Aerostat anti-drag capsule material aerodynamic characteristic test model and test method

Abstract

The invention provides an aerostat anti-drag capsule material aerodynamic characteristic test model and test method, and belongs to the technical field of aerostats, the aerostat anti-drag capsule material aerodynamic characteristic test model comprises a main body, a capsule material sleeve body and a tail boom connecting piece; the main body is streamline-shaped, and the tail section of the main body is provided with a tail wing; the bag material sleeve body is of a sleeve type structure and is attached to the outer surface of the main body in a covering mode through a detachable bonding layer. The capsule material sleeve body is formed by welding one or more capsule material sheets with different surface appearances; the bag body material sleeve body is composed of segmented structures in the axial direction of the main body, the segmented structures are welded and connected into a whole in the circumferential direction of the main body, and a connecting seam is formed in the circumferential direction so that the bag body material sleeve body can be opened and closed in the axial direction during assembly; the tail boom connecting piece is fixed to the tail section of the main body and used for supporting and installing a test model in a wind tunnel. According to the invention, the sleeve type wind tunnel test model which can be attached and can replace different capsule materials is constructed, so that the aerodynamic characteristics of the aerostat anti-drag capsule material under the wind tunnel condition can be truly and effectively tested.

Description

Technical Field

[0001] This invention relates to the field of airship technology, and in particular to a test model and test method for the aerodynamic characteristics of airship drag-reducing capsule material. Background Technology

[0002] As the applications of stratospheric airships and other aerostats expand in fields such as communication, remote sensing, and navigation, higher demands are being placed on their performance in terms of high-altitude loiter capability, energy efficiency, and wind resistance. Aerodynamic drag on the surface of the airship is a crucial factor affecting its performance, and drag reduction design using materials is considered an effective means of improving efficiency. Wind tunnel testing is a commonly used method for evaluating material performance, as it allows for the acquisition of aerodynamic data from models in a controlled environment.

[0003] In existing technologies, metal or resin 3D printing is commonly used to fabricate model shells for wind tunnel testing. These models have smooth surfaces, are fixed and cannot be replaced, and can only test the aerodynamic performance of the structural shape. When testing different shell materials, multiple physical models must be manufactured repeatedly, which is not only costly and inefficient, but also cannot guarantee complete structural consistency between different models, leading to a lack of comparability in test results. Furthermore, because the material application cannot precisely match the model, wrinkles and warping can easily occur, affecting airflow adhesion and measurement accuracy, causing aerodynamic data deviations, and failing to accurately reflect the true impact of the material itself on aerodynamic performance.

[0004] Therefore, how to accurately and effectively test the aerodynamic characteristics of the drag-reducing capsule material of an airship under wind tunnel conditions has become an urgent technical problem to be solved. Summary of the Invention

[0005] This invention provides a test model and test method for the aerodynamic characteristics of aerospace drag reduction capsule material, which solves the problem of difficulty in obtaining real and effective aerodynamic test data in the prior art, and realizes the real and effective testing of the aerodynamic characteristics of aerospace drag reduction capsule material under wind tunnel conditions.

[0006] This invention provides an experimental model of the aerodynamic characteristics of a drag-reducing capsule material for an airship, comprising: a main body, a capsule material sleeve, and a tail support connector; The main body is streamlined, and a tail fin is provided at the rear end of the main body; The capsule material sleeve is a sleeve-type structure, and the capsule material sleeve is attached to the outer surface of the main body by a detachable adhesive layer; the capsule material sleeve is welded together from one or more capsule material sheets with different surface morphologies; the capsule material sleeve is composed of segmented structures along the axial direction of the main body, and each segmented structure is welded together in the circumferential direction of the main body to form a whole, and a connecting seam is formed in the circumferential direction for opening and closing in the axial direction during assembly; The tail support connector is fixed to the tail section of the main body and is used to support and install the test model in the wind tunnel.

[0007] According to the present invention, a test model of aerodynamic characteristics of a drag-reducing capsule material for an airship is provided. The capsule material sleeve is formed by welding together segments of the same capsule material sheet along the axial direction of the main body. The capsule material sheet is continuously attached to the main body along the axial direction and has a consistent surface morphology and surface roughness throughout the attached area.

