A design method for a hinged baffle ejector with a pneumatic valve in the front duct.

Abstract

This invention relates to the field of aero-engine technology, specifically to a design method for a hinged baffle-type front duct ejector with a pneumatic valve. The method includes: determining the geometric parameters of the front duct ejector and the corresponding spacing range between the inner and outer ducts; designing the initial two-dimensional aerodynamic profile of the front duct ejector; obtaining the target two-dimensional aerodynamic profile; determining the final radius of the baffle and designing the baffle; and obtaining the three-dimensional structure of the front duct ejector. This invention comprehensively considers the aerodynamic performance of the front duct ejector under multiple operating conditions, improves design efficiency, reduces the weight and strength requirements of the baffle, and avoids collisions or wear between the baffle and the outer duct wall caused by thermal expansion or vibration of the material.

Description

Technical Field

[0001] This invention relates to the field of aero-engine technology, specifically to a design method for a hinged baffle ejector with pneumatic valves. Background Technology

[0002] Adaptive cycle engines, with their highly efficient bypass ratio regulation and excellent flow rate maintenance capabilities, are becoming ideal power plants for next-generation fighter jets and future supersonic passenger aircraft. The front duct ejector is a key component of the adaptive cycle engine. Its function is to control the mixing of the inner and outer bypass airflows at a reasonable Mach number through geometric adjustment, ensuring uniform outlet airflow properties and minimizing mixing losses. The front duct ejector is a crucial component for achieving flow rate regulation and maintaining high-efficiency operation in adaptive cycle engines; its successful design significantly impacts the overall engine performance.

[0003] Traditional hinged baffle-type front duct ejectors typically close the duct by having the baffle plate contact the duct wall. However, front duct ejectors operate in high-temperature and high-vibration environments, and thermal expansion of materials or vibration can cause the baffle plate to collide and wear against the duct wall. This also results in insufficient baffle plate adjustment flexibility. In other words, traditional methods rely heavily on experimentation and experience to adjust the geometry, making it difficult to consider the aerodynamic performance of the front duct ejector under different operating conditions, leading to low design efficiency and insufficient performance optimization.

[0004] Therefore, there is a need to provide a design method for a hinged baffle ejector with a pneumatic valve to solve the above problems. Summary of the Invention

[0005] This invention provides a design method for a hinged baffle-type front duct ejector with a pneumatic valve to solve existing problems.

[0006] The design method of a hinged baffle ejector with a pneumatic valve according to the present invention adopts the following technical solution, including:

[0007] Based on the engine design requirements, determine the geometric parameters of the front duct ejector and the corresponding spacing range between the inner and outer ducts. The geometric parameters include: the maximum area of ​​the inner duct, the minimum area of ​​the inner duct, the distance from the lower wall of the inner duct inlet to the engine rotation axis, the spacing from the upper wall of the inner duct to the lower wall of the outer duct, the axial distance from the inner duct inlet to the baffle hinge, the maximum area of ​​the outer duct, the minimum area of ​​the outer duct, the axial distance from the outer duct inlet to the baffle hinge, and the total axial length of the front duct ejector.

[0008] Based on the principle that the sum of the mixing areas of the inner and outer ducts of the front duct ejector remains unchanged at the mixing point, and based on the geometric parameters of the front duct ejector, the initial two-dimensional aerodynamic profile of the front duct ejector is designed.

[0009] The presence of local shock waves in the initial two-dimensional aerodynamic profile is detected, and the location of the local shock waves in the initial two-dimensional aerodynamic profile is smoothly transitioned to obtain the target two-dimensional aerodynamic profile.

[0010] The ejector performance of the target two-dimensional aerodynamic profile under various working conditions is obtained. Based on the ejector performance and ejector performance requirements, the minimum radius of the baffle is determined. Based on the minimum and maximum radii of the baffle, the final radius of the baffle is determined and the baffle is designed. The working conditions include: the baffle is located at the minimum area of ​​the outer duct, the maximum area of ​​the outer duct, and the middle area of ​​the outer duct.

[0011] The three-dimensional structure of the front duct ejector is obtained based on the target two-dimensional aerodynamic profile and the final radius of the baffle.

