Design method for axial symmetry nozzle outer runner profile based on drag reduction design

Abstract

The invention belongs to the field of aero-engine exhaust nozzle design, and provides an axial symmetry nozzle outer flow channel profile design method based on drag reduction design, and the method comprises the following steps: determining nozzle outer flow channel size parameters; designing an initial turning point and establishing a turning section initial molded surface line equation; establishing a plurality of initial axisymmetric spray pipe simulation pieces; the aerodynamic resistance of each initial axisymmetric nozzle simulation piece is calculated through a simulation method; and performing length iteration correction on the initial turning point according to the principle of minimum aerodynamic resistance until a corrected turning point meeting the minimum aerodynamic resistance is obtained and serves as a final turning point, and forming an axial symmetry spray pipe outer flow channel profile by using the spray pipe outer flow channel size parameter and the final turning point. According to the spray pipe obtained through the method, the airflow change near the outer flow channel molded surface of the spray pipe can be uniform and stable, the aerodynamic resistance loss of the outer flow channel molded surface is reduced, and the performance of an engine and an aircraft is improved.

Description

Technical Field

[0001] The present invention belongs to the field of aeroengine nozzle design, and relates to a method for designing the external flow channel profile of an axisymmetric nozzle based on drag reduction design. Background Art

[0002] With the rapid development of aviation technology, the requirements for aircraft performance are constantly increasing. Among them, the axisymmetric nozzle, as a typical nozzle form, is widely used in the aviation field. It is an important part of the aircraft and the engine. Its external flow channel is part of the rear fuselage of the aircraft, which is used to ensure the smooth transition between the fuselage and the nozzle, so that the air flow can evenly flow through the rear of the fuselage to reduce the drag of the aircraft tail. Therefore, it has an important impact on the aerodynamic performance of the aircraft.

[0003] When the aircraft is in a near-supersonic or transonic cruise state, the traditional straight external flow channel profile of the nozzle has poor adaptability to the oncoming flow, and strong shock waves and air flow separation are likely to occur, which will affect the uniform flow of the air flow, thereby generating a large aerodynamic drag and reducing the performance of the engine and the aircraft.

[0004] In addition, there is currently no method for designing the external flow channel profile of the nozzle through drag reduction design. Summary of the Invention

[0005] In order to solve the technical problem that the traditional external flow channel profile of the nozzle has poor adaptability to the oncoming flow, which affects the engine performance, and to achieve the purpose of making the air flow change near the external flow channel profile of the nozzle uniform and stable, reducing the aerodynamic drag loss of the external flow channel profile, and improving the performance of the engine and the aircraft, the present invention discloses a method for designing the external flow channel profile of an axisymmetric nozzle based on drag reduction design. The method includes the following steps: S1. According to the lap position on the nozzle, obtain the axial length of the external flow channel of the nozzle, the height of the external flow channel profile of the nozzle, and the length of the straight section of the external flow channel profile of the nozzle. The nozzle is an axisymmetric nozzle; S2. Use the axial length of the external flow channel of the nozzle, the height of the external flow channel profile of the nozzle, and the length of the straight section to establish the initial profile line equation of the transition section; S3. Use the characteristic points selected on the initial profile line equation of the transition section as the initial turning points to design multiple initial turning profiles, and establish an initial axisymmetric nozzle simulation model for each initial turning profile; S4. According to the oncoming flow temperature, pressure, and Mach number under specific working conditions, use the simulation method to calculate the aerodynamic drag of each initial axisymmetric nozzle simulation model; S5. Select the initial turning profile with the minimum aerodynamic drag as the modified profile, and perform multiple iterative corrections on the initial turning points of the modified profile until the aerodynamic drag corresponding to the new turning points obtained is the minimum.