[0008] According to the present invention, a test model of aerodynamic characteristics of a drag-reducing capsule material for an airship is provided. The capsule material sleeve is formed by welding a first capsule material sheet and a second capsule material sheet together along the axial direction of the main body. The first capsule material sheet and the second capsule material sheet are made of different materials, and the first capsule material sheet and the second capsule material sheet are distributed sequentially along the axial direction of the main body.

[0009] According to the present invention, a test model of aerodynamic characteristics of a drag-reducing capsule material for an airship is provided, wherein the first capsule material sheet is attached to the front part of the axial length of the main body, the second capsule material sheet is attached to the remaining part of the axial length of the main body, and the surface roughness of the first capsule material sheet is less than that of the second capsule material sheet.

[0010] According to the present invention, a test model of aerodynamic characteristics of a drag-reducing bladder material for an airship is provided. The main body is made of aluminum alloy material processed in sections and detachably connected by embedded screws. The sections include a blunt-head section, a front section, a middle section, a middle second section, a rear section and a tail section in sequence. A balance connection seat is provided inside the middle section for mounting a force balance.

[0011] According to the present invention, an aerodynamic characteristic test model of a drag-reducing capsule material for an airship is provided, wherein the tail fin is arranged in an X-shape.

[0012] Based on the aerodynamic characteristic test model of the airship drag reduction capsule material provided in the first aspect, this invention provides a test method, comprising the following steps: Based on the dimensions of the wind tunnel test section, determine the scale of the test model and the axial length of the main body; The capsule material sleeve is processed according to the scale, and the capsule material sleeve is attached to the outer surface of the main body through a removable adhesive layer; The tail support connector is fixed to the tail section of the main body, and the test model is installed in the wind tunnel through the tail support connector; Set the airflow velocity in the wind tunnel, and adjust and fix the initial angle of attack and sideslip angle of the test model; According to the predetermined angle of attack or sideslip angle adjustment sequence, the angle of attack or sideslip angle of the test model is adjusted sequentially, and after the adjustment is stable, the aerodynamic force and torque data of the test model are collected. The aerodynamic force and torque data are processed in a dimensionless manner to obtain the aerodynamic force coefficient and torque coefficient.

[0013] According to a testing method provided by the present invention, the step of processing the capsule material sleeve according to the scale and attaching the capsule material sleeve to the outer surface of the body through a removable adhesive layer includes: According to the scaling ratio, the capsule material sleeve is cut into two-dimensional membranes along the axial direction. The two-dimensional diaphragm is welded to form a sleeve-type structure with a connecting seam that can be opened and closed along the axial direction; The capsule material sleeve is attached to the outer surface of the main body through the connecting seam using a removable adhesive layer, and the connecting seam is then closed.

[0014] According to a test method provided by the present invention, the step of sequentially adjusting the angle of attack or sideslip angle of the test model according to a predetermined angle of attack or sideslip angle adjustment sequence, and collecting aerodynamic force and torque data of the test model after the adjustment is stable, includes: During the longitudinal test, the sideslip angle and dynamic pressure are fixed and the angle of attack is adjusted sequentially. After each adjustment is stabilized, the aerodynamic force and torque data of the test model are collected. During the lateral test, the angle of attack and dynamic pressure are fixed and the sideslip angle is adjusted sequentially. After each adjustment is stabilized, the aerodynamic force and torque data of the test model are collected.

[0015] The test method provided by the present invention further includes: Record the zero-point data of the force balance in a windless state; the zero-point data is used to correct the aerodynamic force and torque data.

