Aeroengine composite material counter-propeller cascade configuration suitable for winding process and having non-orthogonal grid and a method for manufacturing the same

Abstract

This invention relates to the field of aero-engine technology, and discloses a composite material thrust reverser cascade configuration suitable for winding processes and having a non-orthogonal grid, as well as its preparation method. This invention employs a continuous fiber winding process to prepare the thrust reverser cascade, ensuring fiber continuity, improving the stiffness and strength of the cascade, facilitating increased production efficiency, reducing production costs, and improving material utilization. Furthermore, by improving thrust reverser aerodynamic efficiency and reducing the thickness of the helical cascade, the weight of the thrust reverser cascade can be reduced. This invention uses a helical first and second helical cascades, which are obliquely positioned at a predetermined angle to the engine axis. This results in a swept-back aerodynamic layout of the helical cascades relative to the incoming flow through the thrust reverser cascade. The resulting swept-back cascade naturally produces aerodynamic effects of increased lift and reduced drag, improving thrust reverser aerodynamic efficiency.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, and discloses an aero-engine composite thrust reverser cascade configuration with a non-orthogonal grid suitable for winding process and its preparation method. Background Technology

[0002] As part of the aircraft engine nacelle, thrust reversers are used during the landing roll phase to improve deceleration efficiency and shorten the landing distance by providing reverse thrust. Blade-type thrust reversers are currently the typical configuration for high-bypass turbofan engines. The overall shape of the blade cascade is cylindrical, and existing cascade configurations consist of grids composed of longitudinal and transverse plates. Traditional thrust reverser blade cascades are made of metal, involving numerous processing steps such as casting, welding, and machining. Generally, this results in long processing cycles, high production costs, and low material utilization.

[0003] Currently, fiber-reinforced composite thrust reverser cascades also exist. However, the configuration of composite thrust reverser cascades directly follows that of metal thrust reverser cascades, and they are typically fabricated using a manual lay-up method. This involves laying prepreg in a specific mold and then hot-pressing it; or laying dry fiber cloth, injecting resin, and then curing it. Unless there are special cases, continuous fiber-reinforced composites are generally unsuitable for fabricating geometrically complex structures, such as traditional cascade configurations. If used in such cases, they inevitably suffer from low production efficiency, high labor intensity, high production costs, long production cycles, poor product quality and consistency, and low material utilization. Furthermore, the extensive cutting involved in the fabrication process not only wastes material but also severely damages the continuity of the fibers. To ensure the strength and stiffness of the cascade structure, the grating must be thickened, which not only increases the weight of the cascade structure but also occupies the air passage area, obstructing airflow. To maintain the air passage area, the overall length of the cascade must be increased, which leads to an increased sliding distance of the fairing when the thrust reverser is engaged, negatively impacting the overall design of the engine nacelle. Summary of the Invention

[0004] The purpose of this invention is to provide a composite material thrust reverser cascade configuration for aero-engines with a non-orthogonal grid that is suitable for winding process and its preparation method. This facilitates efficient production through winding process, reduces production costs, improves material utilization, and helps to shorten the overall length and reduce the weight of the cascade structure.

[0005] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is as follows:

[0006] A composite thrust reverser cascade configuration for aero-engines, suitable for winding processes and featuring a non-orthogonal grid, comprising: The grid mesh is a cylindrical structure made of continuously wound fibers. The grid mesh includes several first helical grid plates and several second helical grid plates distributed on the circumference of the cylindrical structure. At the ends of the cylindrical structure, an arc-shaped connecting grid plate is provided at the transition between the first and second helical grid plates. The cross-sectional shapes of the first and second helical grid plates are appropriately selected airfoils. The axes of the first and second helical grid plates have a predetermined angle with the axis of the cylindrical structure, and the helical directions of the first and second helical grid plates are opposite to facilitate winding. The first and second helical grid plates obliquely intersect to form several quadrilateral grid air passages, used to guide the airflow from the engine's outer bypass duct to be ejected in a predetermined direction and form reverse thrust airflow, generating the required reverse thrust. The frame is respectively set at both ends of the grid and connected to the end of the grid; the arc-shaped connecting grid plate and the frame together form a mounting hole for connecting the thrust reverser blades to the engine.

[0007] Furthermore, a reinforcing element is provided at the intersection of the first and second spiral grid plates to improve the strength of the first and second spiral grid plates along the chord direction.

[0008] Furthermore, the reinforcing element includes reinforcing fiber bundles that are bundled and glued at the junction of the first and second spiral grids.

[0009] Furthermore, a rectification, drag reduction, and noise reduction protrusion is provided at the trailing edge of the intersection of the first and second spiral grid plates, and the rectification, drag reduction, and noise reduction protrusion smoothly transitions with the aerodynamic surfaces of the first and second spiral grid plates.