[0012] Preferably, the steps for designing the initial two-dimensional aerodynamic profile of the front duct ejector based on the principle that the sum of the mixing areas of the inner and outer ducts at the mixing point remains unchanged, and according to the geometric parameters of the front duct ejector, are as follows:

[0013] Draw a horizontal line to represent the rotation axis of the aero-engine. Determine the position of the upper wall of the outer duct based on the distance from the lower wall of the inner duct to the rotation axis, the maximum spacing of the inner duct, the distance from the upper wall of the inner duct to the lower wall of the outer duct, and the maximum spacing of the outer duct. Determine the position of the lower wall of the ejector outlet of the front duct based on the mixing area and the position of the upper wall of the outer duct. Determine the position of the lower wall of the outer duct based on the maximum area of ​​the outer duct and the position of the upper wall of the outer duct.

[0014] Based on the spacing range corresponding to the outer and inner ducts, determine the uppermost and lowermost swing positions of the baffle, i.e., the swing range of the baffle.

[0015] Based on the preset baffle radius and the baffle swing range, the baffle is projected onto the lower wall of the outlet to determine the intersection point of the lower wall of the inner duct and the lower wall of the outlet of the front duct ejector.

[0016] When the baffle is at its highest swing position, draw a perpendicular line from the root of the baffle at this moment. The distance is the maximum spacing within the baffle. The position of the perpendicular line is the position of the cross section at the root of the baffle.

[0017] Based on the distance between the upper wall of the inner duct and the lower wall of the outer duct, the location of the inner duct inlet, and the maximum area of ​​the inner duct, determine the axial relative position of the inner duct inlet section and the distance between the inner duct inlet section and the outer duct inlet section;

[0018] The initial two-dimensional aerodynamic profile can be obtained by generating curved splines based on the cross-section of the baffle root, the inlet cross-section of the inner cavity, and the axial relative position of the inlet cross-section of the inner cavity to the inlet cross-section of the outer cavity, and by determining the upper and lower walls of the inner cavity based on the maximum area of ​​the inner cavity.

[0019] Preferably, the step of obtaining the spacing range corresponding to the connotation and the denotation is as follows:

[0020] The spacing range of the inner cavity is obtained based on the maximum area of ​​the inner cavity, the minimum area of ​​the inner cavity, the distance from the lower wall of the inner cavity to the engine rotation axis, and the distance from the upper wall of the inner cavity to the lower wall of the outer cavity.

[0021] The spacing range of the outer duct is obtained based on the maximum area of ​​the outer duct, the minimum area of ​​the outer duct, the distance from the lower wall of the outer duct to the engine rotation axis, the maximum spacing of the inner duct, and the distance from the upper wall of the inner duct to the lower wall of the outer duct.

[0022] Preferably, the step of obtaining the inner spacing range is as follows:

[0023] The maximum spacing of the inner cavity is obtained based on the maximum area of ​​the inner cavity and the distance from the lower wall of the inner cavity to the engine rotation axis.

[0024] The minimum spacing of the inner cavity is obtained based on the minimum area of ​​the inner cavity, the distance from the lower wall of the inner cavity to the engine rotation axis, and the distance from the upper wall of the inner cavity to the lower wall of the outer cavity.

[0025] The spacing range of the connotation is obtained based on the minimum and maximum spacing of the connotation.

[0026] Preferably, the step of obtaining the duct spacing range is as follows:

[0027] The maximum spacing of the outer duct is obtained based on the maximum area of ​​the outer duct, the distance from the lower wall of the outer duct to the engine rotation axis, the maximum spacing of the inner duct, and the distance from the upper wall of the inner duct to the lower wall of the outer duct.

[0028] The minimum spacing of the outer culvert is obtained based on the minimum area of ​​the outer culvert, the maximum spacing of the outer culvert, the distance from the lower wall of the outer culvert to the engine rotation axis, the maximum spacing of the inner culvert, and the distance from the upper wall of the inner culvert to the lower wall of the outer culvert.

[0029] The spacing range of the outer culverts is obtained based on the minimum and maximum spacing of the outer culverts.

[0030] Preferably, the steps for obtaining the minimum and maximum spacing of the connotation are as follows:

[0031] The expression for the minimum spacing is:

[0032]

[0033] The expression for the maximum internal spacing is:

[0034]

[0035] In the formula, The minimum spacing within the connotation; The maximum spacing within the connotation; This refers to the distance between the lower inner wall and the engine's rotation axis; The maximum area of ​​the interior; The minimum area of ​​the inner meaning; It is the distance between the upper wall of the inner culvert and the lower wall of the outer culvert.