[0016] This invention provides an experimental model and method for testing the aerodynamic properties of airship drag-reducing capsule materials. By constructing an experimental model of the aerodynamic properties of airship drag-reducing capsule materials and covering the model surface with a sleeve-like structural material sleeve formed by welding one or more capsule materials, and simultaneously setting a tail support connector at the stern for stable installation, it achieves realistic simulation and controllable comparative testing of the surface aerodynamic performance of different capsule materials in a wind tunnel environment. By designing the main body dimensions according to the principles of wind tunnel blockage and geometric scaling, reasonable Reynolds numbers and flow field conditions are ensured when the model runs in the wind tunnel, improving the representativeness of the test results. The capsule material sleeve structure design, employing segmented welding and retaining connecting seams, allows for rapid and stable material application and adhesion, facilitating replacement and reuse, thus improving the efficiency and operational flexibility of wind tunnel testing. By arranging materials of different roughnesses sequentially along the hull axis and setting transition bonding treatment at the joints, surface smoothness and flow continuity are ensured, avoiding local interference caused by material joints and ensuring the stability and reliability of aerodynamic data. By setting the airflow velocity and attitude angle adjustment sequence during the experiment, and combining zero-point calibration and dimensionless processing, high-precision and highly comparable aerodynamic coefficients and torque coefficients were obtained, supporting the quantitative analysis and engineering evaluation of the drag reduction effect of the capsule material. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the aerodynamic characteristics test model of a drag-reducing capsule material for an airship provided by the present invention.

[0019] Figure 2 This is a schematic diagram of the segmented structure of an aerodynamic characteristic test model of a drag-reducing capsule material for an airship provided by the present invention.

[0020] Figure 3 This is one of the schematic diagrams of a capsule material sheath provided by the present invention.

[0021] Figure 4 This is the second schematic diagram of a capsule material sheath provided by the present invention.

[0022] Figure 5 This is one of the flowcharts illustrating the test method for the aerodynamic characteristics test model of the drag-reducing capsule material for airships provided by this invention.

[0023] Figure 6This is the second schematic diagram of the test method for the aerodynamic characteristics test model of the drag-reducing capsule material of the airship provided by the present invention.

[0024] Figure 7 This is the third flowchart of the test method for the aerodynamic characteristics test model of the drag-reducing capsule material of the airship provided by the present invention. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0026] The following is combined with Figures 1 to 7 This invention describes the experimental model and method for testing the aerodynamic characteristics of the drag-reducing capsule material for airships.

[0027] In this plan, refer to Figure 1 , Figure 1 This is a schematic diagram of the aerodynamic characteristic test model of an airship drag reduction bladder material provided by the present invention. The aerodynamic characteristic test model of the airship drag reduction bladder material includes: a main body, a bladder material sleeve, and a tail support connector; The main body is streamlined, and a tail fin is provided at the rear of the main body; The capsule material sleeve is a sleeve-type structure, and the capsule material sleeve is attached to the outer surface of the main body through a detachable adhesive layer; the capsule material sleeve is welded together from one or more capsule material sheets with different surface morphologies; the capsule material sleeve is composed of segmented structures along the axial direction of the main body, and each segmented structure is welded together in the circumferential direction of the main body to form a whole, and a connecting seam is formed in the circumferential direction for opening and closing in the axial direction during assembly; The tail support connector is fixed to the tail section of the main body and is used to support and install the test model in the wind tunnel.

[0028] Specifically, in actual experiments, the surface morphology of the airship capsule material has a significant impact on aerodynamic performance. To accurately evaluate the aerodynamic characteristics of different capsule materials, especially those with drag-reducing properties, under actual flow conditions in a wind tunnel, it is necessary to construct a test model that is structurally sound, easy to assemble, reusable, and capable of being fitted with flexible capsule materials. Therefore, this embodiment provides a test model for the aerodynamic characteristics of an airship drag-reducing capsule material. This model possesses good geometrical fidelity and material substitution capabilities, and can meet the requirements of wind tunnel force measurement tests under the Reynolds number similarity criterion.

[0029] In this embodiment, the aerodynamic characteristic test model of the airship drag reduction capsule material includes a main body, a capsule material sleeve, and a tail support connector. The main body has a streamlined structure to closely resemble the actual shape of a stratospheric airship. The tail section of the main body is equipped with a tail fin to reproduce the tail disturbance characteristics of the airship during actual flight and the contribution of the tail fin to aerodynamic forces. The main body is constructed using a segmented processing method to meet the requirements of scale, structural strength, and weight, while also facilitating processing and assembly.