[0010] Furthermore, a guide hole is provided at the intersection of the first spiral grid plate and the second spiral grid plate to guide the airflow in the high-pressure area of ​​the quadrilateral grid air passage to the low-pressure area of ​​the adjacent quadrilateral grid air passage, so as to prevent the airflow in the low-pressure area from separating.

[0011] Furthermore, the composite material thrust reverser grating configuration of the aero-engine is composed of a combination of several grating blocks with different grating densities and airflow directions.

[0012] A method for preparing a composite thrust reverser cascade configuration for aero-engines with a non-orthogonal grid, suitable for winding process, comprising the following steps: Based on the three-dimensional model of the composite thrust reverser cascade configuration of the aero-engine, a continuous fiber winding mold is prepared, wherein the outer surface of the continuous fiber winding mold has grooves for forming the composite thrust reverser cascade configuration of the aero-engine. Continuous fibers are wound into grooves on a continuous fiber winding mold, cured and shaped after winding, and then demolded to obtain the composite thrust reverser cascade configuration of the aero-engine.

[0013] Furthermore, when designing the three-dimensional model of the composite material thrust reverser cascade configuration of the aero-engine, the step of determining the aspect ratio of the quadrilateral grid air passage includes: Based on the three-dimensional model of the thrust reverser cascade with a given helical lattice airfoil, simulation analysis was conducted on quadrilateral lattice air passages with different aspect ratios under design conditions to obtain the maximum non-stall angle of attack of the quadrilateral lattice air passages under different aspect ratios. Using the aspect ratio of the quadrilateral grid air passage as input and the corresponding maximum non-stall angle of attack as output, a function analysis model for the maximum non-stall angle of attack is obtained by fitting. Based on the expression of the maximum non-stall angle of attack function analysis model, the aspect ratio corresponding to the maximum value of the maximum non-stall angle of attack is determined to be the design value of the aspect ratio of the quadrilateral grid air passage.

[0014] Furthermore, the maximum non-stall angle of attack function analysis model is expressed as follows: ; in: This is the maximum angle of attack without stall for the helical lattice airfoil. The aspect ratio of the quadrilateral grid airway; , , Let be the coefficient, and .

[0015] Compared with the prior art, the beneficial effects of this invention are: This invention employs a first and a second helical grid plate with an airfoil-shaped cross-section and a helical shape. The first and second helical grid plates intersect obliquely to form a grid with quadrilateral grid air passages, guiding the airflow from the engine's outer bypass duct along a predetermined direction to form reverse thrust. Furthermore, the helical grid plate has a swept-back aerodynamic layout relative to the incoming flow passing through the reverse thrust blades, providing space for further elevation of the grid plate as the incoming flow passes through the quadrilateral grid air passages, thereby improving the reverse thrust aerodynamic efficiency. Simultaneously, the obliquely positioned helical grid plate of this invention can transfer a portion of the aerodynamic load through axial forces within the helical grid plate, thereby reducing the bending moment borne by the helical grid plate. This is beneficial for the helical grid plate to withstand reverse thrust loads, effectively reducing the strength requirements of the grid plate and thus reducing its thickness. This invention employs a continuous fiber winding process to fabricate the thrust reverser blade cascade, ensuring fiber continuity, improving the stiffness and strength of the cascade, facilitating increased production efficiency, reducing production costs, and improving material utilization. Furthermore, by improving thrust reverser aerodynamic efficiency and reducing the thickness of the helical cascade, the weight of the thrust reverser blade cascade can be reduced. All of these effects contribute to shortening the blade cascade length, thereby reducing the backward sliding distance of the rectifier casing when the thrust reverser is engaged. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of a composite material thrust reverser cascade configuration for an aero-engine that is suitable for winding process and has a non-orthogonal grid, as shown in the embodiment. Figure 2 This is a schematic diagram of the mounting hole structure in the embodiment; Figure 3 This is a schematic diagram of the reinforcing element in the embodiment; Figure 4 This is a schematic diagram of the rectifier drag reduction and noise reduction protrusion in the embodiment; Figure 5 This is a schematic diagram showing the direction of the thrust reverser force on the composite material thrust reverser cascade configuration of the aero-engine in the embodiment. Figure 6 This is a schematic diagram of the airflow passing through the grid air passage and the vortex formed within the grid air passage, as well as the guide holes, in the embodiment. Figure 7 This is a schematic diagram showing the relative relationship between lift, drag, and thrust on the grid in a cross-section perpendicular to the intersection of the grid plates. Figure 8 for Figure 7 The diagram shows the relative positions of adjacent spiral grids when the cross-section is rotated to a horizontal position, and the airflow direction caused by diffusion from the high-pressure area to the low-pressure area. Figure 9 The image shows the Mach number cloud behind the grating of a composite thrust reverser blade configuration of an aero-engine that is suitable for the winding process and has a non-orthogonal grating, as shown in the example. Figure 10The grid block in the embodiment is a combination of thrust reverser blades; Figure 11 This is a flowchart illustrating the method for preparing a composite thrust reverser cascade configuration of an aero-engine that is suitable for winding process and has a non-orthogonal grid in the embodiments. Among them, 1-grid mesh, 11-first spiral grid plate, 12-second spiral grid plate, 13-reinforcing element, 14-rectification, drag reduction and noise reduction protrusion, 15-guide hole, 16-mounting hole, 17-arc connecting grid plate, 18-air passage, 19-grid block, 20-circumferential frame, 21-axial frame, 2-frame, 3-positioning pin. Detailed Implementation

