Method and apparatus for evaluating high-speed inlet starting capability using a protective cover separation

Abstract

This invention relates to a method and apparatus for evaluating the start-up capability of a high-speed air intake using a protective shield separation. The method includes: constructing a background mesh for the overall computational domain of an air-breathing aircraft; constructing overlapping mesh blocks for the protective shield; defining the four boundaries of the overlapping mesh blocks as overlapping boundaries; assembling the overlapping mesh blocks with the background mesh; initializing the flow field of the overall computational domain according to the parameters of the target operating condition, simulating a supersonic flow field; simulating the rotational opening motion of the protective shield and solving for an unsteady flow field to obtain an initial flow field; after the protective shield rotates to a predetermined opening angle, allowing it to continue moving away from the air-breathing aircraft until the protective shield reaches a far-field position; deleting the overlapping mesh blocks from the overall computational domain, and continuously monitoring the evolution of the air intake flow state in the overall computational domain using an unsteady numerical method based on the obtained initial flow field, thereby evaluating the start-up capability of the high-speed air intake.

Description

Technical Field

[0001] This invention relates to the field of numerical simulation technology of air intake aerodynamics, and in particular to a method and apparatus for evaluating the start-up capability of a high-speed air intake using a protective cover separation. Background Technology

[0002] The air intake is a core component of air-breathing aircraft, and improving its start-up performance is crucial in its design. Currently, research on the start-up problem of the air intake has been extensive, resulting in a series of important achievements, represented by the dual-solution theory.

[0003] For air-breathing aircraft, a protective shield is often installed at the engine air intake to reduce the aerodynamic heating effect of the airflow on the engine wall during boost, thus preventing engine damage. Therefore, the typical flight sequence is: protective shield separation → air intake start-up → engine ignition. It is evident that air intake start-up actually occurs after the protective shield separation.

[0004] In existing studies, due to the complex simulation of unsteady moving parts, the protective shield component is often neglected in the evaluation of the intake's startup performance. Researchers typically use a quasi-steady method to simulate its startup process: starting from an initial "non-starting" flow field with a separation zone, the incoming flow velocity is gradually increased in small increments, and the startup of the intake is observed; the Mach number of the incoming flow at the point of successful startup is considered the startup point. This process is essentially the gradual disappearance of the flow separation zone.

[0005] Existing research indicates that air intakes may exhibit multiple non-starting modes, some of which possess strong "self-sustaining" separation regions that are difficult to eliminate, leading to difficulties in inlet start-up. Therefore, the start-up capability of an air intake is closely related to the specific morphology of its internal flow separation. However, traditional quasi-steady methods typically only simulate a fixed separation pattern, making it difficult to comprehensively and realistically assess the inlet's start-up capability. Furthermore, quasi-steady numerical simulations, due to their simplified physical processes, cannot capture the hysteresis effect and unsteady evolution process between start-up and non-start-up flow states. This necessitates continued reliance on expensive wind tunnel ground tests in practical engineering. In these tests, various stable or unstable flow fields, including start-up flow states, large / small separation flow states, and bilateral separation flow states, are actively induced by controlling the incoming Mach number, angle of attack, back pressure, and flow field establishment process (such as rapid "pulse start-up" or slow establishment).

[0006] In recent years, with the continuous improvement of computer hardware performance and the increasing maturity of overlapping mesh technology, the capability of unsteady numerical simulation involving complex moving parts has been significantly enhanced. Numerical simulation has unparalleled advantages over wind tunnel and flight tests in terms of cost control and capturing detailed global flow fields. Therefore, using dynamic separation unsteady simulation methods to comprehensively evaluate inlet performance has significant engineering application value. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide a method and apparatus for evaluating the starting capability of a high-speed air intake using a protective cover separation.

[0008] To achieve the above-mentioned objectives, this invention provides a method for evaluating the starting capability of a high-speed intake duct using a protective cover separation, comprising the following steps:

[0009] S1. Construct a background mesh for the overall computational domain of an air-breathing aircraft; wherein the air-breathing aircraft has a high-speed air intake and a protective shield for the high-speed air intake;

[0010] S2. Construct overlapping mesh blocks for the protective cover; wherein, the overlapping mesh blocks are local mesh blocks that completely cover the protective cover, and the four sides of the overlapping mesh blocks are defined as overlapping boundaries for data exchange with the background mesh;

[0011] S3. Assemble the overlapping mesh blocks with the background mesh;

[0012] S4. Initialize the flow field of the overall computational domain according to the parameters of the target working condition, and start the flow field solver to simulate the supersonic flow field of the air-breathing aircraft with a protective shield.

