Design method, device and equipment for large-scale engine with rough inner wall at isolation section

Abstract

The invention relates to a design method, device and equipment for a large-scale engine with an isolation section provided with a rough inner wall. The method comprises the following steps: taking an obtained position of boundary layer transition of an isolation section as an initial complete turbulence state; calculating a first boundary layer displacement thickness and a second boundary layer displacement thickness; judging whether the first boundary layer displacement thickness is consistent with the second boundary layer displacement thickness or not, and if not, calculating a boundary layer thickness correction value; selecting the roughness, length and position of the rough flow section according to the thickness correction value of the boundary layer; then a rough inner wall is arranged on the isolation section, numerical simulation calculation is carried out, and the displacement thickness of a third boundary layer with the rough flow section in the complete turbulent flow state is obtained; and judging whether the third boundary layer displacement thickness is consistent with the first boundary layer displacement thickness, and if yes, obtaining a final scheme. The total pressure loss of the engine can be prevented from being increased, and the length of the large-scale engine is remarkably shortened.

Description

Technical Field

[0001] The invention relates to the technical field of engine design, and in particular to a method, a device and equipment for designing a large-scale engine with a rough inner wall of an isolation section. Background Art

[0002] The existing ramjet engine with a concave flame stabilizer has a nonlinear relationship between combustion characteristics and scale. When the large-scale engine design is scaled up according to the scaled model, a scale effect will occur, that is, the combustion characteristics will change as the scale increases. At this time, the combustion flow fields between large and small scale engines are no longer similar, and the common similarity theory and dimensional analysis will no longer be applicable, making the design of large-scale engines difficult.

[0003] As the scale increases, the nonlinear change of the combustion chamber boundary layer thickness is one of the important reasons for the scale effect. For a combustion chamber with a concave cavity flame stabilizer, the change in boundary layer thickness will mainly affect the effective flow area and flow field characteristics at the concave cavity trailing edge, that is, the contraction throat, and thus affect the entire supersonic combustion flow field. Figure 1 As shown, the large-scale engine is proportionally enlarged based on the geometric structure of the scaled model, but the relative boundary layer thickness becomes thinner, causing the effective flow area of ​​the thermal throat at the trailing edge of the cavity to be enlarged beyond the design proportion.

[0004] At present, in order to solve the problem that the relative boundary layer thickness of large-scale engines is thinner than that of scaled models, causing the dissimilar engine combustion characteristics, there are two main implementation schemes that focus on geometric structure design and boundary layer development. The first implementation scheme advocates the use of adjusting the throat geometry design to compensate for the boundary layer, that is, the throat compensation scheme, which compensates by raising the rear edge of the cavity, that is, the lifting height of the throat, so that the effective flow area of ​​the thermal throat is restored to the proportional amplification relationship. The second implementation scheme focuses on the nature of the change in the relative thickness of the boundary layer, and advocates lengthening the isolation section to increase the characteristic length of the boundary layer development, thereby causing the relative thickness of the combustion chamber boundary layer to become thicker, thereby restoring the similarity of the large-scale combustion chamber flow field.

[0005] However, the first throat compensation solution can easily cause other factors that affect combustion characteristics to change, such as the cavity flame limit, the total pressure loss of the combustion chamber, etc., which may affect the engine propulsion performance and have poor controllability in solving the problem. The second solution of lengthening the isolation section will increase the overall length of the engine, resulting in a long development distance of the turbulent boundary layer, increase the total pressure loss of the isolation section, and is not conducive to practical application and production. Summary of the invention

[0006] Based on this, it is necessary to provide a large-scale engine design method, device and equipment with a rough inner wall of the isolation section that can solve the problem of dissimilar engine combustion characteristics caused by the thinner boundary layer thickness of the large-scale engine compared to the scaled model in response to the above-mentioned technical problems.