[0017] The present invention will now be described in further detail with reference to the embodiments and accompanying drawings. However, this should not be construed as limiting the scope of the above-described subject matter of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0018] See Figures 1 to 6 This invention provides a composite thrust reverser cascade configuration for aero-engines that is suitable for winding processes and has a non-orthogonal grid, comprising: The grid 1 is a cylindrical structure made of continuously wound fibers. The grid 1 includes several first spiral grid plates 11 and several second spiral grid plates 12 distributed on the circumferential surface of the cylindrical structure. At the end of the cylindrical structure, an arc-shaped connecting grid plate 17 is provided at the transition between the first spiral grid plates 11 and the second spiral grid plates 12. The cross-sectional shape of the first spiral grid plates 11 and the second spiral grid plates 12 is airfoil-shaped. The axes of the first spiral grid plates 11 and the second spiral grid plates 12 have a predetermined angle with the axis of the cylindrical structure, and the spiral directions of the first spiral grid plates 11 and the second spiral grid plates 12 are opposite to facilitate winding. The first spiral grid plates 11 and the second spiral grid plates 12 obliquely intersect to form several quadrilateral grid air passages, used to guide the airflow from the engine's outer bypass duct to be ejected in a predetermined direction and form a reverse thrust airflow, generating the required reverse thrust. The frame 2 is respectively set at both ends of the grid 1 and connected to the end of the grid 1; the arc-shaped connecting grid plate 17 and the frame 2 together form the mounting hole 16, which is used to connect the thrust reverser blade to the engine.

[0019] This invention employs a first helical grid 11 and a second helical grid 12 with an airfoil-shaped cross-section and a helical shape. The first and second helical grids 11 and 12 intersect obliquely to form a grid 1 with quadrilateral grid air passages, used to guide the airflow from the engine's outer bypass duct outwards in a predetermined direction and form reverse thrust airflow. Furthermore, the helical grid has a swept-back aerodynamic layout relative to the incoming flow passing through the reverse thrust blades, providing space for further elevation of the grid as the incoming flow passes through the quadrilateral grid air passages, thereby improving the reverse thrust aerodynamic efficiency. Simultaneously, the obliquely positioned helical grid of this invention can transfer a portion of the aerodynamic load through axial forces within the helical grid, thereby reducing the bending moment borne by the helical grid, which is beneficial for the helical grid to withstand reverse thrust loads, effectively reducing the strength requirements of the grid, and thus reducing the grid thickness. This invention employs a continuous fiber winding process to fabricate the thrust reverser blade cascade, ensuring fiber continuity, improving the stiffness and strength of the cascade, facilitating increased production efficiency, reducing production costs, and improving material utilization. Furthermore, by improving thrust reverser aerodynamic efficiency and reducing the thickness of the helical cascade, the weight of the thrust reverser blade cascade can be reduced. All of these effects contribute to shortening the blade cascade length, thereby reducing the backward sliding distance of the rectifier casing when the thrust reverser is engaged.

[0020] Example This embodiment takes a rhomboid lattice thrust reverser blade cascade as an example to further illustrate the composite material thrust reverser blade cascade configuration of aero-engines that is suitable for winding process and has a non-orthogonal lattice, as detailed below.

[0021] See Figures 1 to 6 The aero-engine composite thrust reverser cascade configuration suitable for winding process and having a non-orthogonal grid includes a grid 1 and a frame 2. Two frames 2 are provided, respectively located at both ends of the grid 1. When preparing the thrust reverser cascade using a continuous fiber winding process, fiber bundles of a designed number of turns are wound circumferentially at both ends of the grid 1 to form the frame 2. Furthermore, the fiber bundles forming the grid 1 and the fiber bundles forming the frame 2 are interwoven and combined, so that the grid 1 and the frame 2 are integrally formed by continuous fiber winding. The description of the method for forming the grid 1 and the frame 2 in this embodiment is only one possible implementation and does not exclude other methods that achieve the same function.

[0022] Continuous fiber winding can use one or more strands of dry reinforcing fiber, or hybrid fibers containing a matrix, or composite prepreg. After winding, appropriate processes are applied, including but not limited to injection molding, followed by curing. In this embodiment, the continuous fiber is a hybrid fiber of carbon fiber and PEEK fiber, with PEEK as the matrix. After winding, it is heated and pressurized to form the final product.