[0013] S5. Simulate the rotating opening motion of the protective shield relative to the high-speed air intake and solve the unsteady flow field to obtain the initial flow field containing various flow characteristics that induce the high-speed air intake to fail to start.

[0014] S6. After the protective cover is rotated to the predetermined opening angle, it continues to move away from the air-breathing aircraft until the protective cover moves to a far-field position that does not interfere with the inlet flow field of the high-speed air intake.

[0015] S7. Remove the overlapping grid blocks from the overall computational domain, and continuously monitor the evolution of the high-speed inlet flow regime in the overall computational domain using an unsteady numerical method based on the obtained initial flow field, and comprehensively evaluate the impact of the shield separation process on the high-speed inlet start-up capability under typical aerodynamic conditions.

[0016] According to one aspect of the present invention, in step S1, in the step of constructing a background mesh for the overall computational domain of the air-breathing aircraft, the outer boundary shape of the overall computational domain is a cone-like shape or a cube.

[0017] The dimensions of the overall computational domain meet the requirements for generating supersonic flow fields during the simulation of an air-breathing aircraft. Specifically, the front end of the overall computational domain is 3C from the head of the air-breathing aircraft, the upper, lower, left, and right ends of the overall computational domain are each 5C from the body of the air-breathing aircraft, and the rear end of the overall computational domain is 10C from the rear end of the air-breathing aircraft. Here, C is the characteristic length of the aircraft.

[0018] According to one aspect of the present invention, in step S3, the step of assembling the overlapping grid block with the background grid involves pre-rotating the protective cover relative to the high-speed air intake by a first preset angle to form an initial gap between the protective cover and the high-speed air intake for assembling the overlapping grid block with the background grid, and also for searching the overlapping boundary interpolation unit of the overlapping grid block and drilling holes in the background grid to complete the assembly between the overlapping grid block and the background grid.

[0019] According to one aspect of the present invention, the first preset angle is 1° to 3°.

[0020] According to one aspect of the present invention, in step S4, the flow field initialization of the overall computational domain based on the parameters of the target operating condition includes the incoming Mach number, flight altitude, and initial angle of attack.

[0021] According to one aspect of the present invention, in step S5, in the step of simulating the rotating opening motion of the protective shield relative to the high-speed air intake, the rotating opening motion is achieved by a forced motion mode or a fluid-structure interaction triggering mode; wherein, if the rotating opening motion is achieved by a forced motion mode, a preset angular velocity-time function is directly specified for the protective shield, and the output of the angular velocity-time function is used as the control parameter for the rotating opening motion.

[0022] If the rotating shield opening motion adopts the fluid-structure interaction triggering mode, the rotating shield opening motion is naturally triggered and driven by the asymmetric aerodynamic torque generated by the shock wave reflection in the air passage gap between the protective shield and the high-speed air intake through the coupling of the six-degree-of-freedom motion equations.

[0023] According to one aspect of the present invention, in step S5, the step of simulating the rotating opening motion of the protective shield relative to the high-speed intake and performing unsteady flow field solution to obtain an initial flow field containing various flow characteristics that induce the high-speed intake to fail to start, the unsteady flow field solution process adopts a time step that satisfies the CFL stability condition, and the shock wave / boundary layer separation induced by the interference between the shock wave at the leading edge of the protective shield and the compression bulge region of the intake is collected during the rotating opening motion as the flow characteristics that induce the high-speed intake to fail to start.

[0024] According to one aspect of the invention, in step S6, when the protective cover is rotated to a predetermined opening angle and then continues to move away from the air-breathing aircraft, the protective cover moves away from the air-breathing aircraft by means of free movement or forced downward movement.

[0025] According to one aspect of the present invention, in step S4, the flow field initialization of the overall computational domain based on the parameters of the target operating condition, and the activation of the flow field solver to simulate the supersonic flow field of the air-breathing aircraft with a protective shield, is performed by a flow field solver that supports six-degree-of-freedom coupled motion, or by a flow field solver that supports forced rotation and translational motion.