[0030] The capsule material sleeve has a sleeve-like structure and can be attached to the outer surface of the main body via a removable adhesive layer. In practice, the adhesive layer uses double-sided adhesive material, which ensures a firm fit while allowing for quick replacement without damaging the main body surface after testing. The capsule material sleeve is welded from one or more capsule material sheets with different surface morphologies, possessing strong expandability. The material sheets are segmented along the axial direction of the main body, with each segment corresponding to a specific area on the main body. Each segment is welded circumferentially to the main body, forming a complete and closed capsule sleeve structure. To facilitate attachment and removal, a connecting seam is retained circumferentially. This connecting seam can be opened axially during assembly and closed after installation.

[0031] The tail boom connector is fixed to the tail section of the main body and is used to connect the wind tunnel support system during model assembly. The tail boom connector ensures that the test model maintains a stable attitude in the wind tunnel, while also preventing interference from the tail support structure from the data measured by the force balance.

[0032] With the above structural design, this experimental model can complete bonding tests of capsule materials with different surface morphologies under the condition of ensuring geometric and Reynolds number similarity. Its sleeve-type capsule material structure facilitates reuse in multiple test rounds, and the detachable bonding structure reduces assembly difficulty. The overall model structure is stable and highly adaptable, which is conducive to carrying out a series of comparative experiments and improving the testing efficiency and accuracy of the aerodynamic drag reduction effect of the capsule material.

[0033] The following examples section will provide a more detailed description of the aerodynamic characteristics test model of the drag-reducing capsule material for airships.

[0034] First, regarding the specific composition of the main body and tail fin, refer to... Figure 2 , Figure 2 This is a schematic diagram of the segmented structure of an aerodynamic characteristic test model of a drag-reducing capsule material for an airship, provided by the present invention. In one possible embodiment, the main body is made of aluminum alloy material, machined into segments and detachably connected by embedded screws. The segments sequentially include a blunt-ended segment, a front segment, a middle segment, a second middle segment, a rear segment, and a tail segment. A balance connection seat is provided inside the middle segment for mounting a force-measuring balance. The tail fin has an X-shaped layout.

[0035] Specifically, when conducting aerodynamic property tests on the airship capsule material, it is necessary to construct a scaled-down model structure that meets the strength requirements of wind tunnel testing while possessing good dimensional accuracy and repeatable assembly capabilities. Considering the complex shape and large size of the airship's main structure, and the need for frequent replacement of capsule materials and adjustment of internal measuring devices during testing, high demands are placed on the structural strength, manufacturing process, and assembly and maintenance methods of the test model. Based on these requirements, this embodiment provides an airship model main structure suitable for wind tunnel testing, whose design ensures structural stability while improving assembly flexibility and force measurement system integration capabilities.

[0036] In this embodiment, the main body is manufactured in sections using aluminum alloy. Aluminum alloy has high specific strength and good machinability, meeting the dual requirements of strength and lightweight in wind tunnel testing. The main body consists of multiple structural sections, namely, a blunt-ended section, a front section, a middle section, a middle second section, a rear section, and a tail section. The sections are detachably connected by embedded screws. This connection method facilitates independent operation of each section during processing, transportation, and assembly, and also allows for replacement of damaged sections or adjustment of structural configuration during subsequent testing, improving overall efficiency.

[0037] A balance connector is installed inside the middle section for mounting a force balance device. This connector ensures the alignment of the balance with the model's central axis and achieves effective transmission of aerodynamic forces during the experiment through a rigid connection. The force balance connection is located in the middle of the model, which avoids error accumulation caused by an excessively long torque transmission path, and also facilitates maintaining a stable support relationship between the tail support connector and the model's center of gravity.

[0038] The main body is connected to the tail section, and the tail fin adopts an X-shaped layout to simulate the stable structure used by the airship in actual flight. The X-shaped tail fin can generate a tail disturbance flow field consistent with the actual situation in wind tunnel tests, thereby improving the representativeness and reliability of the test data. As an important external disturbance component of the model, the geometry and arrangement of the tail fin have a significant impact on the aerodynamic measurement results. Therefore, by strictly replicating the actual layout, the aerodynamic characteristics of the capsule material under tail fin interference conditions can be more accurately reflected.