[0006] Further, in step S1, according to the overlapping position on the nozzle, the axial length of the outer flow channel of the nozzle and the height of the profile of the outer flow channel of the nozzle are obtained, including: S11. Extract the first axial length from the overlapping position on the nozzle to the outlet of the inner flow channel of the nozzle, and determine the axial length of the outer flow channel of the nozzle according to the strategy that the axial length of the outer flow channel of the nozzle ≥ the first axial length; S12. Obtain the radius of the overlapping position on the nozzle, the radius of the outlet of the inner flow channel of the nozzle, and the distance between the outer flow channel profile and the inner flow channel at the outlet position of the nozzle. Subtract the sum of the radius of the overlapping position on the nozzle and the radius of the outlet of the inner flow channel of the nozzle from the distance, and use the calculated difference as the difference between the radius of the outlet of the inner flow channel of the nozzle and the distance as the height of the profile of the outer flow channel of the nozzle; S13. According to the axial length of the outer flow channel of the nozzle and the nozzle overlapping structure, obtain the straight section length of the profile of the outer flow channel of the nozzle, wherein the profile of the outer flow channel of the nozzle includes a front arc section and a rear straight section.

[0007] Preferably, in step S13, the value of the straight section length ≤ 0.1 * the axial length of the outer flow channel of the nozzle.

[0008] Further, in step S2, taking the end point of the rear straight section as the origin, taking the axial length direction backward as the positive direction of the X-axis, and taking the height direction upward as the positive direction of the Y-axis to establish a coordinate system, and establishing an initial profile line equation of the transition section according to the axial length of the outer flow channel of the nozzle, the height of the profile of the outer flow channel of the nozzle, and the straight section length. The expression of the initial profile line equation of the transition section is: Y = -2 * H * (0.75 * (X / (L - L1)) 2 - 0.25 * (X / (L - L1)) 3 ), where X and Y are the abscissa and ordinate of the points on the initial profile line of the transition section respectively, H is the height of the profile of the outer flow channel of the nozzle, L is the axial length of the outer flow channel of the nozzle, and L1 is the straight section length.

[0009] Further, in step S3, select the starting point, the midpoint, and the end point on the initial profile line equation of the transition section as characteristic points, and establish an initial transition profile with each of the characteristic points as an initial turning point.

[0010] Furthermore, the initial transition profile includes a first transition profile, a second transition profile, and a third transition profile; The linear equation of the first transition profile is: Y1 = -H / (L - L1) * X1, X1 ∈ (X A1 , X C1 ); The second transition profile includes a front section profile and a rear section profile. The linear equation of the front section profile is: Y 2前=-2*H*(0.75*(X 2前 / (L - L1)) 2 -0.25*(X 2前 / (L - L1)) 3 ), X 2前 ∈ (X A1 , X B1 ); The linear equation of the rear - section profile is: Y 2后 = ((X 2后 - L + L1)*(2*H*(0.75*(X 2后 / (L - L1)) 2 - 0.25*(X / (L - L1)) 3 )) - (X 2后 - X B1 )*H) / (L - L1 - X B1 ), X 2后 ∈ (X B1 , X C1 ); The linear equation of the third turning profile is: Y3 = -2*H*(0.75*(X3 / (L - L1)) 2 - 0.25*(X3 / (L - L1)) 3 ), X3 ∈ (X A1 , X C1 ); Among them, X A1 is the abscissa of the starting point, X C1 is the abscissa of the ending point, X B1 is the abscissa of the mid - point, H is the height of the external flow path profile of the nozzle, L is the axial length of the external flow path of the nozzle, L1 is the length of the straight section, X1 and Y1 are respectively the abscissa and ordinate of the points on the first turning profile, X 2前 and Y 2前 are respectively the abscissa and ordinate of the points on the front - section profile, X 2后 and Y 2后 are respectively the abscissa and ordinate of the points on the rear - section profile, X3 and Y3 are respectively the abscissa and ordinate of the points on the third turning profile.

[0011] Preferably, a fillet transition is performed between the front - section profile and the rear - section profile in the second turning profile.

[0012] Furthermore, in step S5, select the initial turning profile with the minimum aerodynamic drag as the corrected profile, and perform iterative correction on the initial turning point of the corrected profile, including: S51. Judge the aerodynamic resistance of all the axisymmetric nozzle simulation parts, and select the initial turning profile corresponding to the axisymmetric nozzle simulation part with the minimum aerodynamic resistance as the corrected profile. S52. When the corrected profile is the first turning profile, use the center of the starting point and the midpoint as the corrected turning point; when the corrected profile is the second turning profile, use the centers of the starting point and the midpoint and the centers of the midpoint and the ending point as the corrected turning points respectively; when the corrected profile is the third turning profile, use the center of the midpoint and the ending point as the corrected turning point. S53. Design a corrected turning profile according to the corrected turning point with the same linear equation as that of the second turning profile. S54. Evaluate the aerodynamic resistance of the corrected turning profile, and iteratively correct the corrected turning point according to the aerodynamic resistance evaluation result until the turning point that meets the minimum aerodynamic resistance is obtained as the final turning point.