[0026] To achieve the above-mentioned objective, the present invention provides an apparatus for evaluating the starting capability of a high-speed intake duct using a protective cover separation method, comprising:

[0027] The background mesh construction module is used to construct a background mesh for the overall computational domain of an air-breathing aircraft, which has a high-speed air intake and a protective shield for the high-speed air intake.

[0028] An overlapping mesh block construction module is used to construct overlapping mesh blocks for a protective cover; wherein, the overlapping mesh block is a local mesh block that completely covers the protective cover, and the four sides of the overlapping mesh block are defined as overlapping boundaries for data exchange with the background mesh;

[0029] An assembly module is used to assemble the overlapping mesh blocks with the background mesh;

[0030] The simulation module is used to initialize the flow field of the overall computational domain according to the parameters of the target working condition, and start the flow field solver to simulate the supersonic flow field of an air-breathing aircraft with a protective shield.

[0031] The rotational opening motion of the protective shield relative to the high-speed air intake is simulated and the unsteady flow field is solved to obtain the initial flow field containing various flow characteristics that induce the high-speed air intake to fail to start.

[0032] After the protective cover is rotated to the predetermined opening angle, it continues to move away from the air-breathing aircraft until the protective cover moves to a far-field position that does not interfere with the inlet flow field of the high-speed air intake.

[0033] The overlapping grid blocks are removed from the overall computational domain, and the evolution of the high-speed inlet flow regime is continuously monitored in the overall computational domain using an unsteady numerical method based on the obtained initial flow field. The impact of the shield separation process on the high-speed inlet start-up capability under typical aerodynamic conditions is comprehensively evaluated.

[0034] According to one aspect of the present invention, this approach can achieve accurate simulation of different flow separation states and effective capture of hysteresis boundaries through a dynamic simulation method that is more consistent with actual physical processes, thereby providing a more comprehensive and reliable assessment of the intake duct's start-up performance.

[0035] According to one aspect of the present invention, this method can obtain multiple types of non-startup flow states that cannot be reproduced in traditional quasi-steady simulations. Based on this, unsteady numerical methods can be continuously used to monitor the evolution of the inlet flow state, ultimately achieving a comprehensive evaluation of the inlet performance under typical aerodynamic conditions.

[0036] According to one aspect of the present invention, this approach utilizes overlapping mesh technology to perform unsteady dynamic simulation of the separation process of a rotating protective shield, constructing initial flow conditions in the inlet that more closely resemble real physics. Compared to traditional methods, this approach leverages the transient shock wave interference generated between the shield and the inlet wall during the shield opening process to excite a series of unsteady, non-starting flow fields that evolve over time. This overcomes the limitations of traditional quasi-steady methods, such as the single separation flow pattern and the difficulty in capturing hysteresis boundaries, providing a more comprehensive and realistic initial flow field for subsequent unsteady evaluation of the inlet's start-up performance.

[0037] According to one aspect of the present invention, this approach can provide the intake duct with different initial separation fields by simulating various flow separation modes induced by shock wave interference during the separation process of the protective cover, thereby achieving a more comprehensive and systematic evaluation of the intake duct's start-up performance.

[0038] According to one aspect of the present invention, this approach is based on the characteristic that disturbances in a supersonic flow field cannot propagate upstream. Combined with overlapping mesh technology, the corresponding mesh region can be directly deleted after the protective shield has moved a sufficiently long distance, thus taking into account computational efficiency.

[0039] According to one aspect of the present invention, compared with the traditional quasi-steady method, this approach uses unsteady simulation to more realistically reproduce the dynamic process of the generation, evolution and disappearance of the separation zone, thereby more accurately capturing the hysteresis effect in the flow state transition of the intake duct.

[0040] According to one aspect of the present invention, compared with the method of simply evaluating the start-up capability by increasing the Mach number of the incoming flow, this approach stimulates various non-start-up flow states by simulating the shield separation process, which is closer to the real flight scenario in terms of physical process. Attached Figure Description

[0041] Figure 1 This is a flowchart illustrating the steps of the high-speed intake duct start-up capability evaluation method using a protective cover separation according to the present invention.