[0039] Secondly, regarding the specific composition of the capsule material sheath, the capsule material sheath can be welded together from capsule material sheets with different surface morphologies; it can also be welded together from multiple capsule material sheets with different surface morphologies.

[0040] In wind tunnel testing, to accurately evaluate the aerodynamic performance of the capsule material in the flow field, it is necessary to ensure that the capsule material attached to the surface of the test model has stable consistency. Especially when conducting benchmark or control tests, using capsule materials with uniform surface morphology and roughness can effectively eliminate interference caused by material variations, ensuring that the aerodynamic data are comparable and representative.

[0041] Therefore, in one possible implementation, refer to Figure 3 , Figure 3 This is one of the schematic diagrams of a capsule material sleeve provided by the present invention. The capsule material sleeve is formed by welding together segments of the same capsule material sheet along the axial direction of the main body. The capsule material sheet is continuously attached to the main body along the axial direction and has a consistent surface morphology and surface roughness throughout the attached area.

[0042] Specifically, in this embodiment, the capsule material sheath is composed of sheets of the same capsule material. The selected material is a conventional capsule material, which refers to a flexible material with uniform surface morphology and low surface roughness without the introduction of drag-reducing microstructures. Conventional capsule materials can be coated polyester fiber fabrics (such as PET substrate + PU coating), coated nylon fiber fabrics (such as PA + TPU composite materials), polyester / nylon membranes (such as Mylar, Kapton, and other nonwoven membranes), or polyester-based composite membranes. To adapt to the streamlined structure of the experimental model body, the capsule material sheets are segmented along the axial direction of the body. Each material sheet is unfolded into a two-dimensional membrane by mapping the three-dimensional structure before design to ensure that the unfolded shape is consistent with the shape of the model.

[0043] The material pieces along each axis are joined together to form an integral sleeve structure using heat-sealing welding. During the welding process, the segmented material pieces are spliced ​​and connected according to the predetermined weld positions using a continuous heat-sealing machine or direct heat-sealing equipment to form a sleeve-type capsule material structure. After the connection is completed, the welds are distributed along the axial direction of the main body, and the overall covering area is continuous and stable, avoiding aerodynamic interference caused by uneven welds or material transitions.

[0044] After welding, the capsule material sleeve is assembled through a pre-reserved circumferential connection seam. During the application process, the operator slides the sleeve from the model head along the axial direction onto the outer surface of the model and fixes it to the model surface using a removable adhesive layer. The application area of ​​the capsule material sheet covers the main surface of the model body, and the surface morphology and roughness remain consistent throughout the entire area, without any local flow abrupt changes caused by variations in material type or texture.

[0045] When optimizing the aerodynamic drag of an airship, the microstructure of the material surface significantly affects boundary layer development and flow separation characteristics. Especially at different locations on the streamlined surface, local flow velocities, pressure gradients, and turbulence development stages vary; therefore, using a single material cannot simultaneously meet the optimization requirements of the entire vessel's aerodynamic performance. To achieve coordinated control of the aerodynamic performance of the fore and aft sections, therefore, in another possible implementation, reference is made to... Figure 4 , Figure 4 This is the second schematic diagram of a capsule material sleeve provided by the present invention. The capsule material sleeve is formed by welding a first capsule material sheet and a second capsule material sheet together along the axial direction of the main body. The first capsule material sheet and the second capsule material sheet are made of different materials, and the first capsule material sheet and the second capsule material sheet are distributed sequentially along the axial direction of the main body.

[0046] Furthermore, the first capsule material sheet is attached to the front portion of the main body along its axial length, and the second capsule material sheet is attached to the remaining portion of the main body along its axial length, with the surface roughness of the first capsule material sheet being less than that of the second capsule material sheet.

[0047] Specifically, in this embodiment, the capsule material sleeve is formed by welding a first capsule material sheet and a second capsule material sheet together along the axial direction of the main body. The first and second capsule material sheets are made of different materials, differing in material composition, surface texture, and microstructure design. The material selection is based on aerodynamic simulation and accumulated experience, aiming to control surface drag at different locations while conforming to the actual flight airflow distribution. The first capsule material sheet is made of conventional capsule material, which has been described in detail in the previous embodiments and will not be repeated here. The second capsule material sheet is made of drag-reducing capsule material, which refers to a flexible material with specific surface microstructures or enhanced roughness design, aiming to optimize the flow characteristics of the outer surface of the airship and reduce aerodynamic drag. The drag-reducing capsule material can be a composite fabric material with microstructure, a biomimetic texture material, or a composite material with a functional coating or functional film layer.

