Design method for two-dimensional aerodynamic molded surface of reverse thrust exhaust volute of aero-engine

Abstract

The invention relates to a design method for a two-dimensional aerodynamic profile of a reverse thrust exhaust volute of an aero-engine, belongs to the technical field of aircraft design, and solves the problems that in the prior art, an aerodynamic profile of an exhaust volute is complex in structure and difficult to machine and assemble. The invention provides a method for designing a two-dimensional pneumatic profile of a reverse thrust exhaust volute of an aero-engine, a pressure surface, a first flow deflector, a second flow deflector and a suction surface are designed in sequence according to the size of an exhaust port of the engine and the exhaust direction, the pressure surface and the suction surface adopt arc design with extension lines, and the flow deflectors adopt arc design. The pneumatic molded surface designed through the design method is simple in structure, the machining difficulty and cost are remarkably reduced, and assembling is convenient and fast; a flow field in the reverse thrust exhaust volute adopting the pneumatic molded surface is stable and smooth, streamline / exhaust airflow leaving from an outlet of the volute can smoothly enter an injection barrel, the influence on reverse thrust exhaust back pressure is smaller than or equal to 200 Pa, and the exhaust effect is stable and excellent.

Description

Technical Field

[0001] The invention relates to the technical field of aircraft design, and in particular to a design method for a two-dimensional aerodynamic profile of an aircraft engine thrust reverse exhaust volute. Background Art

[0002] When the engine is tested in reverse thrust on an indoor test bench, the reverse thrust exhaust airflow emitted by the engine is in the opposite direction to the mainstream direction of the engine. Therefore, during the reverse thrust test, the reverse thrust exhaust may be re-inhaled by the engine, causing the intake conditions such as the engine intake temperature and intake uniformity to deviate from the test conditions. In severe cases, the engine may be in an unstable condition, which may lead to engine damage or even danger. Therefore, during the reverse thrust test of the engine, it should be avoided that the engine re-inhales the reverse thrust exhaust airflow.

[0003] During the reverse thrust test of the engine, the reverse thrust exhaust volute can collect the airflow discharged from the reverse thrust blades of the engine, and guide the reverse thrust exhaust airflow to the rear of the engine and discharge it to the ejector tube of the test bench to prevent the engine from re-inhaling it. In order to achieve a good exhaust effect, various existing reverse thrust exhaust volutes often adopt complex structural designs. Although they can achieve a good exhaust effect, the complex structure leads to high processing difficulty and high cost, and the actual assembly is difficult, which requires high operator skills. Summary of the invention

[0004] In view of the above analysis, an embodiment of the present invention aims to provide a method for designing a two-dimensional aerodynamic surface of an aircraft engine thrust reverse exhaust volute, so as to solve at least one of the problems in the prior art of the exhaust volute aerodynamic surface, such as complex structure, difficult processing (difficult processing and high cost), and assembly.

[0005] The present invention provides a design method for a two-dimensional aerodynamic profile of a reverse thrust exhaust volute of an aircraft engine, wherein the aerodynamic profile comprises a pressure surface, a first guide vane, a second guide vane and a suction surface from left to right, wherein the pressure surface and the suction surface are arcs with extension lines at the exhaust end, and the first guide vane and the second guide vane are arcs;

[0006] The specific steps include:

[0007] S1: According to the axial length L of the engine exhaust port x Determine the arc radius R of the pressure surface 压力面 , and according to the engine exhaust angle θ 发动机 , that is, the volute air intake angle θ 进气 , determine the arc tangent angle of the air inlet end of the pressure surface;

[0008] S2: Determine the exhaust angle θ of the volute according to the position of the ejector tube 排气, determine the arc tangent angle of the outlet end of the pressure surface according to the exhaust angle, that is, the extension line angle;

[0009] S3: Determine the arc radius R of the suction surface according to the arc radius of the pressure surface 吸力面 , the tangent angles of the air inlet and air outlet ends of the suction surface arc are the same as the tangent angles of the corresponding ends of the pressure surface arc;

