A rotor airfoil, a rotor blade and a tiltrotor aircraft

Abstract

The application discloses a rotor airfoil, a rotor blade and a tilt rotor aircraft, and particularly relates to the technical field of aircrafts, wherein the ratio of the maximum thickness t of the rotor airfoil to the chord length c of the airfoil is t / c=11.15%, the position of the maximum thickness is x t / c=34.9%; the ratio of the maximum camber f of the rotor airfoil to the chord length c of the airfoil is f / c=2.48%, the position of the maximum camber b is x f / c=22.7%; the airfoil section of the blade body at a distance of 0.34R-0.9R from the hub center is the rotor airfoil, the airfoil section at a distance of R from the hub center is an OA209 airfoil, the rotor airfoil and the OA209 airfoil are connected through a transition airfoil, and the OA209 airfoil is connected with a backward swept section. The application can realize higher aerodynamic performance and smoother mode conversion, and improve the overall flight performance.

Description

Technical Field

[0001] The present invention relates to the technical field of aircraft, and in particular to a rotor airfoil, a rotor blade and a tiltrotor aircraft. Background Art

[0002] Driven by the rapid development of aviation technology and the diversification of demand, tiltrotors, a new type of aircraft that combines the advantages of helicopter vertical takeoff and landing with the high-speed flight of fixed-wing aircraft, have garnered widespread attention in recent years. When transitioning between helicopter and fixed-wing modes, the blades of a tiltrotor aircraft must withstand complex and changing mechanical and airflow conditions, including but not limited to the enormous centrifugal forces generated by high-speed rotation, the drastic angle changes during mode transitions, and the aerodynamic performance requirements at varying flight speeds. These special conditions require blades to possess not only high strength and durability but also optimized aerodynamic performance to ensure flight safety, improve energy efficiency, and extend service life. Summary of the Invention

[0003] The purpose of the present invention is to provide a rotor airfoil, a rotor blade and a tiltrotor aircraft to solve the problems existing in the above-mentioned prior art, to achieve more efficient aerodynamic performance and smoother mode conversion, and to improve the overall flight performance.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] The present invention provides a rotor airfoil, comprising a leading edge, a trailing edge, and an upper camber line and a lower camber line located between the leading edge and the trailing edge. The ratio of the maximum thickness t of the rotor airfoil to the chord length c of the airfoil is t / c=11.15%, and the position of the maximum thickness is x t / c=34.9%;The ratio of the maximum camber f of the rotor airfoil to the chord length c of the airfoil is f / c=2.48%,the position of the maximum camber b is x f / c=22.7%;wherein, the upper arc is composed of the upper arc coordinate value pair x / c, y u / c is defined by the lower arc coordinate value pair x / c, y l / c is limited by the upper arc coordinate value pair x / c, y u / c and the lower arc coordinate value pair x / c, y l / c is defined as follows:

[0006]

[0007]

[0008] Where x is the distance from the leading edge to the trailing edge along the chord line, and y is the distance from the leading edge to the trailing edge along the chord line. uis the distance between the upper arc and the chord, y l is the distance between the lower arc and the chord, and the coordinate value of the upper arc is x / c, y u / c and the lower arc coordinate value pair x / c, y l The maximum error for each of / c is equal to ±3%.

[0009] The present invention also provides a rotor blade, comprising a blade body, wherein the blade body comprises a first airfoil section, a second airfoil section, a transition airfoil section and a swept section, the maximum distance between the end of the second airfoil section and the center of the hub is R, the first airfoil section is at a distance of 0.34R-0.9R from the center of the hub, the first airfoil section is the rotor airfoil, the second airfoil section is at a distance of R from the center of the hub, the second airfoil section is an OA209 airfoil, the first airfoil section and the second airfoil section are connected through the transition airfoil, the transition airfoil is at a distance of 0.9RR from the center of the hub, and the second airfoil section is connected to the swept section.

[0010] Preferably, the blade body adopts a linear negative torsion design with a negative torsion angle of 35°. The torsion angle at the first position where the distance between the blade body and the center of the hub is 0R is 24.5°; the torsion angle at the second position where the distance between the blade body and the center of the hub is 0.34R is 12.6°; the torsion angle at the third position where the distance between the blade body and the center of the hub is 0.7R is 0°; the torsion angle at the fourth position where the distance between the blade body and the center of the hub is R is -10.5°.