[0007] A method for designing a large-scale engine with a rough inner wall of an isolation section, the method comprising: Acquiring a position where a boundary layer transition occurs in the isolation section; taking the position where the boundary layer transition occurs in the isolation section as an initial fully turbulent state; Referring to the small-scale scaled model, under the fully turbulent state, the first boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under an ideal state is calculated; and based on the Reynolds analogy and the 1 / 7 power law of the boundary layer, the second boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under actual conditions is calculated; determining whether the first boundary layer displacement thickness is consistent with the second boundary layer displacement thickness, and if not, calculating a boundary layer thickness correction value according to the first boundary layer displacement thickness and the second boundary layer displacement thickness; According to the boundary layer thickness correction value, the roughness, required length and position of the rough flow section are selected; Based on the roughness of the rough flow section, the length and position to be arranged, a rough inner wall is arranged on the isolation section, and numerical simulation calculation is performed to obtain the displacement thickness of the third boundary layer when the rough flow section is in a fully turbulent state; It is determined whether the third boundary layer displacement thickness is consistent with the first boundary layer displacement thickness. If so, the roughness, required length and position of the rough flow section are used as the final solution.

[0008] A large-scale engine design device with a rough inner wall of an isolation section, the device comprising: An initialization module is used to obtain a position where a boundary layer transition occurs in the isolation section; and the position where the boundary layer transition occurs in the isolation section is used as an initial fully turbulent state; The boundary layer displacement thickness calculation module is used to calculate the first boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under the ideal state with reference to the small-scale scaled model under the fully turbulent state; and to calculate the second boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under the actual situation based on the Reynolds analogy and the 1 / 7 power law of the boundary layer; a judgment module, configured to judge whether the first boundary layer displacement thickness is consistent with the second boundary layer displacement thickness, and if not, to calculate a boundary layer thickness correction value according to the first boundary layer displacement thickness and the second boundary layer displacement thickness; A rough flow section parameter selection module is used to select the roughness, length and position of the rough flow section according to the boundary layer thickness correction value; A simulation calculation module is used to arrange a rough inner wall on the isolation section based on the roughness of the rough flow section, the length and position to be arranged, and perform numerical simulation calculation to obtain the displacement thickness of the third boundary layer under the rough flow section in a fully turbulent state; The scheme determination module is used to determine whether the third boundary layer displacement thickness is consistent with the first boundary layer displacement thickness. If so, the roughness of the rough flow section, the length and position to be arranged are used as the final scheme.

[0009] 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 steps of the large-scale engine design method with a rough inner wall of the isolation section are implemented.

[0010] The above-mentioned large-scale engine design method, device and equipment with a rough inner wall of the isolation section first obtains the position where the boundary layer transition occurs in the isolation section; the position where the boundary layer transition occurs in the isolation section is used as the initial full turbulence state; with reference to the small-scale scaled model, under the full turbulence state, the first boundary layer displacement thickness at the throat of the rear edge of the cavity of the large-scale engine in an ideal state is calculated; and based on the Reynolds analogy and the 1 / 7 power law of the boundary layer, the second boundary layer displacement thickness at the throat of the rear edge of the cavity of the large-scale engine in actual conditions is calculated; it is determined whether the first boundary layer displacement thickness is consistent with the second boundary layer displacement thickness. If not, a boundary layer thickness correction value is calculated according to the first boundary layer displacement thickness and the second boundary layer displacement thickness; according to the boundary layer thickness correction value, the roughness of the rough flow section, the length and position to be arranged are selected; based on the roughness of the rough flow section, the length and position to be arranged, a rough inner wall is arranged on the isolation section, and numerical simulation is performed to obtain the third boundary layer displacement thickness with the rough flow section in a fully turbulent state; it is determined whether the third boundary layer displacement thickness is consistent with the first boundary layer displacement thickness, and if so, the roughness of the rough flow section, the length and position to be arranged are used as the final solution.

[0011] The present invention sets a rough wall surface in the isolation section to make the thickness of the combustion chamber boundary layer thicker according to demand, which can locally accelerate the transition of the boundary layer from laminar flow to turbulent flow, avoiding increasing the total pressure loss of the engine; it can also significantly shorten the length of the large-scale engine while ensuring similar combustion characteristics before and after the combustion chamber scale is increased, avoiding the increase in engine length caused by the long isolation section. By comparing the displacement thickness of the first boundary layer and the displacement thickness of the second boundary layer, the boundary layer thickness correction value is calculated, and the rough wall surface is reasonably designed, which can reduce the total pressure loss of the isolation section and increase the Mach number at the isolation section outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0013] Figure 1 This is a schematic diagram of a large-scale engine in Example 1 based on a proportionally enlarged geometric structure of a scaled model; Figure 2 A schematic flow chart of a method for designing a large-scale engine with a rough inner wall of an isolation section in Example 1; Figure 3 This is a schematic diagram of the complete turbulent state at the end of the rough flow section in Example 1; Figure 4 A structural block diagram of a large-scale engine design device with a rough inner wall of the isolation section in Example 2; Figure 5 This is a diagram of the internal structure of the computer device in Example 3.