[0010] S4: Determine the installation positions of the pressure surface and the suction surface inlet ends according to the size of the engine exhaust port; determine the virtual inlet end positions of the first guide vane and the second guide vane according to the size of the engine exhaust port, and the nearest intersection point of the complete circle corresponding to the guide vane arc and the plane where the engine exhaust port is located is the virtual inlet end;

[0011] S5: the tangent angles of the virtual air inlet and air outlet ends of the arcs of the first guide vane and the second guide vane are the same as the tangent angles of the corresponding ends of the arc of the pressure surface;

[0012] S6: Draw a line connecting the center of the circle corresponding to the pressure surface arc and the center of the circle corresponding to the suction surface arc, and draw perpendicular lines to the tangent lines of the volute intake angle from the virtual intake ends of the first guide vane and the second guide vane, respectively. The intersection of the perpendicular line and the connecting line is the center position of the circle corresponding to the arc of the first guide vane and the second guide vane, and then determine the radius of the first guide vane and the second guide vane;

[0013] S7: removing a portion of the first guide vane and the second guide vane from the virtual air inlet end respectively to obtain an actual air inlet end, that is, to obtain a final aerodynamic profile;

[0014] Among them, the engine exhaust angle θ 发动机 and θ 进气 is the angle with the vertical direction, the volute exhaust angle θ 排气 It is the angle with the horizontal direction, with the counterclockwise direction as a positive value and the clockwise direction as a negative value; the left and right direction is the axial direction X, and the direction perpendicular to the paper surface is the circumferential direction Y.

[0015] Specifically, the arc extension line of the suction surface is ≥150mm;

[0016] After determining the end point of the suction surface arc extension line, draw a perpendicular line from this point to the suction surface arc extension line, and the intersection of the perpendicular line and the pressure surface arc extension line is the end point of the pressure surface arc extension line.

[0017] Specifically, for any point of the engine exhaust port, the centers of the arcs corresponding to the pressure surface, the first guide vane, the second guide vane, and the suction surface are located on the same side of the vertical line and the four points are collinear; the four centers are located on opposite sides of the vertical line from the engine exhaust direction.

[0018] Specifically, in step S1, R压力面 The method of determining is to take twice the axial length L of the engine exhaust port x And the distance upward or downward shall be rounded to the nearest integer multiple of 100 mm;

[0019] 2L x When the value is an integer multiple of 100 mm, both the closest value upward and the closest value downward meet the design requirements, and there is no need to compare the closest value upward and the closest value downward with 2L. x The size of the difference between .

[0020] Specifically, θ 发动机 30°~50°, θ 排气 It is -10°~-20°.

[0021] Specifically, in step S3, R 吸力面 The method to determine R is: 吸力面 =R 压力面 -3*(100~150).

[0022] Specifically, the installation position of the pressure surface air inlet end is located 110 to 130 mm outside the left edge of the engine exhaust port, and the installation position of the suction surface air inlet end is located outside the right edge of the engine exhaust port, and is symmetrical to the installation position of the pressure surface air inlet end; the virtual air inlet end position of the first guide vane overlaps with the left edge of the engine exhaust port; the virtual air inlet end position of the second guide vane overlaps with the right edge of the engine exhaust port.

[0023] Specifically, in step S7, the removal length of the first guide plate or the second guide plate is 80-100 mm, and the removal lengths of the two are the same.

[0024] The present invention also provides a three-dimensional aerodynamic profile, which is obtained by circumferentially expanding the two-dimensional aerodynamic profile designed by the design method; the circumferential lengths of the pressure surface, the first guide vane, the second guide vane and the suction surface are the same and not less than the circumferential length L of the engine exhaust port. Y .

[0025] The present invention also provides an aero-engine thrust reverse exhaust volute, the exhaust volute comprising the three-dimensional aerodynamic profile;

[0026] The exhaust volute also includes two front and rear binding surfaces, the aerodynamic profile is fixed in the middle of the binding surfaces, and the aerodynamic profile and the binding surfaces together form a box-type aircraft engine reverse thrust exhaust volute.