[0042] Figure 2 This is a diagram showing the overall computational domain layout of the present invention;

[0043] Figure 3 This is a schematic diagram of the overlapping mesh blocks of the present invention being loaded into the background mesh before assembly;

[0044] Figure 4 This is a schematic diagram of the overlapping grid blocks and the background grid assembled according to the present invention;

[0045] Figure 5 This is a supersonic flow field diagram obtained during the flow field initialization process of the present invention.

[0046] Figure 6 This is a diagram showing the protective cover of the present invention rotated open;

[0047] Figure 7 This is a schematic diagram of a typical large-scale separation configuration of a typical non-start-up flow field according to the present invention.

[0048] Figure 8 This is a schematic diagram of a typical small-scale separation configuration of a typical non-start-up flow field according to the present invention.

[0049] Figure 9 This is a schematic diagram of a typical two-sided separation pattern of a typical non-start-up flow field according to the present invention;

[0050] Figure 10 This is a far-field position diagram showing the movement of the protective cover of the present invention to a position where it does not interfere with the inlet flow field of the high-speed air intake. Detailed Implementation

[0051] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0052] like Figure 1 As shown, according to one embodiment of the present invention, a method for evaluating the starting capability of a high-speed intake duct using a protective cover separation includes the following steps:

[0053] S1. Construct a background mesh for the overall computational domain of an air-breathing aircraft; wherein the air-breathing aircraft has a high-speed air intake and a protective shield for the high-speed air intake;

[0054] S2. Construct overlapping mesh blocks for the protective cover; wherein, the overlapping mesh block is a local mesh block that completely covers the protective cover, and the four boundaries of the overlapping mesh block are defined as overlapping boundaries for data exchange with the background mesh;

[0055] S3. Assemble the overlapping mesh blocks with the background mesh;

[0056] S4. Initialize the flow field of the overall computational domain according to the parameters of the target working condition, and start the flow field solver to simulate the supersonic flow field of the air-breathing aircraft with a protective shield.

[0057] S5. Simulate the rotating opening motion of the protective shield relative to the high-speed air intake and solve the unsteady flow field to obtain the initial flow field containing various flow characteristics that induce the high-speed air intake to fail to start.

[0058] S6. After the protective shield is rotated to the predetermined opening angle, it continues to move away from the air-breathing aircraft until the protective shield moves to a far-field position that does not interfere with the inlet flow field of the high-speed air intake.

[0059] S7. Remove overlapping grid blocks from the global computational domain, and continuously monitor the evolution of the high-speed inlet flow regime in the global computational domain using an unsteady numerical method based on the obtained initial flow field, to comprehensively evaluate the impact of the shield separation process on the high-speed inlet start-up capability under typical aerodynamic conditions.

[0060] like Figure 2 As shown, according to one embodiment of the present invention, in step S1, the outer boundary shape of the overall computational domain for constructing a background mesh for the air-breathing aircraft is a cone-like or cube-like shape. In this embodiment, the background mesh is used to divide the overall computational domain as the simulation subject, wherein the background mesh completely covers the overall computational domain. In this embodiment, the size of the overall computational domain meets the requirements for generating supersonic flow fields during the simulation of the air-breathing aircraft. Specifically, the front end of the overall computational domain is 3C from the head of the air-breathing aircraft, the upper, lower, left, and right ends of the overall computational domain are each 5C from the body of the air-breathing aircraft, and the rear end of the overall computational domain is 10C from the rear end of the air-breathing aircraft, where C is the characteristic length of the aircraft.

[0061] According to one embodiment of the present invention, in step S2, in the step of constructing overlapping mesh blocks for the protective cover, by defining the four sides of the overlapping mesh blocks as overlapping boundaries, the overlapping mesh blocks and the background mesh can be fully allowed to overlap and intersect, thereby enabling data exchange between the overlapping mesh blocks and the background mesh during the flow field simulation process.