[0014] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0015] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] The following will describe the implementation of the present invention in detail with reference to the accompanying drawings in the embodiment diagram of the present invention.

[0017] Example 1 This embodiment discloses a large-scale engine design method with a rough inner wall of an isolation section. By setting a rough wall surface in the isolation section, the thickness of the combustion chamber boundary layer is thickened according to demand, which can locally accelerate the transition of the boundary layer from laminar flow to turbulent flow, avoiding increasing the total pressure loss of the engine; it can also significantly shorten the length of the large-scale engine while ensuring similar combustion characteristics before and after the combustion chamber scale is increased, avoiding the increase in engine length caused by the long isolation section. By comparing the displacement thickness of the first boundary layer with the displacement thickness of the second boundary layer, calculating the boundary layer thickness correction value, and thus reasonably designing the rough wall surface, the total pressure loss of the isolation section can be reduced and the Mach number at the isolation section outlet can be increased.

[0018] like Figure 2 As shown, the large-scale engine design method with a rough inner wall of the isolation section provided in this embodiment includes the following steps: Step 201, obtaining the position where the boundary layer transition occurs in the isolation section; taking the position where the boundary layer transition occurs in the isolation section as the initial complete turbulence state.

[0019] Step 202, referring to the small-scale scaled model, under a fully turbulent state, calculate the first boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under an ideal state; and based on the Reynolds analogy and the 1 / 7 power law of the boundary layer, calculate the second boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under actual conditions.

[0020] Step 203, determining whether the first boundary layer displacement thickness is consistent with the second boundary layer displacement thickness, if not, calculating a boundary layer thickness correction value according to the first boundary layer displacement thickness and the second boundary layer displacement thickness.

[0021] Step 204, selecting the roughness of the rough flow section, the length and position to be arranged according to the boundary layer thickness correction value.

[0022] Step 205, based on the roughness of the rough flow section, the length and position to be arranged, arrange the rough inner wall on the isolation section, and perform numerical simulation calculation to obtain the third boundary layer displacement thickness when the rough flow section is in a fully turbulent state.

[0023] Step 206, determining whether the third boundary layer displacement thickness is consistent with the first boundary layer displacement thickness, if so, taking the roughness of the rough flow section, the length and position to be arranged as the final solution.

[0024] In the specific implementation process of step 201, the basic information of the large-scale engine flow field is first obtained, and the basic flow field information includes the incoming flow velocity, total pressure, total temperature, wall roughness, fluid viscosity, etc. The RANS equation is constructed based on the initial information; then the RANS method is numerically solved to obtain the boundary layer information under the incoming flow conditions of the isolation section, and the boundary layer information includes velocity, velocity gradient, local Reynolds number, etc. Based on the boundary layer theory, combined with the boundary layer information and the local physical quantity information of the flow field, the flow is disturbed by the linear stability analysis of the flow transition, and then the boundary layer transition position is determined according to the estimation method of the boundary layer transition. In this embodiment, it is preferred e n The method is used to estimate e n When the method is used, the transition position of the boundary layer is determined by the transition amplification factor N.

[0025] In the specific implementation process of step 202 and step 203, referring to the small-scale scaled model, under the fully turbulent state, the first boundary layer displacement thickness at the throat of the concave cavity trailing edge of the large-scale engine under the ideal state is calculated, including: based on the geometric structure design parameters of the small-scale engine and the large-scale engine, the proportional relationship of the effective flow area of ​​the thermal throat before and after the associated proportional amplification is obtained to obtain the deviation of its boundary layer thickness from the design ratio, that is, the first boundary layer displacement thickness at the thermal throat and the boundary layer thickness correction value.