[0027] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0028] 1. The two-dimensional aerodynamic surface designed by the present invention greatly simplifies the structure while ensuring the exhaust effect, significantly reduces the difficulty of processing and assembly, and reduces the processing cost and operator level requirements.

[0029] When designing the two-dimensional aerodynamic profile of the thrust reverser exhaust volute, the suction surface and pressure surface of the aerodynamic profile are both in the form of a straight line plus an arc; the aerodynamic scheme adopts a double guide vane volute scheme, and the shapes of the suction surface and pressure surface of the volute and the shape of the guide vanes are determined according to the axial length of the engine exhaust outlet (or nacelle outlet), the thrust reverser exhaust airflow angle and the volute exhaust angle. The above-mentioned aerodynamic profile can significantly improve the gas flow state in the volute.

[0030] 2. The two-dimensional aerodynamic surface design of the thrust-reverse exhaust volute designed in the present invention can produce a volute product suitable for various engine exhaust ports by constructing a three-dimensional aerodynamic surface axially symmetrically within the required circumferential range.

[0031] 3. The aerodynamic profile of the reverse thrust exhaust volute designed in the present invention makes the flow field inside the volute stable and unobstructed, the streamline / exhaust airflow leaving the volute outlet can smoothly enter the ejector tube, and the impact on the reverse thrust exhaust back pressure is ≤200Pa, the gas leakage is low (almost no leakage), and the exhaust effect is stable and excellent.

[0032] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained through the contents particularly pointed out in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The drawings are only for the purpose of illustrating particular embodiments and are not to be considered limiting of the present invention. Like reference symbols denote like components throughout the drawings.

[0034] Figure 1 Schematic diagram of the two-dimensional pneumatic profile structure in Example 1;

[0035] Figure 2 Schematic diagram of volute streamlines in Example 1 (simulation);

[0036] Figure 3 Schematic diagram of forward leakage of the volute in Example 1 (simulation);

[0037] Figure 4 Schematic diagram of backward leakage of the volute in Example 1 (simulation);

[0038] Figure 5 It is a schematic diagram of the three-dimensional structure of the volute in Example 1.

[0039] Reference numerals:

[0040] 1. Pressure surface; 2. First guide vane; 3. Second guide vane; 4. Suction surface; 5. Binding surface. DETAILED DESCRIPTION

[0041] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not used to limit the scope of the present invention.

[0042] In the existing technology, the commonly used solution is to give priority to meeting the aerodynamic performance requirements of the reverse thrust exhaust volute when designing the reverse thrust exhaust volute, and not to optimize the aerodynamic profile with a complex shape; or to give priority to determining a reverse thrust exhaust volute structure that is easy to process or assemble, and then design the aerodynamic profile on this basis. The traditional solution starts from one of the aerodynamic performance or processing and manufacturing, gives priority to and determines one of them, and then requires the other to cooperate during the design process, which brings difficulties to implementation and does not take these two aspects into account well. In addition, no detailed design scheme for the reverse thrust exhaust volute guide vane is given in the existing technology.

[0043] After extensive literature research and summary, the present invention proposes that when designing the reverse thrust exhaust volute, the following conditions must be met: 1. The reverse thrust exhaust is not allowed to be re-inhaled by the engine; 2. The reverse thrust exhaust volute has a small impact on the back pressure of the reverse thrust exhaust outlet; 3. The leakage between the reverse thrust exhaust volute and the nacelle is small. On this basis, the processing difficulty and assembly difficulty of the volute should be taken into account at the same time, and the cost and the required operator level should be further reduced.