[0036] Preferably, the steps for obtaining the minimum and maximum spacing of the outer culverts are as follows:

[0037] The expression for the minimum spacing of the outer bypass is:

[0038]

[0039] The expression for the maximum spacing of the outer duct is:

[0040]

[0041] In the formula, This represents the minimum spacing between the outer culverts; This represents the maximum spacing between the outer culverts; The maximum spacing within the connotation; This refers to the distance between the lower inner wall and the engine's rotation axis; This represents the maximum area of ​​the outer culvert. This represents the minimum area of ​​the outer duct. It is the distance between the upper wall of the inner culvert and the lower wall of the outer culvert.

[0042] Preferably, the step of determining the minimum radius of the baffle plate is as follows:

[0043] The ejector performance is the total pressure recovery coefficient, which is obtained by taking into account the pressure and flow rate at the inlet and outlet of the front duct ejector corresponding to the inner and outer ducts.

[0044] The flow field is simulated again and the radius of the baffle is reduced multiple times until the baffle radius is reduced to a certain value and the outer bypass cannot be completely closed or the ejector performance does not meet the performance requirements. Then the previous baffle radius is taken as the minimum baffle radius.

[0045] Preferably, the step of determining the final radius of the baffle plate based on its minimum and maximum radii is as follows:

[0046]

[0047] In the formula, The final radius of the baffle plate; This is the proportionality coefficient; The minimum radius of the baffle plate; This represents the maximum radius of the baffle plate.

[0048] Preferably, the steps for obtaining the three-dimensional aerodynamic profile of the ejector based on the target two-dimensional aerodynamic profile and the baffle plate with the final radius are as follows:

[0049] The target two-dimensional aerodynamic surface is rotated around the engine main shaft to generate a three-dimensional annular section; the baffle plate of the final radius is connected to the front end of the junction of the inner and outer ducts through a hinge to obtain the three-dimensional structure of the front duct ejector.

[0050] The beneficial effects of this invention are:

[0051] By keeping the mixing area of ​​the inner and outer ducts constant, a two-dimensional design of the front duct ejector is carried out. The pressure difference between the inlet and outlet of the inner and outer ducts of the front duct ejector is used to form a pneumatic valve to close the outer duct. The aerodynamic performance of the front duct ejector under multiple working conditions can be comprehensively considered, improving design efficiency, reducing the weight and strength requirements of the baffle plate, and avoiding collisions or wear between the baffle plate and the outer duct wall caused by thermal expansion or vibration of the material. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 A flowchart illustrating the design method of a hinged baffle ejector with a pneumatic valve according to the present invention.

[0054] Figure 2 This is a two-dimensional aerodynamic profile diagram of the front duct ejector in an embodiment of the present invention;

[0055] Figure 3 This is a schematic diagram of the streamline of the outer duct closure of the present invention;

[0056] Figure 4 This is a schematic diagram of the distribution of the baffle plates of the three-dimensional front duct ejector in an embodiment of the present invention. Detailed Implementation

[0057] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0058] An embodiment of the design method for a hinged baffle-type front duct ejector with a pneumatic valve according to the present invention is as follows: Figure 1 As shown, it includes:

[0059] S1. Determine the geometric parameters of the front duct ejector and the corresponding spacing range of the inner and outer ducts;

[0060] Specifically, based on engine design requirements, the geometric parameters of the front bypass ejector and the corresponding spacing range between the inner and outer bypasses are determined. The geometric parameters include: the maximum area S of the inner bypass. 2max Minimum area S 2min 1. Distance I0 from the lower wall of the inner duct inlet to the engine rotation axis; 2. Spacing H from the upper wall of the inner duct to the lower wall of the outer duct; 3. Axial distance L2 from the inner duct inlet to the baffle hinge; 4. Maximum area S of the outer duct. 1max Minimum area S of the outer duct 1min The axial distance L1 from the outer duct inlet to the baffle hinge and the total axial length L of the front duct ejector.

[0061] For example, in one specific embodiment, the step of obtaining the spacing range corresponding to the inner and outer ducts is as follows: obtaining the spacing range of the inner duct based on the maximum area of ​​the inner duct, the minimum area of ​​the inner duct, the distance from the lower wall of the inner duct to the engine rotation axis, and the spacing from the upper wall of the inner duct to the lower wall of the outer duct; obtaining the spacing range of the outer duct based on the maximum area of ​​the outer duct, the minimum area of ​​the outer duct, the distance from the lower wall of the outer duct to the engine rotation axis, the maximum spacing of the inner duct, and the spacing from the upper wall of the inner duct to the lower wall of the outer duct.