[0026] Specifically, the geometric cross-sectional area of ​​the combustion chamber throat is defined as , the effective geometric area is The combustion chamber inlet area is . Then we have: ; In the formula, is the area of ​​the flow channel occupied by the boundary layer displacement thickness. If you want to ensure that the combustion effect before and after the combustion chamber is similar, you should ensure that the combustion chamber inlet size is proportionally scaled. times (corresponding to flow scaling times), the effective area of ​​the thermal throat is also scaled times, that is, the proportional relationship of the effective flow area of ​​the thermal throat before and after the proportional amplification is expressed as: ; In the formula, Represents the effective flow area at the throat of a large-scale engine; Represents the geometric cross-sectional area of ​​the combustion chamber throat of a large-scale engine; Represents the flow channel area occupied by the boundary layer displacement thickness of the large-scale engine; represents the combustion chamber inlet area of ​​a large-scale engine; It represents the effective flow area at the throat of a small-scale engine; Represents the geometric cross-sectional area of ​​the combustion chamber throat of a small-scale engine; Represents the flow channel area occupied by the boundary layer displacement thickness of the small-scale engine; represents the combustion chamber inlet area of ​​a small-scale engine; Indicates the zoom factor.

[0027] Taking the rectangular combustion chamber as an example, the span width is , the height of the throat is The entrance height is , then: ; The displacement thickness of the first boundary layer at the throat of a large-scale engine combustion chamber under ideal conditions is obtained, and the calculation expression is: ; In the formula, It represents the displacement thickness of the first boundary layer of a large-scale engine under ideal conditions; Indicates the height of the throat of a large-scale engine; Indicates the height of the throat of the small-scale engine; represents the span width of the small-scale engine; Indicates the width of the large-scale engine; Represents the actual boundary layer displacement thickness of a small-scale model engine.

[0028] At the same time, based on the Reynolds analogy and the 1 / 7 power law of the boundary layer, the displacement thickness of the second boundary layer at the throat of the cavity trailing edge is calculated. The expression of the displacement thickness of the second boundary layer is: ; In the formula, represents the boundary layer displacement thickness; , is the coefficient; represents the characteristic length; Reynolds number.

[0029] The standard equation for the Reynolds number is: Among them, the coefficient , According to the 1 / 7 power law of the boundary layer, in this embodiment, , ; Characteristic length It can be approximately defined as the distance from the transition point to the throat of the combustion chamber.

[0030] Then, determine whether the first boundary layer displacement thickness is consistent with the second boundary layer displacement thickness. If so, end the calculation and determine the geometric design parameters of the large-scale engine. If not, calculate the difference between the first boundary layer displacement thickness and the second boundary layer displacement thickness to determine the size of the boundary layer thickness missing from the throat and obtain the boundary layer thickness correction value.

[0031] It can be understood that the first boundary layer displacement thickness calculated based on the scaling ratio is the boundary layer displacement thickness at the throat of the trailing edge of the large-scale engine cavity under ideal conditions, which is the data directly calculated after scaling from the small-scale engine. The second boundary layer displacement thickness is the boundary layer displacement thickness obtained by approximate calculation, which establishes a similar relationship between momentum transfer and heat transfer in turbulence through the Reynolds analogy, and empirically describes the velocity distribution in the turbulent boundary layer through the 1 / 7 power law of the boundary layer. On this basis, certain deductions and approximations are performed to obtain the boundary layer displacement thickness.

[0032] Through the first boundary layer displacement thickness, when designing a large-scale engine, the first boundary layer displacement thickness can be directly calculated according to the scaling ratio through the relevant data of the small-scale engine, so as to quickly obtain the ideal reference value under the large-scale engine without the need for complex calculations from scratch on the large-scale engine, thus shortening the design cycle; at the same time, by comparing the first boundary layer displacement thickness under the ideal state with the second boundary layer displacement thickness obtained by approximate calculation, it can provide a basis for the design of subsequent rough flow sections, thereby improving engine performance.

[0033] In the specific implementation process of step 204, the characteristics of the boundary layer are analyzed according to the boundary layer thickness correction value and the specific conditions of the flow; then the layout position of the rough flow section is determined according to the position where the first oblique shock wave is generated; and the roughness and length of the rough flow section are determined according to the engine operating Mach number.

