A design method for the outer flow path profile of an axisymmetric nozzle based on drag reduction design

Abstract

The present invention belongs to the field of aero-engine tail nozzle design, and provides a method for designing an axisymmetric nozzle outer flow channel profile based on drag reduction design, the method comprising: determining nozzle outer flow channel size parameters; designing an initial turning point and establishing an initial profile line equation for the turning section; establishing multiple initial axisymmetric nozzle simulations; calculating the aerodynamic drag of each initial axisymmetric nozzle simulation by a simulation method; performing multiple iterative corrections on the initial turning point according to the principle of minimum aerodynamic drag, until a corrected turning point that satisfies the minimum aerodynamic drag is obtained as the final turning point, and forming an axisymmetric nozzle outer flow channel profile using the nozzle outer flow channel size parameters and the final turning point. The nozzle obtained by the method of the present invention can make the airflow changes near the nozzle outer flow channel profile uniform and stable, reduce the aerodynamic drag loss of the outer flow channel profile, and improve the performance of the engine and the aircraft.

Description

Technical Field

[0001] The invention belongs to the field of aero-engine tail nozzle design and relates to a method for designing an axisymmetric nozzle outer flow channel profile 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, axisymmetric nozzles, as a typical nozzle type, are widely used in the aviation field and are an important component of aircraft and engines. Their outer flow path is part of the aircraft's rear fuselage and is used to ensure a smooth transition between the fuselage and the nozzle, ensuring uniform airflow through the rear fuselage to reduce aircraft tail drag. Therefore, it has a significant impact on the aircraft's aerodynamic performance.

[0003] When the aircraft is in a state of near-sonic or transonic cruising, the traditional straight nozzle outer flow path profile has poor adaptability to the incoming flow, and is prone to strong shock waves and airflow separation, which will affect the uniform flow of the airflow, thereby generating greater aerodynamic resistance and reducing the performance of the engine and aircraft.

[0004] In addition, there is currently no method to design the nozzle outer flow path profile by reducing drag. Summary of the Invention

[0005] In order to solve the technical problem that the conventional nozzle outer flow channel profile has poor adaptability to the incoming flow, thereby affecting the engine performance, achieve uniform and stable airflow changes near the nozzle outer flow channel profile, reduce the aerodynamic drag loss of the outer flow channel profile, and thus improve the performance of the engine and aircraft, the present invention discloses a method for designing the axisymmetric nozzle outer flow channel profile based on drag reduction design, the method comprising the following steps:

[0006] S1. Obtaining the axial length of the nozzle outer flow channel, the profile height of the nozzle outer flow channel, and the straight section length of the profile of the nozzle outer flow channel according to the overlap position on the nozzle, wherein the nozzle is an axisymmetric nozzle;

[0007] S2. Establishing an initial profile line equation for the turning section using the axial length of the nozzle outer flow channel, the profile height of the nozzle outer flow channel, and the length of the straight section;

[0008] S3, using the characteristic points selected from the initial profile line equation of the turning section as initial turning points to design multiple initial turning profiles, and establishing an initial axisymmetric nozzle simulation part for each of the initial turning profiles;

[0009] S4. Calculating the aerodynamic drag of each of the initial axisymmetric nozzle simulations using a simulation method based on the incoming flow temperature, pressure, and Mach number under specific operating conditions;

[0010] S5. Select the initial turning surface with the smallest aerodynamic resistance as the modified surface, and perform multiple iterative corrections on the initial turning point of the modified surface until the aerodynamic resistance corresponding to the obtained new turning point is minimized.

[0011] Furthermore, in step S1, the axial length of the nozzle outer flow channel and the profile height of the nozzle outer flow channel are obtained according to the overlap position on the nozzle, including:

[0012] S11, extracting a first axial length from the upper overlap position of the nozzle to the outlet of the inner flow channel of the nozzle, and determining 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 is greater than or equal to the first axial length;

[0013] S12. Obtaining the radius of the nozzle upper overlap position, the nozzle inner flow channel outlet radius, and the distance between the outer flow channel profile and the inner flow channel at the nozzle outlet position; subtracting the sum of the nozzle upper overlap position radius, the nozzle inner flow channel outlet radius, and the distance; and using the calculated difference as the difference between the nozzle inner flow channel outlet radius and the distance, and as the height of the nozzle outer flow channel profile;

[0014] S13. Obtaining the straight section length of the nozzle outer flow channel profile according to the axial length of the nozzle outer flow channel and the nozzle overlap structure, wherein the nozzle outer flow channel profile includes a front arc section and a rear straight section.