[0062] According to one embodiment of the present invention, in step S3, the step of assembling the overlapping mesh block with the background mesh involves pre-rotating the protective cover relative to the high-speed air intake by a first preset angle. This creates an initial gap between the protective cover and the high-speed air intake for assembling the overlapping mesh block and the background mesh. This also serves as an interpolation unit for searching the overlap boundary of the overlapping mesh block and for creating holes in the background mesh to complete the assembly between the overlapping mesh block and the background mesh. In this embodiment, the first preset angle is 1° to 3°. By setting it within this angle range, a certain gap is effectively ensured between the protective cover and the high-speed air intake to facilitate mesh overlap, and calculation errors caused by excessively large gaps due to excessively large angles are effectively avoided.

[0063] In this embodiment, in the steps of searching interpolation units for the overlapping boundaries of the overlapping mesh blocks and punching holes in the background mesh to complete the assembly between the overlapping mesh blocks and the background mesh, in order to successfully achieve the assembly between the overlapping mesh blocks and the background mesh, the following steps can be further implemented, including:

[0064] The protective shield, along with its external overlapping mesh blocks, is pre-rotated by a small angle (i.e., a first preset angle, 1°~3°) around its designed rotation axis (such as the hinge axis hinged to the high-speed air intake). This creates an initial physical gap between the surface of the protective shield and the inlet lip of the high-speed air intake in terms of the mesh geometry.

[0065] To execute the standard overlapping mesh assembly process, based on the geometry with the initial gap formed by preset rotation, call the overlapping mesh processor (e.g., the solver's built-in or third-party tools such as the DCF module in Overflow) to execute the standard assembly process: a) See Figure 3 After the overlapping mesh blocks are added to the background mesh, there is an overlap between the overlapping mesh blocks and the background mesh. Therefore, interpolation elements are searched for, and suitable interpolation contributing elements (i.e., "donor" elements) are found in the background mesh for each node on the "overlapping boundary" of the overlapping mesh blocks. b) Background mesh "hole-cutting" is performed, identifying background mesh elements completely covered by the overlapping mesh blocks that do not need to participate in the flow field solution and marking them as "hole" elements for exclusion in subsequent calculations. This completes the search for interpolation elements at the interface and the "hole-cutting" operation on the background mesh, thus completing the assembly of the overlapping mesh blocks. See [link to documentation]. Figure 4 .

[0066] Once the above process is completed, a complete interpolation communication relationship is established between the overlapping mesh blocks and the background mesh, thus completing the assembly.

[0067] According to one embodiment of the present invention, in step S4, the flow field initialization of the overall computational domain based on the parameters of the target operating condition includes the incoming Mach number, flight altitude, and initial angle of attack. See also... Figure 5 As shown, during the flow field initialization process, due to the small gap between the protective cover and the air intake, the airflow cannot effectively enter the air intake, so the internal flow of the high-speed air intake is basically in a low-speed subsonic state.

[0068] like Figure 6As shown, according to one embodiment of the present invention, in step S5, the step of simulating the rotating opening motion of the protective shield relative to the high-speed air intake is implemented using either a forced motion mode or a fluid-structure interaction (FSI) triggering mode. When the rotating opening motion uses the forced motion mode, a preset angular velocity-time function (such as constant rotation or accelerated rotation) is directly specified for the protective shield, thus the output of the angular velocity-time function can be used as the control parameter for the rotating opening motion. When the rotating opening motion uses the FSI triggering mode, the rotating opening motion of the protective shield is naturally triggered and driven by the asymmetric aerodynamic torque generated by the shock wave reflection within the air gap between the protective shield and the high-speed air intake through coupling six-degree-of-freedom motion equations. In this embodiment, the FSI triggering mode requires a solver. For the natural triggering process achieved by utilizing the asymmetric aerodynamic torque generated by the shock wave reflection within the air gap between the protective shield and the high-speed air intake, it is based on the good aerodynamic shape design of the protective shield itself. For example, based on the aerodynamic shape design of the protective shield itself, there can be a sloping surface at the incoming flow end to generate downforce and opening torque in the airflow, thereby enabling the calculation of the natural triggering process.

[0069] Furthermore, in step S5, the step of simulating the rotating opening motion of the protective shield relative to the high-speed inlet and solving for the unsteady flow field to obtain the initial flow field containing various flow characteristics that induce the high-speed inlet to fail to start, uses a time step that satisfies the CFL stability condition in the unsteady flow field solution process. During the rotating opening motion, the shock wave / boundary layer separation induced by the interference between the shock wave at the leading edge of the protective shield and the compression bulge region of the inlet is collected as the flow characteristics that induce the high-speed inlet to fail to start. Therefore, during the simulation of the rotating opening motion, these supersonic flow fields with flow characteristics can be used as the corresponding initial flow fields.