[0062] The steps for obtaining the spacing range of the connotation are as follows:

[0063] The maximum spacing of the inner walls is obtained based on the maximum area of ​​the inner walls and the distance from the lower wall of the inner walls to the engine rotation axis; the expression for the minimum spacing of the inner walls is:

[0064]

[0065] Based on the minimum area of ​​the inner cavity, the distance from the lower wall of the inner cavity to the engine rotation axis, and the distance from the upper wall of the inner cavity to the lower wall of the outer cavity, the minimum spacing of the inner cavity is obtained, i.e., the expression for the minimum spacing of the inner cavity is:

[0066]

[0067] In the formula, The minimum spacing within the connotation; The maximum spacing within the connotation; This refers to the distance between the lower inner wall and the engine's rotation axis; The maximum area of ​​the interior; The minimum area of ​​the inner meaning; The distance between the upper wall of the inner culvert and the lower wall of the outer culvert;

[0068] The spacing range of the connotation is obtained based on the minimum and maximum spacing of the connotation. The spacing range of the connotation is ( , ).

[0069] The steps for obtaining the spacing range of the culvert are as follows: First, obtain the maximum spacing of the culvert based on its maximum area, the distance from the lower wall of the culvert to the engine rotation axis, the maximum spacing of the inner culvert, and the distance from the upper wall of the inner culvert to the lower wall of the culvert. Second, obtain the minimum spacing of the culvert based on its minimum area, the maximum spacing of the culvert, the distance from the lower wall of the culvert to the engine rotation axis, the maximum spacing of the inner culvert, and the distance from the upper wall of the inner culvert to the lower wall of the culvert. Third, obtain the spacing range of the culvert based on the minimum and maximum spacing.

[0070] The expression for the minimum spacing of the outer duct is:

[0071]

[0072] The expression for the maximum spacing of the outer duct is:

[0073]

[0074] In the formula, This represents the minimum spacing between the outer culverts; This represents the maximum spacing between the outer culverts; The maximum spacing within the connotation; This refers to the distance between the lower inner wall and the engine's rotation axis; This represents the maximum area of ​​the outer culvert. This represents the minimum area of ​​the outer duct. It is the distance between the upper wall of the inner culvert and the lower wall of the outer culvert.

[0075] The spacing range of the outer culvert is ( , ).

[0076] S2. Design the initial two-dimensional aerodynamic profile of the front duct ejector;

[0077] Specifically, based on the principle that the sum of the mixing areas of the inner and outer ducts of the front duct ejector remains unchanged at the mixing point, and according to the geometric parameters of the front duct ejector, the initial two-dimensional aerodynamic profile of the front duct ejector is designed.

[0078] The steps for designing the initial two-dimensional aerodynamic profile of the front duct ejector include: drawing a horizontal line to represent the aero-engine's rotation axis; determining the position of the outer duct's upper wall based on the distance from the lower wall of the inner duct to the rotation axis, the maximum spacing of the inner duct, the distance from the upper wall of the inner duct to the lower wall of the outer duct, and the maximum spacing of the outer duct; determining the position of the lower wall of the front duct ejector outlet based on the mixing area and the position of the upper wall of the outer duct; determining the position of the lower wall of the outer duct based on the maximum area of ​​the outer duct and the position of the upper wall of the outer duct; determining the uppermost and lowermost swing positions of the baffle plate, i.e., the swing range of the baffle plate, based on the corresponding spacing range of the outer duct and the inner duct; and projecting the baffle plate onto the lower wall of the outlet based on the preset baffle plate radius and swing range to determine the inner duct... The intersection of the lower wall surface and the lower wall surface of the ejector outlet of the front duct; when the baffle plate swings to its highest swing position, draw a perpendicular line from the root of the baffle plate at this moment, the distance being the maximum spacing of the inner cavity, and the position of the perpendicular line is the cross-sectional position of the inner cavity at the root of the baffle plate; based on the spacing between the upper wall surface of the inner cavity and the lower wall surface of the outer duct, the inlet position of the inner cavity, and the maximum area of ​​the inner cavity, since the inlet cross-section of the inner cavity is parallel to the inlet cross-section of the outer duct, the axial relative position of the inlet cross-section of the inner cavity and the distance between the inlet cross-section of the inner cavity and the inlet cross-section of the outer duct can be determined; based on the cross-section of the root of the baffle plate, the inlet cross-section of the inner cavity, and the axial relative position of the inlet cross-section of the inner cavity and the inlet cross-section of the outer duct, a curved spline is generated, and the upper and lower walls of the inner cavity are determined based on the maximum area of ​​the inner cavity, thus obtaining the initial two-dimensional aerodynamic profile.