[0015] Preferably, in step S13, the length of the straight section is ≤0.1*axial length of the nozzle outer flow channel.

[0016] Furthermore, in step S2, a coordinate system is established with the end point of the rear straight section as the origin, the axial length direction is backward as the positive direction of the X axis, and the height direction is upward as the positive direction of the Y axis. The initial profile line equation of the turning section is established according to the axial length of the nozzle outer flow channel, the profile height of the nozzle outer flow channel, and the length of the straight section. The expression of the initial profile line equation of the turning section is:

[0017] Y=-2*H*(0.75*(X / (L-L1)) 2 -0.25*(X / (L-L1)) 3 ), where X and Y are the horizontal and vertical coordinates of the point on the initial profile line of the turning section, H is the profile height of the nozzle outer flow channel, L is the axial length of the nozzle outer flow channel, and L1 is the length of the straight section.

[0018] Furthermore, in step S3, a starting point, a midpoint and an end point are selected as feature points on the initial profile line equation of the turning section, and each of the feature points is used as an initial turning point to establish an initial turning profile.

[0019] Furthermore, the initial turning profile includes a first turning profile, a second turning profile and a third turning profile;

[0020] The linear equation of the first turning surface is: Y1=-H / (L-L1)*X1, X1∈(X A1 , X C1 );

[0021] The second turning profile includes a front profile and a rear profile, and the linear equation of the front profile is:

[0022] 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 );

[0023] The linear equation of the rear section profile is:

[0024] 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 );

[0025] The linear equation of the third turning surface is:

[0026] Y3=-2*H*(0.75*(X3 / (L-L1)) 2 -0.25*(X3 / (L-L1)) 3 ), X3∈(X A1 , X C1 );

[0027] Among them, X A1 is the horizontal coordinate of the starting point, X C1 is the horizontal coordinate of the end point, X B1 is the horizontal coordinate of the midpoint, H is the height of the nozzle outer flow channel profile, L is the axial length of the nozzle outer flow channel, L1 is the length of the straight section, X1 and Y1 are the horizontal and vertical coordinates of the point of the first turning surface respectively, X 2前 and Y 2前 are the horizontal and vertical coordinates of the points on the front section of the profile, X 2后 and Y2后 X3 and Y3 are the horizontal and vertical coordinates of the point on the rear section profile, respectively. X3 and Y3 are the horizontal and vertical coordinates of the point on the third turning profile, respectively.

[0028] Preferably, a rounded transition process is performed between the front section profile and the rear section profile in the second turning profile.

[0029] Furthermore, in step S5, the initial turning surface with the minimum aerodynamic drag is selected as the correction surface, and the initial turning point of the correction surface is iteratively corrected, including:

[0030] S51, judging the aerodynamic drag of all the axisymmetric nozzle simulations, and selecting the initial turning surface corresponding to the axisymmetric nozzle simulation with the smallest aerodynamic drag as the correction surface;

[0031] S52: When the modified surface is a first turning surface, the center of the starting point and the midpoint is used as a correction turning point; when the modified surface is a second turning surface, the center of the starting point and the midpoint and the center of the midpoint and the end point are used as correction turning points respectively; when the modified surface is a third turning surface, the center of the midpoint and the end point are used as correction turning points respectively;

[0032] S53, designing a modified turning surface having the same linear equation as the second turning surface according to the modified turning point;

[0033] S54 , performing aerodynamic drag evaluation on the modified turning surface, and iteratively correcting the modified turning point according to the aerodynamic drag evaluation result, until a turning point that satisfies the minimum aerodynamic drag is obtained as the final turning point.

[0034] The final turning point can be determined by iteratively executing the above steps S51 to S54 in a loop. The aerodynamic resistance of the turning profile established by the final turning point is the smallest.

