Ground-based test models and methods for studying the impact of localized perforation on static stability.

Abstract

This invention discloses a ground test model and method for studying the impact of localized perforation on static stability, relating to the field of aerodynamic ground force measurement testing technology. The model includes: a transition structure whose inner side fits tightly with a balance; a support component that fits with the outer side of the transition structure; a model base mounted on the keel-like support component, the model base having multiple mounting positions; a standardized module group that, after matching with each mounting position, constructs a complete test model surface; and a perforation model group, after matching with each mounting position, used to simulate various perforation patterns on the nose, sides, abdomen, and back of an aircraft; and self-aligning modules are respectively provided on both sides of the transition structure via mounting mechanisms. This invention specifically designs a perforation model group for aerodynamic characteristic measurement, enabling dozens of perforation modules to be matched on a single transition assembly, greatly reducing the processing cost and ground test preparation time in model perforation testing.

Description

Technical Field

[0001] This invention relates to the field of ground-based force measurement testing technology for aircraft. More specifically, this invention relates to a ground-based test model and method for studying the effect of localized perforation on static stability. Background Technology

[0002] During flight, aircraft may face various unforeseen circumstances, such as encounters with birds, which could cause localized perforations in their structure. These perforations may or may not penetrate the aircraft. Such perforations significantly alter the surrounding flow field structure (such as incoming flow height and Reynolds number) and the aircraft's aerodynamic / thermal characteristics, thereby affecting the aircraft's stability and controllability.

[0003] Currently, research on the aerodynamic characteristics affected by perforation has the following main shortcomings: 1. Crude perforation simulation method: Traditional methods usually involve direct machining or blasting on the overall model to simulate perforation. This method is costly, and a model can only simulate one perforation state, making it impossible to conduct multi-state comparative studies. 2. Limited perforation patterns: Lack of systematic simulation of various patterns such as scattered micro-perforation, continuous surface perforation, and localized perforation; 3. Lack of static stability assessment: Most studies focus on the impact of perforation on aircraft drag or lift, while there is a lack of targeted and systematic research on static stability, a key flight quality. 4. Model is not reusable: There is a lack of a standardized model scheme that allows for quick replacement of perforation types, making it impossible to conduct parametric and control group experiments, resulting in low experimental efficiency.

[0004] 5. Insufficient control of interference variables: Existing methods ignore the changes in mass distribution caused by different damage modules, resulting in a shift in the center of gravity. This causes the aerodynamic data to be mixed with mass interference and pure aerodynamic effects, reducing the reliability of the conclusions.

[0005] Therefore, there is an urgent need in this field for a dedicated ground test model that can efficiently, economically, and accurately simulate various penetrating and non-penetrating perforation modes, quantitatively study their impact on static stability, and precisely control the key variable of the center of gravity. Summary of the Invention

[0006] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.

[0007] To achieve these objectives and other advantages of the present invention, a ground-based test model for studying the effect of localized perforation on static stability is provided, comprising: The adapter structure fits tightly with the balance on its inner side. Support components that mate with the outer side of the transition structure; A model base is mounted on a support member, and the model base has multiple mounting positions; After matching each mounting position, a standardized modular group is constructed to obtain the complete test model surface; Once matched with each mounting position, a perforation model set is used to simulate various perforation patterns on the nose, sides, abdomen, and back of an aircraft. The adapter structure has self-aligning modules installed on both sides via an installation mechanism. The experimental model integrates a six-component balance force measurement system to measure changes in aerodynamic forces and torques during ground tests.

[0008] Preferably, each mounting position includes: a mounting interface and a mounting cavity reserved on the base; The model base has a thickness of 5mm and is made of aluminum alloy or stainless steel.

[0009] Preferably, the perforation model group includes: A scattered perforated module with multiple regularly or irregularly distributed arrays of small holes on its surface; The surface features a recessed module with smooth indentations; A damaged module with areas of missing material on its surface; A composite module with at least two of the following on its surface: scattered perforations, smooth depressions, and areas of missing material; The head perforation module is used to replace the head cone part of the model.

[0010] Preferably, the perforated model group and the benchmark module group are connected to the base via positioning pins and quick-lock screws.

[0011] Preferably, the center-adjusting module includes: Slide rails are installed between the mounting mechanisms; A slider mounted on a slide rail; The lead screw is threadedly connected to the slider; The motor connected to the lead screw.

