Boundary layer ingestion anti-distortion ducted fan

Abstract

The application provides a boundary layer suction anti-distortion ducted fan, and belongs to the technical field of aviation electric propulsion. The boundary layer suction anti-distortion ducted fan comprises an inlet casing, a fan casing, a nozzle, a fan rotor and a fan stator. The inlet casing is used for connecting the outlet end of a square-to-circle S-bend air inlet. A plurality of adjustable blades are rotatably arranged on the inner wall of the inlet casing. The plurality of adjustable blades are located on a continuous circular arc segment on the inlet casing. The corresponding fan-shaped area of the circular arc segment on the inlet casing corresponds to a continuous circumferential strong distortion sector on the outlet surface of the square-to-circle S-bend air inlet. The rotation shaft of the adjustable blade is arranged along the radial direction of the inlet casing. The boundary layer suction anti-distortion ducted fan further comprises a driving assembly. The driving assembly is used for driving the adjustable blade to rotate, and is used for adjusting the chord length of the adjustable blade and the included angle in the axial direction of the inlet casing. Through the processing scheme, the overall performance of the boundary layer suction ducted fan is improved.

Description

Technical Field

[0001] This application relates to the field of aviation electric propulsion, and in particular to a boundary layer intake anti-distortion ducted fan. Background Technology

[0002] Boundary layer inhalation ducted fans remove the boundary layer from an aircraft fuselage, increasing lift and reducing drag, thus becoming one of the main propulsion units in aero-electric propulsion systems. To achieve better boundary layer suction and minimize flight drag, boundary layer inhalation ducted fans typically employ a buried or semi-buried layout, combined with a square-to-round S-curve inlet to reduce effective frontal drag. However, large-offset S-curve inlets can cause flow separation, which intensifies when the boundary layer is drawn in, resulting in significant circumferential / radial distortion of total pressure and swirling distortion at the inlet cross-section. This inflow distortion significantly reduces the aerodynamic performance of boundary layer inhalation ducted fans, including their adiabatic efficiency and stall margin. According to published literature, inlet distortion caused by boundary layer inhalation can reduce the efficiency of boundary layer inhalation ducted fans by approximately 2-7% and the flow margin by over 40%, severely deteriorating their aerodynamic performance. Boundary layer inlet ducted fans operate continuously under conditions of strong inflow distortion, such as total pressure distortion and swirling distortion. This leads to a significant decrease in their efficiency and a deterioration in their stability, consequently affecting their thrust and power consumption, reducing propulsion efficiency, and drastically diminishing the benefits of boundary layer inlet. Therefore, boundary layer inlet ducted fans face a severe distortion resistance problem.

[0003] To improve the distortion resistance of boundary layer inlet ducted fans, one approach is to optimize the fan's flow path and blade design to reduce distortion sensitivity. However, this method requires high aerodynamic performance and is costly. Alternatively, controlling flow separation in the inlet can reduce the intensity of incoming flow distortion before the fan inlet, thereby improving performance. However, this method generally results in poorer flow control under off-design conditions, and may even further deteriorate flow field quality. Summary of the Invention

[0004] In view of this, this application provides a boundary layer intake anti-distortion ducted fan, which solves the problems in the prior art and improves the overall performance of the boundary layer intake ducted fan.

[0005] This application provides a boundary layer intake anti-distortion ducted fan with the following technical solution:

[0006] A boundary layer inhalation anti-distortion ducted fan includes an inlet casing, a fan casing, a nozzle, a fan rotor, and a fan stator. The inlet casing is used to connect to the outlet end of a square-to-round S-curve inlet. A plurality of spaced adjustable blades are rotatably mounted on the inner wall of the inlet casing. The plurality of adjustable blades are located on a continuous arc segment on the inlet casing. The fan-shaped area corresponding to the arc segment inside the inlet casing corresponds to a continuous circumferentially highly distorted sector on the outlet end face of the square-to-round S-curve inlet. The total pressure distortion intensity of the airflow in the circumferentially highly distorted sector is greater than a first preset value. The rotation axis of the adjustable blades is arranged along the radial direction of the inlet casing. The boundary layer inhalation anti-distortion ducted fan also includes a drive assembly for driving the adjustable blades to rotate and for adjusting the angle between the chord length of the adjustable blades and the axial direction of the inlet casing.

[0007] Optionally, the adjustable blade is provided with a mounting shaft that is rotatably connected to the intake casing. One end of the mounting shaft passes through the side wall of the intake casing and extends out of the intake casing. The mounting shaft is connected to the output end of the drive assembly. The axial direction of the mounting shaft is set along the radial direction of the intake casing, and the axis of the mounting shaft is coaxial with the center of gravity overlap line of the adjustable blade.