[0013] By iteratively executing the above steps S51 to S54, the final turning point can be determined. The aerodynamic resistance of the turning profile established by this final turning point is the minimum.

[0014] Compared with the prior art, the beneficial effects that can be achieved by at least one of the above technical solutions adopted in the embodiments of this specification at least include: 1. Adopting the design form of matching the outer flow path profile of the nozzle with the incoming flow pressure change can make the airflow change near the outer flow path profile of the nozzle uniform and stable, and reduce the aerodynamic resistance loss of the outer flow path profile. 2. When determining the position of the turning point of the profile, the actual flow state of the airflow under different usage scenarios and different working conditions is considered for the corrected design of the turning position of the outer flow path profile, which can achieve smooth turning of the airflow, improve the airflow stability, reduce the airflow separation situation, and improve the airflow change stability. 3. The method of the present invention can effectively support the engine engineering design, and has been applied and verified on the nozzle, with high generality and operability, can be popularized and applied in the industry, and has good economic benefits and great practical engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1Flowchart of the external flow channel profile design method for an axisymmetric nozzle based on drag reduction design disclosed in the embodiments of the present invention; Figure 2 Schematic diagram of the external flow channel profile of an axisymmetric nozzle disclosed in the embodiments of the present invention; Figure 3 Architecture diagram of the external flow channel profile design system for an axisymmetric nozzle based on drag reduction design disclosed in the embodiments of the present invention; Among them, 301, Axisymmetric nozzle size acquisition module; 302, Initial profile line equation establishment module for the transition section; 303, Transition profile design module; 304, Simulation module; 305, Iterative correction module for the turning point. Specific implementation mode

[0017] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0018] The following uses specific specific examples to illustrate the implementation manners of the present application. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The present application can also be implemented or applied through other different specific implementation manners, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features of the embodiments can be combined with each other. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without making creative efforts belong to the scope of protection of the present application.

[0019] The embodiments of the present invention disclose a method for designing the external flow channel profile of an axisymmetric nozzle based on drag reduction design. Refer to Figure 1 As shown, the method includes the following steps: S1. According to the overlapping position on the nozzle, obtain the axial length of the external flow channel of the nozzle, the height of the external flow channel profile of the nozzle, and the length of the straight section of the external flow channel profile of the nozzle. The nozzle is an axisymmetric nozzle; S2. Use the axial length of the external flow channel of the nozzle, the height of the external flow channel profile of the nozzle, and the length of the straight section to establish an initial profile line equation for the transition section; S3. Use the characteristic points selected on the initial profile line equation of the transition section as the initial turning points to design a plurality of initial transition profiles, and establish an initial axisymmetric nozzle simulation part for each of the initial transition profiles; S4. According to the incoming flow temperature, pressure, and Mach number under specific working conditions, use the simulation method to calculate the aerodynamic drag of each of the initial axisymmetric nozzle simulation parts; S5. Select the initial turning surface with the minimum aerodynamic drag as the modified surface, and perform multiple iterative corrections on the initial turning point of the modified surface until the aerodynamic drag corresponding to the obtained new turning point is minimized.

[0020] Further, in step S1, according to the overlapping position on the nozzle, obtain the axial length of the outer flow path of the nozzle and the height of the outer flow path profile of the nozzle, including: S11. Extract the first axial length B from the overlapping position on the nozzle to the outlet of the inner flow path of the nozzle. Determine the axial length of the outer flow path of the nozzle according to the strategy that the axial length L of the outer flow path of the nozzle ≥ the first axial length B. In implementation, preferably select the method of making the axial length L of the outer flow path of the nozzle slightly greater than the first axial length B to give the value of the axial length L of the outer flow path of the nozzle. For example, the axial length L of the outer flow path of the nozzle can be 1.0 - 1.05 times the first axial length B.