[0012] A modular ground testing method, comprising: S1. Install the benchmark module group on the model base, and use the centering module to adjust the model's center of gravity to the designed benchmark center of gravity position; S2. Conduct ground benchmark tests to collect aerodynamic and torque data under non-perforated conditions; S3. Replace different perforated modules at different positions on the model base, and after each replacement, adjust the model's center of gravity back to the reference center of gravity position by changing the position of the slider on the centering module. S4. Conduct the perforation test under the same test conditions as the ground reference test, and collect aerodynamic and torque data under the perforation state.

[0013] Preferably, it also includes: S5. Keeping the selected perforation module unchanged, after adjusting the center of gravity position step by step, perform a stability boundary scan test on each center of gravity point to obtain the static stability margin change curve under the corresponding damage state.

[0014] Preferably, the stepwise adjustment of the center of gravity position refers to moving it stepwise from the 25% average aerodynamic string to the 40% average aerodynamic string.

[0015] Preferably, it also includes: S6. Compare and analyze the aerodynamic data under each perforation condition with the baseline data to assess directional stability by the deviation of the pitching moment coefficient curve, the change of lateral force or yaw moment. S7. Based on the influence of aerodynamic data under various perforation conditions on directional stability, establish a database or empirical model of quantitative relationships between perforation type, location, area, static stability changes, and stability boundary contraction.

[0016] The present invention has at least the following beneficial effects: Firstly, this invention is specifically designed with a perforation model set for aerodynamic characteristic measurement, which allows dozens of perforation modules to be matched on a single adapter assembly, greatly reducing the processing cost and ground test preparation time in model perforation tests. Secondly, the perforation model group of the present invention is installed through a modular interface, which ensures the accurate reproduction of the perforation shape and position, avoids the random errors caused by traditional destructive simulation, and ensures high reliability of the test data. Third, the perforation model group of the present invention, because the perforations are only on each module and do not penetrate into the interior of the model, can realistically and accurately simulate the specific and important perforation scenario of "the insulation layer being intact or partially damaged", filling the gap in existing research. Fourth, in the experimental model, the present invention eliminates the quality interference after perforation replacement by building a self-aligning module, making the aerodynamic influence analysis results reliable and improving the scientific value of the data. Fifth, this invention directly addresses the key scientific question of "the effect of perforation on static stability," and through comparative experiments, it can clearly and quantitatively reveal the mechanism and laws of influence.

[0017] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description

[0018] Figure 1This is an exploded view of the cooperation between the benchmarking module and the adapter structure in this invention; Figure 2 This is a schematic diagram showing the distribution of the perforated model group in this invention; The components include: front end of the basic model -1, middle section of the basic model -2, rear section of the basic model I -3, rear section of the basic model II -4, adapter structure -5, tail support rod -6, self-aligning module -7, drive motor unit -8, head perforation module -9, scattered perforation module I -10, scattered perforation module II -11, front replaceable perforation module -12, middle replaceable perforation module -13, tail replaceable perforation module I -14, and tail replaceable perforation module II -15. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.

[0020] The modular ground test model of this invention mainly adopts a modular design of "basic body + replaceable perforation module" to simulate various non-penetrating perforation modes (scattered, large area, head / side perforation), such as... Figures 1-2 As shown, structurally, it mainly includes: 1. Adapter structure 5: It is a precisely machined and aerodynamically smooth adapter structure for a test model (such as an aircraft). In practical applications, the inner side of the adapter structure 5 is tightly fitted with the balance, but there is a sufficient gap between it and the balance support. The rear end of the adapter structure 5 is fitted with the tail support rod 6. The outer side of the adapter structure is provided with a support member. The support member adopts a frame structure and is connected to the model's outer support.