[0008] Optionally, the total airflow pressure of the circumferentially highly distorted sector is less than the average total airflow pressure of the entire outlet end face of the square-to-circular S-curve inlet.

[0009] Optionally, the central angle of the circumferential coverage area of ​​several of the adjustable blades on the inner wall of the intake casing is less than 180°.

[0010] Optionally, the length of the adjustable blade along the radial direction of the intake casing is less than or equal to half the blade tip radius of the fan rotor.

[0011] For a single adjustable blade, at the circumferential position of the adjustable blade, the distribution section of the adjustable blade in the radial direction of the inlet casing corresponds to a continuous radially highly distorted section on the outlet end face of the square-to-circular S-curve inlet, and the total airflow pressure of the radially highly distorted section is less than the average total airflow pressure of the entire outlet end face of the square-to-circular S-curve inlet.

[0012] Optionally, the chord length of the adjustable blade is less than or equal to 60% of the tip chord length of the fan rotor blades.

[0013] Optionally, the blade angle of the adjustable blade is less than or equal to 45°.

[0014] Optionally, the actual number of adjustable blades on the arc segment is... The consistency of the multiple adjustable blades on the root side of the arc segment is The blade tip density of the fan rotor is The chord length of the adjustable blade is The central angle corresponding to the circumferential coverage area of ​​the adjustable blade on the inner wall of the intake casing is . The root pitch of the adjustable blade is The blade tip radius of the fan rotor is ;

[0015] The method for determining the actual number of adjustable blades on the arc segment is as follows:

[0016] Theoretical calculation of the number of adjustable blades on the arc segment. :

[0017] ,in, , ;

[0018] Theoretical calculation of the number of adjustable blades on the arc segment. The actual number of adjustable blades on the arc segment is obtained by rounding to the nearest integer. .

[0019] Optionally, in the initial state, the exhaust side of the adjustable blade is biased towards the side of the fan rotor rotation direction relative to the intake side, and from the circumferential center of the arc segment to both sides, the angle between the chord length of the adjustable blade and the axial direction of the intake casing gradually decreases.

[0020] In summary, this application includes the following beneficial technical effects:

[0021] This application involves installing adjustable blades at circumferential intervals in the circumferentially distorted sector between the outlet of the square-to-circular S-curve inlet and the inlet of the fan rotor. This alters the incoming flow angle at the blade tips of the downstream fan rotor affected by distortion. The adjustable blades are adjusted in angle according to operating conditions, incoming flow distortion, and boundary layer thickness, causing the angle of attack at the fan rotor blade tips to shift towards the design state. This simultaneously enhances energy exchange of the low-energy fluid in the distorted region, improves the aerodynamic performance of the fan rotor, and achieves multi-condition anti-distortion design for boundary layer intake ducted fans, thereby improving the overall performance of the boundary layer intake ducted fan.

[0022] Compared with existing square-to-circular S-curve inlet flow control technology, the boundary layer intake anti-distortion ducted fan of this application can adjust the installation angle of the adjustable blades according to different incoming flow velocities, boundary layer thicknesses and operating conditions. It has the advantages of simple structure, good adaptability to different operating conditions, and superior anti-distortion performance under multiple operating conditions. Attached Figure Description

[0023] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 This is a schematic diagram of the external structure of the boundary layer intake anti-distortion duct fan in an embodiment of this application;

[0025] Figure 2 This is a schematic diagram of the internal structure of the boundary layer intake anti-distortion duct fan in the embodiments of this application;

[0026] Figure 3 This is a schematic diagram of the distribution structure of the adjustable blades in an embodiment of this application;

[0027] Figure 4 This is a schematic diagram of the distribution structure of the adjustable blades from another perspective in an embodiment of this application;

[0028] Figure 5 This is a schematic diagram of the adjustable blades, mounting shaft, and rocker arm of this application.

[0029] Explanation of reference numerals in the attached drawings: 1. Intake casing; 11. Fan casing; 12. Nozzle; 13. Fan rotor; 14. Fan stator; 15. Intake cone; 16. Exhaust cone; 17. Square-to-round S-curve intake duct; 2. Adjustable blade; 21. Mounting shaft; 22. Rocker arm. Detailed Implementation

[0030] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0031] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0032] It should be noted that the following description covers various aspects of embodiments within the scope of the appended claims. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number of aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0033] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0034] Furthermore, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the described aspects can be practiced without these specific details.