[0021] S12. Obtain the radius R at the overlapping position on the nozzle w , the radius R at the outlet of the inner flow path of the nozzle A9 and the distance H0 between the outer flow path profile and the inner flow path at the outlet position of the nozzle. Subtract the sum of the radius at the overlapping position on the nozzle and the radius at the outlet of the inner flow path of the nozzle from the distance. Take the calculated difference as the difference between the radius at the outlet of the inner flow path of the nozzle and the distance as the height H of the outer flow path profile of the nozzle. The calculation process of the height H of the outer flow path profile of the nozzle can be expressed as: H = R w - R A9 - H0.

[0022] S13. According to the axial length L of the outer flow path of the nozzle and the nozzle overlapping structure, obtain the straight section length L1 of the outer flow path profile of the nozzle, where the outer flow path profile of the nozzle includes a front arc section and a rear straight section.

[0023] Preferably, in step S13, the value of the straight section length L1 ≤ 0.1 * the axial length L of the outer flow path of the nozzle.

[0024] Further, in step S2, taking the end point of the rear straight section as the origin, taking the axial length direction backward as the positive direction of the X - axis, and taking the height direction upward as the positive direction of the Y - axis to establish a coordinate system. According to the axial length L of the outer flow path of the nozzle, the height H of the outer flow path profile of the nozzle, and the straight section length L1, establish the initial profile line equation of the turning section. The expression of the initial profile line equation of the turning section is: Y = - 2 * H * (0.75 * (X / (L - L1)) 2 - 0.25 * (X / (L - L1)) 3 ), where X and Y are the abscissa and ordinate of the points on the initial profile line of the turning section respectively, H is the height of the outer flow path profile of the nozzle, L is the axial length of the outer flow path of the nozzle, and L1 is the straight section length.

[0025] Further, in step S3, a starting point, a midpoint, and an end point are selected as characteristic points on the initial profile line equation of the turning section, and each of the characteristic points is used as an initial turning point to establish an initial turning profile.

[0026] Specifically, as shown in Figure 2 , three characteristic points A1, B1, and C1 are selected on the initial profile line equation of the turning section. Among them, point A1 is the starting point, and its abscissa is X A1 = 0; point B1 is the midpoint, and its abscissa is X B1 = (L - L1) / 2; point C1 is the end point, and its abscissa is X C1 = L - L1; Furthermore, the initial turning profile includes a first turning profile, a second turning profile, and a third turning profile; The linear equation of the first turning profile is: Y1 = -H / (L - L1)*X1, X1 ∈ (X A1 , X C1 ); The second turning profile includes a front - section profile and a rear - section profile. The linear equation of the front - section profile is: Y 2前 = -2*H*(0.75*(X 2前 / (L - L1)) 2 - 0.25*(X 2前 / (L - L1)) 3 ), X 2前 ∈ (X A1 , X B1 ); The linear equation of the rear - section profile is: Y 2后 = ((X 2后 - L + L1)*(2*H*(0.75*(X 2后 / (L - L1)) 2 - 0.25*(X / (L - L1)) 3 )) - (X 2后 - X B1 )*H) / (L - L1 - X B1 ), X 2后 ∈ (X B1 , X C1 ); The linear equation of the third turning profile is: Y3 = -2*H*(0.75*(X3 / (L - L1)) 2 - 0.25*(X3 / (L - L1)) 3 ), X3 ∈ (X A1 , XC1 ); Among them, X A1 is the abscissa of the starting point, X C1 is the abscissa of the ending point, X B1 is the abscissa of the midpoint, H is the height of the outer flow path profile of the nozzle, L is the axial length of the outer flow path of the nozzle, L1 is the length of the straight section, X1 and Y1 are respectively the abscissa and ordinate of the point of the first turning profile, X 2前 and Y 2前 are respectively the abscissa and ordinate of the point of the front section profile, X 2后 and Y 2后 are respectively the abscissa and ordinate of the point of the rear section profile, X3 and Y3 are respectively the abscissa and ordinate of the point of the third turning profile.

[0027] Preferably, a fillet transition treatment is carried out between the front section profile and the rear section profile in the second turning profile. A fillet with a size of R = 500 mm can be designed between the two to make the front section profile and the rear section profile have a smooth transition.

[0028] Further, in step S4, the specific working condition can be selected as the cruise working condition or the design working condition. The oncoming flow temperature, pressure and Mach number can be obtained through the aerodynamic parameters of the specific working condition. The aerodynamic drag of the outer flow path profile of each scheme is evaluated by using a flow field simulation software according to the oncoming flow temperature, pressure and Mach number.