[0035] Compared with the prior art, the at least one technical solution adopted in the embodiments of this specification can achieve the following beneficial effects:

[0036] 1. The design of the nozzle outer flow channel profile matching the incoming flow pressure change can make the airflow near the nozzle outer flow channel profile change uniform and stable, reducing the aerodynamic drag loss of the outer flow channel profile;

[0037] 2. When determining the turning point of the profile, the actual flow state of the airflow under different usage scenarios and working conditions was taken into consideration to modify the turning point of the outer flow channel profile. This can achieve smooth airflow turning, improve airflow stability, reduce airflow separation, and improve airflow change stability.

[0038] 3. The method of the present invention can effectively support engine engineering design and has been applied and verified on nozzles. It has high versatility and operability, can be promoted and applied within the industry, and has good economic benefits and great practical engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0040] Figure 1 This is a flow chart of a method for designing an axisymmetric nozzle outer flow channel profile based on drag reduction design disclosed in an embodiment of the present invention;

[0041] Figure 2 This is a schematic diagram of the outer flow channel profile of the axisymmetric nozzle disclosed in an embodiment of the present invention;

[0042] Figure 3 This is an architectural diagram of a system for designing an axisymmetric nozzle outer flow channel profile based on a drag reduction design disclosed in an embodiment of the present invention;

[0043] Among them, 301 is an axisymmetric nozzle size acquisition module; 302 is a turning section initial profile line equation establishment module; 303 is a turning profile design module; 304 is a simulation module; 305 is a turning point iterative correction module. DETAILED DESCRIPTION

[0044] The embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0045] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents 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 embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, in the absence of conflict, the features of the following embodiments and embodiments can be combined with each other. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of this application.

[0046] The embodiment of the present invention discloses a method for designing the outer flow channel profile of an axisymmetric nozzle based on a drag reduction design, see Figure 1 As shown, the method includes the following steps:

[0047] S1. Obtaining the axial length of the nozzle outer flow channel, the profile height of the nozzle outer flow channel, and the straight section length of the profile of the nozzle outer flow channel according to the overlap position on the nozzle, wherein the nozzle is an axisymmetric nozzle;

[0048] S2. Establishing an initial profile line equation for the turning section using the axial length of the nozzle outer flow channel, the profile height of the nozzle outer flow channel, and the length of the straight section;

[0049] S3, using the characteristic points selected from the initial profile line equation of the turning section as initial turning points to design multiple initial turning profiles, and establishing an initial axisymmetric nozzle simulation part for each of the initial turning profiles;

[0050] S4. Calculating the aerodynamic drag of each of the initial axisymmetric nozzle simulations using a simulation method based on the incoming flow temperature, pressure, and Mach number under specific operating conditions;

[0051] S5. Select the initial turning surface with the smallest aerodynamic resistance as the modified surface, and perform multiple iterative corrections on the initial turning point of the modified surface until the aerodynamic resistance corresponding to the obtained new turning point is minimized.

[0052] Furthermore, in step S1, the axial length of the nozzle outer flow channel and the profile height of the nozzle outer flow channel are obtained according to the overlap position on the nozzle, including:

[0053] S11. Extract the first axial length B 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 L of the outer flow channel of the nozzle ≥ the first axial length B. During implementation, preferably select the value of the axial length L of the outer flow channel of the nozzle in a manner that makes the axial length L of the outer flow channel of the nozzle slightly larger than the first axial length B. For example, the axial length L of the outer flow channel of the nozzle can be made 1.0~1.05 times the first axial length B.

[0054] S12. Obtain the radius R of the overlap position on the nozzle w , nozzle inner flow channel outlet radius R A9 As well as the distance H0 between the outer flow channel profile and the inner flow channel at the nozzle outlet position, the difference between the radius of the nozzle upper overlap position and the sum of the radius of the nozzle inner flow channel outlet and the distance is taken as the difference between the nozzle inner flow channel outlet radius and the distance as the nozzle outer flow channel profile height H. The calculation process of the nozzle outer flow channel profile height H can be expressed as: H=R w -R A9 -H0.

[0055] S13. Obtain the straight section length L1 of the nozzle outer flow channel profile according to the axial length L of the nozzle outer flow channel and the nozzle overlap structure, wherein the nozzle outer flow channel profile includes a front arc section and a rear straight section.

[0056] Preferably, in step S13, the value of the straight section length L1 is ≤0.1*the axial length L of the nozzle outer flow channel.