[0044] The present invention provides a design method for a two-dimensional aerodynamic profile of a reverse thrust exhaust volute of an aircraft engine, wherein the aerodynamic profile comprises a pressure surface, a first guide vane, a second guide vane and a suction surface from left to right, wherein the pressure surface and the suction surface are arcs with extension lines at the exhaust end, and the first guide vane and the second guide vane are arcs;

[0045] Verified by simulation, the above structural design has excellent exhaust effect while significantly reducing processing difficulty.

[0046] The design method specifically comprises the following steps:

[0047] S1: According to the axial length L of the engine exhaust port x Determine the arc radius R of the pressure surface 压力面 , and according to the engine exhaust angle θ 发动机 , that is, the volute air intake angle θ 进气 , determine the arc tangent angle of the pressure surface inlet end, that is, the arc tangent angle of the pressure surface inlet end = θ 进气The tangent angle of the arc at the volute inlet end is the same as the volute inlet angle, which is conducive to a better transition of the reverse thrust exhaust from the initial exhaust direction to the rear exhaust, avoiding additional pressure loss caused by the existence of a component velocity perpendicular to the volute wall when the reverse thrust exhaust enters the volute.

[0048] S2: Determine the exhaust angle θ of the volute according to the position of the ejector tube 排气 , determine the arc tangent angle of the outlet end of the pressure surface according to the exhaust angle, that is, the extension line angle;

[0049] S3: Determine the arc radius R of the suction surface according to the arc radius of the pressure surface 吸力面 , the tangent angles of the air inlet and air outlet ends of the suction surface arc are the same as the tangent angles of the corresponding ends of the pressure surface arc;

[0050] S4: Determine the installation positions of the pressure surface and the suction surface inlet ends according to the size of the engine exhaust port; determine the virtual inlet end positions of the first guide vane and the second guide vane according to the size of the engine exhaust port, and the nearest intersection point of the complete circle corresponding to the guide vane arc and the plane where the engine exhaust port is located is the virtual inlet end;

[0051] S5: the tangent angles of the virtual air inlet and air outlet ends of the arcs of the first guide vane and the second guide vane are the same as the tangent angles of the corresponding ends of the arc of the pressure surface;

[0052] S6: Draw a line connecting the center of the circle corresponding to the pressure surface arc and the center of the circle corresponding to the suction surface arc, and draw perpendicular lines to the tangent lines of the volute intake angle from the virtual intake ends of the first guide vane and the second guide vane, respectively. The intersection of the perpendicular line and the connecting line is the center position of the circle corresponding to the arc of the first guide vane and the second guide vane, and then determine the radius of the first guide vane and the second guide vane;

[0053] S7: removing a portion of the first guide vane and the second guide vane from the virtual air inlet end respectively to obtain an actual air inlet end, that is, to obtain a final aerodynamic profile;

[0054] Among them, the engine exhaust angle θ 发动机 and θ 进气 is the angle with the vertical direction, the volute exhaust angle θ 排气 It is the angle with the horizontal direction, with the counterclockwise direction as a positive value and the clockwise direction as a negative value; the left and right direction is the axial direction X, and the direction perpendicular to the paper surface is the circumferential direction Y.

[0055] Specifically, the arc extension line of the suction surface is ≥150mm, and the volute outlet length can be appropriately shortened according to the volute weight requirement, but it should not be too short, and should at least exceed the air outlet end point of the arc of the suction surface by 150mm;

[0056] After determining the end point of the suction surface arc extension line, draw a perpendicular line from this point to the suction surface arc extension line, and the intersection of the perpendicular line and the pressure surface arc extension line is the end point of the pressure surface arc extension line.

[0057] Specifically, for any point of the engine exhaust port, the centers of the arcs corresponding to the pressure surface, the first guide vane, the second guide vane, and the suction surface are located on the same side of the vertical line and the four points are collinear; the four centers of the circles are located on the opposite side of the vertical line from the engine exhaust direction. In layman's terms, when the exhaust direction of the engine exhaust port is to the upper left, all the arcs of the aerodynamic profile are bent to the right.