[0070] In this embodiment, the time step is set as follows: to accurately capture transient flow, the unsteady solution uses a time step that satisfies the CFL stability condition. This time step can be estimated based on the minimum mesh size and the local flow field sound velocity, and the maximum CFL number is typically controlled below 1.0 to fully ensure the stability and accuracy of the calculation, providing reliable support for improving the accuracy of the evaluation results of this scheme.

[0071] In this embodiment, during the rotating opening motion, the shock wave / boundary layer separation induced by the interference between the shock wave at the leading edge of the protective shield and the compression bulge region of the inlet is collected as the flow characteristic inducing the non-starting of the high-speed inlet. The flow characteristic collection method is as follows: a snapshot of the flow field is taken on the symmetry plane of the high-speed inlet, and the typical non-starting flow field is determined according to the flow state. There are three typical non-starting flow fields, namely: typical large separation morphology of the body (see...). Figure 7 Typical small separation morphology of organism (see) Figure 8) and typical bilateral separation pattern (see Figure 9 ).exist Figure 7 In a typical large-scale separation configuration, a large separation zone 1a can be formed on the body side, and a small-scale separation flow zone 1b induced by the separation shock wave from the large separation zone on the body side can be formed; Figure 8 In the typical small separation morphology of the organism, a small separation zone 1c can be formed on the side of the organism; Figure 9 In the typical bilateral separation morphology, a bilateral separation region 1d can be formed.

[0072] like Figure 10 As shown, according to one embodiment of the present invention, in step S6, after the protective cover is rotated to a predetermined opening angle, it continues to move away from the air-breathing aircraft in a direction away from the air-breathing aircraft. The protective cover moves away from the air-breathing aircraft by means of free movement or forced downward movement.

[0073] According to one embodiment of the present invention, in step S7, overlapping grid blocks are removed from the overall computational domain, and the evolution of the inlet flow regime of the high-speed inlet is continuously monitored in the overall computational domain using an unsteady numerical method based on the obtained initial flow field. This step comprehensively evaluates the impact of the shield separation process on the high-speed inlet's start-up capability under typical aerodynamic conditions. Based on the initial flow field acquired in step S5, continuous simulation can be performed without setting up a shield or its rotational motion. Specifically, the flow characteristics contained in the initial flow field can fully simulate the strong shock wave reflection and interference generated between the shield and the lower surface of the high-speed inlet during the shield separation process, thereby inducing a series of initial conditions for flow evolution unfavorable to the start-up of the high-speed inlet. Furthermore, it can effectively and fully acquire multiple types of non-start-up flow regimes that cannot be reproduced in traditional quasi-steady simulations. Based on this, unsteady numerical methods can be continuously used to monitor the inlet flow regime evolution, ultimately achieving a comprehensive evaluation of the inlet performance under typical aerodynamic conditions. This allows for a more comprehensive and accurate analysis of the performance changes in the high-speed inlet's start-up capability caused by the shield separation process.

[0074] According to one embodiment of the present invention, in step S4, the flow field initialization of the overall computational domain is performed according to the parameters of the target working condition, and the flow field solver is started to simulate the supersonic flow field of the air-breathing aircraft with a protective shield. The flow field solver used is a solver that supports six-degree-of-freedom coupled motion, or a solver that supports forced rotation and translational motion.

[0075] According to one embodiment of the present invention, the present invention provides an apparatus for evaluating the start-up capability of a high-speed intake duct using a protective cover separation method, comprising:

[0076] The background mesh construction module is used to construct a background mesh for the overall computational domain of an air-breathing aircraft, which has a high-speed air intake and a protective shield for the high-speed air intake.

[0077] The overlapping mesh block construction module is used to construct overlapping mesh blocks for the protective cover; wherein, the overlapping mesh block is a local mesh block that completely covers the protective cover, and the four boundaries of the overlapping mesh block are defined as the overlapping boundary for data exchange with the background mesh;

[0078] The assembly module is used to assemble overlapping mesh blocks with the background mesh;

[0079] The simulation module is used to initialize the flow field of the overall computational domain according to the parameters of the target working condition, and start the flow field solver to simulate the supersonic flow field of an air-breathing aircraft with a protective shield.

