plate being fixed on the longitudinal beam;

[0009] A motor, wherein the motor is fixed on the frame 1;

[0010] The ESC is connected to the motor and is mounted on the ESC mounting plate;

[0011] a propeller hub, the propeller hub being fixedly connected to the protruding end of the motor;

[0012] The fairing is fixedly connected to the propeller hub and rotates with the propeller hub. It is characterized by including

[0013] Propeller blades, wherein the propeller blades are hingedly mounted on the hub, the upper surface of the propeller blades being the nacelle outer surface, and the lower surface being the optimized airfoil surface;

[0014] The propeller dock is opened on the surface of the nacelle body. After the propeller blades are folded, they are completely attached to the nacelle propeller dock to achieve shape preservation. After the propeller blades are stored, they are completely embedded in the propeller dock, and the outer surface is a rotationally symmetrical teardrop shape.

[0015] As an embodiment of the present invention, the hub is circumferentially provided with a plurality of ears and openings, the root of the propeller blade is opened and cooperates with the hole of the hub ear and is fixed by bolts and nuts. The propeller can rotate at least 100° around the hole axis to achieve the folding and unfolding of the propeller blade.

[0016] As an embodiment of the present invention, a conformal folding propeller and a nacelle design method matching a teardrop-shaped nacelle are provided, characterized in that a battery is connected to an electric regulator and is installed on frame three and frame four, and the equipment can be installed through a hole in the bottom of the nacelle.

[0017] As an embodiment of the present invention, it includes

[0018] Shape parameterization under geometric compatibility constraints: The shape parameterization under geometric compatibility constraints includes establishing a geometric parameterized model of the nacelle body, a geometric parameterized model of the rotor airfoil, and a geometric parameterized model of the rotor airfoil family;

[0019] Aerodynamic performance analysis and modeling: The aerodynamic performance analysis and modeling includes rotor performance analysis modeling, airfoil performance analysis modeling, and airfoil preprocessing using strip theory;

[0020] Optimization of outer arc airfoil family: The optimization of outer arc airfoil family includes optimizing the outer arc airfoil family, setting optimization conditions, and establishing an aerodynamic database.

[0021] As an embodiment of the present invention, the parameterization of the rotor airfoil includes: parameterizing the outer wing surface of the airfoil, the lower wing surface of the airfoil, and the leading edge of the airfoil. The given outer arc is divided into N parts. At this time, the position of the Fi type value point can be determined according to the length aiR of the line segment OaFi and the angle biζ between OaFi and OaF0. By defining ai and bi, the position of each type value point can be obtained, and the lower airfoil surface is fitted. The radius of the airfoil leading edge is determined based on the tangent conditions of the three sides of the upper wing surface, the lower wing surface, and the OaF0 line segment. Oa represents the center of the outer arc, Fi represents the type value point of one of the tangent lines divided into N parts, ai represents the coefficient of the lower wing surface radius corresponding to the Fi type value point, and bi represents the angle coefficient of the center angle corresponding to the Fi type value point.

[0022] As one embodiment of the present invention, the rotor airfoil parameterization includes rotor radius position mapping, twist angle distribution mapping, and chord length distribution mapping. Each point on the rotor is represented using an offset x, a cross-sectional radius r corresponding to the offset, and an angular offset θ, which can be represented by a folded parameter set ΩF = {x, r, θ}. Then, based on the invariance of the rotor shape, a mapping relationship is established between the folded parameter set Ωzd and the unfolded parameter set Ωzk.

[0023] As an embodiment of the present invention, the rotor is mapped along the radius, and its power deck generatrix equation is obtained by S1, which is simply expressed as r=f(x). Cross-section in unfolded state One-to-one correspondence. The rotor blade position xi in the folded state corresponds to the rotor position along the radial radius in the unfolded state.

[0024]

[0025] As an embodiment of the present invention, the torsion angle distribution map is composed of Figure 10 The geometric relationship shown in the figure shows that the cross section in the folded state Relative to the starting arc section The torsion angle is the relative torsion angle βi which can be expressed as:

[0026]

[0027] when The median vector at When θi coincides with the Y-axis (θ0 = 0), βi = θi. Therefore, simply by defining the variation of θi along the x-direction, the torsion angle of each control section relative to the starting section in the folded state can be determined. A quartic Bezier curve is used to represent the relative torsion angle, and the relative torsion angle in the unfolded state is consistent with that in the folded state.