[0023] In this embodiment, see Figure 1The grid 1 is a cylindrical structure, including several first spiral grid plates 11 and several second spiral grid plates 12 distributed on the circumference of the cylindrical structure. The first spiral grid plates 11 and the second spiral grid plates 12 are arranged along spiral lines with the same constant pitch. The spiral directions of the first spiral grid plates 11 and the second spiral grid plates 12 are opposite, and the axes of the first spiral grid plates 11 and the second spiral grid plates 12 have a preset angle with the axis of the cylindrical structure, thus forming several diamond-shaped grid air passages 18. The value of the preset angle can be determined by simulation or given based on experience. Moreover, at the end of the grid 1, the first spiral grid plates 11 and the second spiral grid plates 12 are connected and transitioned by arc-shaped connecting grid plates 17. See [link to relevant documentation]. Figure 2 The frame 2 is respectively disposed at both ends of the grid 1 and connected to the arc-shaped connecting plate 17; the arc-shaped connecting plate 17 and the frame 2 together form a mounting hole 16, which is used for connecting the thrust reverser blade cascade to the engine or combined blade cascade frame. See [reference needed] Figure 2 In the continuous fiber winding process for preparing the thrust reverser blade cascade, a positioning pin 3 is set on the mold. Then, a continuous fiber bundle is wound along the groove of the first helical grid plate 11 on the mold. When the fiber bundle reaches the end of the grid 1, it bypasses the positioning pin 3 and switches to the groove of the second helical grid plate 12. This process is repeated to gradually form the first helical grid plate 11 and the second helical grid plate 12, and an arc-shaped connecting grid plate 17 is formed near the positioning pin 3. When the first helical grid plate 11 and the second helical grid plate 12 have been wound to a set number of turns, they are wound circumferentially at both ends of the grid 1 to form the borders 2 at both ends of the grid 1. Finally, the winding continues along the grooves of the first helical grid plate 11 and the second helical grid plate 12, repeating this process until the first helical grid plate 11, the second helical grid plate 12, the borders 2, and the arc-shaped connecting grid plate 17 are finally formed. After the thrust reverser blade cascade is formed, the positioning pin 3 is removed, automatically forming the mounting hole 16 for connecting the thrust reverser blade cascade to the engine. The mounting hole 16 is entirely made of continuous fiber winding, which eliminates the need to drill and cut the continuous fiber to form the mounting hole 16. No machining is required, ensuring the continuity of the fiber and meeting the design principles of minimum material usage, lightest weight, and net manufacturing.

[0024] Furthermore, the cross-sectional shape of the first helical grid plate 11 and the second helical grid plate 12 is an airfoil. The airfoil can be a symmetrical airfoil, a double-convex airfoil, a plano-convex airfoil, a concave-convex airfoil, etc. Those skilled in the art can select or design the airfoil structure as needed. In this embodiment, the cross-sectional shape of the first helical grid plate 11 and the second helical grid plate 12 is a concave-convex airfoil structure with a preset curvature. This embodiment uses a helical grid plate with an airfoil cross-section, which can effectively improve the performance of the grid mesh 1 in airflow guidance, optimize the flow characteristics of the airflow, reduce the energy loss of the airflow when passing through the diamond grid air passage 18, and enhance the stability and directionality of the reverse thrust airflow, thereby achieving a better reverse thrust effect.

[0025] Furthermore, the first spiral grid plate 11 and the second spiral grid plate 12 each form a preset tilt angle relative to the plane of their forming spiral lines, so that the first spiral grid plate 11 and the second spiral grid plate 12 form a preset angle of attack relative to the airflow flowing through the diamond grid air passage 18, thereby generating aerodynamic lift L and aerodynamic drag D on the surfaces of the first spiral grid plate 11 and the second spiral grid plate 12. See [link to relevant documentation] Figure 7 and Figure 8 The aerodynamic lift L tends towards the engine axis but at a slight angle, and the aerodynamic drag D is perpendicular to the aerodynamic lift L. Both form components in the axial direction of the grid 1, and the axial components are in opposite directions. The remaining amount after the axial component of the lift overcomes the axial component of the drag is the reverse thrust generated by a single helical grid plate. The sum of the reverse thrusts on all helical grid plates constitutes the total reverse thrust of the reverse thrust blade cascade.