[0048] The first capsule material sheet is attached to the front portion of the main body's axial length, preferably 60% of the area. This area has strong airflow adhesion and high flow field stability, making it suitable for using materials with low surface roughness to reduce frictional resistance. The second capsule material sheet is attached to the remaining 40% of the main body's axial length. This area is close to the tail end, where flow separation and wakes are prone to occur, and it is sensitive to surface disturbances. Therefore, a drag-reducing capsule material sheet with a certain degree of roughness or special microstructure is selected to improve the local flow field and delay separation.

[0049] During manufacturing, the two materials are first cut into two-dimensional membranes of corresponding shapes based on the structure of the scaled-down model. Each segment is then joined using a heat-sealing welding process. Finally, the two materials are welded together circumferentially at their interface to form a continuous and stable integral sleeve structure. Before final assembly, a circumferential connecting seam is reserved in the sleeve for opening during installation and closing after application. The entire capsule material sleeve is bonded to the outer surface of the main body via a removable adhesive layer, ensuring a tight surface fit, a smooth material transition area, and no impact on local aerodynamic characteristics.

[0050] Furthermore, this embodiment also provides a test method for an aerodynamic property test model of a drag-reducing capsule material for an airship, referring to... Figure 5 , Figure 5 This is one of the flowcharts illustrating the test method for the aerodynamic properties test model of the drag-reducing capsule material for airships provided by the present invention. The method includes the following steps: Step 101: Determine the scale of the test model and the axial length of the main body based on the dimensions of the wind tunnel test section.

[0051] Before conducting aerodynamic property tests on the airship capsule material, it is necessary to determine the geometric parameters of the scaled-down model to ensure that the test model has reasonable dimensions within the wind tunnel test section and can meet the Reynolds number similarity criterion during the test, thereby ensuring the validity and comparability of the aerodynamic measurement results. Therefore, in this embodiment, the scaled-down model and the axial length of the main body need to be determined first based on the dimensions of the wind tunnel test section, which corresponds to step 101.

[0052] The reason for implementing this step is that the geometric relationship between the model and the test section in wind tunnel testing directly affects the airflow distribution and force measurement accuracy. If the model size is too large, it will cause wind tunnel blockage, leading to airflow deviation; if the model size is too small, the Reynolds number will deviate from the actual flight conditions, failing to effectively reflect the aerodynamic characteristics of the capsule material under actual flight conditions. Therefore, by reasonably calculating the model scale and axial length, an aerodynamic environment as close as possible to the actual Reynolds number can be obtained while controlling the blockage degree.

[0053] In this step, the model scale is determined by both the cross-sectional area of ​​the test section and the upper limit of the allowable blockage. The cross-sectional area of ​​the wind tunnel test section is... Set the maximum allowed blocking level to be The model at an angle of attack of The maximum windward area at that time is The following equation is satisfied: The conclusion is as follows: Based on this formula, combined with the known dimensions of the wind tunnel test section and the set maximum angle of attack range, the maximum allowable frontal area of ​​the model can be deduced. Then, based on the geometric proportions of the prototype airship, the diameter, axial length, and overall scale of the model can be determined.

[0054] In terms of specific implementation, firstly, the cross-sectional width and height of the wind tunnel test section are measured, and its cross-sectional area is calculated. Secondly, the maximum test angle of attack (e.g., ±20°) is selected and substituted into the formula to calculate the maximum allowable frontal area of ​​the model. Subsequently, based on the external proportions of the prototype airship, the maximum frontal area is converted into a diameter at a scaled-down scale, and the axial length of the test model is determined in conjunction with the length-to-diameter ratio of the prototype. The resulting model parameters not only meet the physical requirements of the wind tunnel but also enable the model to maintain a stable flow field boundary during the test, avoiding data errors caused by geometric scale misalignment.