[0028]

[0029] Then the rotor rotation is decomposed. The rotation around the O'Z' axis makes the rotor fully open; while the rotation around the O'Y' axis adds the root chord installation angle to the deployed blade. Then, when the rotor is fully deployed, the actual torsion angle of the i-th control section is for

[0030]

[0031] Where ψ is the Euler angle of the rotor around the O′Y′ axis.

[0032] As an embodiment of the present invention, the chord length distribution mapping is consistent with the chord length distribution in the expanded state and the folded state, so the chord length ci of each section can be solved in the folded state, that is,

[0033] c i =|A i B i |=2r i sin(ζ i / 2)

[0034] Where ζi is Corresponding to the central angle of the circle. In this paper, the distribution of the central angle ζ along the x-direction can be represented by two tangent quadratic curves. When the vertex coordinates of the quadratic curve are (xp, yp), the starting coordinates of the first quadratic curve are (0, y0), and the ending coordinates of the second quadratic curve are (1, y1).

[0035]

[0036] As an embodiment of the present invention, the aerodynamic performance analysis modeling: rotor performance analysis model: the present invention adopts strip theory for analysis; airfoil preprocessing makes the shape compatible with the nacelle shape.

[0037] As an embodiment of the present invention, the outer arc airfoil parameterization includes

[0038] The outer arc airfoil parameterization includes improving the airfoil's thrust efficiency factor C1.5 L / CD in the design state based on the rotor airfoil family and taking geometric compatibility and thickness constraints as the premise. Two checkpoints CL1 and CL2 are set on both sides of the airfoil's design lift coefficient CLd. The weighted sum of the thrust efficiency factors corresponding to the three design lift coefficients is used as the design goal of the airfoil optimization.

[0039] Setting optimization conditions: The setting optimization conditions limit the thickness of the airfoil at the characteristic section, and the typical thickness distribution from the root to the tip Changes according to the following quadratic curve:

[0040]

[0041] Where: The root section is positioned along the radius. In the embodiment, the blade tip relative thickness δ1 is required to be no less than 8%, and the blade root thickness δ0 is required to be no less than 20%. In the embodiment, multi-point optimization is performed on the outer arc airfoil with a central angle of 20°, 30°, 40°, 50°, and 60°, respectively, with the maximum relative thickness being no less than 8%, 15%, 20%, and 25% as constraints, to ultimately obtain an outer arc airfoil family and its aerodynamic characteristics.

[0042] Establishment of an aerodynamic database: The aerodynamic database is established based on the optimized outer arc airfoil family shape, and aerodynamic characteristics calculations are performed under a given Reynolds number sequence to obtain the changes in the aerodynamic characteristics of each airfoil at different Reynolds numbers with the angle of attack. Based on this, through interpolation calculations, aerodynamic characteristic data of the outer arc airfoil family is constructed with the airfoil central angle, airfoil relative thickness, operating Reynolds number, and angle of attack as inputs, and the lift coefficient and drag coefficient as outputs.

[0043] The present invention provides a conformal, foldable propeller compatible with a teardrop-shaped nacelle and a design method thereof. The nacelle is the compartment housing the engine, and the teardrop-shaped nacelle has a teardrop-shaped exterior and a hollow, shell-like interior. The teardrop-shaped exterior effectively reduces aerodynamic drag during cruising, while the hollow interior provides space for equipment installation. This mechanism and method comprehensively consider the power requirements of a distributed tilt-wing UAV in different flight modes, resulting in a conformal rotor power nacelle design that satisfies geometric compatibility conditions and tension constraints, while exhibiting high tension efficiency and low cruising drag. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a structural diagram of the nacelle body according to the present invention;

[0045] Figure 2 This is a state diagram of the nacelle body according to the present invention;

[0046] Figure 3 This is a schematic diagram of the airfoil optimization process of the present invention;