[0026] In this embodiment, the first helical grid 11 and the second helical grid 12 are obliquely positioned relative to the engine axis. During thrust reverser operation, the obliquely positioned helical grid can transfer a portion of the aerodynamic load through axial forces within the grid, thereby reducing the bending moment borne by the grid. This is beneficial for the grid to withstand thrust reverser loads, effectively reducing the strength requirements of the grid and consequently reducing the grid thickness. From a structural stress perspective, the first helical grid 11 and the second helical grid 12 bear the longitudinal thrust reverser force generated by the aerodynamic forces of the thrust reverser blades. The obliquely positioned helical grid is more advantageous than the grids arranged orthogonally along the longitudinal and transverse axes in the prior art. In the orthogonal longitudinal and transverse arrangement, the transverse grid is perpendicular to the engine axis, and the longitudinal grid is parallel to the engine axis. The transverse grid provides all the thrust reverser force and is subjected to bending deformation like a beam. While the longitudinal grid has a lateral flow guiding effect, it does not generate thrust reverser force and only serves as a structural element supporting the transverse grid. It is subjected to tensile and compressive deformation like a rod, and also bears a certain bending moment due to the lateral flow guiding relationship. In the obliquely arranged thrust reverser blade grid of this embodiment, both inclined helical grids can provide thrust reverser force. Compared with the prior art, the rhomboid grid thrust reverser blade grid of this embodiment has higher aerodynamic efficiency. Moreover, during thrust reverser operation, part of the aerodynamic load along the longitudinal direction of the engine can be transmitted through the inclined helical grid in the form of tension or compression of a rod. Therefore, the first helical grid 11 and the second helical grid 12 of the obliquely arranged configuration of this embodiment transmit force more effectively.

[0027] Furthermore, since the thrust reverser blade cascade of this embodiment is manufactured by a continuous fiber winding process, the continuity of the fibers can be guaranteed. Combined with the oblique layout structure of the first helical grid plate 11 and the second helical grid plate 12, the thickness of the grid plate can be reduced compared with the prior art, thereby reducing the net material usage of the thrust reverser blade cascade and achieving weight reduction of the thrust reverser blade cascade. Moreover, after the grid plate is thinned, the thickness encroachment introduced in the existing design to compensate for the discontinuity of the fibers is eliminated. Under the premise that the overall radial / circumferential dimensions of the blade cascade remain unchanged, the effective flow area of ​​the air passage is directly increased. Conversely, if the same effective flow area as the conventional blade cascade is to be guaranteed, there is no need to compensate for the loss of flow area by increasing the axial length of the blade cascade, which helps to shorten the length of the thrust reverser blade cascade and thus shorten the sliding distance of the rectifier casing when the thrust reverser is opened.

[0028] In this embodiment, see Figure 3 A reinforcing element 13 is provided at the junction of the first spiral grid 11 and the second spiral grid 12 to improve the chordal strength of the first spiral grid 11 and the second spiral grid 12. The reinforcing element 13 may be one or more bundles of reinforcing fibers bound at the junction of the first spiral grid 11 and the second spiral grid 12. The reinforcing fiber bundle is bonded and cured with the fiber bundle at the junction to form a whole.

[0029] In this embodiment, see Figure 4 At the trailing edge of the intersection of the first spiral grid plate 11 and the second spiral grid plate 12, a rectification drag reduction and noise reduction protrusion 14 is provided. Specifically, the rectification drag reduction and noise reduction protrusion 14 can be a reinforcing fiber bundle of a designed length solidified on the trailing edge of the intersection and smoothly transitioned with the aerodynamic surface of the rhomboid grid air channel 18, forming a small local protrusion with a topological shape of a quadrangular pyramid on the trailing edge of the intersection, which serves as a rectification trailing edge at the node and plays the role of drag reduction and noise reduction.

[0030] In this embodiment, see Figure 6Taking one of the rhomboid grid air passages 18 of the thrust reverser blade cascade as the target rhomboid grid air passage 18, the target rhomboid grid air passage 18 is formed by the intersection of two parallel first helical grid plates 11 and two parallel second helical grid plates 12, and the target rhomboid grid air passage 18 has a short diagonal line along the axial direction of the thrust reverser blade cascade and a long diagonal line perpendicular to the axial direction of the thrust reverser blade cascade; in this embodiment, in the axial direction of the thrust reverser blade cascade, the V-shaped structure formed by the intersection of the first helical grid plates 11 and the second helical grid plates 12 below the long diagonal line is defined as the lower V-shaped structure, and the intersection point of the lower V-shaped structure is defined as the lower intersection point. O1, and the lower V-shaped structure is the upper aerodynamic surface on the aerodynamic surface of the target rhombic grid air passage 18; the V-shaped structure formed by the intersection of the first spiral grid plate 11 and the second spiral grid plate 12 above the long diagonal is defined as the upper V-shaped structure, and the intersection point of the upper V-shaped structure is defined as the upper intersection point O2, and the upper V-shaped structure is the lower aerodynamic surface on the aerodynamic surface of the target rhombic grid air passage 18; the grid intersection point of the target rhombic grid air passage 18 located on the left side of the short diagonal is defined as the left intersection point O3; the grid intersection point of the target rhombic grid air passage 18 located on the right side of the short diagonal is defined as the right intersection point O4.