[0021] The model's external support consists of a model base approximately 5mm thick. The inner side of the model base is mounted on a keel support, while the outer side serves as a mounting base for either a standardized module group (which includes: a base model front end 1, a base model middle section 2, a base model rear section I 3, and a base model rear section II 4) or a perforated model group (which includes: a head perforated module 9, scattered perforated modules I 10, scattered perforated modules II 11, a front replaceable perforated module 12, a middle replaceable perforated module 13, a tail replaceable perforated module I 14, and a tail replaceable perforated module II 15). The model base features pre-drilled standard interfaces and cavities to facilitate the installation or replacement of the standardized module group or the perforated model group. In practical applications, the main material of the model base is typically high-strength aluminum alloy or stainless steel to ensure sufficient rigidity and strength for use. 2. Replaceable Modules: These are a collection of modules designed to conform to the shape of the original experimental model. It should be noted that the replaceable modules mainly include: a perforated model group and a benchmark module group. A complete benchmark module group, through a replaceable design, is a smooth module group that perfectly fits the original experimental model body without any perforations. This is used to obtain baseline aerodynamic data as a baseline for comparative analysis. Each module in the perforation model group is pre-configured with specific types, sizes, and distributions of perforations or other damage types, mainly simulating the following typical perforation modes: (1) Scattered perforated module: In a specific area of ​​this module, multiple arrays of small holes are designed, either regularly or irregularly distributed. The diameter, depth, density, and distribution pattern of the holes can be varied as needed. The key point is that the depth of the holes is precisely calculated to penetrate only the module itself without touching the model base, thus simulating the working condition of "the insulation layer being punctured but the main load-bearing structure not being severely damaged". It should be noted that the model base is used to simulate the main load-bearing structure or internal components of the aircraft. Once damaged, the aircraft will fail. The replaceable module, on the other hand, simulates the insulation layer, etc., and the aircraft can still work after damage.

[0022] (2) Large-area recessed module: The surface of this module is designed with large-area smooth recesses or areas where material is missing, to simulate shape damage caused by effects such as scratching. In practical applications, various corresponding recessed module variations can be obtained by changing the contour, depth, and area of ​​the recesses.

[0023] (3) Large-area defect module: The surface of this module is designed with a large area of ​​missing material to simulate the shape damage caused by ablation or partial structural tearing. In practical applications, various corresponding defect module variations can be obtained by changing the outline and area of ​​the defect.

[0024] (4) Head perforation module: This module is specifically designed to replace the head cone of the model. It can simulate different perforation morphologies such as head blunting, asymmetric defects, and perforations, which is crucial for studying the static stability changes in pitch and yaw directions.

[0025] (5) Composite module: The surface of the module has at least two of the following: scattered perforations, smooth depressions, and material missing areas, which are used to simulate shape damage under complex conditions.

[0026] In practical applications, the design concept of replaceable modules can be applied to aircraft models with different layouts, and the types of perforated modules can be continuously expanded according to new research needs, so as to have a wider range of adaptability and scalability.

[0027] Furthermore, all the above modules are quickly and accurately installed and fixed to the model base using high-precision positioning pins and quick-lock screws, ensuring that the repeatability error of the aerodynamic shape is minimal after each module replacement; 3. Internal force measurement system: A six-component balance force measurement system is integrated inside the model to accurately measure the changes in aerodynamic forces and torques during ground tests. In practical applications, the installation, connection, and measurement methods of the six-component balance force measurement system are existing technologies, so they will not be described in detail here.

[0028] 4. Built-in centering module 7: Integrated inside the model body, this system is used to precisely control and adjust the model's center of gravity position. The centering module is the core of achieving high-precision stability research, and its specific composition is as follows: (1) A high-precision slide rail module, which uses one or more high-strength lead screws arranged along the longitudinal axis (X-axis) of the model to adjust the position of the counterweight slider. The slider is then positioned and guided by the slide rail, so that when the lead screw rotates, the slider remains stationary under the constraint of the slide rail, converting the rotation of the lead screw into a positional change on the slide rail, thus achieving X-axis centering. It should be noted that in practical applications, the centering module of this invention at least includes the center of gravity adjustment function along the longitudinal axis (X-axis) of the model. Depending on research needs, it can be extended to a multi-dimensional center of gravity control system that includes adjustment functions in the horizontal axis (Y-axis) and / or vertical axis (Z-axis) directions. (2) Counterweight slider: One or more standard counterweights made of high-density materials (such as tungsten alloys) are used to make the slider perfectly fit the lead screw through precision threads; (3) Drive motor unit 8 for driving and positioning: a micro stepper motor or servo motor is used as the drive source. The counterweight slider is driven by ball screw transmission. The unit has a built-in high-resolution encoder, which can realize micron-level closed-loop control and precise feedback of slider position, making its variable control capability strong.

[0029] Furthermore, a method for evaluating the impact on static stability using a modular ground test model for perforation testing mainly includes the following steps: Step 1, Baseline Test: Install the baseline module and use the centering module to adjust the model's center of gravity to the designed "baseline center of gravity position". Conduct ground tests to collect aerodynamic and moment data under non-perforated conditions.