[0035] This application provides a boundary layer intake anti-distortion ducted fan.

[0036] like Figures 1 to 4 As shown, a boundary layer intake anti-distortion ducted fan includes an intake casing 1, a fan casing 11, a nozzle 12, a fan rotor 13, a fan stator 14, an intake cone 15, and an exhaust cone 16. The intake casing 1 is used to connect to the outlet end of a square-to-round S-curve intake duct 17. The outlet end of the square-to-round S-curve intake duct 17, the intake casing 1, the fan casing 11, the nozzle 12, the fan rotor 13, the fan stator 14, the intake cone 15, and the exhaust cone 16 are coaxially arranged. The above structure and specific distribution are existing technologies, and this application does not change the structure other than the intake casing 1. For the intake casing 1, the innovation of this application is only that the structure is installed on the intake casing 1, without changing the original distribution position and original functional structure of the intake casing 1. Therefore, the design of the above structure will not be described in detail in the embodiments of this application.

[0037] In this application, a plurality of adjustable blades 2 are rotatably mounted on the inner wall of the intake casing 1. These adjustable blades 2 are located on a continuous arc segment of the intake casing 1. The fan-shaped region corresponding to the arc segment within the intake casing 1 corresponds to a continuous circumferentially highly distorted sector on the outlet end face of the square-to-circular S-curve intake duct 17. The total pressure distortion intensity of the airflow in the circumferentially highly distorted sector is greater than a first preset value. The rotation axis of the adjustable blades 2 is arranged along the radial direction of the intake casing 1. The boundary layer intake anti-distortion duct fan also includes a drive assembly for driving the adjustable blades 2 to rotate and for adjusting the installation angle of the adjustable blades 2. The installation angle of the adjustable blades 2 is the angle between the chord length of the adjustable blades 2 and the axial direction of the intake casing 1. In this application, the spacing between adjacent adjustable blades 2 can be the same or different.

[0038] This application involves installing adjustable blades 2 at circumferential intervals in the circumferentially distorted sector between the outlet of the square-to-circular S-curve inlet 17 and the inlet of the fan rotor 13. This alters the incoming flow angle at the blade tip region of the downstream fan rotor 13 affected by distortion. The adjustable blades 2 are adjusted in angle according to operating conditions, incoming flow distortion, and boundary layer thickness, causing the angle of attack of the fan rotor 13 blade tip to change towards the design state. Simultaneously, this enhances the energy exchange of the low-energy fluid in the distorted region, improves the aerodynamic performance of the fan rotor 13, and achieves multi-condition anti-distortion design for the boundary layer intake ducted fan, thereby improving the overall performance of the boundary layer intake ducted fan.

[0039] The total airflow pressure of the circumferentially distorted sector is less than the average total airflow pressure of the entire outlet end face of the square-to-circular S-curve intake duct 17. That is, on the projection of the outlet end face of the intake casing 1, the sector area corresponding to the arc segment coincides with the circumferentially distorted sector.

[0040] The central angle of the circumferential coverage area of ​​the several adjustable blades 2 on the inner wall of the intake casing 1 is less than 180°. In the embodiment of this application, the central angle of the circumferential strong distortion sector is 117°, and the central angle of the circumferential coverage area of ​​the several adjustable blades 2 on the inner wall of the intake casing 1 is 80°.

[0041] The length of the adjustable blade 2 along the radial direction of the intake casing 1 is less than or equal to half the blade tip radius of the fan rotor 13.

[0042] For a single adjustable blade 2, at its circumferential position, the distribution section of the adjustable blade 2 in the radial direction of the inlet casing 1 corresponds to a continuous radially highly distorted section on the outlet end face of the square-to-circular S-curve inlet 17. The total airflow pressure of the radially highly distorted section is less than the average total airflow pressure of the entire outlet end face of the square-to-circular S-curve inlet 17. The radial length and radial distribution section of the adjustable blade 2 at different circumferential positions are set according to the radially highly distorted section at its circumferential position. In this embodiment, the length of the adjustable blade 2 along the radial direction of the inlet casing 1 is 10%-16% of the blade tip radius of the fan rotor 13. In other embodiments, the length of the adjustable blade 2 along the radial direction of the inlet casing 1 and its distribution section in the radial direction of the inlet casing 1 can be adaptively changed according to the ducted fan operating conditions.