[0031] See Figure 6 During reverse thrust, the main stream of the incoming flow flows radially through the target diamond-shaped grid air passage 18 along the reverse thrust blade cascade. During this process, the airflow simultaneously passes through both the upper aerodynamic surface (lower V-shaped structure) and the lower aerodynamic surface (upper V-shaped structure) within the target diamond-shaped grid air passage 18. Because the cross-sectional shape of the first helical grating 11 and the second helical grating 12 is an airfoil, and because the first helical grating 11 and the second helical grating 12 have a preset angle of attack relative to the incoming flow, the flow velocity and pressure are high on the upper aerodynamic surface within the target diamond-shaped grid air passage 18, thus forming a low-pressure zone near the lower V-shaped structure. Conversely, the flow velocity on the lower aerodynamic surface is lower than that on the upper aerodynamic surface, resulting in a higher pressure zone near the upper V-shaped structure. Furthermore, because the helical gratings have a swept-back characteristic relative to the incoming flow, when the airflow passes through the target diamond-shaped grid air passage 18, two spanwise components are formed along the spanwise direction of the lower V-shaped structure. v 1 and v 2. Transverse component v 1 and v The horizontal components of 2 are in opposite directions; simultaneously, two spanning components are formed along the spanning direction of the upper V-shaped lattice structure. v 3 and v 4. Transverse component v 3 and v 4 simultaneously points to the intersection point O2, such as Figure 6 As indicated by the arrows in the diagram. Spread component. v 1 and v 2. Starting from the lower junction O1, the airflow flows along the upper aerodynamic surface of the lower V-shaped structure towards the left junction O3 and the right junction O4, thus forming a low-pressure region above the lower junction O1. (The spanwise component...) v3 and v 4. The lower aerodynamic surfaces along the upper V-shaped structure converge at the upper junction point O2, thus forming a high-pressure zone below the upper junction point O2. Similarly, during reverse thrust, all rhomboid grating passages 18 in the reverse thrust blade cascade form high-pressure and low-pressure zones based on the above mechanism. Due to the pressure difference between the upper and lower aerodynamic surfaces of any rhomboid grating passage 18, lift is generated. The relative concentration of lift at the intersection of the helical gratings is the main characteristic of the lift distribution of the rhomboid grating blade cascade. Figure 9 The Mach number cloud diagram shown can prove this. Furthermore, a diffusion flow will form in the high-pressure area and flow towards the diffusion low-pressure area. v 5. Diffusion airflow v 5. The combined circulation of the spanwise component caused by the sweepback, as described above, forms a pair of stable vortices on the left and right sides within the target diamond-shaped grid air passage 18, carrying the fluid from the high-pressure area to the low-pressure area, such as... Figure 6 As shown.

[0032] Figure 7 The cross section is a vertical line drawn down from the intersection of the grid panels. Figure 7 When the cross-section shown is rotated to a horizontal position relative to adjacent grid plates, the relative positions of the adjacent grid plates are as follows: Figure 8 As shown. Due to the angle of attack of the incoming flow, the grid position shifts backward layer by layer from bottom to top relative to the incoming flow, as... Figure 8 As shown, the diffusion airflow corresponding to each grid layer v The starting and ending points of grid 5 are located at different chordal positions. The high-pressure zone of the upper grid is close to the leading edge, while the corresponding low-pressure zone of the lower grid is close to the trailing edge, i.e., where the airflow is easily separated. Therefore, the diffused airflow flowing from the high-pressure zone... v 5. It helps to prevent airflow separation that may occur in low-pressure areas. In other words, compared with existing thrust reverser blades with rectangular grids formed by orthogonal grids, the thrust reverser blades with diamond grids formed by oblique helical grids in this embodiment can suppress airflow separation at the trailing edge of the grid, allowing the grid airfoil to have a larger angle of attack or camber, thereby generating greater lift and improving thrust reverser efficiency.

[0033] Furthermore, in order to utilize a larger angle of attack or a larger camber of the blade grating, thereby further improving thrust reverse efficiency, this embodiment provides a guide hole 15 at the intersection of the spiral gratings to guide the airflow in the high-pressure zone within the diamond-shaped grating air passage 18 to the low-pressure zone within the adjacent quadrilateral grating air passage 18, further delaying or preventing airflow separation in the low-pressure zone, such as... Figure 6 As shown.

[0034] Based on the same inventive concept, see [link to inventive concept] Figure 11 This embodiment also provides a method for preparing a composite material thrust reverser cascade configuration for aero-engines that is suitable for winding processes and has a non-orthogonal grid, for preparing the aforementioned composite material thrust reverser cascade configuration for aero-engines, including the following steps: Step 1: Based on the three-dimensional model of the aero-engine composite thrust reverser cascade configuration, prepare a continuous fiber winding mold. The mold can be made of a soluble solid material, or it can be made by 3D printing and machining, or it can be a reusable metal mold (to meet the high melting point requirements of thermoplastic composite materials). The outer surface of the continuous fiber winding mold has grooves for forming the aero-engine composite thrust reverser cascade configuration. It should be noted that, due to the complex geometry of the air passage 18 in the thrust reverser cascade, the part of the mold embedded in the air passage 18 may be difficult to demold after the cascade is formed. Therefore, a combination mold can be used as needed for disassembly piece by piece.