[0057] Furthermore, in step S2, a coordinate system is established with the end point of the rear straight section as the origin, the axial length direction is backward as the positive direction of the X axis, and the height direction is upward as the positive direction of the Y axis. The initial profile line equation of the turning section is established according to the axial length L of the nozzle outer flow channel, the profile height H of the nozzle outer flow channel, and the straight section length L1. The expression of the initial profile line equation of the turning section is:

[0058] Y=-2*H*(0.75*(X / (L-L1)) 2 -0.25*(X / (L-L1)) 3 ), where X and Y are the horizontal and vertical coordinates of the point on the initial profile line of the turning section, H is the profile height of the nozzle outer flow channel, L is the axial length of the nozzle outer flow channel, and L1 is the length of the straight section.

[0059] Furthermore, in step S3, a starting point, a midpoint and an end point are selected as feature points on the initial profile line equation of the turning section, and each of the feature points is used as an initial turning point to establish an initial turning profile.

[0060] Specifically, see Figure 2 As shown, three characteristic points A1, B1, and C1 are selected from the initial profile line equation of the turning section, where point A1 is the starting point and its horizontal coordinate is X A1 =0; point B1 is the midpoint, and its horizontal coordinate is X B1 = (L-L1) / 2; C1 is the end point, and its horizontal coordinate is X C1 =L-L1;

[0061] Furthermore, the initial turning profile includes a first turning profile, a second turning profile and a third turning profile;

[0062] The linear equation of the first turning surface is: Y1=-H / (L-L1)*X1, X1∈(X A1 , X C1 );

[0063] The second turning profile includes a front profile and a rear profile, and the linear equation of the front profile is:

[0064] 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 );

[0065] The linear equation of the rear section profile is:

[0066] 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 );

[0067] The linear equation of the third turning surface is:

[0068] Y3=-2*H*(0.75*(X3 / (L-L1)) 2 -0.25*(X3 / (L-L1)) 3 ), X3∈(X A1 , X C1 );

[0069] Among them, X A1 is the horizontal coordinate of the starting point, X C1 is the horizontal coordinate of the end point, X B1 is the horizontal coordinate of the midpoint, H is the height of the nozzle outer flow channel profile, L is the axial length of the nozzle outer flow channel, L1 is the length of the straight section, X1 and Y1 are the horizontal and vertical coordinates of the point of the first turning surface respectively, X 2前 and Y 2前 are the horizontal and vertical coordinates of the points on the front surface, X 2后 and Y 2后 X3 and Y3 are the horizontal and vertical coordinates of the point on the rear section profile, respectively. X3 and Y3 are the horizontal and vertical coordinates of the point on the third turning profile, respectively.

[0070] Preferably, a fillet transition process is performed between the front section profile and the rear section profile in the second turning profile, and a fillet with a size of R=500mm can be designed between the two to make a smooth transition between the front section profile and the rear section profile.

[0071] Furthermore, in step S4, the specific operating condition can be selected to use the cruise operating condition or the design operating condition. The incoming flow temperature, pressure and Mach number can be obtained through the aerodynamic parameters of the specific operating condition. The aerodynamic resistance of the outer flow duct surface of each scheme can be evaluated based on the incoming flow temperature, pressure and Mach number using flow field simulation software.

[0072] Furthermore, in step S5, the initial turning surface with the minimum aerodynamic drag is selected as the correction surface, and the initial turning point of the correction surface is iteratively corrected multiple times, including:

[0073] S51, judging the aerodynamic drag of all the axisymmetric nozzle simulations, and selecting the initial turning surface corresponding to the axisymmetric nozzle simulation with the smallest aerodynamic drag as the correction surface;

[0074] S52: When the modified surface is a first turning surface, the center of the starting point and the midpoint is used as a correction turning point; when the modified surface is a second turning surface, the center of the starting point and the midpoint and the center of the midpoint and the end point are used as correction turning points respectively; when the modified surface is a third turning surface, the center of the midpoint and the end point are used as correction turning points respectively;

[0075] S53. Designing a modified turning surface having the same linear equation as that of the second turning surface according to the modified turning point.

