Supersonic nozzle contraction section generation curve design method, device, equipment and medium

Abstract

The invention belongs to the technical field of engine nozzles, and relates to a supersonic nozzle contraction section generation curve design method, device and equipment and a medium, and the method comprises the following steps: carrying out fluid mechanics analysis on a supersonic nozzle to obtain a supersonic nozzle transonic three-order progressive solution; and an improved contraction section is designed, the end point slope of the improved contraction section is made to be zero, the end point curvature of the improved contraction section is consistent with the design curvature of the supersonic velocity section, and therefore the supersonic velocity spray pipe contraction section generation curve providing the transonic velocity third-order progressive solution of the supersonic velocity spray pipe is obtained. By adopting the method, the transonic velocity three-order progressive solution of the supersonic velocity nozzle can be obtained based on aerodynamics, and the influence of the contraction section can be independently evaluated, so that the improved contraction section capable of providing the accurate transonic velocity three-order progressive solution is designed.

Description

Technical Field

[0001] The present application relates to the technical field of engine nozzles, and in particular to a design method, device, equipment and medium for generating a curve for a supersonic nozzle contraction section. Background Art

[0002] Experiment, calculation and theory are the three major methods of fluid mechanics research. Among them, wind tunnel experiments are very effective because they can pass through nozzles (such as Figure 1 , where A is the contraction section, B is the supersonic section, C is the symmetry axis, and L c is the length of the contraction section, L s is the length of the supersonic section, y i is the entrance height, y t is the throat height, y e The nozzle is the core facility of the wind tunnel, and its design directly determines the performance of the wind tunnel. Any defects will lead to increased wind tunnel noise, turbulence and unevenness of the flow field. In addition, supersonic nozzles are widely used in engineering practice and scientific research, and have an important impact on the thrust performance of aircraft. In the last century, researchers carried out a large number of studies on supersonic nozzle design methods, and successively obtained research results such as the maximum thrust nozzle and the shortest nozzle. Therefore, conducting research on nozzle design is crucial to improving the performance of nozzles and wind tunnels.

[0003] At present, the design of the supersonic section of the nozzle has been improved by generations of VABusemann, AOAtkin, K.Foelsch, RJCresci and JC Sivells, and a relatively mature theory has been formed. However, the nozzle contraction section, that is, the subsonic convergence section upstream of the throat, is designed using a method that is far less rigorous than the supersonic surface theory in aerodynamics; this is because for the contraction section of the low-speed nozzle, its incompressible flow can still use the series solution of the stream function, such as Qian Xuesen and RLBarger obtained various contraction section shapes by presetting the axis speed; in contrast, the compressible subsonic flow of the supersonic nozzle contraction section is very difficult to solve in space stepping due to the elliptical nature of the control equation. This is the first difficulty encountered in the study of the contraction section.

[0004] As a result, almost all supersonic nozzle convergences use analytical curves rather than aerodynamics. Current supersonic nozzle convergences use several methods, such as Figure 2 shown.

[0005] 1) Bicubic curves by T.Morel:

[0006]

[0007] In the formula, y i is the half height of the inlet of the contraction section, y t is the throat half height, y is the cross-sectional radius at the axial distance x, x m It is the relative position of the connection point of the segmented curve, generally xm=0.5.

[0008] 2) JHBell's quintic curve:

[0009]

[0010] 3) Vickers curve:

[0011]

[0012] 4) Axis-shifted Vickers curve, modified based on the definition of the Vickers curve:

[0013]

[0014] 5) CQCQ curve:

[0015]

[0016] in:

[0017] At present, all the contraction sections used in supersonic nozzles use one of the above five methods. These five contraction sections conform to the contraction section design experience criteria accumulated by the Arnold Engineering Development Center (AEDC) of the United States and the China Air Development Center (CARDC).

[0018] Another difficulty in studying the contraction section of a supersonic nozzle is to independently evaluate the impact of the contraction section. A contraction section without a supersonic profile is not enough to produce supersonic flow, which means that the design of the supersonic profile must be perfect enough, otherwise any defects will easily cover up the impact of the contraction section. Commonly used supersonic profile design methods such as K. Foelsch and RJ Cresci introduced the source flow hypothesis, which has a greater impact on the flow than the contraction section; and supersonic profile design methods based on stream function series expansion, such as Baron and Ishii, after deviating from the sonic expansion point, the rejection error increases rapidly, and it is also impossible to accurately evaluate the impact of the contraction section.