[0058] Specifically, in step S1, R 压力面 The method of determining is to take twice the axial length L of the engine exhaust port x And take the nearest integer multiple of 100mm upward or downward to facilitate subsequent processing; x When the value is an integer multiple of 100 mm, both the closest value upward and the closest value downward meet the design requirements, and there is no need to compare the closest value upward and the closest value downward with 2L. x The size of the difference between .

[0059] It is worth noting that the pressure surface is mainly used to guide the engine reverse thrust exhaust from the oblique front of the engine to the rear of the engine. The larger the radius of the pressure surface, the smoother the transition of the reverse thrust exhaust direction and the lower the reverse thrust exhaust pressure loss. However, if the radius of the pressure surface is too large, the reverse thrust exhaust volute will conflict with the engine bracket and other structures, and the size of the volute bracket will also increase, which will also conflict with the engine bracket and other structures, making the volute unusable in practice. Therefore, it is necessary to strictly control the radius of the reverse thrust exhaust volute pressure surface.

[0060] Specifically, θ 发动机 30°~50°, θ 排气 After the reverse thrust exhaust of the engine is guided by the volute, its direction is deflected from the oblique direction in front of the engine to the rear of the engine and enters the ejector tube. In order to ensure that the reverse thrust exhaust can smoothly enter the ejector tube, θ 排气 It should be a negative value to make the reverse thrust exhaust deviate toward the engine axis; but θ 排气 Too large a value will cause interference between the reverse thrust exhaust and the internal exhaust of the engine, which may result in the reverse thrust exhaust and the internal high-temperature exhaust not being able to enter the ejector tube completely, causing damage to the engine and other equipment in the test room. 排气 Should be a finite negative value.

[0061] Specifically, in step S3, R 吸力面 The method to determine R is: 吸力面 =R 压力面-3*(100~150). When determining the radius of the suction surface arc, first of all, we must ensure that the arc of the suction surface cannot intersect with the arc of the pressure surface, otherwise the volute cannot be used. Therefore, it is necessary to subtract a part of the pressure surface radius to get the suction surface radius; at the same time, the suction surface radius cannot be too small. In order to allow the reverse thrust exhaust to enter the ejector smoothly, a contraction section is usually made at the outlet end of the volute to reduce the flow area and increase the exhaust flow rate. If a contraction section cannot be made, the volute outlet area should be kept as small as possible as possible. The inlet area here refers to the inlet surrounded by the two internal guide vanes, because the reverse thrust exhaust mainly flows between these two guide vanes); after a large number of experimental tests, optimization and summary, the pressure surface radius minus an integer multiple of 100 to 150 mm is used to get the suction surface radius, where the integer multiple is the number of guide vanes + 1.

[0062] Further, if the axial length of the nacelle outlet (or exhaust port, in actual production, the nacelle outlet and the exhaust port are directly connected, and the structural dimensions are highly close, and the two are considered to be basically equivalent in the present invention) does not exceed 400mm, select an integer multiple of 100mm, if it exceeds 600mm, select an integer multiple of 150mm, if the axial length of the nacelle outlet is between 400 and 600mm, it can be appropriately taken between 100 and 150mm. In Example 1, the length of the nacelle outlet is 550mm. On the one hand, considering the actual processing, on the other hand, it is considered that this length is closer to 600mm, so 150mm is used for calculation and design during the design process.

[0063] Specifically, the installation position of the pressure surface air inlet end is located 110 to 130 mm outside the left edge of the engine exhaust port, and the installation position of the suction surface air inlet end is located outside the right edge of the engine exhaust port, and is symmetrical to the installation position of the pressure surface air inlet end; the virtual air inlet end position of the first guide vane overlaps with the left edge of the engine exhaust port; the virtual air inlet end position of the second guide vane overlaps with the right edge of the engine exhaust port.