[0043] Regarding the installation method of the adjustable blade 2, since the adjustable blade 2 needs to rotate relative to the intake casing 1, the adjustable blade 2 is spaced apart from the inner wall of the intake casing 1 near the end face of the mounting shaft 21 to ensure that the intake casing 1 does not interfere with the rotation of the adjustable blade 2. The specific size of the interval is set according to the chord length of the adjustable blade 2, the inner diameter of the intake casing 1, and the maximum value of the rotation angle of the adjustable blade 2. However, while ensuring that the adjustable blade 2 meets the rotation range requirements, the interval needs to be as small as possible to reduce the amount of air leakage between the adjustable blade 2 and the inner wall of the intake casing 1.

[0044] The chord length of the adjustable blade 2 is less than or equal to 60% of the tip chord length of the blades of the fan rotor 13. The blade angle of the adjustable blade 2 is less than or equal to 45°.

[0045] In this embodiment, the chord length of the adjustable blade 2 is equal to 32% of the blade tip chord length of the fan rotor 13; the blade angle of the adjustable blade 2 is 24°.

[0046] In its initial state, the adjustable blade 2 is offset from the intake side relative to the fan rotor 13's rotation direction on the exhaust side. Furthermore, from the center of the arc segment's circumferential direction towards both sides, the angle between the chord length of the adjustable blade 2 and the axial direction of the intake casing 1 gradually decreases; that is, from the center of the arc segment's circumferential direction towards both sides, the installation angle of the adjustable blade 2 gradually decreases. In this embodiment, the adjustable blade 2 with the largest installation angle at the center of the arc segment's circumferential direction has an installation angle of 10°, and the adjustable blade 2 located at the outermost edge of the arc segment's circumferential direction has an installation angle of 1°. In this embodiment, the adjustable range of the adjustable blade 2's installation angle is 50°.

[0047] The actual number of adjustable blades 2 on the arc segment is [value missing]. The consistency of the multiple adjustable blades on the arc segment at the root side is... The blade tip density of the fan rotor 13 is The chord length of the adjustable blade 2 is The central angle corresponding to the circumferential coverage area of ​​the adjustable blade 2 on the inner wall of the intake casing 1 is . The root pitch of the adjustable blade 2 is The blade tip radius of fan rotor 13 is ;

[0048] The method for determining the actual number of adjustable blades 2 on the arc segment is as follows:

[0049] Theoretical calculation of the number of adjustable blades 2 on the arc segment. :

[0050] ,in, , ;

[0051] Theoretical calculation of the number of adjustable blades 2 on the arc segment. The actual number of adjustable blades 2 on the arc segment is obtained by rounding to the nearest integer. .

[0052] In the embodiments of this application The value is 0.897. The value is 0.86, and the number of adjustable blades 2 is 9.

[0053] like Figures 3 to 5 As shown, the adjustable blade 2 is provided with a mounting shaft 21 rotatably connected to the intake casing 1. One end of the mounting shaft 21 passes through the side wall of the intake casing 1 and extends out of the intake casing 1. The mounting shaft 21 is connected to the output end of the drive assembly. The axial direction of the mounting shaft 21 is arranged along the radial direction of the intake casing 1, and the axis of the mounting shaft 21 is coaxial with the centroid overlap line of the adjustable blade 2. In one embodiment, a rocker arm 22 fixedly connected to the mounting shaft 21 is provided on the outside of the intake casing 1. The length direction of the rocker arm 22 is perpendicular to the axial direction of the mounting shaft 21. The drive assembly drives the rocker arm 22 to swing around the axis of the mounting shaft 21 as the rotation center, thereby driving the rotation of the mounting shaft 21 and the adjustable blade 2. The drive assembly is a conventional swing drive mechanism. In other embodiments, the drive assembly can also be a combination mechanism of a motor and a reduction gear structure, which drives the rotation of the mounting shaft 21. Each adjustable blade 2 corresponds to an independent drive assembly.

[0054] The performance of the boundary layer intake anti-distortion ducted fan of this application was verified by simulation. The simulation results show that there is total pressure circumferential distortion at the outlet of the square-to-circular S-curve inlet 17. The circumferential range of the strong circumferential distortion sector is 117°, and the total pressure distortion index of the 60° sector is 0.122. The distortion degree at the inlet of the fan rotor 13 is reduced, and the total pressure distortion index of the 60° sector is reduced to 0.077. The flow field uniformity at the outlet of the fan stator 14 is improved. Ultimately, the adiabatic efficiency of the boundary layer intake ducted fan under the same boundary conditions is increased by 0.4% compared with the prototype scheme without adjustable blades 2. It can be explained that the design of the adjustable blade 2 in this application, by controlling the airflow direction in the distortion zone, causes the downstream fan rotor 13 to move its working state towards the high-efficiency zone. At the same time, the adjustable blade 2 enhances the energy exchange between the low-energy fluid in the distortion zone and the high-energy fluid in the mainstream zone. In other words, the technical solution of this application can effectively improve the aerodynamic performance of the boundary layer inlet ducted fan, realize the anti-distortion design of the boundary layer inlet ducted fan, and provide a possible technical solution for improving the overall performance of the boundary layer inlet ducted fan.