[0079] For example, in one specific embodiment, in conjunction with the appendix Figure 2 Step 2 is explained as follows:

[0080] Step 21: Make as follows Figure 3 The reference horizontal line PP1 represents the engine main shaft. According to the engine's geometric constraints, regardless of the direction the baffle rotates, the sum of the areas of the outer and inner sections of the front duct ejector at the mixing point remains constant. Therefore, firstly, based on the mixing area, two straight lines AE and FF1 parallel to the reference horizontal line PP1 are created above it. The distance from line AE to the reference horizontal line PP1 is I0 + I... 2max +H+I 1max The length is L, the total axial length of the front duct ejector, and the distance I0+I from the straight line FF1 to the reference horizontal line PP1. 2max +HI 2min AE represents the upper wall of the duct ejector outer wall, and FF1 represents the lower wall of the duct ejector outlet.

[0081] Step 22: Based on the maximum area of ​​the outer culvert Draw a line BM parallel to line AE. The distance from the parallel line BM to the reference horizontal line PP1 is I0 + I. 2max+H, the length is the distance L1 from the duct inlet to the baffle hinge, BM represents the lower wall of the duct, and point M is the position of the baffle hinge.

[0082] Based on the maximum area of ​​the outer culvert Given the minimum area of ​​the outer culvert, draw two parallel lines KK1 and JJ1 to line AE. Both lines KK1 and JJ1 are located below line AE, and the distance from line KK1 to line AE is I. 1min The distance between parallel line JJ1 and line AE is I. 1max Parallel lines KK1 and AE represent the minimum spacing of the culvert, and parallel lines JJ1 and AE represent the maximum area of ​​the culvert.

[0083] Choose the radius R of the baffle plate. With point M as the center, the baffle plate with radius R intersects the parallel line KK1 of the minimum area of ​​the outer duct at point K. The baffle plate with radius R intersects the parallel line JJ1 of the maximum area of ​​the outer duct at point J. MK is the maximum position of the baffle plate swinging upward, and MJ is the maximum position of the baffle plate swinging downward.

[0084] Step 23: Based on the radius and swing range of the baffle plate, project the baffle plate onto the lower wall of the outlet. Draw a perpendicular line from point K to line FF1, and the intersection point is N. Draw a perpendicular line from point J to line FF1, and the intersection point is Q. The point between Q and N that is closest to the inlet of the outer duct is the intersection point of the lower wall of the inner duct and the lower wall of the outlet of the front duct ejector. In this example, point N is the intersection point.

[0085] Step 24: Since the outer duct outlet area of ​​the front duct ejector is the smallest and the inner duct outlet area is the largest when the baffle swings to its highest swing position, a perpendicular line with length I is drawn from point M to MK. 2max Obtain MS and connect line segment SN.

[0086] Step 25: Draw the baffle end face line CD parallel to the outer bypass inlet line AB. The distance from the baffle end face line CD to point M is L2, the hinge distance from the inner bypass inlet to the baffle, and the distance from D to the engine main shaft PP1 is I0. The length of CD is I. 2max CD represents imported content.

[0087] Step 26: Generate a curved center spline using the midpoints of CD and MS, and evenly distribute points along the center spline. At these points, construct the normal to the center spline with a height of I. 2max The points on the spline centerline are the discovered midpoints. Finally, the upper part of the points above the normal and the lower part of the points below the normal are fitted into spline curves to form the upper and lower walls of the inner cavity. That is, AE, BM, CM, DS, SN, NF and MK (MJ) constitute the two-dimensional aerodynamic profile of the front duct ejector. MK indicates that the baffle is in the uppermost swing position; MJ indicates that the baffle is in the lowermost position.

[0088] S3. Obtain the target two-dimensional aerodynamic profile;

[0089] Specifically, the presence of local shock waves in the initial two-dimensional aerodynamic profile is detected, and the location of the local shock waves in the initial two-dimensional aerodynamic profile is smoothly transitioned to obtain the target two-dimensional aerodynamic profile.

[0090] For example, in a specific embodiment, point N in the design process of step 2 is considered a sharp corner. Through numerical simulation, a local shock wave may occur at point N. To address the potential local supersonic and shock wave problems caused by point N, appropriate rounding is used to reduce or even eliminate shock wave losses. However, the rounding should not be too large and should not exceed point Q, thereby keeping the sum of the areas of the outer and inner ducts of the front duct ejector at the mixing point unchanged. After smooth transition processing at the location where a local shock wave exists, the target two-dimensional aerodynamic profile is obtained.