[0055] Step 102: Process the capsule material sleeve according to the scale, and attach the capsule material sleeve to the outer surface of the main body through a removable adhesive layer.

[0056] Since the focus of aerodynamic performance testing is on the influence of the capsule material surface on the boundary layer and flow separation, poor material adhesion or geometric fit can lead to uneven adhesion, localized wrinkling, or voids, severely affecting the accuracy and reproducibility of aerodynamic measurements. Therefore, after determining the geometric parameters of the test model, the capsule material structure needs to be fabricated into an assemblable form and attached to the outer surface of the test model's main body to construct a test model with realistic surface aerodynamic characteristics. The core of this step is to ensure that the flexible capsule material is stably attached to the surface of the rigid scaled-down model by adapting to the model's geometry, and to have the ability to be disassembled, replaced, and repeated in testing. This avoids the need to rebuild the structural model for each test, thus meeting the needs of multiple rounds of wind tunnel aerodynamic comparison testing and reducing testing efficiency and costs.

[0057] In this step, the capsule material sleeve refers to a large-area sleeve structure made from flexible capsule material, processed to cover the outer surface of the model. This structure matches the main body structure, with its inner surface corresponding to the shape of the main body, and its dimensions are designed based on the scaled-down dimensions determined in the previous step. The removable adhesive layer is a temporary connecting medium between the capsule material sleeve and the surface of the model body, usually using double-sided adhesive, which ensures a tight fit while allowing for non-destructive removal after testing.

[0058] In terms of specific implementation, firstly, a capsule material that meets the experimental requirements is selected, and the unfolding form of the capsule material sleeve is designed according to the geometry of the model. During the material processing stage, flexible film or fabric materials are used, cut and welded to form an overall structure matching the shape of the model. In the application stage, operators assemble the sleeve along the model's axis and evenly attach it to various parts of the main body surface using double-sided adhesive. During assembly, attention must be paid to a smooth fit, eliminating localized air bubbles, wrinkles, or curling edges, ensuring that airflow glides evenly along the surface. After application, a complete capsule material surface covering the main body is formed, preparing for subsequent aerodynamic testing.

[0059] Step 103: Fix the tail support connector to the tail section of the main body, and install the test model in the wind tunnel through the tail support connector.

[0060] After the shell material is applied, to ensure the test model maintains a stable attitude in the wind tunnel and guarantees the accuracy of force measurement data, it needs to be installed in the wind tunnel test section. Because aerodynamic testing places extremely high demands on the model's attitude maintenance and support stability, the model must be reliably fixed in the wind tunnel using a tail support structure and effectively connected to the force measurement system. Specific connection methods can be found in [reference needed]. Figure 1 .

[0061] In this step, the support connector refers to the connecting component installed at the tail end of the test model, used to fix the model to the wind tunnel support device. This connector not only bears all the aerodynamic forces and moments experienced by the test model, but also needs to ensure its connection stiffness and dimensional accuracy to ensure that the data collected by the force balance accurately reflects the aerodynamic response of the model.

[0062] In a specific implementation, a pre-set tail support connection interface is installed at the tail section of the model body. This interface is typically machined integrally with the tail section structure or added using a rigid connector, and is fixedly connected to the tail structure by embedded screws. Positioning holes matching the wind tunnel tail support device are provided in the connector, allowing the test model to be inserted and fixed in the wind tunnel test section via the tail support device. The tail support connector and the force balance are rigidly coupled using a standard interface. During the connection process, a fine-tuning mechanism ensures that the model's centerline is aligned with the wind tunnel's main axis, avoiding test errors caused by eccentricity or tilt.

[0063] Step 104: Set the airflow velocity in the wind tunnel, and adjust and fix the initial angle of attack and sideslip angle of the test model.

[0064] After the test model is installed, in order to obtain the aerodynamic and torque responses under different attitudes, the attitude parameters of the model in the wind tunnel need to be initialized, including setting the airflow velocity and adjusting the initial angle of attack and sideslip angle of the model.