[0019] Although these supersonic nozzle designs have been used in ground test facilities to date, the supersonic nozzle contraction section uses analytical curves instead of aerodynamics, and the impact of the contraction section cannot be independently evaluated. Therefore, their design accuracy is not enough for the study of the contraction section. In addition, it is also necessary to consider that the engine or wind tunnel facilities where the nozzle is located are expensive and have a long construction period. These difficulties have led to the fact that the corresponding research on the supersonic nozzle contraction section is still rare and not systematic and in-depth. Summary of the invention

[0020] Based on this, it is necessary to provide a supersonic nozzle contraction section generation curve design method, device, equipment and medium to address the above-mentioned technical problems, which can obtain the supersonic third-order asymptotic solution of the supersonic nozzle based on aerodynamics, and can independently evaluate the influence of the contraction section, so as to design an improved contraction section that can provide an accurate transonic third-order asymptotic solution.

[0021] The design method of supersonic nozzle contraction section generation curve includes:

[0022] The fluid dynamics analysis of the supersonic nozzle is carried out, and the third-order asymptotic solution of the supersonic nozzle transonic speed is obtained;

[0023] An improved contraction section is designed so that the terminal slope of the improved contraction section is zero, and the terminal curvature of the improved contraction section is consistent with the design curvature of the supersonic section, so as to obtain a supersonic nozzle contraction section generation curve that provides a transonic third-order asymptotic solution of the supersonic nozzle.

[0024] In one embodiment, a fluid mechanics analysis is performed on a supersonic nozzle to obtain a supersonic nozzle transonic third-order asymptotic solution, including:

[0025] The fluid dynamics analysis of the supersonic nozzle is carried out to obtain the gas dynamics equation at the sonic point;

[0026] The gas dynamics equation is subjected to dimensionless hardening to obtain dimensionless coordinates;

[0027] Expanding the gas dynamics equation to obtain an expansion velocity;

[0028] According to the gas dynamics equation, the dimensionless coordinates and the expansion speed, and in combination with the position of the speed of sound line, a third-order asymptotic solution of the supersonic nozzle transonic speed is obtained.

[0029] In one embodiment, according to the gas dynamics equation, the dimensionless coordinates and the expansion velocity, and in combination with the position of the speed of sound line, a supersonic nozzle transonic third-order asymptotic solution is obtained, including:

[0030] According to the gas dynamics equation, the dimensionless coordinates and the expansion velocity, a velocity component in the x-direction and a velocity component in the y-direction are obtained;

[0031] Define the speed of sound for the supersonic nozzle and obtain the position of the speed of sound line;

[0032] According to the velocity component in the x-direction, the velocity component in the y-direction and the position of the speed of sound line, a third-order asymptotic solution of the supersonic nozzle transonic speed is obtained.

[0033] In one embodiment, a fluid mechanics analysis is performed on the supersonic nozzle to obtain the gas dynamics equation at the sonic point:

[0034]

[0035] In the formula, a is the speed of sound, u is the streamwise velocity, v is the spanwise velocity, x is the x-axis coordinate, y is the y-axis coordinate, and δ is the flow characteristic;

[0036] The gas dynamics equation is tempered dimensionlessly to obtain dimensionless coordinates:

[0037] X = [2R / (γ+1)] 0.5 (x / r t ),Y=y / r t

[0038] Where X is the dimensionless coordinate of the x-axis, Y is the dimensionless coordinate of the y-axis, R is the relative curvature radius of the throat, γ is the gas specific heat ratio, and rt is the throat radius;

[0039] The gas dynamics equation is expanded to obtain the expansion velocity:

[0040] V x =a * +v x ,V y =v y

[0041] Where V x is the dimensionless velocity in the flow direction, V y is the spanwise dimensionless velocity, vy is the spanwise dimensionless disturbance velocity, vx is the streamwise dimensionless disturbance velocity, and a* is the critical sound speed;

[0042] According to the gas dynamics equation, the dimensionless coordinates and the expansion velocity, the velocity component in the x direction and the velocity component in the y direction are obtained:

[0043]

[0044]