[0034] Specifically, the layout of the rough flow section is determined according to the engine design requirements, and the rough flow section should be arranged as close to the inlet of the isolation section as possible. In order to avoid premature transition and adverse effects such as increased total pressure loss caused by long-distance development of the boundary layer, the rough flow section should be arranged near the location where the first oblique shock wave of the isolation section is generated.

[0035] According to the engine operating Mach number, the length and friction coefficient of the rough flow section of the appropriate isolation section are determined, and the surface roughness of the rough flow section is determined by the friction coefficient. Among them, for high Mach number engines, the friction coefficient of the rough flow section should be as small as possible and the length should be relatively long; for low Mach number engines, the friction coefficient of the rough flow section should be as large as possible and the length should be relatively short.

[0036] In the specific implementation process of step 205, according to the roughness of the rough flow section, the length and position to be arranged, after the rough inner wall is arranged on the isolation section accordingly, as shown in FIG. Figure 3 As shown in the figure, the end position of the rough flow section is taken as a reference to the complete turbulent state, and the third boundary layer displacement thickness of the turbulent flow at the throat is calculated with the rough flow section as the complete turbulent state. The calculation formula of the third boundary layer displacement thickness is the same as the formula of the second boundary layer displacement thickness, which will not be repeated here.

[0037] In the specific implementation process of step 206, iterative calculation is performed by judging whether the third boundary layer displacement thickness is consistent with the first boundary layer displacement thickness to obtain the roughness of the final rough flow section, the length and position to be arranged, and when designing a large-scale engine, it is arranged in the isolation section as the final solution to form an isolation section design solution with a rough flow section.

[0038] Through the present invention, the position where the boundary layer transition occurs in the isolation section is taken as the initial complete turbulent state, which can more accurately grasp the development stage of the boundary layer, provide accurate starting conditions for subsequent design and calculation, and thus achieve precise control of the transition of the boundary layer from laminar to turbulent. The first boundary layer displacement thickness and the second boundary layer displacement thickness at the throat of the rear edge of the cavity are calculated based on different theories, and through comparison and correction, the calculation of the boundary layer displacement thickness is made more accurate; it helps to make the actual development of the boundary layer closer to the ideal state, reduce the uncertainty of the boundary layer thickness, and improve the stability of the flow field inside the engine. Based on the boundary layer thickness correction value, the roughness of the rough flow section, the length and position to be arranged are reasonably selected, which can best avoid the increase in engine length caused by the long isolation section, and effectively improve the flow conditions in the isolation section, so that the airflow will produce appropriate disturbances when passing through the rough inner wall, promote the mixing of the boundary layer, thereby reducing the possibility of flow separation, reducing flow losses, and improving the overall efficiency of the engine. Moreover, by arranging a rough inner wall, the airflow in the isolation section can reach a more ideal state in a completely turbulent state, thereby enhancing the stability of the airflow, reducing the pulsation and vortex of the airflow, reducing the engine performance fluctuation caused by the unstable airflow, and improving the reliability and stability of the engine operation. By matching the rough flow section design of the isolation section of the boundary layer transition and the thermal throat of the combustion chamber, the changes in the combustion characteristics of large-scale engines caused by the scale effect can be effectively corrected, which is beneficial to the design of large-scale engines. In addition, through iterative calculations through numerical simulation, the design of the rough flow section can be judged and corrected multiple times, which can reduce the risks in the actual manufacturing and testing process, and reduce the cost increase and time delay caused by design errors.

[0039] Although this embodiment Figure 2 The steps in the process are shown in sequence as indicated by the arrows, but the 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 the steps, and the steps can be executed in other orders. Figure 2 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.

[0040] Example 2 Based on the large-scale engine design method with a rough inner wall of the isolation section in Example 1, this embodiment discloses a large-scale engine design device with a rough inner wall of the isolation section, such as Figure 4As shown, the large-scale engine design device with a rough inner wall of the isolation section includes: an initialization module 401, a boundary layer displacement thickness calculation module 402, a judgment module 403, a rough flow section parameter selection module 404, a simulation calculation module 405 and a scheme determination module 406, wherein: The initialization module 401 is used to obtain the position where the boundary layer transition occurs in the isolation section; the position where the boundary layer transition occurs in the isolation section is used as the initial complete turbulence state.