[0047] Figure 4 is a schematic diagram of the propeller blade according to the present invention;

[0048] Figure 5 is a partial schematic diagram of the rotor hub according to the present invention;

[0049] Figure 6 This is a schematic diagram of the nacelle frame beam according to the present invention;

[0050] Figure 7 is a schematic cross-sectional view of the rotor according to the present invention;

[0051] Figure 8 Schematic diagram of the rotor strip division and key cross-sections according to the present invention;

[0052] Figure 9 Schematic diagram of the relative torsion angle in the folded state according to the present invention;

[0053] Figure 10 This is a flow chart of the nacelle design method for the propeller blade according to the present invention;

[0054] Figure 11 This is the shape parameterization flow chart of the present invention;

[0055] Figure 12 This is the outer arc optimization flow chart of the present invention;

[0056] Figure 13 This is a schematic diagram of the outer arc cross section of the present invention.

[0057] In the figure, 1. propeller blades; 2. fairing; 3. hub; 4. frame one; 5. frame two; 6. frame three; 7. frame four; 8. frame five; 9. longitudinal beam; 10. nacelle; 11. battery; 12. ESC; 13. ESC mounting plate; 14. motor; 15. nacelle outline; 16. curved airfoil upper surface; 17. curved airfoil lower surface; 18. leading edge; 19. bolts; 20. nuts; 21. propeller dock. DETAILED DESCRIPTION

[0058] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0059] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in the embodiments of the present invention should have the usual meanings understood by people with ordinary skills in the field to which the present disclosure belongs. The "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0060] like Figures 1 to 13 , a conformal folding propeller matching a teardrop-shaped nacelle, the teardrop-shaped nacelle includes

[0061] The nacelle body 10 is generally teardrop-shaped. Frame 1 4, frame 2 5, frame 3 6, frame 4 7, and frame 5 8 are sequentially arranged within the nacelle body 10 from front to back. Frame 1 4, frame 2 5, frame 3 6, frame 4 7, and frame 5 8 are connected by a longitudinal beam 9. Frame 1 4 has a lightening hole, which facilitates wiring. Frame 2 5 provides structural reinforcement. Frame 3 has a lightening hole. Frame 5 8 also provides structural reinforcement.

[0062] The electric adjustment mounting plate 13 is fixed on the longitudinal beam 9

[0063] Motor 14, wherein the motor 14 is fixed on frame 1;

[0064] The electric regulator 12 is connected to the motor 14 and is mounted on the electric regulator mounting plate 13;

[0065] The propeller hub 3 is fixedly connected to the protruding end of the motor.

[0066] The fairing 2 is fixedly connected to the hub 3 and rotates with the hub 3.

[0067] A propeller blade 1 is hingedly mounted on a hub 3, wherein the upper surface of the propeller blade is a nacelle outer surface, and the lower surface is an optimized airfoil surface;

[0068] The propeller dock 21 is provided on the surface of the nacelle body 10. The propeller blades 1 are completely attached to the nacelle propeller dock 21 after being folded to achieve shape retention. After the propeller blades are stored, they are completely embedded in the propeller dock 21, and the outer surface is a rotationally symmetrical teardrop shape.

[0069] The hub 3 is circumferentially provided with a plurality of ears and holes. The root of the propeller blade 1 is opened and matched with the hole of the hub 3 ear and is fixed by bolts 19 and nuts 20. The propeller can rotate at least 100° around the hole axis to realize the folding and unfolding of the propeller blade 1.

[0070] The battery is connected to the electric regulator and installed on frame three 6 and frame four 7. The equipment can be installed through the opening at the bottom of the nacelle.

[0071] Shape parameterization under geometric compatibility constraints: The shape parameterization under geometric compatibility constraints includes establishing a geometric parameterized model of the nacelle body, a geometric parameterized model of the rotor airfoil, and a geometric parameterized model of the rotor airfoil family;

[0072] Aerodynamic performance analysis and modeling: The aerodynamic performance analysis and modeling includes rotor performance analysis modeling, airfoil performance analysis modeling, and airfoil preprocessing using strip theory;

[0073] Optimization of outer arc airfoil family: The optimization of outer arc airfoil family includes optimizing the outer arc airfoil family, setting optimization conditions, and establishing an aerodynamic database.