[0076] Specifically, when the correction profile corresponding to the correction turning point is the first turning profile, see Figure 2 As shown, the correction turning point can be expressed as A2, and its horizontal coordinate can be expressed as X A2 =(X B1 -X A1 ) / 2, and then the equation of the modified turning surface is:

[0077] Y 11 =-2*H*(0.75*(X 11 / (L-L1)) 2 -0.25*(X 11 / (L-L1)) 3 ), X 11 ∈(X A1 , X A2 );

[0078] 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 Y12 are the ordinates of the front and rear sections of the modified turning section of the first turning section; 11 and X 12 They are respectively the horizontal coordinates of the front section profile and the rear end profile of the modified turning profile of the first turning profile.

[0079] When the correction profile corresponding to the correction turning point is the second turning profile, see Figure 2 As shown, there are two turning points for this correction, which are represented by B 21 、B 22 , these two points are the corrections to the initial turning point as the midpoint. At this time, the horizontal coordinates of these two points can be expressed as X B21 =(X B1 -X A1 ) / 2,X B22 =(X C1 –X B1 ) / 2, there are two types of modified turning surfaces, the modified turning point B 21 The equation is:

[0080] Y 211 =-2*H*(0.75*(X 211 / (L-L1)) 2 -0.25*(X 211 / (L-L1)) 3 ), X 211 ∈(X A1 , X B21 );

[0081] 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 and rear sections of the modified turning section of the first turning section; 211 and X 212 They are respectively the horizontal coordinates of the front section profile and the rear end profile in the first modified turning profile in the second turning profile.

[0082] Among them, the revised turning point B 22 The corresponding equation is:

[0083] Y 221 =-2*H*(0.75*(X 221 / (L-L1)) 2 -0.25*(X 221 / (L-L1)) 3 ), X 221 ∈(X A1 , X B21 )

[0084] 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 and rear sections of the modified turning section of the first turning section; 221 and X 222 They are respectively the horizontal coordinates of the front section profile and the rear end profile in the second modified turning profile in the second turning profile.

[0085] When the correction profile corresponding to the correction turning point is the third turning profile, see Figure 2 As shown, the correction turning point can be expressed as C2, and its horizontal coordinate can be expressed as X C2 =(X C1 –X B1 ) / 2, and then the equation of the modified turning surface is:

[0086] Y 31 =-2*H*(0.75*(X 31 / (L-L1)) 2 -0.25*(X 31 / (L-L1)) 3 ), X 31 ∈(X A1 , X A2 )

[0087] 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 and rear sections of the modified turning section of the first turning section; 31 and X 32 They are respectively the horizontal coordinates of the front section profile and the rear end profile of the modified turning profile of the third turning profile.

[0088] S54 , performing aerodynamic drag evaluation on the modified turning surface, and iteratively correcting the modified turning point according to the aerodynamic drag evaluation result, until a turning point that satisfies the minimum aerodynamic drag is obtained as the final turning point.

[0089] When the aerodynamic drag of the corrected turning surface is recalculated, the turning point of the surface is iteratively corrected according to the aerodynamic drag. After the position of the turning point of the surface is determined, the nozzle outer flow channel size parameters determined in step S1 can be used to form an axisymmetric nozzle outer flow channel surface.

[0090] The final turning point can be determined by iteratively executing the above steps S51 to S54 in a loop. The aerodynamic resistance of the turning profile established by the final turning point is the minimum.

[0091] The method of the present invention has the following advantages:

[0092] 1. The design of the nozzle outer flow channel profile matching the incoming flow pressure change can make the airflow near the nozzle outer flow channel profile change uniform and stable, reducing the aerodynamic drag loss of the outer flow channel profile;

[0093] 2. When determining the turning point of the profile, the actual flow state of the airflow under different usage scenarios and working conditions was taken into consideration to modify the turning point of the outer flow channel profile. This can achieve smooth airflow turning, improve airflow stability, reduce airflow separation, and improve airflow change stability.

[0094] 3. The method of the present invention can effectively support engine engineering design and has been applied and verified on nozzles. It has high versatility and operability, can be promoted and applied within the industry, and has good economic benefits and great practical engineering application value.