[0035] Step 2: Continuous fibers are wound into the grooves on a continuous fiber winding mold. After winding, the fibers are cured and molded, and then demolded to obtain the aero-engine composite thrust reverser cascade configuration. It should be noted that those skilled in the art can select a suitable curing process from existing processes as needed.

[0036] In this embodiment, the composite material thrust reverser cascade configuration of the aero-engine can also be a composite structure. In other words, the thrust reverser cascade is composed of several cascade blocks 19 with different cascade densities and airflow directions. Each cascade block can be cut from a cylindrical integral thrust reverser cascade prepared according to different requirements. Each cascade block 19 has a circumferential frame 20, which is a part cut from the frame 2 on the cylindrical integral thrust reverser cascade, thereby connecting to the engine through the mounting hole 16. An axial frame 21 can be provided at the perpendicular edge of the cascade block 19, such as... Figure 10 As shown, after cutting the grid block 19, the prefabricated straight axial frame 21 is connected to the grid block 19. The connection process includes, but is not limited to, bonding or welding. It should be noted that if the combined blade cascade has its own skeleton, the combined blade cascade may not need to be provided with an axial frame 21. It can be directly connected to the skeleton through the axial edge of the grid block 19. The connection process includes, but is not limited to, bonding or welding.

[0037] In this embodiment, when designing the three-dimensional model of the composite material thrust reverser cascade configuration of the aero-engine, the step of determining the aspect ratio of the rhombic grid air passage 18 includes: 1) After determining the airfoil of the helical grating, based on the three-dimensional model of the thrust reverser cascade with the given helical grating airfoil, simulation analysis is carried out under the design conditions for the diamond grating air passage 18 with different aspect ratios to obtain the maximum non-stall angle of attack of the diamond grating air passage 18 under different aspect ratios. 2) Using the aspect ratio of the rhomboid grid air passage 18 as input and the corresponding maximum non-stall angle of attack as output, a maximum non-stall angle of attack function analysis model is obtained by fitting, and the expression is: ; in, is the maximum non-stall angle of attack of the helical lattice airfoil, and is the angle of attack of the helical lattice airfoil when it reaches its maximum lift coefficient and does not stall. The aspect ratio of the diamond-shaped grid airway 18 is equal to the ratio of the length of the long diagonal to the length of the short diagonal of the diamond-shaped grid airway 18. , , Let be the coefficient, and The specific values ​​were all determined through fitting.

[0038] 3) Based on the maximum non-stall angle of attack function analysis model expression, through... The aspect ratio corresponding to the maximum non-stall angle of attack is determined as the design value of the aspect ratio of the rhomboid grid air passage 18, ensuring that the reverse thrust efficiency of the rhomboid grid air passage 18 is optimal.

[0039] When fabricating thrust reverser cascades, for a given helical lattice airfoil, if the angle of attack of the helical lattice airfoil relative to the airflow is too large, airflow separation will occur due to the low air pressure in the low-pressure area, leading to a sharp drop in lift and a sharp increase in drag, which seriously affects the thrust reverser. Therefore, in determining the aspect ratio of the diamond lattice air duct 18, this embodiment considers the coupling relationship between the aerodynamic characteristics of the helical lattice airfoil and the structural parameters of the diamond lattice. By establishing an analysis model of the maximum non-stall angle of attack function based on the aspect ratio, the complex three-dimensional aerodynamic simulation optimization is transformed into a quantifiable parameter solution process. The aspect ratio corresponding to the maximum non-stall angle of attack is obtained and used as the design value of the optimal aspect ratio. This can effectively improve the lift coefficient and thrust reverser efficiency of the thrust reverser cascade, while avoiding aerodynamic problems such as airflow separation and stall caused by unreasonable structural parameters. It takes into account both aerodynamic performance and the engineering feasibility of structural design, and can provide reliable technical support for the efficient and accurate design of composite material thrust reverser cascade configurations for aero-engines.

[0040] The composite thrust reverser cascade configuration for aero-engines with a non-orthogonal grid, suitable for winding technology, described in this invention, can be efficiently manufactured using a continuous fiber winding process, while also achieving advantages in structural stress and thrust reverser aerodynamics. The continuous fiber winding process ensures fiber continuity, improving the strength and stiffness of the composite thrust reverser cascade. Compared to existing manually laid-up thrust reverser cascades, this invention reduces weight while meeting the same strength and stiffness requirements. Furthermore, it saves on the material usage of the thrust reverser cascade itself, and by avoiding fiber trimming, material utilization is improved, facilitating near-net-shape manufacturing. Simultaneously, because the cascade can be thinned, it helps to shorten the cascade length, thereby reducing the sliding distance of the fairing.

[0041] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention, such as replacing winding with additive manufacturing or 3D printing (winding is also a form of additive manufacturing), should be included within the scope of protection of the present invention.