[0011] Preferably, the blade body includes a skin and a beam, a trailing edge strip, a leading edge counterweight and a filling material arranged in the skin. The beam is arranged in the direction from the root to the tip of the blade body. The beam is arranged at the leading edge of the blade body. The leading edge counterweight is arranged in the beam. The leading edge counterweight is close to the leading edge side of the blade body. The trailing edge strip is fixedly installed at the trailing edge of the blade body. The filling material can be evenly filled inside the skin.

[0012] Preferably, the blade root of the blade body is provided with two connection holes connected to the hub, and the two connection holes are provided with blade root bushings.

[0013] Preferably, the beam includes two root beams and a C-shaped beam, the root beam is sleeved outside the blade root bushing, the two root beams are fixedly connected to the C-shaped beam, and the outer wall of the C-shaped beam is tightly fitted with the inner wall of the skin of the leading edge of the blade body.

[0014] Preferably, the filling material comprises a first filling material, a second filling material, a third filling material and a fourth filling material, the first filling material is filled between the C-shaped girder and the trailing edge strip, the second filling material is filled in the gap between the root girder and the root bushing, the third filling material is filled in the gap between the two root girders and the gap between the root girder and the leading edge of the blade body, and the fourth filling material is filled in the gap between the two root girders and the end inner side of the root of the blade body.

[0015] Preferably, the skin is laid by a medium-temperature curing epoxy glass cloth prepreg, an epoxy carbon cloth prepreg and an epoxy unidirectional carbon cloth prepreg, and the girder is laid by a medium-temperature curing epoxy glass coarse sand prepreg tape.

[0016] Preferably, the material of the leading edge weight is tungsten-based high specific gravity alloy, and the trailing edge strip is laid by an epoxy glass coarse sand prepreg tape.

[0017] The application also provides a tilt-rotor aircraft comprising the rotor blade.

[0018] The application has the following technical effects relative to the prior art:

[0019] The application provides a rotor airfoil, a rotor blade and a tilt-rotor aircraft, the rotor airfoil improves the lift characteristics and increases the lift-drag ratio of the airfoil; according to the different airflow velocities and pressure distributions of different parts of the rotor blade in the rotation process, the rotor blade combines the characteristics of the rotor airfoil and the OA209 airfoil, the middle part is connected through a transition airfoil to form a hybrid airfoil splicing structure to meet the complex aerodynamic requirements and improve the efficiency and flight performance of the rotor; compared with the existing straight blades, the swept-back section of the rotor blade can improve the working performance of the forward blade at a high Mach number and delay the occurrence time of the increase in aerodynamic drag. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments. Obviously, the drawings in the following description only constitute some embodiments of the application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0021] Figure 1 It is a parameter diagram of the rotor airfoil of embodiment 1.

[0022] Figure 2 It is a geometric shape comparison diagram of the rotor airfoil of embodiment 1 and the reference airfoil.

[0023] Figure 3is the polar curve of the rotor airfoil of Example 1 and the reference airfoil (Ma=0.5);

[0024] Figure 4 This is an exploded view of the rotor blade of Example 2;

[0025] Figure 5 Schematic diagram of the spanwise twist distribution of the rotor blades of Example 2;

[0026] Figure 6 Schematic diagram of the cross-sectional distribution of the rotor blades of Example 2;

[0027] Figure 7 Schematic diagram of the cross section of rotor blade Z0 of Example 2;

[0028] Figure 8 Schematic cross-sectional view of rotor blade Z64 of Example 2;

[0029] Figure 9 Schematic cross-sectional view of rotor blade Z100 of Example 2;

[0030] Figure 10 Schematic cross-sectional view of rotor blade Z180 of Example 2;

[0031] Figure 11 Schematic cross-sectional view of rotor blade Z250 of Example 2;

[0032] Figure 12 Schematic cross-sectional view of rotor blade Z380 of Example 2;

[0033] Figure 13 Schematic cross-sectional view of rotor blade Z440 of Example 2;

[0034] Figure 14 This is a schematic cross-sectional view of the rotor blade Z620 of Example 2.

[0035] In the figure: 1-upper wing skin; 2-propeller root bushing; 3-second filling material; 4-third filling material; 5-first filling material; 6-C-shaped beam; 7-lower wing skin; 8-fourth filling material; 9-leading edge counterweight; 10-trailing edge strip; 11-root beam. DETAILED DESCRIPTION

[0036] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] The purpose of the present invention is to provide a rotor airfoil, a rotor blade and a tiltrotor aircraft to solve the problems existing in the above-mentioned prior art, to achieve more efficient aerodynamic performance and smoother mode conversion, and to improve the overall flight performance.