[0045] Where V x (x,y) is the dimensionless velocity of the flow direction, V y (x,y) is the dimensionless velocity in the span direction, v x1(X,Y) is the first-order disturbance coefficient component of the dimensionless disturbance velocity in the flow direction, v x2 (X,Y) is the second-order disturbance coefficient component of the dimensionless disturbance velocity in the flow direction, v x3 (X,Y) is the third-order disturbance coefficient component of the dimensionless disturbance velocity in the flow direction, v y1 (X,Y) is the first-order disturbance coefficient component of the spanwise dimensionless disturbance velocity, v y2 (X,Y) is the second-order perturbation coefficient component of the spanwise dimensionless perturbation velocity, v y3 (X,Y) is the third-order disturbance coefficient component of the spanwise dimensionless disturbance velocity;

[0046] Define the speed of sound for the supersonic nozzle and get the position of the speed of sound line:

[0047]

[0048] According to the velocity component in the x direction, the velocity component in the y direction and the position of the sonic line, the third-order asymptotic solution of the supersonic nozzle transonic speed is obtained:

[0049]

[0050] In one embodiment, the design of the improved contraction section includes:

[0051] Designing an arc segment, wherein the radius of curvature of the arc segment is consistent with the profile of the supersonic segment;

[0052] The contraction section is intercepted at a position where the slope is equal to the starting point slope of the arc section to obtain an upstream section and a downstream section;

[0053] The arc segment is connected to the end of the upstream segment to obtain an improved contraction segment.

[0054] In one embodiment, the design of the improved contraction section includes:

[0055] Designing an arc segment, wherein the radius of curvature of the arc segment is consistent with the profile of the supersonic segment;

[0056] Design a polynomial segment that satisfies:

[0057]

[0058] In the formula, y is the y-axis coordinate, x is the x-axis coordinate, a0, a1, …, a n are polynomial coefficients, y ρ is the y-axis coordinate of the arc segment, x J is the x-axis coordinate of the point where the arc segment and the polynomial segment meet;

[0059] The arc segment is connected to the end of the polynomial segment to obtain an improved contraction segment.

[0060] In one embodiment, the polynomial segment is an n-degree polynomial, and the polynomial coefficients are determined by boundary conditions;

[0061] The boundary conditions include: the starting point coordinates of the polynomial segment, the ending point coordinates of the polynomial segment, and the derivatives of the polynomial segment, and the derivatives include: first-order derivatives to n-2-order derivatives.

[0062] A supersonic nozzle contraction section generation curve design device, comprising:

[0063] The analysis module is used to perform fluid dynamics analysis on the supersonic nozzle and obtain the third-order asymptotic solution of the supersonic nozzle transonic speed;

[0064] The output module is used to design an improved contraction section so that the terminal slope of the improved contraction section is zero, and the terminal curvature of the improved contraction section is consistent with the design curvature of the supersonic section, so as to obtain a supersonic nozzle contraction section generation curve that provides a transonic third-order asymptotic solution of the supersonic nozzle.

[0065] A computer device comprises a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the following steps are implemented:

[0066] The fluid dynamics analysis of the supersonic nozzle is carried out, and the third-order asymptotic solution of the supersonic nozzle transonic speed is obtained;

[0067] An improved contraction section is designed so that the terminal slope of the improved contraction section is zero, and the terminal curvature of the improved contraction section is consistent with the design curvature of the supersonic section, so as to obtain a supersonic nozzle contraction section generation curve that provides a transonic third-order asymptotic solution of the supersonic nozzle.

[0068] A computer-readable storage medium stores a computer program, which, when executed by a processor, implements the following steps:

[0069] The fluid dynamics analysis of the supersonic nozzle is carried out, and the third-order asymptotic solution of the supersonic nozzle transonic speed is obtained;

[0070] An improved contraction section is designed so that the terminal slope of the improved contraction section is zero, and the terminal curvature of the improved contraction section is consistent with the design curvature of the supersonic section, so as to obtain a supersonic nozzle contraction section generation curve that provides a transonic third-order asymptotic solution of the supersonic nozzle.