[0041] The boundary layer displacement thickness calculation module 402 is used to refer to the small-scale scaled model and, under a fully turbulent state, calculate the first boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under an ideal state; and based on the Reynolds analogy and the 1 / 7 power law of the boundary layer, calculate the second boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under actual conditions.

[0042] The judgment module 403 is used to judge whether the first boundary layer displacement thickness is consistent with the second boundary layer displacement thickness. If not, a boundary layer thickness correction value is calculated according to the first boundary layer displacement thickness and the second boundary layer displacement thickness. The rough flow section parameter selection module 404 is used to select the roughness, required length and position of the rough flow section according to the boundary layer thickness correction value.

[0043] The simulation calculation module 405 is used to arrange the rough inner wall on the isolation section based on the roughness of the rough flow section, the length and position to be arranged, and perform numerical simulation calculations to obtain the third boundary layer displacement thickness when the rough flow section is in a fully turbulent state.

[0044] The scheme determination module 406 is used to determine whether the third boundary layer displacement thickness is consistent with the first boundary layer displacement thickness. If so, the roughness of the rough flow section, the length and position to be arranged are used as the final scheme to be arranged on the wall of the isolation section of the large-scale engine.

[0045] In this embodiment, the specific working process and working principle of the initialization module 401, the boundary layer displacement thickness calculation module 402, the judgment module 403, the rough flow section parameter selection module 404, the simulation calculation module 405 and the scheme determination module 406 are the same as those in the method of embodiment 1, so they are not described in detail in this embodiment. Each unit module can be implemented in whole or in part by software, hardware and a combination thereof, and each unit module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute the operations corresponding to each of the above unit modules.

[0046] Example 3 like Figure 5The terminal device disclosed in this embodiment includes a transmitter, a receiver, a memory, and a processor. The transmitter is used to send instructions and data, the receiver is used to receive instructions and data, the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions stored in the memory to implement the method in the above-mentioned embodiment 1.

[0047] It should be noted that the above memory can be independent or integrated with the processor. When the memory is independently provided, the terminal device further includes a bus for connecting the memory and the processor.

[0048] Those of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be implemented 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 may include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of 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), etc.

[0049] The technical features of the above embodiments may be combined arbitrarily. 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.

[0050] The above-mentioned embodiments only express several implementation modes of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A method for designing a large-scale engine with a rough inner wall of an isolation section, characterized in that: The method comprises: Acquiring a position where a boundary layer transition occurs in the isolation section; taking the position where the boundary layer transition occurs in the isolation section as an initial fully turbulent state; Referring to the small-scale scaled model, under the fully turbulent state, the first boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under an ideal state is calculated; and based on the Reynolds analogy and the 1 / 7 power law of the boundary layer, the second boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under actual conditions is calculated; determining whether the first boundary layer displacement thickness is consistent with the second boundary layer displacement thickness, and if not, calculating a boundary layer thickness correction value according to the first boundary layer displacement thickness and the second boundary layer displacement thickness; According to the boundary layer thickness correction value, the roughness, required length and position of the rough flow section are selected; Based on the roughness of the rough flow section, the length and position to be arranged, a rough inner wall is arranged on the isolation section, and numerical simulation calculation is performed to obtain the displacement thickness of the third boundary layer when the rough flow section is in a fully turbulent state; It is determined whether the third boundary layer displacement thickness is consistent with the first boundary layer displacement thickness. If so, the roughness, required length and position of the rough flow section are used as the final solution.

2. The large-scale engine design method with a rough inner wall of the isolation section according to claim 1 is characterized in that: Obtain the location where the boundary layer transition occurs in the isolation segment, including: According to the basic information of the flow field, the RANS method is used to numerically solve the boundary conditions, and the boundary layer information under the incoming flow conditions of the isolation section is obtained; Based on boundary layer theory, combined with the boundary layer information and local physical quantity information of the flow field, the flow is disturbed by linear stability analysis of flow transition, and then the boundary layer transition position is determined according to the estimation method of boundary layer transition.