[0064] It is worth noting that in order to ensure that the reverse thrust exhaust can smoothly enter the volute, the axial length of the volute needs to exceed the axial length of the reverse thrust exhaust outlet (or the engine nacelle outlet), which will make it difficult for the suction surface and the pressure surface of the reverse thrust exhaust volute to simultaneously guide the reverse thrust exhaust entering the volute so that it can be smoothly deflected from the initial direction to the volute exhaust direction, thereby increasing the total pressure loss of the reverse thrust exhaust airflow in the volute and the reverse thrust exhaust back pressure. In response to this situation, the present invention guides the reverse thrust exhaust by arranging guide vanes at specific positions in the volute, thereby reducing the total pressure loss of the reverse thrust exhaust in the volute and avoiding a significant impact on the reverse thrust exhaust back pressure. At the same time, since the distance between the pressure surface and the suction surface is slightly greater than the axial length L of the reverse thrust exhaust outlet x This can avoid air leakage (such as Figure 3 , Figure 4 shown).

[0065] Specifically, in step S7, the removal length of the first guide vane or the second guide vane is 80-100 mm, and the removal lengths of the two are the same. The above design is to reduce the total pressure loss caused by the guide vane and avoid significant impact on the reverse thrust exhaust back pressure.

[0066] Furthermore, the two-dimensional aerodynamic profile of the thrust reverser exhaust volute is determined according to the above method, and a three-dimensional aerodynamic profile can be axisymmetrically constructed for the two-dimensional aerodynamic profile according to the circumferential range of the thrust reverser exhaust outlet, and the circumferential shape of the three-dimensional volute inlet can be adjusted according to the circumferential shape of the engine.

[0067] The present invention also provides a three-dimensional aerodynamic profile, which is obtained by circumferentially expanding the two-dimensional aerodynamic profile designed by the design method; the circumferential lengths of the pressure surface, the first guide vane, the second guide vane and the suction surface are the same and not less than the circumferential length L of the engine exhaust port. Y .

[0068] The present invention also provides an aero-engine thrust reverse exhaust volute, the exhaust volute comprising the three-dimensional aerodynamic profile;

[0069] The exhaust volute also includes two front and rear binding surfaces, the aerodynamic surface is fixed in the middle of the binding surfaces, and the aerodynamic surface and the binding surfaces together form a box-type aircraft engine reverse thrust exhaust volute.

[0070] Specifically, the three-dimensional pneumatic profile can be fixed on the restraining surface by bonding, splicing or welding.

[0071] Example 1

[0072] 1. The axial length of the engine nacelle outlet (exhaust port) is 550mm. The radius of the arc on the volute pressure surface is determined to be twice the length (1100mm). For ease of processing, the arc radius is appropriately taken as an integer multiple of 100mm upward or downward, which is 1100mm in this case. Then, the volute inlet angle is determined to be 40° based on the thrust reverse exhaust airflow angle (vertical angle). In order to ensure that the thrust reverse exhaust can smoothly enter the ejector tube after passing through the volute, the volute exhaust angle and the horizontal angle are determined to be -15°, and the airflow deflection angle is obtained to be 145°. The shape of the arc on the volute pressure surface is determined based on the arc radius of 1100mm, the volute inlet angle of 40°, the volute exhaust angle of -15°, and the airflow deflection angle of 145°.

[0073] 2. The arc radius of the volute suction surface is smaller than the arc radius of the pressure surface. In this case, the number of guide vanes in the volute is 2. The space in the volute is divided into 3 parts. The radius of the pressure surface arc is subtracted from 3×150mm to get the radius of the suction surface arc (1100mm-3×150mm=650mm). The shape of the volute suction surface arc is determined based on the arc radius of 650mm, the volute inlet angle of 40°, the volute exhaust angle of -15°, and the airflow deflection angle of 145°.

[0074] 3. Draw tangents on the arc endpoints of the volute pressure surface and suction surface and extend them to obtain the profile of the volute outlet. The volute outlet length can be appropriately shortened according to the volute weight requirements, but it should not be too short and should at least exceed the arc endpoint of the suction surface by 150mm. In this case, the volute outlet exceeds the suction surface endpoint by about 350mm.