[0091] S4. Determine the final radius of the baffle plate and design the baffle plate;

[0092] Specifically, the ejector performance of the target two-dimensional aerodynamic profile under various operating conditions is obtained. Based on the ejector performance and ejector performance requirements, the minimum radius of the baffle is determined. Based on the minimum and maximum radii of the baffle, the final radius of the baffle is determined and the baffle is designed. The operating conditions include: the baffle is located at the minimum area of ​​the outer duct, the baffle is located at the maximum area of ​​the outer duct, and the baffle is located at the middle area of ​​the outer duct.

[0093] For example, in one specific embodiment, the steps of designing a flow barrier include:

[0094] Step 41: Select operating conditions. Based on the engine adjustment requirements and the performance requirements of the front duct ejector, select the position where the baffle plate is at the smallest outer duct area (MK), the position where the outer duct area is at the largest (MJ), and the intermediate typical operating conditions. Determine the flow state of the inner and outer ducts of the engine under the corresponding operating conditions, including but not limited to the pressure and flow rate at the inlet and outlet. The ejector performance is the total pressure recovery coefficient. The total pressure recovery coefficient of the front duct ejector is obtained based on the pressure and flow rate at the corresponding inlet and outlet of the inner and outer ducts.

[0095] Step 42: Reduce the radius of the baffle plate and analyze the recirculation zone. Examine the recirculation zone formed at the mixing point of the bypass. A schematic diagram of the streamlines near the recirculation zone is shown below. Figure 3 As shown, when the baffle plate swings to its highest swing position, the return zone blocks the outer bypass channel, reducing the outer bypass airflow to 0, thus achieving the effect of a pneumatic valve.

[0096] Step 43: Repeat the process of reducing the baffle radius in step 42. After each reduction, re-simulate the flow field when the baffle is at its highest swing position to find the minimum baffle radius that meets the requirements. That is, if the choke radius cannot completely close the outer bypass or the ejector performance fails to meet the performance requirements when it is reduced to a certain value, then the previous choke radius is taken as the minimum choke radius; the final choke radius is determined by extending an appropriate margin according to the design requirements of the engine and the front bypass ejector. Increment of margin The longest baffle radius in contact with the outer wall of the flow barrier. With minimum baffle radius The difference calculation, i.e., the final radius of the baffle plate. The expression is:

[0097]

[0098] In the formula, The final radius of the baffle plate; The minimum radius of the baffle plate; The maximum radius of the baffle plate This is a proportionality coefficient; it is adjusted based on the engine's inner and outer duct radii and the performance of the front duct ejector under various operating conditions.

[0099] S5. Obtain the three-dimensional structure of the front duct ejector;

[0100] The three-dimensional structure of the ejector is obtained based on the target two-dimensional aerodynamic profile and the baffle plate of the final radius. Specifically, the target two-dimensional aerodynamic profile is rotated around the engine main axis to generate a three-dimensional annular cross section. The baffle plate of the final radius is connected to the front end of the junction of the inner and outer ducts through a hinge to obtain the three-dimensional structure of the ejector.

[0101] For example, in one specific embodiment, the steps for designing the three-dimensional structure of the front duct ejector are as follows:

[0102] Step 51: For the target two-dimensional aerodynamic profile of the ducted ejector designed in step S3, the upper and lower walls of the inner and outer ducts are fixed geometry, and the center distance between the inner and outer ducts and the relative positions of the inlet and outlet have been determined through two-dimensional design, such as... Figure 3 As shown. Only around the engine main shaft ( Figure 3 The three-dimensional model configuration can be completed by rotating the PP1 line, and the inner and outer connotations form a coaxial three-dimensional annular cross section.

[0103] Step 52: For the adjustable hinged baffle structure, a three-dimensional arc surface structure is generated by rotating around the engine main shaft. Multiple baffles are spliced ​​together to form this arc surface structure, achieving the baffle's adjustability. Each baffle unfolds into a fan-shaped ring structure, and airtightness is maintained during adjustment by the overlapping of its edges. A schematic diagram of the axial projection distribution of the baffles is shown below. Figure 4 As shown, the curvature of the baffle plate is consistent with the curvature of the lower wall of the duct ejector.