[0080] The rotational opening motion of the protective shield relative to the high-speed air intake is simulated and the unsteady flow field is solved to obtain the initial flow field containing various flow characteristics that induce the high-speed air intake to fail to start.

[0081] Once the protective shield has rotated to the predetermined opening angle, it continues to move away from the air-breathing aircraft until it reaches a far-field position where it does not interfere with the inlet flow field of the high-speed air intake.

[0082] Overlapping grid blocks are removed from the global computational domain, and the evolution of the high-speed inlet flow regime is continuously monitored in the global computational domain using an unsteady numerical method based on the obtained initial flow field. The impact of the shield separation process on the high-speed inlet start-up capability under typical aerodynamic conditions is comprehensively evaluated.

[0083] Specific limitations regarding the high-speed intake duct start-up capability assessment device utilizing protective cover separation can be found in the limitations of the high-speed intake duct start-up capability assessment method utilizing protective cover separation described above, and will not be repeated here. Each module in the aforementioned high-speed intake duct start-up capability assessment device utilizing protective cover separation can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the corresponding operations of each module.

[0084] In this embodiment, the memory may be, but is not limited to, Random Access Memory (RAM), Read Only Memory (ROM), Programmable Read-Only Memory (PROM), Erasable Programmable Read-Only Memory (EPROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), etc.

[0085] In this embodiment, the processor can be an integrated circuit chip with signal processing capabilities. The processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0086] The above description is merely an example of a specific solution of the present invention. For any devices and structures not described in detail herein, it should be understood that they are implemented using common devices and methods already available in the art.

[0087] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for evaluating the starting capability of a high-speed inlet with a protective cover separation, characterized in that, Includes the following steps: S1. Construct a background mesh for the overall computational domain of an air-breathing aircraft; wherein the air-breathing aircraft has a high-speed air intake and a protective shield for the high-speed air intake; S2. Construct overlapping mesh blocks for the protective cover; wherein, the overlapping mesh blocks are local mesh blocks that completely cover the protective cover, and the four sides of the overlapping mesh blocks are defined as overlapping boundaries for data exchange with the background mesh; S3. Assemble the overlapping mesh blocks with the background mesh; S4. Initialize the flow field of the overall computational domain according to the parameters of the target working condition, and start the flow field solver to simulate the supersonic flow field of the air-breathing aircraft with a protective shield. S5. Simulate the rotating opening motion of the protective shield relative to the high-speed air intake and solve the unsteady flow field to obtain the initial flow field containing various flow characteristics that induce the high-speed air intake to fail to start. S6. After the protective cover is rotated to the predetermined opening angle, it continues to move away from the air-breathing aircraft until the protective cover moves to a far-field position that does not interfere with the inlet flow field of the high-speed air intake. S7. Remove the overlapping grid blocks from the overall computational domain, and continuously monitor the evolution of the high-speed inlet flow regime in the overall computational domain using an unsteady numerical method based on the obtained initial flow field, and comprehensively evaluate the impact of the shield separation process on the high-speed inlet start-up capability under typical aerodynamic conditions.

2. The method of evaluating the start capability of a high-speed inlet with a protection shield separation according to claim 1, characterized in that, In step S1, the outer boundary shape of the overall computational domain of the air-breathing aircraft is a cone-like shape or a cube. The dimensions of the overall computational domain meet the requirements for generating supersonic flow fields during the simulation of an air-breathing aircraft. Specifically, the front end of the overall computational domain is 3C away from the head of the air-breathing aircraft, the upper, lower, left, and right ends of the overall computational domain are each 5C away from the body of the air-breathing aircraft, and the rear end of the overall computational domain is 10C away from the rear end of the air-breathing aircraft. Here, C is the characteristic length of the aircraft.

3. The method of evaluating the start capability of a high-speed inlet with a protection shield separation according to claim 2, characterized in that, In step S3, the step of assembling the overlapping grid block with the background grid involves rotating the protective cover relative to the high-speed air intake by a first preset angle to create an initial gap between the protective cover and the high-speed air intake for assembling the overlapping grid block with the background grid. This also serves as a search interpolation unit for the overlapping boundary of the overlapping grid block and a hole is cut into the background grid to complete the assembly between the overlapping grid block and the background grid.