[0071] The above-mentioned supersonic nozzle contraction section generation curve design method, device, equipment and medium use the series expansion method to linearize the gas dynamics equation of the sonic point, obtain the third-order asymptotic solution of the supersonic nozzle theoretical sonic line, and determine the core parameters of the supersonic nozzle contraction section, so as to design a contraction section that can provide the theoretical transonic flow required for supersonic profile design, greatly improve the accuracy of the sonic line provided by the nozzle contraction section, and help to understand the control mechanism of the nozzle flow, especially the impact on the transonic flow, and can be applied to: (hyper) supersonic wind tunnels, engine nozzles, aerodynamic experimental equipment and other technical fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] Figure 1 It is a schematic diagram of a supersonic nozzle;

[0073] Figure 2 Design methods for different supersonic nozzle contraction sections;

[0074] Figure 3 It is an application scenario diagram of a supersonic nozzle contraction section generation curve design method in one embodiment;

[0075] Figure 4 A schematic flow chart of a method for designing a curve for generating a supersonic nozzle contraction section in one embodiment;

[0076] Figure 5 A schematic diagram of a transonic third-order asymptotic solution for a supersonic nozzle in one embodiment;

[0077] Figure 6 A comparison diagram of the third-order asymptotic solution for the transonic speed of a supersonic nozzle in the present application and the transonic speed solution provided for the contraction section of a supersonic nozzle in the prior art;

[0078] Figure 7 Schematic diagram of two improved contraction sections in one embodiment;

[0079] Figure 8 A schematic diagram of sonic velocity lines provided for two improved contraction sections in one embodiment;

[0080] Fig. 9 Schematic diagrams of the slope and curvature of the contraction section of a supersonic nozzle in the prior art, wherein (a) is a schematic diagram of the slope of the contraction section, and (b) is a schematic diagram of the curvature of the contraction section;

[0081] Fig.10 A structural block diagram of a device for designing a curve for generating a supersonic nozzle contraction section in one embodiment;

[0082] Fig.11 FIG. 4 is a diagram showing the internal structure of a computer device in one embodiment. DETAILED DESCRIPTION

[0083] In order to make the purpose, technical solutions and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0084] It should be noted that all directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0085] In addition, the descriptions of "first", "second", etc. in this application are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, "multiple groups" means at least two groups, such as two groups, three groups, etc., unless otherwise clearly and specifically defined.

[0086] In this application, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, a physical connection, or a wireless communication connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0087] In addition, the technical solutions between the various embodiments of the present application can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0088] The method provided in this application can be applied to Figure 3 In the application environment shown, the terminal 302 communicates with the server 304 through the network, and the terminal 302 may include but is not limited to various personal computers, laptops, smart phones, tablet computers and portable wearable devices, and the server 304 may be various portal websites, servers corresponding to the backend of the work system, etc.

[0089] The present application provides a method for designing a curve for generating a supersonic nozzle contraction section. Figure 4 As shown, in one embodiment, the method is applied to Figure 3 The following is an example of a terminal in the example, including:

[0090] Step 402: Perform fluid mechanics analysis on the supersonic nozzle to obtain a third-order asymptotic solution of the supersonic nozzle.

[0091] Specifically:

[0092] The fluid dynamics analysis of the supersonic nozzle is carried out to obtain the gas dynamics equation at the sonic point;

[0093] The gas dynamics equations are tempered dimensionlessly to obtain dimensionless coordinates;

[0094] Expand the gas dynamics equation to obtain the expansion velocity;

[0095] According to the gas dynamics equation, dimensionless coordinates and expanded velocity, the velocity component in the x direction and the velocity component in the y direction are obtained;

[0096] Define the speed of sound for the supersonic nozzle and obtain the position of the speed of sound line;

[0097] According to the velocity component in the x-direction, the velocity component in the y-direction and the position of the line of sound, the third-order asymptotic solution of the transonic speed of the supersonic nozzle is obtained.

[0098] More specifically:

[0099] The fluid mechanics analysis of the supersonic nozzle yields the gas dynamics equation at the sonic point:

[0100]

[0101] In the formula, a is the speed of sound, u is the streamwise velocity, v is the spanwise velocity, x is the x-axis coordinate, y is the y-axis coordinate, and δ is the flow characteristic;

[0102] According to the gas dynamics equation, for the nozzle flow, the Cartesian coordinates are dimensionlessly tempered to obtain dimensionless coordinates:

[0103] X = [2R / (γ+1)] 0.5 (x / r t ),Y=y / r t (1.7)

[0104] Where X is the dimensionless coordinate of the x-axis, Y is the dimensionless coordinate of the y-axis, R is the relative curvature radius of the throat, γ is the specific heat ratio of the gas, and r is t is the throat radius;

[0105] Using the small perturbation method, the velocity of the gas dynamics equation is expanded to obtain the expanded velocity:

[0106] V x =a * +v x ,V y =v y (1.8)

[0107] Where V x is the dimensionless velocity in the flow direction, V y is the dimensionless spanwise velocity, v y is the spanwise dimensionless disturbance velocity, v x is the dimensionless disturbance velocity in the stream direction, a * is the critical speed of sound;

[0108] According to the gas dynamics equation, dimensionless coordinates and expansion velocity, we can substitute equations 1.8 and 1.7 into

[0109] Formula 1.6, we get the velocity component in the x direction and the velocity component in the y direction:

[0110]

[0111]

[0112] Where V x (x,y) is the dimensionless velocity of the flow direction, which is a variable related to the x-coordinate and the y-coordinate. V y (x,y) is the dimensionless velocity in the span direction, v x1 (X,Y) is the first-order disturbance coefficient component of the dimensionless disturbance velocity in the flow direction, v x2 (X,Y) is the second-order disturbance coefficient component of the dimensionless disturbance velocity in the flow direction, v x3 (X,Y) is the third-order disturbance coefficient component of the dimensionless disturbance velocity in the flow direction, v y1 (X,Y) is the first-order disturbance coefficient component of the spanwise dimensionless disturbance velocity, v y2 (X,Y) is the second-order perturbation coefficient component of the spanwise dimensionless perturbation velocity, v y3 (X,Y) is the third-order disturbance coefficient component of the spanwise dimensionless disturbance velocity;

[0113] Define the speed of sound for the supersonic nozzle and get the position of the speed of sound line:

[0114]

[0115] According to the velocity component in the x direction, the velocity component in the y direction and the position of the speed of sound line, that is, the simultaneous equations 1.9 to 1.11, ignoring the small amount of the square term of the disturbance velocity component, the third-order asymptotic solution of the supersonic nozzle transonic speed is obtained:

[0116]

[0117] In this step, the obtained third-order asymptotic solution of the supersonic nozzle transonic speed (also the third-order asymptotic solution of the supersonic nozzle theoretical sound line) is as follows: Figure 5 shown.

[0118] The comparison between the supersonic nozzle transonic third-order asymptotic solution in this application and the transonic solution provided by the supersonic nozzle contraction section in the prior art is as follows: Figure 6 As shown in the figure, most of them cannot provide accurate transonic solutions (Hall solution speed line), and only the CQCQ contraction section can provide accurate transonic solutions, but CQCQ has too many parameters, complex design, and no real number solution when the length is small. It has not been used in wind tunnels or engines.

[0119] Step 404, designing an improved contraction section so that the terminal slope of the improved contraction section is zero, and the terminal curvature of the improved contraction section is consistent with the design curvature of the supersonic section, so as to obtain a supersonic nozzle contraction section generation curve that provides a supersonic nozzle transonic third-order asymptotic solution.

[0120] In one embodiment, the design of an improved contraction section, recorded as a first improved contraction section, includes: designing an arc section, the curvature radius of the arc section is consistent with the profile of the supersonic section, so as to ensure that the end curvature is consistent with the design curvature of the supersonic section; and converting the contraction section (any contraction section in the prior art, such as a quintic contraction section, so that this embodiment can modify almost all existing nozzles that have been built) into a starting point slope of the arc section (i.e., k=k J ) to obtain an upstream section (the section close to the contraction section is the upstream section) and a downstream section (the section close to the supersonic section is the downstream section); the arc section is connected at the end of the upstream section to obtain a first improved contraction section;

[0121] The coordinates of the arc segment satisfy:

[0122]

[0123] In the formula, x ρ is the x coordinate of the arc segment, y ρ is the y coordinate of the arc segment, ρ t is the radius of the arc segment, y t is the throat height, θ is the arc segment angle;

[0124] The slope of the arc segment starting point J satisfies:

[0125] k J = -tan(θ J )

[0126] In the formula, k J is the slope of the arc segment starting point J, θ Jis the angle of the arc segment starting point J.