Claims

1. A composite material thrust reverser cascade configuration for aero-engines, suitable for winding processes and having a non-orthogonal grid, characterized in that, include: The grid (1) is a cylindrical structure made of continuous fiber winding. The grid (1) includes a plurality of first spiral grid plates (11) and a plurality of second spiral grid plates (12) distributed on the circumferential surface of the cylindrical structure. At the end of the cylindrical structure, an arc-shaped connecting grid plate (17) is provided at the transition between the first spiral grid plate (11) and the second spiral grid plate (12). The cross-sectional shape of the first spiral grid plate (11) and the second spiral grid plate (12) is airfoil-shaped. The axes of the first spiral grid plate (11) and the second spiral grid plate (12) have a preset angle with the axis of the cylindrical structure. The spiral directions of the first spiral grid plate (11) and the second spiral grid plate (12) are opposite. The first spiral grid plate (11) and the second spiral grid plate (12) obliquely intersect to form a plurality of quadrilateral grid air passages (18) for guiding the airflow of the engine bypass duct to be ejected in a preset direction and forming a reverse thrust airflow to generate the required reverse thrust. The frame (2) is respectively set at both ends of the grid (1) and connected to the end of the grid (1); the arc-shaped connecting grid plate (17) and the frame (2) together form a mounting hole (16) for connecting the thrust reverser blade to the engine.

2. The composite material thrust reverser cascade configuration for aero-engines according to claim 1, characterized in that, A reinforcing element (13) is provided at the intersection of the first spiral grid (11) and the second spiral grid (12) to improve the strength of the first spiral grid (11) and the second spiral grid (12) along the chord direction.

3. The composite material thrust reverser cascade configuration for aero-engines according to claim 2, characterized in that, The reinforcing element (13) includes a bundle of reinforcing fibers, which is bundled and glued at the junction of the first spiral grid (11) and the second spiral grid (12).

4. The composite material thrust reverser cascade configuration for aero-engines according to claim 3, characterized in that, A rectification, drag reduction, and noise reduction protrusion (14) is provided at the tail edge where the first spiral grid (11) and the second spiral grid (12) meet. The rectification, drag reduction, and noise reduction protrusion (14) smoothly transitions with the aerodynamic surfaces of the first spiral grid (11) and the second spiral grid (12).

5. The composite material thrust reverser cascade configuration for aero-engines according to claim 4, characterized in that, A guide hole (15) is also provided at the intersection of the first spiral grid plate (11) and the second spiral grid plate (12) to guide the airflow in the high-pressure area of ​​the quadrilateral grid air passage (18) to the low-pressure area of ​​the adjacent quadrilateral grid air passage (18) to prevent the airflow in the low-pressure area from separating.

6. The composite material thrust reverser cascade configuration for aero-engines according to any one of claims 1-5, characterized in that, The composite material thrust reverser grating configuration of the aero-engine is composed of several grating blocks (19) with different grating densities and airflow directions.

7. A method for preparing a composite thrust reverser cascade configuration for aero-engines with a non-orthogonal grid, suitable for winding process, for preparing the composite thrust reverser cascade configuration for aero-engines according to any one of claims 1-6, characterized in that, Includes the following steps: Based on the three-dimensional model of the composite thrust reverser cascade configuration of the aero-engine, a continuous fiber winding mold is prepared, wherein the outer surface of the continuous fiber winding mold has grooves for forming the composite thrust reverser cascade configuration of the aero-engine. Continuous fibers are wound into grooves on a continuous fiber winding mold, cured and shaped after winding, and then demolded to obtain the composite thrust reverser cascade configuration of the aero-engine.

8. The method for preparing the composite material thrust reverser cascade configuration for aero-engines according to claim 7, characterized in that, When designing the three-dimensional model of the composite material thrust reverser cascade configuration of the aero-engine, the steps for determining the aspect ratio of the quadrilateral grid air passage (18) include: Based on the three-dimensional model of the thrust reverser cascade with a given helical lattice airfoil, simulation analysis was performed on quadrilateral lattice air passages (18) with different aspect ratios under the design conditions to obtain the maximum non-stall angle of attack of the quadrilateral lattice air passages (18) under different aspect ratios. Using the aspect ratio of the quadrilateral grid air passage (18) as input and the corresponding maximum non-stall angle of attack as output, a maximum non-stall angle of attack function analysis model is obtained by fitting. Based on the expression of the maximum non-stall angle of attack function analysis model, the aspect ratio corresponding to the maximum non-stall angle of attack is determined as the design value of the aspect ratio of the quadrilateral grid air passage (18).

9. The method for preparing the composite material thrust reverser cascade configuration for aero-engines according to claim 8, characterized in that, The maximum non-stall angle of attack function analysis model is expressed as follows: ； in: This is the maximum angle of attack without stall for the helical lattice airfoil. The aspect ratio of the quadrilateral grid airway (18); , , Let be the coefficient, and .

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