[0030] Step 2, Perforation Effect Test: Replace the perforation modules sequentially. After each replacement, first activate the centering module to precisely calibrate the model's center of gravity back to the "reference center of gravity position." Then, repeat the test under the same conditions (Mach number, Reynolds number, angle of attack range). This step ensures that the measured aerodynamic changes are purely caused by the perforation.

[0031] Step 3, Stability Boundary Scan Test: After completing Step 2, keeping a key perforated module unchanged, actively and stepwise adjust the center of gravity position (e.g., from 25% of the average aerodynamic chord to 40%), repeating the test at each center of gravity point. This directly obtains the static stability margin change curve under this damage state. It should be noted that the static stability margin = (aerodynamic center position - center of gravity position) / average aerodynamic chord length.

[0032] 4. Data processing and analysis: Compare the aerodynamic data under each perforation condition with the baseline data, analyze the deviation of the pitching moment coefficient curve, analyze the changes in lateral force or yaw moment, and evaluate the heading stability.

[0033] The above solution is merely an illustration of a preferred example and is not limited thereto. When implementing this invention, appropriate substitutions and / or modifications can be made according to the user's needs.

[0034] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. It can be applied to various fields suitable for the present invention. Other modifications can be readily made by those skilled in the art. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and examples shown and described herein.

Claims

1. A ground-based test model for studying the effect of localized perforation on static stability, characterized in that, include: The adapter structure fits tightly with the balance on its inner side. Support components that mate with the outer side of the transition structure; A model base is mounted on a support member, and the model base has multiple mounting positions; After matching each mounting position, a standardized modular group is constructed to obtain the complete test model surface; Once matched with each mounting position, a perforation model set is used to simulate various perforation patterns on the nose, sides, abdomen, and back of an aircraft. The adapter structure has self-aligning modules installed on both sides via an installation mechanism. The experimental model integrates a six-component balance force measurement system to measure changes in aerodynamic forces and torques during ground tests. Each mounting position includes: a mounting interface and a mounting cavity reserved on the base; The model base has a thickness of 5mm and is made of aluminum alloy or stainless steel. The perforation model group includes: A scattered perforated module with multiple regularly or irregularly distributed arrays of small holes on its surface; The surface features a recessed module with smooth indentations; A damaged module with areas of missing material on its surface; A composite module with at least two of the following on its surface: scattered perforations, smooth depressions, and areas of missing material; Head perforation module used to replace the head cone part of the model; Modular ground testing methods include: S1. Install the benchmark module group on the model base, and use the centering module to adjust the model's center of gravity to the designed benchmark center of gravity position; S2. Conduct ground benchmark tests to collect aerodynamic and torque data under non-perforated conditions; S3. Replace different perforated modules at different positions on the model base, and after each replacement, adjust the model's center of gravity back to the reference center of gravity position by changing the position of the slider on the centering module. S4. Conduct the perforation test under the same test conditions as the ground reference test, and collect aerodynamic and torque data under the perforation state; S5. Keeping the selected perforation module unchanged, after adjusting the center of gravity position step by step, perform a stability boundary scan test on each center of gravity point to obtain the static stability margin change curve under the corresponding damage state. The step-by-step adjustment of the center of gravity position refers to moving the center of gravity from the 25% average aerodynamic string to the 40% average aerodynamic string in a step-by-step manner.

2. The ground test model for studying the effect of local perforation on static stability as described in claim 1, characterized in that, The perforated model group and the benchmark module group are connected to the base via locating pins and quick-lock screws.

3. The ground test model for studying the effect of local perforation on static stability as described in claim 1, characterized in that, The centering module includes: Slide rails are installed between the mounting mechanisms; A slider mounted on a slide rail; The lead screw is threadedly connected to the slider; The motor connected to the lead screw.

4. The ground test model for studying the effect of local perforation on static stability as described in claim 1, characterized in that, Modular ground testing methods also include: S6. Compare and analyze the aerodynamic data under each perforation condition with the baseline data to assess directional stability by the deviation of the pitching moment coefficient curve, the change of lateral force or yaw moment. S7. Based on the influence of aerodynamic data under various perforation conditions on directional stability, establish a database or empirical model of quantitative relationships between perforation type, location, area, static stability changes, and stability boundary contraction.

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