[0127] In another embodiment, designing an improved contraction section, denoted as a second improved contraction section, includes: designing an arc section, the curvature radius of the arc section is consistent with the supersonic section profile; designing a polynomial section, the polynomial section satisfies equation 1.14; connecting the arc section at the end of the polynomial section to obtain the second improved contraction section;

[0128] The coordinates of the arc segment satisfy:

[0129]

[0130] In the formula, x ρ is the x coordinate of the arc segment, y ρ is the y coordinate of the arc segment, ρ t is the arc segment radius, y t is the throat height, θ is the arc segment angle;

[0131] The slope of the arc segment starting point J satisfies:

[0132] k J = -tan(θ J )

[0133] In the formula, k J is the slope of the arc segment starting point J, θ J is the angle of the arc segment;

[0134] The polynomial segment has an analytical curve form, which satisfies equation 1.14 and can obtain satisfactory results under different aspect ratios and contraction ratios:

[0135]

[0136] In the formula, y is the y-axis coordinate, x is the x-axis coordinate, a0, a1, …, a n are polynomial coefficients, y ρ is the y-axis coordinate of the arc segment, x J is the x-axis coordinate of the point where the arc segment and the polynomial segment meet;

[0137] It should be noted that the polynomial segment is an n-order polynomial, and the polynomial coefficients are determined by boundary conditions; the boundary conditions include: the starting point coordinates of the polynomial segment, the end point coordinates of the polynomial segment, and the derivatives of the polynomial segment, and the derivatives include: first-order derivatives to n-2-order derivatives;

[0138] Taking a cubic polynomial as an example, the following four boundary conditions can be met to determine the polynomial coefficients:

[0139]

[0140] In the formula, y Jis the y coordinate of the point where the arc segment meets the polynomial segment.

[0141] In this step, two improved contraction sections are Figure 7 As shown, the connection point J is the starting point of the arc segment.

[0142] Both improved contraction sections meet the requirements of core design parameters (slope and curvature). Numerical simulations are performed and the sound velocity lines are extracted, such as Figure 8 As shown. Figure 8 It can be seen that the actual sound speed line provided by the contraction section completely coincides with the theoretical sound speed line, which means that both improved contraction sections successfully provide the third-order asymptotic solution of the nozzle transonic speed and have more stringent aerodynamic requirements.

[0143] In this embodiment, numerical simulation is performed to compare the actual sound velocity lines provided by different contraction sections with the third-order asymptotic solution of the theoretical sound velocity lines, such as Fig. 9 shown.

[0144] Fig. 9 Among them, the speed of sound lines of the bicubic curve and the quintic curve differ the most from the theoretical speed of sound line, with an error of about 5mm. Considering that the throat height is only 50mm, the error is about 1 / 10, which is unacceptable for the sensitive nozzle throat, especially the speed of sound line of the bicubic curve has obvious velocity gradient discontinuity. The speed of sound line of the Vickers curve derived by incompressible theory is slightly better than the first two curves, and the performance of the Vickers curve after axis shift has been further improved; if the axis shift amount is taken as the independent variable and the speed of sound line error is taken as the dependent variable for optimization, the Vickers contraction section has the potential to provide a speed of sound line consistent with the theoretical speed of sound line. The CQCQ curve contraction section with multiple parameters has been carefully designed, and the actual speed of sound line provided is basically consistent with the theoretical speed of sound line, but the CQCQ curve has too many parameters, the design is complex, and there is no real number solution when the length is small. It has not been used in wind tunnels or engines so far.

[0145] Further analysis, Fig. 9 The slope and curvature of the existing nozzle contraction section are also provided. It should be noted that: first, the slope of all contraction sections is less than 0 throughout the whole process, that is, the profile height decreases monotonically. Although the reduction amplitude is different from the starting position, it is at the end of the contraction section, that is, the throat reaches the slope, and the slope of all contraction sections is 0; second, pay attention to the degree of deviation of the curvature of the end of the contraction section curve from the design curvature of the supersonic section. Although the curvature of the CQCQ curve has a sudden change, and the curvature change amplitude is also greater than the fifth power and the axis-shifted Vickers curve, only the curvature of the CQCQ end point is consistent with the curvature of the theoretical sound speed solution used in the supersonic section design. This is the decisive reason why the CQCQ sound speed line is consistent with the theoretical sound speed line. Therefore, the core parameters that affect the transonic solution of the contraction section are obtained, and the contraction section design is carried out accordingly.