[0075] 4. Before determining the position of the guide vane, first determine the positional relationship between the volute and the engine. The gap between the volute and the engine is 120mm, and the distance between the end point of the volute pressure surface and the leading edge of the engine nacelle outlet is the same as the distance between the end point of the volute suction surface and the trailing edge of the engine nacelle outlet.

[0076] 5. The inlet angle and exhaust angle of the guide vane (virtual intake end) are the same as the volute inlet angle of 40° and the exhaust angle of -15°, and the airflow deflection angle is also the same. In order to reduce the total pressure loss caused by the guide vane and avoid a significant impact on the reverse thrust exhaust back pressure, a part of the guide vane at the volute inlet is removed, and both guide vanes are removed by about 90mm.

[0077] 6. According to the above scheme, the two-dimensional aerodynamic surface of the reverse thrust exhaust volute is determined. The three-dimensional aerodynamic surface can be constructed axially symmetrically according to the circumferential range of the reverse thrust exhaust outlet, and the circumferential shape of the three-dimensional volute inlet is adjusted according to the circumferential shape of the engine. (Only two-dimensional surface simulation is performed during simulation, so the circumferential length L of the engine nacelle outlet (exhaust port) is not calculated here. Y In fact, the circumferential length has little effect on the gas flow pattern and can be basically ignored.)

[0078] The above-mentioned profiles were simulated for exhaust conditions, and the fluid simulation software Fluent was used to test the engine in the reverse thrust design point state and the slow engine state. The reverse thrust exhaust blades, the internal nozzle, and the test chamber inlet were set with pressure inlet boundary conditions, the ejector outlet was set with pressure outlet boundary conditions, the engine inlet was set with flow outlet boundary conditions, and the other wall surfaces were set with no-slip wall boundary conditions. The results are shown in Table 1 and Figures 2 to 4 shown.

[0079] Among them, the reverse thrust design point and slow speed are two common operating states of the engine.

[0080] Table 1 Effect of reverse thrust exhaust volute on reverse thrust exhaust back pressure

[0081] unit Back-calculation of design point local No snail case Pa 125306 102593 With snail shell Pa 125118 102589 Absolute value Pa 188 4 Relative value 0.15％ 0.0039％

[0082] According to the simulation results, the flow field in the thrust reverse exhaust volute using the above-mentioned aerodynamic surface is stable and smooth, the streamline / exhaust airflow leaving the volute outlet can smoothly enter the ejector tube, and the impact on the thrust reverse exhaust back pressure is ≤200Pa, there is almost no air leakage, and the exhaust effect is stable and excellent.

[0083] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for designing a two-dimensional aerodynamic profile of an aircraft engine thrust reverse exhaust volute, characterized in that: The aerodynamic profile includes a pressure surface, a first guide vane, a second guide vane and a suction surface from left to right, the pressure surface and the suction surface are arcs with extended lines at the exhaust end, and the first guide vane and the second guide vane are arcs; The specific steps include: S1: According to the axial length L of the engine exhaust port x Determine the arc radius R of the pressure surface 压力面 , and according to the engine exhaust angle θ 发动机 , that is, the volute air intake angle θ 进气 , determine the arc tangent angle of the air inlet end of the pressure surface; S2: Determine the exhaust angle θ of the volute according to the position of the ejector tube 排气 , determine the arc tangent angle of the outlet end of the pressure surface according to the exhaust angle, that is, the extension line angle; S3: Determine the arc radius R of the suction surface according to the arc radius of the pressure surface 吸力面 , the tangent angles of the air inlet and air outlet ends of the suction surface arc are the same as the tangent angles of the corresponding ends of the pressure surface arc; S4: Determine the installation positions of the pressure surface and the suction surface inlet ends according to the size of the engine exhaust port; determine the virtual inlet end positions of the first guide vane and the second guide vane according to the size of the engine exhaust port, and the nearest intersection point of the complete circle corresponding to the guide vane arc and the plane where the engine exhaust port is located is the virtual inlet end; S5: the tangent angles of the virtual air inlet and air outlet ends of the arcs of the first guide vane and the second guide vane are the same as the tangent angles of the corresponding ends of the arc of the pressure surface; S6: Draw a line connecting the center of the circle corresponding to the pressure surface arc and the center of the circle corresponding to the suction surface arc, and draw perpendicular lines to the tangent lines of the volute intake angle from the virtual intake ends of the first guide vane and the second guide vane, respectively. The intersection of the perpendicular line and the connecting line is the center position of the circle corresponding to the arc of the first guide vane and the second guide vane, and then determine the radius of the first guide vane and the second guide vane; S7: removing a portion of the first guide vane and the second guide vane from the virtual air inlet end respectively to obtain an actual air inlet end, that is, to obtain a final aerodynamic profile; Among them, the engine exhaust angle θ 发动机 and θ 进气 is the angle with the vertical direction, the volute exhaust angle θ 排气 It is the angle with the horizontal direction, with the counterclockwise direction as a positive value and the clockwise direction as a negative value; the left and right direction is the axial direction X, and the direction perpendicular to the paper surface is the circumferential direction Y.