4. The method for evaluating the starting capability of a high-speed intake duct using a protective cover separation according to claim 3, characterized in that, The first preset angle is 1°~3°.

5. The method for evaluating the starting capability of a high-speed intake duct using a protective cover separation according to claim 3 or 4, characterized in that, In step S4, the flow field initialization of the overall computational domain based on the parameters of the target operating condition includes the incoming Mach number, flight altitude, and initial angle of attack.

6. The method for evaluating the starting capability of a high-speed intake duct using a protective cover separation according to claim 5, characterized in that, In step S5, the step of simulating the rotating opening motion of the protective shield relative to the high-speed air intake is implemented by a forced motion mode or a fluid-structure interaction trigger mode. If the rotating opening motion is implemented by a forced motion mode, a preset angular velocity-time function is directly specified for the protective shield, and the output of the angular velocity-time function is used as the control parameter for the rotating opening. If the rotating shield opening motion adopts the fluid-structure interaction triggering mode, the rotating shield opening motion is naturally triggered and driven by the asymmetric aerodynamic torque generated by the shock wave reflection in the air passage gap between the protective shield and the high-speed air intake through the coupling of the six-degree-of-freedom motion equations.

7. The method for evaluating the starting capability of a high-speed intake duct using a protective cover separation according to claim 6, characterized in that, In step S5, the unsteady flow field is obtained by simulating the rotating opening motion of the protective shield relative to the high-speed intake and solving the unsteady flow field. In this step, the unsteady flow field solution process adopts a time step that satisfies the CFL stability condition. The shock wave / boundary layer separation induced by the interference between the shock wave at the leading edge of the protective shield and the compression bulge region of the intake is collected during the rotating opening motion as the flow characteristics that induce the high-speed intake to not start.

8. The method for evaluating the starting capability of a high-speed intake duct using a protective cover separation according to claim 7, characterized in that, In step S6, after the protective cover rotates to a predetermined opening angle, it continues to move away from the air-breathing aircraft. In this step, the protective cover moves away from the air-breathing aircraft either freely or under forced downward movement.

9. The method for evaluating the starting capability of a high-speed intake duct using a protective cover separation as described in claim 8, characterized in that, In step S4, the flow field is initialized in the overall computational domain according to the parameters of the target working condition, and the flow field solver is started to simulate the supersonic flow field of the air-breathing aircraft with a protective shield. The flow field solver used is a solver that supports six-degree-of-freedom coupled motion, or a solver that supports forced rotation and translation motion.

10. An apparatus for evaluating the starting capability of a high-speed intake duct using a protective cover separation method as described in any one of claims 1 to 9, characterized in that, include: The background mesh construction module is used to construct a background mesh for the overall computational domain of an air-breathing aircraft, which has a high-speed air intake and a protective shield for the high-speed air intake. An overlapping mesh block construction module is used to construct overlapping mesh blocks for a protective cover; wherein, the overlapping mesh block is a local mesh block that completely covers the protective cover, and the four sides of the overlapping mesh block are defined as overlapping boundaries for data exchange with the background mesh; An assembly module is used to assemble the overlapping mesh blocks with the background mesh; The simulation module is used to initialize the flow field of the overall computational domain according to the parameters of the target working condition, and start the flow field solver to simulate the supersonic flow field of an air-breathing aircraft with a protective shield. The rotational opening motion of the protective shield relative to the high-speed air intake is simulated and the unsteady flow field is solved to obtain the initial flow field containing various flow characteristics that induce the high-speed air intake to fail to start. After the protective cover is rotated to the predetermined opening angle, it continues to move away from the air-breathing aircraft until the protective cover moves to a far-field position that does not interfere with the inlet flow field of the high-speed air intake. The overlapping grid blocks are removed from the overall computational domain, and the evolution of the high-speed inlet flow regime is continuously monitored in the overall computational domain using an unsteady numerical method based on the obtained initial flow field. The impact of the shield separation process on the high-speed inlet start-up capability under typical aerodynamic conditions is comprehensively evaluated.

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