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Example 1

[0040] This embodiment provides a rotor airfoil, such as Figure 1-3 As shown, including the leading edge, the trailing edge and the upper camber and lower camber located between the leading edge and the trailing edge, the ratio of the maximum thickness t of the rotor airfoil to the chord length c of the airfoil is t / c=11.15%, and the position of the maximum thickness is x t / c=34.9%; the ratio of the maximum camber f of the rotor airfoil to the chord length c of the airfoil is f / c=2.48%, and the position of the maximum camber b is x f / c=22.7%;wherein, the upper arc is composed of the upper arc coordinate value pair x / c, y u / c, the lower arc is defined by the lower arc coordinate value pair x / c, y l / c is limited to the upper arc coordinate value pair x / c, y u / c and the lower arc coordinate value pair x / c, y l / c is defined as follows:

[0041] x / c <![CDATA[y u / c]]> x / c <![CDATA[y l / c]]> 0 0 0 0 0.03141 0.03554 0.04128 -0.01908 0.07571 0.05645 0.08911 -0.02337 0.12315 0.06887 0.13708 -0.02567 0.17176 0.07545 0.18507 -0.02773 0.22074 0.07855 0.23305 -0.02975 0.26981 0.07981 0.28105 -0.03152 0.31890 0.08000 0.32906 -0.03280 0.36797 0.07936 0.37709 -0.03350 0.41703 0.07787 0.42511 -0.03363 0.46605 0.07536 0.47314 -0.03334 0.51500 0.07174 0.52117 -0.03277 0.56384 0.06695 0.56919 -0.03199 0.61256 0.06102 0.61722 -0.03096 0.66114 0.05399 0.66522 -0.02954 0.70956 0.04592 0.71320 -0.02751 0.75781 0.03697 0.76115 -0.02466 0.80595 0.02738 0.80903 -0.02085 0.85407 0.01769 0.85684 -0.01625 0.90234 0.00884 0.90460 -0.01118 0.95099 0.00231 0.95234 -0.00586 1 0 1 0

[0042] Where x is the distance from the leading edge to the trailing edge along the chord line, and y is the distance from the leading edge to the trailing edge along the chord line. u is the distance between the upper arc and the chord, y l is the distance between the lower arc and the chord, and the coordinate value of the upper arc is x / c, y u / c and the lower arc coordinate value pair x / c, y l The maximum error of each of / c is equal to ±3%. The rotor airfoil of this embodiment is an optimized airfoil obtained based on the OA212 airfoil by combining an airfoil aerodynamic numerical simulation method, a Kriging model, and an airfoil aerodynamic shape optimization method constructed by a genetic algorithm. With a Mach number Ma = 0.5 and ensuring that the lift coefficient does not decrease, the rotor airfoil of this embodiment is compared with the reference airfoil at angles of attack of 3.58° and 10°, and the drag coefficient is reduced by 12.5% ​​and 0.84%, respectively; when the drag coefficient is the same, the rotor airfoil of this embodiment can produce a larger lift coefficient.

[0043] Example 2

[0044] This embodiment provides a rotor blade, such as Figure 4-14 As shown, the blade body includes a first airfoil section, a second airfoil section, a transition airfoil section, and a swept section. The maximum distance R between the end of the second airfoil section and the center of the hub is R. The first airfoil section is at a distance of 0.34R-0.9R from the center of the hub. The first airfoil section is the rotor airfoil of Example 1. The second airfoil section is at a distance R from the center of the hub. The second airfoil section is an OA209 airfoil. The first airfoil section and the second airfoil section are connected by a transition airfoil. The transition airfoil is at a distance of 0.9RR from the center of the hub. The second airfoil section is connected to the swept section. The maximum distance R between the end of the second airfoil section and the center of the hub of the rotor blade of this embodiment is 0.9m. The actual length from the first airfoil section to the second airfoil section is 0.694m.

[0045] It is further preferred in the implementation manner of this embodiment that the blade body adopts a linear negative torsion design, the negative torsion angle is 35°, the torsion angle of the first position where the distance between the blade body and the center of the hub is 0R is 24.5°, the torsion angle of the second position where the distance between the blade body and the center of the hub is 0.34R is 12.6°; the torsion angle of the third position where the distance between the blade body and the center of the hub is 0.7R is 0°; the torsion angle of the fourth position where the distance between the blade body and the center of the hub is R is -10.5°, there is a linear transition between the first position and the second position, a linear transition between the second position and the third position, and a linear transition between the third position and the fourth position.