[0029] Further, in step S5, the initial turning profile with the minimum aerodynamic drag is selected as the modified profile, and the initial turning points of the modified profile are iteratively corrected multiple times, including: S51. Judge the aerodynamic drag of all the axisymmetric nozzle simulation parts, and select the initial turning profile corresponding to the axisymmetric nozzle simulation part with the minimum aerodynamic drag as the modified profile; S52. When the modified profile is the first turning profile, use the center of the starting point and the midpoint as the modified turning point; when the modified profile is the second turning profile, use the center of the starting point and the midpoint and the center of the midpoint and the ending point as the modified turning points respectively; when the modified profile is the third turning profile, use the center of the midpoint and the ending point as the modified turning point; S53. Design a modified turning profile with the same linear equation as the second turning profile according to the modified turning point.

[0030] Specifically, when the modified profile corresponding to the modified turning point is the first turning profile, as shown in Figure 2 , this modified turning point can be expressed as A2, and its abscissa can be expressed as X A2 = (X B1 - X A1) / 2, and thus the equation of its corrected turning surface is: Y 11 = -2 * H * (0.75 * (X 11 / (L - L1)) 2 - 0.25 * (X 11 / (L - L1)) 3 ), X 11 ∈ (X A1 , X A2 ); Y 12 = ((X 12 - L + L1) * (2 * H * (0.75 * (X 12 / (L - L1)) 2 - 0.25 * (X 12 / (L - L1)) 3 )) - (X 12 - X A2 ) * H / (L - L1 - X A2 ), X 12 ∈ (X A2 , X C1 ); Y 11 and Y 12 are the ordinates of the front - end surface and the rear - end surface of the corrected turning surface of the first turning surface respectively; X 11 and X 12 are the abscissas of the front - end surface and the rear - end surface of the corrected turning surface of the first turning surface respectively.

[0031] When the corrected turning surface corresponding to the corrected turning point is the second turning surface, as shown in Figure 2 , there are two corrected turning points, which are respectively denoted as B 21 , B 22 . These two points are also the corrections to the initial turning point being the mid - point. At this time, the abscissas of these two points can be respectively expressed as X B21 = (X B1 - X A1 ) / 2, X B22 = (X C1 – X B1 ) / 2. There are two types of corrected turning surfaces. The equation of the corrected turning point B 21 is: Y 211 = -2 * H * (0.75 * (X 211 / (L - L1)) 2 - 0.25 * (X 211 / (L - L1)) 3 ), X 211 ∈ (X A1 , X B21 ); Y 212 = ((X 212 - L + L1) * (2 * H * (0.75 * (X 212 / (L - L1)) 2 - 0.25 * (X 212 / (L - L1)) 3 )) - (X 212 - X A2 ) * H) / (L - L1 - X A2 ), X 212 ∈ (X B21 , X C1 ); Y 211 and Y 212 are the ordinates of the front - end surface and the rear - end surface of the modified turning surface of the first turning surface respectively; X 211 and X 212 are the abscissas of the front - end surface and the rear - end surface of the first modified turning surface of the second turning surface respectively.

[0032] Among them, the equation corresponding to the modified turning point B 22 is: Y 221 = - 2 * H * (0.75 * (X 221 / (L - L1)) 2 - 0.25 * (X 221 / (L - L1)) 3 ), X 221 ∈ (X A1 , X B21 ) Y 222 = ((X 222 - L + L1) * (2 * H * (0.75 * (X 222 / (L - L1)) 2 - 0.25 * (X 222 / (L - L1)) 3 )) - (X 222 - X A2 ) * H) / (L - L1 - X A2 ), X 222 ∈ (X B21 , X C1 ); Y 221 and Y 222 are the ordinates of the front - end surface and the rear - end surface of the modified turning surface of the first turning surface respectively; X 221 and X 222 are the abscissas of the front - end surface and the rear - end surface of the second modified turning surface of the second turning surface respectively.