2. The design method according to claim 1, characterized in that: The arc extension line of the suction surface is ≥150mm; After determining the end point of the suction surface arc extension line, draw a perpendicular line from this point to the suction surface arc extension line, and the intersection of the perpendicular line and the pressure surface arc extension line is the end point of the pressure surface arc extension line.

3. The design method according to claim 1, characterized in that: For any point of the engine exhaust port, the centers of the arcs corresponding to the pressure surface, the first guide vane, the second guide vane, and the suction surface are located on the same side of the vertical line and the four points are collinear; the four centers are located on the opposite side of the vertical line from the engine exhaust direction.

4. The design method according to claim 1, characterized in that: In step S1, R 压力面 The method of determining is to take twice the axial length L of the engine exhaust port x And the distance upward or downward shall be rounded to the nearest integer multiple of 100 mm; 2L x When the value is an integer multiple of 100 mm, both the closest value upward and the closest value downward meet the design requirements, and there is no need to compare the closest value upward and the closest value downward with 2L. x The size of the difference between .

5. The design method according to claim 1, characterized in that: θ 发动机 30°~50°, θ 排气 It is -10°~-20°.

6. The design method according to claim 1, characterized in that: In step S3, R 吸力面 The method to determine R is: 吸力面 =R 压力面 -3*(100~150).

7. The design method according to claim 1, characterized in that: The installation position of the pressure surface air inlet end is located 110 to 130 mm outside the left edge of the engine exhaust port, and the installation position of the suction surface air inlet end is located outside the right edge of the engine exhaust port, and is symmetrical to the installation position of the pressure surface air inlet end; the virtual air inlet end position of the first guide vane overlaps with the left edge of the engine exhaust port; the virtual air inlet end position of the second guide vane overlaps with the right edge of the engine exhaust port.

8. The design method according to claim 1, characterized in that: In step S7, the removal length of the first guide plate or the second guide plate is 80-100 mm, and the removal lengths of the two are the same.

9. A three-dimensional pneumatic profile, characterized in that: The three-dimensional aerodynamic profile is obtained by circumferentially expanding the two-dimensional aerodynamic profile designed by the design method according to any one of claims 1 to 8; The circumferential lengths of the pressure surface, the first guide vane, the second guide vane and the suction surface are the same and not less than the circumferential length L of the engine exhaust port. Y .

10. An aircraft engine thrust reverse exhaust volute, characterized in that: The exhaust volute comprises the three-dimensional aerodynamic profile of claim 9; The exhaust volute also includes two front and rear binding surfaces, the aerodynamic profile is fixed in the middle of the binding surfaces, and the aerodynamic profile and the binding surfaces together form a box-type aircraft engine reverse thrust exhaust volute.

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