[0055] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A boundary layer intake anti-distortion ducted fan, comprising an intake casing (1), a fan casing (11), a nozzle (12), a fan rotor (13), and a fan stator (14), wherein the intake casing (1) is used to connect to the outlet end of a square-to-round S-curve intake duct (17), characterized in that, A plurality of adjustable blades (2) are rotatably mounted on the inner wall of the intake casing (1). The plurality of adjustable blades (2) are located on a continuous arc segment on the intake casing (1). The fan-shaped area corresponding to the arc segment inside the intake casing (1) corresponds to a continuous circumferential strong distortion sector on the outlet end face of the square-to-circular S-curve intake duct (17). The total pressure distortion intensity of the airflow in the circumferential strong distortion sector is greater than a first preset value. The rotation axis of the adjustable blades (2) is arranged along the radial direction of the intake casing (1). The boundary layer intake anti-distortion duct fan also includes a drive assembly. The drive assembly is used to drive the adjustable blades (2) to rotate and to adjust the angle between the chord length of the adjustable blades (2) and the axial direction of the intake casing (1). The length of the adjustable blade (2) along the radial direction of the intake casing (1) is less than or equal to half the blade tip radius of the fan rotor (13); For a single adjustable blade (2), at the circumferential position of the adjustable blade (2), the distribution section of the adjustable blade (2) in the radial direction of the intake casing (1) corresponds to a continuous radially strongly distorted section on the outlet end face of the square-to-circular S-curve intake duct (17), and the total airflow pressure of the radially strongly distorted section is less than the average total airflow pressure of the entire outlet end face of the square-to-circular S-curve intake duct (17). The actual number of adjustable blades (2) on the arc segment is The consistency of the multiple adjustable blades (2) on the arc segment at the leaf root side is The blade tip density of the fan rotor (13) is The chord length of the adjustable blade (2) is The central angle corresponding to the circumferential coverage area of ​​the adjustable blade (2) on the inner wall of the intake casing (1) is . The root pitch of the adjustable blade (2) is The blade tip radius of the fan rotor (13) is ; The method for determining the actual number of adjustable blades (2) on the arc segment is as follows: Theoretical calculation of the number of adjustable blades (2) on the arc segment. : ,in, , ; Theoretical calculation of the number of adjustable blades (2) on the arc segment. The actual number of adjustable blades (2) on the arc segment is obtained by rounding to the nearest integer. .

2. The boundary layer intake anti-distortion ducted fan according to claim 1, characterized in that, The adjustable blade (2) is provided with a mounting shaft (21) that is rotatably connected to the intake casing (1). One end of the mounting shaft (21) passes through the side wall of the intake casing (1) and extends out of the intake casing (1). The mounting shaft (21) is connected to the output end of the drive assembly. The axial direction of the mounting shaft (21) is set along the radial direction of the intake casing (1), and the axis of the mounting shaft (21) is coaxial with the center of gravity overlap line of the adjustable blade (2).

3. The boundary layer intake anti-distortion ducted fan according to claim 1, characterized in that, The total airflow pressure of the circumferentially distorted sector is less than the average total airflow pressure of the entire outlet end face of the square-to-circular S-curve inlet (17).

4. The boundary layer intake anti-distortion ducted fan according to claim 1, characterized in that, The central angle of the circumferential coverage area of ​​several of the adjustable blades (2) on the inner wall of the intake casing (1) is less than 180°.

5. The boundary layer intake anti-distortion ducted fan according to claim 1, characterized in that, The chord length of the adjustable blade (2) is less than or equal to 60% of the tip chord length of the fan rotor (13).

6. The boundary layer intake anti-distortion ducted fan according to claim 1, characterized in that, The blade angle of the adjustable blade (2) is less than or equal to 45°.

7. The boundary layer intake anti-distortion ducted fan according to claim 1, characterized in that, In the initial state, the exhaust side of the adjustable blade (2) is biased towards the side of the fan rotor (13) rotation direction relative to the intake side, and from the middle position of the circumferential direction of the arc segment to both sides, the angle between the chord length of the adjustable blade (2) and the axial direction of the intake casing (1) gradually decreases.

Images