[0074] The rotor airfoil parameterization includes parameterizing the airfoil outer surface 16, the airfoil lower surface 17, and the airfoil leading edge 18. Divide the given outer arc into N parts, such as Figure 7 As shown, the position of the Fi type value point can be determined based on the length aiR of the line segment OaFi and the angle biζ between OaFi and OaF0. By defining ai and bi, the position of each type value point can be obtained, and the lower airfoil surface can be fitted. The leading edge radius of the airfoil is determined based on the tangent conditions of the three sides of the upper airfoil surface, the lower airfoil surface, and the OaF0 line segment. Oa represents the center of the outer arc, Fi represents the type value point of one of the tangent lines in the N parts, ai represents the coefficient of the lower airfoil radius corresponding to the Fi type value point, and bi represents the angle coefficient of the center angle corresponding to the Fi type value point.

[0075] The rotor wing parameterization includes the rotor position mapping along the radius, the torsion angle distribution mapping, and the chord length distribution mapping: the offset x, the cross-sectional radius r corresponding to the offset, and the angular offset θ are used to represent the various value points on the rotor, such as Figure 8 As shown, it can be represented by the folded parameter set ΩF = {x, r, θ}. Then, based on the invariance of the rotor shape, a mapping relationship is established from the folded parameter set Ωzd to the unfolded parameter set Ωzk.

[0076] The rotor is mapped along the radius, and its power deck generatrix equation is obtained from S1, which is abbreviated as r=f(x). Cross-section in unfolded state One-to-one correspondence. The rotor blade position xi in the folded state corresponds to the rotor position along the radial radius in the unfolded state, as shown in Figure 9 shown

[0077]

[0078] The torsion angle distribution map is given by Figure 10 The geometric relationship shown in the figure shows that the cross section in the folded state Relative to the starting arc section The torsion angle is the relative torsion angle βi which can be expressed as:

[0079]

[0080] when The median vector at When θi coincides with the Y-axis (θ0 = 0), βi = θi. Therefore, simply defining the variation of θi along the x-direction yields the torsion angle of each control section relative to the starting section in the folded state. The relative torsion angle is expressed using a quartic Bezier curve, as shown in Equation 6. The relative torsion angle in the unfolded state is consistent with that in the folded state.

[0081]

[0082] Then the rotor rotation is decomposed. The rotation around the O'Z' axis makes the rotor fully open; while the rotation around the O'Y' axis adds the root chord installation angle to the deployed blade. Then, when the rotor is fully deployed, the actual torsion angle of the i-th control section is for

[0083]

[0084] Where ψ is the Euler angle of the rotor around the O′Y′ axis.

[0085] The chord length distribution mapping shows that the chord length distribution of the blade in the unfolded state is consistent with that in the folded state, so the chord length ci of each section can be solved in the folded state, that is,

[0086] c i =|A i B i |=2r i sin(ζ i / 2) (8)

[0087] Where ζi is Corresponding to the central angle of the circle. In this paper, the distribution of the central angle ζ along the x-direction can be represented by two tangent quadratic curves. When the vertex coordinates of the quadratic curve are (xp, yp), the starting coordinates of the first quadratic curve are (0, y0), and the ending coordinates of the second quadratic curve are (1, y1).

[0088]

[0089] The aerodynamic performance analysis modeling: Rotor performance analysis model: The present invention adopts strip theory for analysis; airfoil preprocessing makes the shape compatible with the nacelle shape.

[0090] The outer arc airfoil parameterization includes

[0091] The outer arc airfoil parameterization includes improving the airfoil's thrust efficiency factor C1.5 L / CD in the design state based on the rotor airfoil family and taking geometric compatibility and thickness constraints as the premise. Two checkpoints CL1 and CL2 are set on both sides of the airfoil's design lift coefficient CLd. The weighted sum of the thrust efficiency factors corresponding to the three design lift coefficients is used as the design goal of the airfoil optimization.