[0046] It is further preferred in the implementation manner of this embodiment that the blade body includes a skin and a beam, a trailing edge strip 10, a leading edge counterweight 9 and a filling material arranged in the skin, the beam is arranged in the direction from the root to the tip of the blade body, the beam is arranged at the leading edge of the blade body, a leading edge counterweight 9 is arranged in the beam, the leading edge counterweight 9 is close to the leading edge side of the blade body, the trailing edge strip 10 is fixedly installed on the trailing edge of the blade body, and the trailing edge strip 10 is tightly fitted with the inner side wall of the skin at the trailing edge of the blade body, and the filling material can be evenly filled inside the skin. The skin includes an upper wing skin 1 and a lower wing skin 7, and the upper wing skin 1 and the lower wing skin 7 are closed to form the outer shape of the blade body, and the filling material inside the skin supports the skin. The skin itself constitutes a torsion-resistant box-shaped part, providing torsional stiffness of the blade section. The upper and lower wing skins (1 and 7) are laid down in layers at the blade root to reinforce the blade. The thickness decreases along the span, with three layers laid down at the blade tip. Unidirectional carbon prepreg (0° and ±45°) is used on the inner side, while a layer of glass prepreg (0°) is applied to the outer surface to protect the carbon skins and achieve a high surface roughness. Leading-edge weights (9) adjust the blade's chordwise center of gravity. Trailing edge strips (10) adjust the profile rollover stiffness.

[0047] In the embodiment of the present invention, the blade body has two connection holes at the root thereof for connection to the hub, and the two connection holes are provided with blade root bushings. The blade root bushings 2 are used to connect to the blade pins on the hub, and the blade root bushings 2 are made of stainless steel, with the outer surface thereof being the surface to be glued.

[0048] In the implementation of this embodiment, it is further preferred that the beam includes two root beams 11 and a C-shaped beam 6. The root beam 11 is mounted outside the blade root bushing 2. The two root beams 11 are fixedly connected to the C-shaped beam 6. The outer wall of the C-shaped beam 6 is tightly fitted with the inner wall of the skin at the leading edge of the blade body. The root beam 11 is the wrapped portion of the beam at the blade root, used to fix the blade root bushing 2 and transmit part of the centrifugal force; the C-shaped beam 6 can withstand large rotational centrifugal force, flapping bending moment and oscillation bending moment, thereby enabling the blade body to withstand a large rotational speed. Furthermore, the root beam 11 and the C-shaped beam 6 are integrally formed.

[0049] In the implementation of this embodiment, it is further preferred that the filling material includes a first filling material 5, a second filling material 3, a third filling material 4, and a fourth filling material 8. The first filling material 5 is filled between the C-shaped beam 6 and the trailing edge strip 10, the second filling material 3 is filled between the root beam 11 and the blade root bushing 2, the third filling material 4 is filled between the two root beams 11 and the gap between the root beam 11 and the leading edge of the blade body, and the fourth filling material 8 is filled between the two root beams 11 and the inner side surface of the root end of the blade body. The first filling material 5 is PMI foam, which is closely attached to the inner side of the C-shaped beam 6 and the upper and lower wing skins 1 and 7, supporting the skins and providing partial torsional stiffness to the cross-section. Second filler material 3 fills the gap between root beam 11 and blade root bushing 2, tightening the connection between blade root components and maintaining the beam's alignment. Fourth filler material 8, formed from a solidified mixture of chopped fibers, wraps around the two root beams 11 at the blade root end. The blade body utilizes a modular design, breaking it down into multiple easily disassembled and replaceable components. Each component is replaceable, reducing maintenance costs and time while improving operability and efficiency.

[0050] In this embodiment, the skin is preferably constructed from a combination of medium-temperature-cured epoxy glass cloth prepreg, epoxy carbon cloth prepreg, and epoxy unidirectional carbon cloth prepreg, while the girder is constructed from medium-temperature-cured epoxy glass coarse sand prepreg tape. The C-shaped girder 6 provides 75% to 80% of the blade's flapping stiffness and 30% to 40% of its roll stiffness, leveraging the composite material's superior longitudinal tensile and fatigue strength to meet the blade's design requirements for centrifugal and flapping loads.

[0051] In the implementation of this embodiment, it is further preferred that the material of the leading edge counterweight 9 is a tungsten-based high-density alloy, and the trailing edge strip 10 is formed by laying epoxy glass coarse sand prepreg tape.