[0033] When the modified surface corresponding to the modified turning point is the third turning surface, refer to Figure 2 As shown, the modified turning point can be expressed as C2, and its abscissa can be expressed as X C2 =(X C1 –X B1 ) / 2. Furthermore, the equation of its modified turning surface is: Y 31 =-2 * H * (0.75 * (X 31 / (L - L1)) 2 -0.25 * (X 31 / (L - L1)) 3 ), X 31 ∈(X A1 , X A2 ) Y 32 =((X 32 -L + L1) * (2 * H * (0.75 * (X 32 / (L - L1)) 2 -0.25 * (X 32 / (L - L1)) 3 ))-(X 32 -X A2 ) * H) / (L - L1 - X A2 ), X 32 ∈(X A2 , X C1 ); Y 31 and Y 32 are the ordinates of the front - end surface and the rear - end surface of the modified turning surface of the first turning surface respectively; X 31 and X 32 are the abscissas of the front - end surface and the rear - end surface of the modified turning surface of the third turning surface respectively.

[0034] S54. Conduct an aerodynamic drag assessment on the modified turning surface, and perform iterative correction on the modified turning point according to the aerodynamic drag assessment result until a turning point that satisfies the minimum aerodynamic drag is obtained as the final turning point.

[0035] When recalculating the aerodynamic drag of the modified turning surface after correction, perform iterative correction of the turning point of the surface according to the aerodynamic drag. After determining the position of the turning point of the surface, the size parameters of the nozzle external flow channel determined in step S1 can be used to form an axisymmetric nozzle external flow channel surface.

[0036] By repeatedly executing the above steps S51 to S54 for iteration, the final turning point can be determined, and the aerodynamic drag of the turning surface established through this final turning point is the minimum.

[0037] The method of the present invention has the following advantages: 1. By adopting a design form in which the profile of the nozzle outer flow path matches the change in the oncoming flow pressure, the airflow change near the profile of the nozzle outer flow path can be made uniform and stable, reducing the aerodynamic drag loss of the outer flow path profile; 2. When determining the position of the profile turning point, the actual flow state of the airflow under different usage scenarios and working conditions is considered for the correction design of the turning position of the outer flow path profile, which can achieve smooth turning of the airflow, improve the stability of the airflow, reduce the airflow separation, and enhance the stability of the airflow change; 3. The method of the present invention can effectively support the engine engineering design, and has been applied and verified on the nozzle, with high versatility and operability, can be popularized and applied in the industry, and has good economic benefits and great practical engineering application value.

[0038] Based on the same inventive concept, an axisymmetric nozzle outer flow path profile design system based on drag reduction design is also provided in the embodiments of the present invention, as described in the following embodiments. Since the principle of solving problems by the axisymmetric nozzle outer flow path profile design system based on drag reduction design is similar to that of the axisymmetric nozzle outer flow path profile design based on drag reduction design disclosed in the above embodiments, the implementation of the axisymmetric nozzle outer flow path profile design system based on drag reduction design can refer to the implementation of the axisymmetric nozzle outer flow path profile design method based on drag reduction design, and the repeated parts will not be described again. As used hereinafter, the term "unit" or "module" can be a combination of software and / or hardware that can achieve a predetermined function. Although the devices described in the following embodiments are preferably implemented in software, implementation in hardware, or a combination of software and hardware is also possible and contemplated.

[0039] Figure 3 is a structural block diagram of an axisymmetric nozzle outer flow path profile design system based on drag reduction design disclosed in the embodiments of the present invention, as Figure 3 shown, the system includes an axisymmetric nozzle size acquisition module 301, an initial profile line equation establishment module 302 for the turning section, a turning profile design module 303, a simulation module 304, and a turning point iterative correction module 305. The following describes this structure.

[0040] Among them, the axisymmetric nozzle size acquisition module 301 is used to obtain the axial length of the nozzle outer flow path, the height of the nozzle outer flow path profile, and the length of the straight section of the nozzle outer flow path according to the overlapping position on the nozzle, and the nozzle is an axisymmetric nozzle; The initial profile line equation establishment module 302 for the turning section is used to establish an initial profile line equation for the turning section using the axial length of the nozzle outer flow path, the height of the nozzle outer flow path profile, and the length of the straight section; The turning surface design module 303 is used to design a plurality of initial turning surfaces by using the characteristic points selected on the initial turning surface line equation of the turning section, and establish an initial axisymmetric nozzle simulation part for each of the initial turning surfaces; The simulation module 304 is used to calculate the aerodynamic drag of each of the initial axisymmetric nozzle simulation parts by using a simulation method according to the incoming flow temperature, pressure and Mach number under specific working conditions; The turning point iterative correction module 305 is used to select the initial turning surface with the minimum aerodynamic drag as the corrected surface, and perform multiple iterative corrections on the initial turning points of the corrected surface until the aerodynamic drag corresponding to the new turning points obtained is the minimum.