3. The large-scale engine design method with a rough inner wall of the isolation section according to claim 1 is characterized in that: Referring to the small-scale scaled model, under the fully turbulent state, the first boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under the ideal state is calculated, including: Based on the geometric design parameters of the small-scale engine and the large-scale engine, the proportional relationship of the effective flow area of ​​the thermal throat before and after proportional amplification is associated to obtain the displacement thickness of the first boundary layer at the thermal throat.

4. The large-scale engine design method with a rough inner wall of the isolation section according to claim 3 is characterized in that: Based on the geometric design parameters of the small-scale engine and the large-scale engine, the proportional relationship of the effective flow area of ​​the thermal throat before and after the proportional amplification is related, including: Based on the geometric design parameters of the large-scale engine, the effective area of ​​the thermal throat of the small-scale engine is scaled proportionally, and the proportional relationship between the effective flow area of ​​the thermal throat before and after the proportional enlargement is constructed. The expression is: ； In the formula, Represents the effective flow area at the throat of a large-scale engine; Represents the geometric cross-sectional area of ​​the combustion chamber throat of a large-scale engine; Represents the flow channel area occupied by the boundary layer displacement thickness of the large-scale engine; represents the combustion chamber inlet area of ​​a large-scale engine; It represents the effective flow area at the throat of a small-scale engine; Represents the geometric cross-sectional area of ​​the combustion chamber throat of a small-scale engine; Represents the flow channel area occupied by the boundary layer displacement thickness of the small-scale engine; represents the combustion chamber inlet area of ​​a small-scale engine; Indicates the zoom factor.

5. The large-scale engine design method with a rough inner wall of the isolation section according to claim 4 is characterized in that: The calculation expression of the first boundary layer displacement thickness is: ； In the formula, It represents the displacement thickness of the first boundary layer of a large-scale engine under ideal conditions; Indicates the height of the throat of a large-scale engine; Indicates the height of the throat of the small-scale engine; represents the span width of the small-scale engine; Indicates the width of the large-scale engine; Represents the actual boundary layer displacement thickness of a small-scale model engine.

6. The method for designing a large-scale engine with a rough inner wall of an isolation section according to any one of claims 1 to 5, characterized in that: The second boundary layer displacement thickness and the third boundary layer displacement thickness are calculated using the following expressions: ； In the formula, represents the boundary layer displacement thickness; , is the coefficient; represents the characteristic length; Reynolds number.

7. The method for designing a large-scale engine with a rough inner wall of an isolation section according to claim 6, characterized in that: According to the boundary layer thickness correction value, the roughness of the rough flow section, the length and position to be arranged are selected, including: The characteristics of the boundary layer are analyzed by the boundary layer thickness correction value; then the arrangement position of the rough flow section is determined according to the position where the first oblique shock wave is generated; and the roughness and length of the rough flow section are determined according to the engine operating Mach number.

8. A large-scale engine design device with a rough inner wall of the isolation section, characterized in that: The device comprises: An initialization module is used to obtain a position where a boundary layer transition occurs in the isolation section; and the position where the boundary layer transition occurs in the isolation section is used as an initial fully turbulent state; The boundary layer displacement thickness calculation module is used to calculate the first boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under the ideal state with reference to the small-scale scaled model under the fully turbulent state; and to calculate the second boundary layer displacement thickness at the throat of the cavity trailing edge of the large-scale engine under the actual situation based on the Reynolds analogy and the 1 / 7 power law of the boundary layer; a judgment module, configured to judge whether the first boundary layer displacement thickness is consistent with the second boundary layer displacement thickness, and if not, to calculate a boundary layer thickness correction value according to the first boundary layer displacement thickness and the second boundary layer displacement thickness; A rough flow section parameter selection module is used to select the roughness, length and position of the rough flow section according to the boundary layer thickness correction value; A simulation calculation module is used to arrange a rough inner wall on the isolation section based on the roughness of the rough flow section, the length and position to be arranged, and perform numerical simulation calculation to obtain the displacement thickness of the third boundary layer under the rough flow section in a fully turbulent state; The scheme determination module is used to determine whether the third boundary layer displacement thickness is consistent with the first boundary layer displacement thickness. If so, the roughness of the rough flow section, the length and position to be arranged are used as the final scheme.

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 large-scale engine design method with a rough inner wall of the isolation section as described in any one of claims 1 to 7 are implemented.

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