[0095] Based on the same inventive concept, an embodiment of the present invention further provides an axisymmetric nozzle outer flow channel profile design system based on drag reduction design, as described in the following embodiments. Since the principle of solving the problem by the axisymmetric nozzle outer flow channel profile design system based on drag reduction design is similar to the axisymmetric nozzle outer flow channel profile design based on drag reduction design disclosed in the above embodiments, the implementation of the axisymmetric nozzle outer flow channel profile design system based on drag reduction design can refer to the implementation of the axisymmetric nozzle outer flow channel profile design method based on drag reduction design, and the repetitions will not be repeated. As used below, the terms "unit" or "module" can be a combination of software and / or hardware that implements predetermined functions. 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 conceived.

[0096] Figure 3 This is a structural block diagram of an axisymmetric nozzle outer flow channel profile design system based on drag reduction design disclosed in an embodiment of the present invention, such as Figure 3 As shown, the system includes an axisymmetric nozzle size acquisition module 301, a turning section initial profile line equation establishment module 302, a turning profile design module 303, a simulation module 304 and a turning point iterative correction module 305. The structure is described below.

[0097] The axisymmetric nozzle dimension acquisition module 301 is used to acquire the axial length of the nozzle outer flow channel, the profile height of the nozzle outer flow channel, and the straight section length of the profile of the nozzle outer flow channel according to the overlap position on the nozzle, wherein the nozzle is an axisymmetric nozzle;

[0098] The turning section initial profile line equation establishing module 302 is used to establish the turning section initial profile line equation using the axial length of the nozzle outer flow channel, the profile height of the nozzle outer flow channel and the length of the straight section;

[0099] The turning surface design module 303 is used to design multiple initial turning surfaces using the characteristic points selected from the initial turning surface line equation of the turning section as initial turning points, and to establish an initial axisymmetric nozzle simulation part for each of the initial turning surfaces;

[0100] The simulation module 304 is used to calculate the aerodynamic drag of each of the initial axisymmetric nozzle simulation parts using a simulation method according to the incoming flow temperature, pressure and Mach number under specific working conditions;

[0101] The turning point iterative correction module 305 is used to select the initial turning surface with the minimum aerodynamic drag as the correction surface, and perform multiple iterative corrections on the initial turning point of the correction surface until the aerodynamic drag corresponding to the new turning point is minimized.

[0102] In this embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, any of the above-mentioned methods for designing the outer flow channel profile of an axisymmetric nozzle based on drag reduction design is implemented.

[0103] Specifically, the computer device may be a computer terminal, a server or a similar computing device.

[0104] In this embodiment, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program for executing any of the above-mentioned methods for designing the outer flow channel profile of an axisymmetric nozzle based on drag reduction design.

[0105] Specifically, computer-readable storage media include permanent and non-permanent, removable and non-removable media that can be used to store information by any method or technology. The information can 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 technology, compact disc read-only memory (CD-ROM), digital versatile disc (DVD) or other optical storage, magnetic cassettes, tape disk storage or other magnetic storage devices or any other non-transmission media that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable storage media does not include transitory media such as modulated data signals and carrier waves.

[0106] Obviously, those skilled in the art should understand that the various modules or steps of the above-mentioned embodiments of the present invention can be implemented using a general-purpose computing device, they can be concentrated on a single computing device, or distributed across a network composed of multiple computing devices. Alternatively, they can be implemented using program code executable by the computing device, so that they can be stored in a storage device and executed by the computing device. In some cases, the steps shown or described can be performed in a different order than herein, or they can be made into separate integrated circuit modules, or multiple modules or steps can be made into a single integrated circuit module for implementation. Thus, the embodiments of the present invention are not limited to any specific combination of hardware and software.