[0146] The above-mentioned supersonic nozzle contraction section generation curve design method, based on aerodynamics, adopts the series expansion method to linearize and solve the gas dynamics equation at the sound speed point, and obtains the third-order asymptotic solution of the theoretical sound speed line of the supersonic nozzle (that is, the third-order asymptotic solution of the transonic speed), and can independently evaluate the influence of the contraction section, determine the core parameters of the supersonic nozzle contraction section, and thus design a contraction section that can provide the theoretical transonic flow required for supersonic profile design, greatly improves the accuracy of the sound speed line provided by the nozzle contraction section and the outlet uniformity, and at the same time helps to understand the control mechanism of the nozzle flow, especially the influence on the transonic flow, and can be applied to: (hyper) supersonic wind tunnels, engine nozzles, aerodynamic experimental equipment and other technical fields.

[0147] It should be understood that although Figure 4 The steps in the flowchart are shown in sequence as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified in this document, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, Figure 4 At least part of the steps may include multiple sub-steps or multiple stages. These sub-steps or stages are not necessarily executed at the same time, but can be executed at different times. The execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least part of the sub-steps or stages of other steps.

[0148] The present application also provides a supersonic nozzle contraction section generation curve design device, such as Fig.10 As shown, in one embodiment, it includes: an analysis module 1002 and an output module 1004, wherein:

[0149] The analysis module is used to perform fluid dynamics analysis on the supersonic nozzle and obtain the third-order asymptotic solution of the supersonic nozzle transonic speed;

[0150] The output module is used to design an improved contraction section so that the terminal slope of the improved contraction section is zero, and the terminal curvature of the improved contraction section is consistent with the design curvature of the supersonic section, so as to obtain a supersonic nozzle contraction section generation curve that provides a supersonic nozzle transonic third-order asymptotic solution.

[0151] The specific definition of the supersonic nozzle contraction section generation curve design device can be found in the above-mentioned definition of the supersonic nozzle contraction section generation curve design method, which will not be repeated here. Each module in the above-mentioned device can be implemented in whole or in part by software, hardware and a combination thereof. Each of the above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the operations corresponding to each of the above modules.

[0152] In one embodiment, a computer device is provided. The computer device may be a terminal, and its internal structure diagram may be as follows: Fig.11 As shown. The computer device includes a processor, a memory, a network interface, a display screen and an input device connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, a method for designing a supersonic nozzle contraction section generation curve is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covered on the display screen, or a key, trackball or touchpad set on the computer device housing, or an external keyboard, touchpad or mouse, etc.

[0153] Those skilled in the art will understand that Fig.11 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have a different arrangement of components.

[0154] In one embodiment, a computer device is provided, including a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method in the above embodiment when executing the computer program.

[0155] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the steps of the method in the above embodiment are implemented.

[0156] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

[0157] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0158] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A method for designing a curve for generating a supersonic nozzle contraction section, characterized in that: include: The fluid dynamics analysis of the supersonic nozzle is carried out, and the third-order asymptotic solution of the supersonic nozzle transonic speed is obtained; An improved contraction section is designed so that the terminal slope of the improved contraction section is zero, and the terminal curvature of the improved contraction section is consistent with the design curvature of the supersonic section, so as to obtain a supersonic nozzle contraction section generation curve that provides a transonic third-order asymptotic solution of the supersonic nozzle.

2. The method for designing a supersonic nozzle contraction section generation curve according to claim 1, characterized in that: The fluid dynamics analysis of the supersonic nozzle is carried out, and the third-order asymptotic solution of the supersonic nozzle is obtained, including: The fluid dynamics analysis of the supersonic nozzle is carried out to obtain the gas dynamics equation at the sonic point; The gas dynamics equation is subjected to dimensionless hardening to obtain dimensionless coordinates; Expanding the gas dynamics equation to obtain an expansion velocity; According to the gas dynamics equation, the dimensionless coordinates and the expansion speed, and in combination with the position of the speed of sound line, a third-order asymptotic solution of the supersonic nozzle transonic speed is obtained.

3. The method for designing a supersonic nozzle contraction section generation curve according to claim 2, characterized in that: According to the gas dynamics equation, the dimensionless coordinates and the expansion velocity, and in combination with the position of the speed of sound line, a supersonic nozzle transonic third-order asymptotic solution is obtained, including: According to the gas dynamics equation, the dimensionless coordinates and the expansion velocity, a velocity component in the x-direction and a velocity component in the y-direction are obtained; Define the speed of sound for the supersonic nozzle and obtain the position of the speed of sound line; According to the velocity component in the x-direction, the velocity component in the y-direction and the position of the speed of sound line, a third-order asymptotic solution of the supersonic nozzle transonic speed is obtained.