[0104] Step 53: Each baffle plate is connected to the duct wall via a hinge. The hinge is designed at the contact point between the baffle plate and the duct wall. The baffle plates are evenly distributed in the front duct ejector with equal arc lengths. The radial length of a single baffle plate remains unchanged, while the circumferential length of the baffle plate is increased. At the same time, adjacent baffle plates are staggered front to back, and the edge areas overlap, so that the arc surface structure spliced ​​within the adjustment range of the baffle plates can maintain good airtightness.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A design method for a hinged baffle-type front duct ejector with a pneumatic valve, characterized in that, include: Based on the engine design requirements, determine the geometric parameters of the front duct ejector and the corresponding spacing range between the inner and outer ducts. The geometric parameters include: the maximum area of ​​the inner duct, the minimum area of ​​the inner duct, the distance from the lower wall of the inner duct inlet to the engine rotation axis, the spacing from the upper wall of the inner duct to the lower wall of the outer duct, the axial distance from the inner duct inlet to the baffle hinge, the maximum area of ​​the outer duct, the minimum area of ​​the outer duct, the axial distance from the outer duct inlet to the baffle hinge, and the total axial length of the front duct ejector. Based on the principle that the sum of the mixing areas of the inner and outer ducts of the front duct ejector remains unchanged at the mixing point, and based on the geometric parameters of the front duct ejector, the initial two-dimensional aerodynamic profile of the front duct ejector is designed. The presence of local shock waves in the initial two-dimensional aerodynamic profile is detected, and the location of the local shock waves in the initial two-dimensional aerodynamic profile is smoothly transitioned to obtain the target two-dimensional aerodynamic profile. The ejector performance of the target two-dimensional aerodynamic profile under various working conditions is obtained. Based on the ejector performance and ejector performance requirements, the minimum radius of the baffle is determined. Based on the minimum and maximum radii of the baffle, the final radius of the baffle is determined and the baffle is designed. The working conditions include: the baffle is located at the minimum area of ​​the outer duct, the maximum area of ​​the outer duct, and the middle area of ​​the outer duct. The three-dimensional structure of the front duct ejector is obtained based on the target two-dimensional aerodynamic profile and the final radius of the baffle.

2. The design method of a hinged baffle-type front duct ejector with a pneumatic valve according to claim 1, characterized in that, Based on the principle that the sum of the mixing areas of the inner and outer ducts of the front duct ejector remains constant at the mixing point, and according to the geometric parameters of the front duct ejector, the steps for designing the initial two-dimensional aerodynamic profile of the front duct ejector are as follows: Draw a horizontal line to represent the rotation axis of the aero-engine. Determine the position of the upper wall of the outer duct based on the distance from the lower wall of the inner duct to the rotation axis, the maximum spacing of the inner duct, the distance from the upper wall of the inner duct to the lower wall of the outer duct, and the maximum spacing of the outer duct. Determine the position of the lower wall of the ejector outlet of the front duct based on the mixing area and the position of the upper wall of the outer duct. Determine the position of the lower wall of the outer duct based on the maximum area of ​​the outer duct and the position of the upper wall of the outer duct. Based on the spacing range corresponding to the outer and inner ducts, determine the uppermost and lowermost swing positions of the baffle, i.e., the swing range of the baffle. Based on the preset baffle radius and the baffle swing range, the baffle is projected onto the lower wall of the outlet to determine the intersection point of the lower wall of the inner duct and the lower wall of the outlet of the front duct ejector. When the baffle is at its highest swing position, draw a perpendicular line from the root of the baffle at this moment. The distance is the maximum spacing within the baffle. The position of the perpendicular line is the position of the cross section at the root of the baffle. Based on the distance between the upper wall of the inner duct and the lower wall of the outer duct, the location of the inner duct inlet, and the maximum area of ​​the inner duct, since the inner duct inlet section is parallel to the outer duct inlet section, the axial relative position of the inner duct inlet section and the distance between the inner duct inlet section and the outer duct inlet section can be determined. The initial two-dimensional aerodynamic profile can be obtained by generating curved splines based on the cross-section of the baffle root, the inlet cross-section of the inner cavity, and the axial relative position of the inlet cross-section of the inner cavity to the inlet cross-section of the outer cavity, and by determining the upper and lower walls of the inner cavity based on the maximum area of ​​the inner cavity.