[0107] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for designing the outer flow channel profile of an axisymmetric nozzle based on drag reduction design, characterized in that: include: According to the overlap position on the nozzle, the axial length of the nozzle outer flow channel, the height of the nozzle outer flow channel profile, and the length of the straight section of the nozzle outer flow channel profile are obtained, wherein the nozzle is an axisymmetric nozzle; The end point of the rear straight section of the nozzle outer flow channel profile is taken as the origin, the axial length direction is set as the positive direction of the X axis, and the height direction is set as the positive direction of the Y axis to establish a coordinate system. The axial length of the nozzle outer flow channel, the height of the nozzle outer flow channel profile, and the length of the straight section are used to 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 horizontal and vertical coordinates of the point on the initial profile line of the turning section, H is the profile height of the nozzle outer flow channel, L is the axial length of the nozzle outer flow channel, and L1 is the length of the straight section; Selecting a starting point, a midpoint, and an end point on the initial profile line equation of the turning section as characteristic points, using the characteristic points selected on the initial profile line equation of the turning section as initial turning points to design a plurality of initial turning profiles, and establishing an initial axisymmetric nozzle simulation for each of the initial turning profiles, wherein the initial turning profiles include a first turning profile, a second turning profile, and a third turning profile; The linear equation of the first turning surface is: Y1=-H / (L-L1)*X1, X1∈(X A1 , X C1 ); The second turning profile includes a front profile and a rear profile, and the linear equation of the front profile is: AND 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: AND 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 surface 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 horizontal coordinate of the starting point, X C1 is the horizontal coordinate of the end point, X B1 is the horizontal coordinate of the midpoint, H is the height of the nozzle outer flow channel profile, L is the axial length of the nozzle outer flow channel, L1 is the length of the straight section, X1 and Y1 are the horizontal and vertical coordinates of the point of the first turning surface respectively, X 2前 and Y 2前 are the horizontal and vertical coordinates of the points on the front section of the profile, X 2后 and Y 2后 are the horizontal and vertical coordinates of the point on the rear section profile, respectively; X3 and Y3 are the horizontal and vertical coordinates of the point on the third turning profile, respectively; Calculating the aerodynamic drag of each of the initial axisymmetric nozzle simulations using a simulation method based on the incoming flow temperature, pressure, and Mach number under specific operating conditions; The initial turning surface with the smallest aerodynamic resistance is selected as the modified surface, and the initial turning point of the modified surface is iteratively corrected multiple times until the aerodynamic resistance corresponding to the new turning point is minimized.

2. The method for designing the outer flow channel profile of an axisymmetric nozzle based on drag reduction design according to claim 1, characterized in that: According to the overlap position on the nozzle, the axial length of the nozzle outer flow channel and the profile height of the nozzle outer flow channel are obtained, including: Extracting a first axial length from the upper overlap position of the nozzle to the outlet of the inner flow channel of the nozzle, and determining 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 is greater than or equal to the first axial length; Obtaining the radius of the nozzle upper overlap position, the nozzle inner flow channel outlet radius, and the distance between the outer flow channel profile and the inner flow channel at the nozzle outlet position, subtracting the sum of the nozzle upper overlap position radius, the nozzle inner flow channel outlet radius, and the distance, and using the calculated difference as the difference between the nozzle inner flow channel outlet radius and the distance as the height of the nozzle outer flow channel profile; According to the axial length of the nozzle outer flow channel and the nozzle overlap structure, the straight section length of the nozzle outer flow channel profile is obtained, wherein the nozzle outer flow channel profile includes a front arc section and a rear straight section.

3. The method for designing the outer flow channel profile of an axisymmetric nozzle based on drag reduction design according to claim 2, characterized in that: The length of the straight section is ≤0.1*the axial length of the nozzle outer flow channel.

4. The method for designing the outer flow channel profile of an axisymmetric nozzle based on drag reduction design according to claim 1, characterized in that: A rounded transition process is performed between the front section profile and the rear section profile.

5. The method for designing the outer flow channel profile of an axisymmetric nozzle based on drag reduction design according to claim 1, characterized in that: The initial turning surface with the smallest aerodynamic drag is selected as the modified surface, and the initial turning point of the modified surface is iteratively modified multiple times, including: Determining the aerodynamic drag of all the axisymmetric nozzle simulations, and selecting the initial turning profile corresponding to the axisymmetric nozzle simulation with the smallest aerodynamic drag as the correction profile; When the modified surface is a first turning surface, the center of the starting point and the midpoint is used as the correction turning point; when the modified surface is a second turning surface, the center of the starting point and the midpoint and the center of the midpoint and the end point are used as correction turning points respectively; when the modified surface is a third turning surface, the center of the midpoint and the end point are used as correction turning points respectively; Designing a modified turning surface having the same linear equation as the second turning surface according to the modified turning point; An aerodynamic drag evaluation is performed on the modified turning surface, and the modified turning point is iteratively modified according to the aerodynamic drag evaluation result until a turning point that satisfies the minimum aerodynamic drag is obtained as the final turning point.

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