4. The method for designing a supersonic nozzle contraction section generation curve according to claim 3, characterized in that: The fluid mechanics analysis of the supersonic nozzle yields the gas dynamics equation at the sonic point: In the formula, a is the speed of sound, u is the streamwise velocity, v is the spanwise velocity, x is the x-axis coordinate, y is the y-axis coordinate, and δ is the flow characteristic; The gas dynamics equation is tempered dimensionlessly to obtain dimensionless coordinates: X=[2R / (γ+1)] 0.5 (x / r t ),Y=y / r t Where X is the dimensionless coordinate of the x-axis, Y is the dimensionless coordinate of the y-axis, R is the relative curvature radius of the throat, γ is the gas specific heat ratio, and rt is the throat radius; The gas dynamics equation is expanded to obtain the expansion velocity: V x =a * +v x ,V y =v y Where V x is the dimensionless velocity in the flow direction, V y is the spanwise dimensionless velocity, vy is the spanwise dimensionless disturbance velocity, and v x is the dimensionless disturbance velocity in the stream direction, a * is the critical speed of sound; According to the gas dynamics equation, the dimensionless coordinates and the expansion velocity, the velocity component in the x direction and the velocity component in the y direction are obtained: Where V x (x,y) is the dimensionless velocity of the flow direction, V y (x,y) is the dimensionless velocity in the span direction, v x1 (X,Y) is the first-order disturbance coefficient component of the dimensionless disturbance velocity in the flow direction, v x2 (X,Y) is the second-order disturbance coefficient component of the dimensionless disturbance velocity in the flow direction, v x3 (X,Y) is the third-order disturbance coefficient component of the dimensionless disturbance velocity in the flow direction, v y1 (X,Y) is the first-order disturbance coefficient component of the spanwise dimensionless disturbance velocity, v y2 (X,Y) is the second-order perturbation coefficient component of the spanwise dimensionless perturbation velocity, v y3 (X,Y) is the third-order disturbance coefficient component of the spanwise dimensionless disturbance velocity; Define the speed of sound for the supersonic nozzle and get the position of the speed of sound line: According to the velocity component in the x direction, the velocity component in the y direction and the position of the sonic line, the third-order asymptotic solution of the supersonic nozzle transonic speed is obtained:

5. The method for designing a supersonic nozzle contraction section generation curve according to any one of claims 1 to 4, characterized in that: Design improvements to the contraction section, including: Designing an arc segment, wherein the radius of curvature of the arc segment is consistent with the profile of the supersonic segment; The contraction section is intercepted at a position where the slope is equal to the starting point slope of the arc section to obtain an upstream section and a downstream section; The arc segment is connected to the end of the upstream segment to obtain an improved contraction segment.

6. The method for designing a supersonic nozzle contraction section generation curve according to any one of claims 1 to 4, characterized in that: Design improvements to the contraction section, including: Designing an arc segment, wherein the radius of curvature of the arc segment is consistent with the profile of the supersonic segment; Design a polynomial segment that satisfies: In the formula, y is the y-axis coordinate, x is the x-axis coordinate, a0, a1, …, a n are polynomial coefficients, y ρ is the y-axis coordinate of the arc segment, x J is the x-axis coordinate of the point where the arc segment and the polynomial segment meet; The arc segment is connected to the end of the polynomial segment to obtain an improved contraction segment.

7. The method for designing a supersonic nozzle contraction section generation curve according to claim 6, characterized in that: The polynomial segment is an n-order polynomial, and the polynomial coefficients are determined by boundary conditions; The boundary conditions include: the starting point coordinates of the polynomial segment, the ending point coordinates of the polynomial segment, and the derivatives of the polynomial segment, and the derivatives include: first-order derivatives to n-2-order derivatives.

8. A supersonic nozzle contraction section generation curve design device, characterized in that: include: The analysis module is used to perform fluid dynamics analysis on the supersonic nozzle and obtain the third-order asymptotic solution of the supersonic nozzle transonic speed; The output module is used to design an improved contraction section so that the terminal slope of the improved contraction section is zero, and the terminal curvature of the improved contraction section is consistent with the design curvature of the supersonic section, so as to obtain a supersonic nozzle contraction section generation curve that provides a transonic third-order asymptotic solution of the supersonic nozzle.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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