[0041] In this embodiment, a computer device is provided, which includes a memory, a processor, and a computer program stored on the memory and executable on the processor. When the processor executes the computer program, the above-mentioned arbitrary axisymmetric nozzle external flow path surface design method based on drag reduction design is implemented.

[0042] Specifically, the computer device may be a computer terminal, a server or a similar computing device.

[0043] In this embodiment, a computer-readable storage medium is provided, and the computer-readable storage medium stores a computer program for executing the above-mentioned arbitrary axisymmetric nozzle external flow path surface design method based on drag reduction design.

[0044] Specifically, the computer-readable storage medium includes permanent and non-permanent, removable and non-removable media, and information storage can be realized by any method or technology. The information may be computer-readable instructions, data structures, program modules or other data. Examples of computer-readable storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassette tapes, magnetic disk storage or other magnetic storage devices, or any other non-transmission medium that can be used to store information accessible by a computing device. As defined herein, computer-readable storage media does not include transitory media such as modulated data signals and carrier waves.

[0045] Obviously, those skilled in the art should understand that the various modules or steps of the above embodiments of the present invention can be implemented by a general-purpose computing device. They can be concentrated on a single computing device or distributed on a network composed of multiple computing devices. Optionally, they can be implemented by program code executable by the computing device. Thus, they can be stored in a storage device and executed by the computing device. And in some cases, the steps shown or described can be executed in a different order from here, or they can be separately fabricated into individual integrated circuit modules, or multiple modules or steps among them can be fabricated into a single integrated circuit module for implementation. In this way, the embodiments of the present invention are not limited to any specific combination of hardware and software.

[0046] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various changes and modifications can be made to the embodiments of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for designing the outer flow path profile of an axisymmetric nozzle based on drag reduction design, characterized in that Including: According to the overlapping position on the nozzle, obtain the axial length of the external flow path of the nozzle, the height of the profile of the external flow path of the nozzle, and the length of the straight section of the profile of the external flow path of the nozzle, where the nozzle is an axisymmetric nozzle; Use the axial length of the external flow path of the nozzle, the height of the profile of the external flow path of the nozzle, and the length of the straight section to establish the equation of the initial profile line of the transition section; Adopt the characteristic points selected on the equation of the initial profile line of the transition section as the initial turning points to design multiple initial transition profiles, and establish an initial axisymmetric nozzle simulation component for each of the initial transition profiles; According to the incoming flow temperature, pressure, and Mach number under specific working conditions, use the simulation method to calculate the aerodynamic drag of each of the initial axisymmetric nozzle simulation components; Select the initial transition profile with the minimum aerodynamic drag as the corrected profile, and perform multiple iterative corrections on the initial turning points of the corrected profile until the aerodynamic drag corresponding to the new turning points obtained is the minimum.

2. The method for designing the external flow channel profile of an axisymmetric nozzle based on drag reduction design according to claim 1, characterized in that According to the overlapping position on the nozzle, obtain the axial length of the external flow path of the nozzle and the height of the profile of the external flow path of the nozzle, including: Extract the first axial length from the overlapping position on the nozzle to the outlet of the internal flow path of the nozzle, and determine the axial length of the external flow path of the nozzle according to the strategy that the axial length of the external flow path of the nozzle ≥ the first axial length; Obtain the radius at the overlapping position on the nozzle, the radius at the outlet of the internal flow path of the nozzle, and the distance between the external flow path profile and the internal flow path at the outlet position of the nozzle. Subtract the sum of the radius at the overlapping position on the nozzle and the radius at the outlet of the internal flow path of the nozzle from the distance, and use the calculated difference as the difference between the radius at the outlet of the internal flow path of the nozzle and the distance as the height of the profile of the external flow path of the nozzle; According to the axial length of the external flow path of the nozzle and the nozzle overlapping structure, obtain the length of the straight section of the profile of the external flow path of the nozzle, where the profile of the external flow path of the nozzle includes a front arc section and a rear straight section.

3. The method for designing the external flow channel profile of an axisymmetric nozzle based on drag reduction design according to claim 2, wherein The value of the length of the straight section ≤ 0.1 * the axial length of the external flow path of the nozzle.