[0092] Setting optimization conditions: The setting optimization conditions limit the thickness of the airfoil at the characteristic section, and the typical thickness distribution from the root to the tip Changes according to the following quadratic curve:

[0093]

[0094] Where: The root section is positioned along the radius. In the embodiment, the blade tip relative thickness δ1 is required to be no less than 8%, and the blade root thickness δ0 is required to be no less than 20%. In the embodiment, multi-point optimization is performed on the outer arc airfoil with a central angle of 20°, 30°, 40°, 50°, and 60°, respectively, with the maximum relative thickness being no less than 8%, 15%, 20%, and 25% as constraints, to ultimately obtain an outer arc airfoil family and its aerodynamic characteristics.

[0095] Establishment of aerodynamic database: The aerodynamic database is established based on the optimized outer arc airfoil family shape. The aerodynamic characteristics calculation is performed under a given Reynolds number sequence to obtain the change of aerodynamic characteristics of each airfoil with the angle of attack at different Reynolds numbers. Based on this, through interpolation calculation, an aerodynamic characteristics database of the outer arc airfoil family is constructed with the airfoil central angle, airfoil relative thickness, operating Reynolds number, and angle of attack as inputs and the lift coefficient and drag coefficient as outputs. The specific process is as follows: Figure 11 shown.

[0096] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

[0097] Those skilled in the art should understand that the discussion of any of the above embodiments is merely illustrative and is not intended to imply that the scope of the present disclosure (including the claims) is limited to these examples. Within the scope of the present invention, the above embodiments or technical features in different embodiments may be combined, the steps may be implemented in any order, and there are many other variations of the different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity.

[0098] The embodiments of the present invention are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A conformal folding propeller matching a teardrop-shaped nacelle, the teardrop-shaped nacelle comprising A nacelle body (10) is in the shape of a teardrop as a whole and is formed by rotating a given nacelle busbar around an axis. Frame 1 (4), frame 2 (5), frame 3 (6), frame 4 (7), and frame 5 (8) are sequentially arranged in the nacelle body (10) from front to back. Frame 1 (4), frame 2 (5), frame 3 (6), frame 4 (7), and frame 5 (8) are connected by a longitudinal beam (9); a lightening hole is opened in frame 1 (4); A motor (14), wherein the motor (14) is fixed on the first frame; An electric regulator (12), the electric regulator (12) is connected to the motor (14), and the electric regulator (12) is mounted on an electric regulator mounting plate (13); A propeller hub (3), the propeller hub (3) is fixedly connected to the protruding end of the motor, The fairing (2) is fixedly connected to the propeller hub (3) and rotates along with the propeller hub (3), and is characterized in that: include A propeller blade (1), wherein the propeller blade (1) is mounted on a hub (3) in a hinged manner, the upper wing surface of the propeller blade (1) being a nacelle outer surface, and the lower wing surface being an optimized wing surface; The propeller dock (21) is provided on the surface of the nacelle body (10). The propeller blades (1) are completely attached to the nacelle propeller dock (21) after being folded to achieve shape preservation. After the propeller blades (1) are stored, they are completely embedded in the propeller dock (21), and the outer surface is a rotationally symmetrical teardrop shape.

2. A conformal folding propeller with a teardrop-shaped nacelle according to claim 1, characterized in that: The hub (3) is provided with a plurality of lugs and holes in the circumference thereof. The root of the propeller blade (1) is provided with holes which cooperate with the holes of the lugs of the hub (3) and are fixed by bolts (19) and nuts (20). The propeller can be rotated at least 100 degrees around the hole axis to realize the folding and unfolding of the propeller blade (1).

3. The method for designing a conformal folding propeller and nacelle matching a teardrop-shaped nacelle according to claim 2, characterized in that: The battery is connected to the electric regulator and installed on frame three (6) and frame four (7). The equipment can be installed through the opening at the bottom of the nacelle.