[0052] Example 3

[0053] This embodiment provides a tiltrotor aircraft, including the rotor blades of Example 2.

[0054] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A rotor airfoil, characterized in that: The rotor airfoil comprises a leading edge, a trailing edge, and an upper camber line and a lower camber line between the leading edge and the trailing edge. The ratio of the maximum thickness t of the rotor airfoil to the chord length c of the airfoil is t / c=11.15%. The position of the maximum thickness is x t / c=34.9%;The ratio of the maximum curvature f of the rotor airfoil to the chord length c of the airfoil is f / c=2.48%,the position of the maximum curvature b is x f / c=22.7%;wherein, the upper arc is composed of the upper arc coordinate value pair x / c, y u / c is defined by the lower arc coordinate value pair x / c, y l / c is limited by the upper arc coordinate value pair x / c, y u / c and the lower arc coordinate value pair x / c, y l / c is defined as follows: Where x is the distance from the leading edge to the trailing edge along the chord line, and y is the distance from the leading edge to the trailing edge along the chord line. u is the distance between the upper arc and the chord, y l is the distance between the lower arc and the chord, and the coordinate value of the upper arc is x / c, y u / c and the lower arc coordinate value pair x / c, y l The maximum error for each of / c is equal to ±3%.

2. A rotor blade, characterized in that: The invention comprises a blade body, wherein the blade body comprises a first airfoil section, a second airfoil section, a transition airfoil section and a swept section, the maximum distance between the end of the second airfoil section and the center of the hub is R, the first airfoil section is at a distance of 0.34R-0.9R from the center of the hub, the first airfoil section is the rotor airfoil according to claim 1, the second airfoil section is at a distance of R from the center of the hub, the second airfoil section is an OA209 airfoil, the first airfoil section and the second airfoil section are connected through the transition airfoil, the transition airfoil is at a distance of 0.9RR from the center of the hub, and the second airfoil section is connected to the swept section.

3. The rotor blade according to claim 2, characterized in that: The blade body adopts a linear negative torsion design with a negative torsion angle of 35°. The torsion angle at the first position where the distance between the blade body and the center of the hub is 0R is 24.5°; the torsion angle at the second position where the distance between the blade body and the center of the hub is 0.34R is 12.6°; the torsion angle at the third position where the distance between the blade body and the center of the hub is 0.7R is 0°; the torsion angle at the fourth position where the distance between the blade body and the center of the hub is R is -10.5°.

4. The rotor blade according to claim 2, characterized in that: The blade body includes a skin and a beam, a trailing edge strip, a leading edge counterweight and a filling material arranged in the skin. The beam is arranged in the direction from the root to the tip of the blade body. The beam is arranged at the leading edge of the blade body. The leading edge counterweight is arranged in the beam. The leading edge counterweight is close to the leading edge side of the blade body. The trailing edge strip is fixedly installed at the trailing edge of the blade body. The filling material can be evenly filled inside the skin.

5. The rotor blade according to claim 4, characterized in that: The blade root of the blade body is provided with two connection holes connected to the hub, and the two connection holes are provided with blade root bushings.

6. The rotor blade according to claim 5, characterized in that: The beam includes two root beams and a C-shaped beam. The root beam is mounted outside the blade root bushing. The two root beams are fixedly connected to the C-shaped beam. The outer wall of the C-shaped beam fits tightly with the inner wall of the skin of the leading edge of the blade body.

7. The rotor blade according to claim 6, characterized in that: The filling material includes a first filling material, a second filling material, a third filling material and a fourth filling material. The first filling material is filled between the C-shaped beam and the trailing edge strip, the gap between the root beam and the root bushing is filled with the second filling material, the gap between the two root beams and the gap between the root beam and the leading edge of the blade body are filled with the third filling material, and the gap between the two root beams and the inner side surface of the root end of the blade body is filled with the fourth filling material.

8. The rotor blade according to claim 4, characterized in that: The skin is formed by laying medium-temperature curing epoxy glass cloth prepreg, epoxy carbon cloth prepreg and epoxy unidirectional carbon cloth prepreg, and the beam is formed by laying medium-temperature curing epoxy glass coarse sand prepreg.

9. The rotor blade according to claim 4, characterized in that: The material of the leading edge counterweight is a tungsten-based high-density alloy, and the trailing edge strip is paved with epoxy glass coarse sand prepreg tape.

10. A tiltrotor aircraft, characterized in that: The invention comprises the rotor blade according to any one of claims 2 to 9.

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