3. The design method of a hinged baffle ejector with a pneumatic valve according to claim 2, characterized in that, The steps to obtain the spacing range corresponding to the connotation and denotation are as follows: The spacing range of the inner cavity is obtained based on the maximum area of ​​the inner cavity, the minimum area of ​​the inner cavity, the distance from the lower wall of the inner cavity to the engine rotation axis, and the distance from the upper wall of the inner cavity to the lower wall of the outer cavity. The spacing range of the outer duct is obtained based on the maximum area of ​​the outer duct, the minimum area of ​​the outer duct, the distance from the lower wall of the outer duct to the engine rotation axis, the maximum spacing of the inner duct, and the distance from the upper wall of the inner duct to the lower wall of the outer duct.

4. The design method of a hinged baffle-type front duct ejector with a pneumatic valve according to claim 3, characterized in that, The steps to obtain the spacing range of the connotation are as follows: The maximum spacing of the inner cavity is obtained based on the maximum area of ​​the inner cavity and the distance from the lower wall of the inner cavity to the engine rotation axis. The minimum spacing of the inner cavity is obtained based on the minimum area of ​​the inner cavity, the distance from the lower wall of the inner cavity to the engine rotation axis, and the distance from the upper wall of the inner cavity to the lower wall of the outer cavity. The spacing range of the connotation is obtained based on the minimum and maximum spacing of the connotation.

5. The design method of a hinged baffle type front duct ejector with a pneumatic valve according to claim 3, characterized in that, The steps to obtain the duct spacing range are as follows: The maximum spacing of the outer duct is obtained based on the maximum area of ​​the outer duct, the distance from the lower wall of the outer duct to the engine rotation axis, the maximum spacing of the inner duct, and the distance from the upper wall of the inner duct to the lower wall of the outer duct. The minimum spacing of the outer culvert is obtained based on the minimum area of ​​the outer culvert, the maximum spacing of the outer culvert, the distance from the lower wall of the outer culvert to the engine rotation axis, the maximum spacing of the inner culvert, and the distance from the upper wall of the inner culvert to the lower wall of the outer culvert. The spacing range of the outer culverts is obtained based on the minimum and maximum spacing of the outer culverts.

6. The design method of a hinged baffle type front duct ejector with a pneumatic valve according to claim 4, characterized in that, The steps to obtain the minimum and maximum spacing of the connotation are as follows: The expression for the minimum spacing is: The expression for the maximum internal spacing is: In the formula, The minimum spacing within the connotation; The maximum spacing within the connotation; This refers to the distance between the lower inner wall and the engine's rotation axis; The maximum area of ​​the interior; The minimum area of ​​the inner meaning; It is the distance between the upper wall of the inner culvert and the lower wall of the outer culvert.

7. The design method of a hinged baffle-type front duct ejector with a pneumatic valve according to claim 5, characterized in that, The steps to obtain the minimum and maximum spacing of the outer ducts are as follows: The expression for the minimum spacing of the outer bypass is: The expression for the maximum spacing of the outer duct is: In the formula, This represents the minimum spacing between the outer culverts; This represents the maximum spacing between the outer culverts; The maximum spacing within the connotation; This refers to the distance between the lower inner wall and the engine's rotation axis; This represents the maximum area of ​​the outer culvert. This represents the minimum area of ​​the outer duct. It is the distance between the upper wall of the inner culvert and the lower wall of the outer culvert.

8. The design method of a hinged baffle type front duct ejector with a pneumatic valve according to claim 1, characterized in that, The steps to determine the minimum radius of the baffle plate are as follows: The ejector performance is the total pressure recovery coefficient, which is obtained by taking into account the pressure and flow rate at the inlet and outlet of the front duct ejector corresponding to the inner and outer ducts. The flow field is simulated again and the radius of the baffle is reduced multiple times until the baffle radius is reduced to a certain value and the outer bypass cannot be completely closed or the ejector performance does not meet the performance requirements. Then the previous baffle radius is taken as the minimum baffle radius.

9. The design method of a hinged baffle type front duct ejector with a pneumatic valve according to claim 1, characterized in that, The steps to determine the final radius of the baffle plate based on its minimum and maximum radii are as follows: In the formula, The final radius of the baffle plate; This is the proportionality coefficient; The minimum radius of the baffle plate; This represents the maximum radius of the baffle plate.

10. The design method of a hinged baffle ejector with a pneumatic valve according to claim 1, characterized in that, The steps for obtaining the three-dimensional aerodynamic profile of the ejector based on the target two-dimensional aerodynamic profile and the baffle plate with the final radius are as follows: The target two-dimensional aerodynamic surface is rotated around the engine main shaft to generate a three-dimensional annular section; the baffle plate of the final radius is connected to the front end of the junction of the inner and outer ducts through a hinge to obtain the three-dimensional structure of the front duct ejector.

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