4. A method for designing a nacelle for a conformal folding propeller matching a teardrop-shaped nacelle, characterized in that: include Shape parameterization under geometric compatibility constraints: The shape parameterization under geometric compatibility constraints includes establishing a geometric parameterized model of the nacelle body, a geometric parameterized model of the rotor airfoil, and a geometric parameterized model of the rotor airfoil family; Aerodynamic performance analysis and modeling: The aerodynamic performance analysis and modeling includes rotor performance analysis modeling, airfoil performance analysis modeling, and airfoil preprocessing using strip theory; Optimization of outer arc airfoil family: The optimization of outer arc airfoil family includes optimizing the outer arc airfoil family, setting optimization conditions, and establishing an aerodynamic database.

5. The method for designing a nacelle for a conformal folding propeller matching a teardrop-shaped nacelle according to claim 4, characterized in that: The rotor airfoil parameterization includes parameterizing the airfoil outer surface (16), the airfoil lower surface (17), and the airfoil leading edge (18). The rotor airfoil parameterization includes rotor position mapping along the radius, twist angle distribution mapping, and chord length distribution mapping: by folding the parameter set ΩF = {x, r, θ}.

6. The method for designing a nacelle for a conformal folding propeller matching a teardrop-shaped nacelle according to claim 6, characterized in that: The rotor is mapped along the radius, and the arc control cross section in the folded state Cross-section in unfolded state One to one correspondence.

7. The method for designing a nacelle for a conformal folding propeller matching a teardrop-shaped nacelle according to claim 7, characterized in that: The torsion angle distribution map, cross section in folded state Relative to the starting arc section The torsion angle is the relative torsion angle βi which can be expressed as: when The median vector at When it coincides with the Y axis (θ0=0), βi=θi, and the relative torsion angle is expressed using the quartic Bezier curve. Decomposing the rotor rotation, the rotation around the O′Z′ axis makes the rotor fully open; and the rotation around the O′Y′ axis is the root chord installation angle of the deployed blade. When the rotor is fully deployed, the actual torsion angle of the i-th control section is for Where ψ is the Euler angle of the rotor around the O′Y′ axis.

8. The method for designing a nacelle for a conformal folding propeller matching a teardrop-shaped nacelle according to claim 7, characterized in that: The chord length distribution mapping shows that the chord length distribution of the blade in the unfolded state is consistent with that in the folded state. The chord length ci of each section in the folded state is solved, that is, c i =|A i B i |=2r i sin(ζ i / 2) Where ζi is Corresponding to the central angle of the circle, when the vertex coordinates of the quadratic curve are (xp, yp), the starting coordinates of the first quadratic curve are (0, y0), and the ending coordinates of the second quadratic curve are (1, y1).

9. The method for designing a nacelle for a conformal folding propeller matching a teardrop-shaped nacelle according to claim 7, characterized in that: The aerodynamic performance analysis modeling includes adopting the strip theory for analysis, and airfoil preprocessing to make the shape compatible with the nacelle shape.

10. The method for designing a nacelle for a conformal folding propeller matching a teardrop-shaped nacelle according to claim 6, characterized in that: The outer arc airfoil parameterization includes Parameterization of the outer arc airfoil, wherein the parameterization includes improving the thrust efficiency factor C1.5 L / CD of the airfoil in the design state based on the rotor airfoil family and subjecting it to geometric compatibility and thickness constraints, setting two checkpoints CL1 and CL2 on both sides of the airfoil design lift coefficient CLd, and taking a weighted sum of the thrust efficiency factors corresponding to the three design lift coefficients as the design target for airfoil optimization; Setting optimization conditions: The setting optimization conditions limit the thickness of the airfoil at the characteristic section, and the typical thickness distribution from the root to the tip Changes according to the following quadratic curve: Where: The wing root section is positioned along the radius; Establishment of an aerodynamic database: The aerodynamic database is established based on the optimized outer arc airfoil family shape. Aerodynamic characteristics calculations are performed under a given Reynolds number sequence to obtain the changes in the aerodynamic characteristics of each airfoil at different Reynolds numbers with the angle of attack. Based on this, through interpolation calculations, an aerodynamic characteristics database of the outer arc airfoil family is constructed with the airfoil central angle, airfoil relative thickness, operating Reynolds number, and angle of attack as inputs and the lift coefficient and drag coefficient as outputs.

Images