4. The method for designing the external flow channel profile of an axisymmetric nozzle based on drag reduction design according to claim 1, wherein Taking the end point of the rear straight section as the origin, taking the axial length direction backward as the positive direction of the X-axis, and taking the height direction upward as the positive direction of the Y-axis to establish a coordinate system, and establish the equation of the initial profile line of the transition section according to the axial length of the external flow path of the nozzle, the height of the profile of the external flow path of the nozzle, and the length of the straight section. The expression of the equation of the initial profile line of the transition section is: Y = -2 * H * (0.75 * (X / (L - L1)) 2 - 0.25 * (X / (L - L1)) 3 ), where X and Y are the abscissa and ordinate of the points on the initial profile line of the turning section respectively, H is the height of the external flow path profile of the nozzle, L is the axial length of the external flow path of the nozzle, and L1 is the length of the straight section.

5. The method for designing the outer flow path profile of an axisymmetric nozzle based on drag reduction design according to claim 1, wherein Select the starting point, midpoint, and end point on the equation of the initial profile line of the transition section as the characteristic points, and establish the initial transition profile with each of the characteristic points as the initial turning point respectively.

6. The method for designing the outer flow path profile of an axisymmetric nozzle based on drag reduction design according to claim 5, wherein The initial transition profile includes a first transition profile, a second transition profile, and a third transition profile; The linear equation of the first turning surface is: Y1 = -H / (L - L1)*X1, where X1 ∈ (X A1 , X C1 ); The second transition profile includes a front section profile and a rear section profile. The linear equation of the front section profile is: Y 2前 = -2 * H * (0.75 * (X 2前 / (L - L1)) 2 - 0.25 * (X 2前 / (L - L1)) 3 ), X 2前 ∈ (X A1 , X B1 ); The linear equation of the rear section profile is: Y 2后 =((X 2后 -L+L1)*(2*H*(0.75*(X 2后 / (L-L1)) 2 -0.25*(X / (L-L1)) 3 ))-(X 2后 -X B1 )*H) / (L-L1-X B1 ),X 2后 ∈(X B1 ,X C1 ); The linear equation of the third transition profile is: Y3 = -2 * H * (0.75 * (X3 / (L - L1)) 2 - 0.25 * (X3 / (L - L1)) 3 ), X3 ∈ (X A1 , X C1 ); Among them, X A1 is the abscissa of the starting point, X C1 is the abscissa of the ending point, X B1 is the abscissa of the midpoint, H is the height of the external flow path profile of the nozzle, L is the axial length of the external flow path of the nozzle, L1 is the length of the straight section, X1 and Y1 are respectively the abscissa and ordinate of the point of the first turning profile, X 2前 and Y 2前 are respectively the abscissa and ordinate of the point of the front section profile, X 2后 and Y 2后 are respectively the abscissa and ordinate of the point of the rear section profile, X3 and Y3 are respectively the abscissa and ordinate of the point of the third turning profile.

7. The method for designing the outer flow path profile of an axisymmetric nozzle based on drag reduction design according to claim 6, characterized in that, Perform fillet transition processing between the front section profile and the rear section profile.

8. The method for designing the outer flow path profile of an axisymmetric nozzle based on drag reduction design according to claim 6, wherein Select the initial transition profile with the minimum aerodynamic drag as the corrected profile, and perform multiple iterative corrections on the initial turning points of the corrected profile, including: Judge the aerodynamic drag of all the axisymmetric nozzle simulation components, and select the initial transition profile corresponding to the axisymmetric nozzle simulation component with the minimum aerodynamic drag as the corrected profile; When the modified surface is the first turning surface, the center of the starting point and the midpoint is used as the modified turning point; when the modified surface is the second turning surface, the centers of the starting point and the midpoint and the centers of the midpoint and the end point are respectively used as the modified turning points; when the modified surface is the third turning surface, the center of the midpoint and the end point is respectively used as the modified turning point; Design a modified turning surface with the same linear equation as the second turning surface according to the modified turning point; Conduct an aerodynamic drag evaluation on the modified turning surface, and iteratively modify the modified turning point according to the aerodynamic drag evaluation result until the turning point that satisfies the minimum aerodynamic drag is obtained as the final turning point.

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