[0065] Since wind tunnel aerodynamic testing uses the model's initial attitude as a baseline, it involves progressively adjusting the angle of attack and sideslip angle, and measuring aerodynamic forces. If the initial angle is deviated, subsequent measurements at various attitudes will not accurately reflect the actual aerodynamic behavior of the material surface, affecting the calculation results of aerodynamic coefficients. Simultaneously, the stability of the airflow velocity directly affects the accuracy of dynamic pressure measurements, determining the reference scale for aerodynamic forces during the experiment. Therefore, ensuring the model is at the set airflow velocity and accurate attitude in the wind tunnel is a prerequisite for the entire force measurement experiment.

[0066] In this step, the airflow velocity refers to the steady-state incoming flow velocity applied to the model surface in the wind tunnel. It must be consistent with or close to the Reynolds number corresponding to the actual flight of the airship to satisfy aerodynamic similarity conditions. The angle of attack is the angle between the model's longitudinal axis and the incoming flow direction, used to simulate the airship's upwind state; the sideslip angle is the angle between the model's transverse axis and the incoming flow direction, used to simulate the aerodynamic response under lateral disturbances. The settings for these parameters are typically determined based on the angle sequence in the pre-designed test plan.

[0067] In specific implementation, the target airflow velocity of the wind tunnel test section is first set through the wind tunnel control system, and the air supply system is activated to stabilize the wind speed at the set value. Then, before the wind tunnel is turned on or under low-speed air supply conditions, the initial angle of attack and sideslip angle of the model are adjusted through the tail boom control mechanism. The adjustment process is completed by a hydraulic drive device or a manual fine-tuning device, combined with real-time monitoring of the model's attitude using an angle sensor. To ensure attitude accuracy, the setting error of the initial angle of attack and sideslip angle is typically required to be controlled within 3′. After the attitude adjustment is completed, the model is fixed and locked, forming a repeatable test start state.

[0068] Step 104 establishes a stable and standard initial aerodynamic state for the model in the wind tunnel. By setting the airflow velocity and attitude angle, a unified benchmark can be provided for subsequent point-by-point adjustments of the angle of attack or sideslip angle according to the angle sequence, avoiding measurement deviations caused by errors in the initial conditions.

[0069] Step 105: According to the predetermined angle of attack or sideslip angle adjustment sequence, adjust the angle of attack or sideslip angle of the test model in sequence, and collect the aerodynamic force and torque data of the test model after the adjustment is stable.

[0070] Aerodynamic performance is significantly affected by the model's attitude. Under different angles of attack or sideslip angles, the flow state on the model surface changes, leading to significant differences in aerodynamic forces and moments. Therefore, after setting the initial attitude of the experimental model, to comprehensively obtain the aerodynamic response characteristics of the capsule material under different attitudes, it is necessary to systematically adjust the angle of attack or sideslip angle of the experimental model and collect the aerodynamic force and moment data under each stable attitude. This will establish the correspondence between the material surface morphology and the aerodynamic response, thereby achieving an effective evaluation of the performance of different capsule materials.

[0071] In this step, the predetermined angle of attack or sideslip angle adjustment sequence refers to the attitude change path set according to the test plan. It typically includes several attitude points with fixed angular step sizes, such as an angle of attack ranging from -10° to +20°, with each 2° increment representing one level; or a sideslip angle ranging from -8° to +8°. This adjustment sequence ensures a uniform distribution of test data in the attitude space, facilitating the analysis of the regularity and trend of the material response curve. Data acquisition after stabilization refers to recording data only after each level of attitude adjustment has been completed, once the model attitude and wind speed have stabilized and the aerodynamic signal shows no significant fluctuations, ensuring that the measured results reflect the true flow state.

[0072] In specific implementation, the angle of attack or sideslip angle of the test model is first adjusted step-by-step according to a predetermined attitude angle sequence. This adjustment is achieved by controlling the tail boom drive mechanism, while the wind tunnel control system synchronously records the attitude change process. Once the model reaches the target attitude, the control system sends a command to the data acquisition device to initiate the sampling of the balance signal. During sampling, the system records the six-component output of the balance, including aerodynamic forces and aerodynamic moments in three directions, while simultaneously acquiring the current angle of attack, sideslip angle, and wind speed data. The sampling duration is set for a set time (e.g., 10 seconds), and all signals are recorded at a fixed frequency (e.g., 100Hz). After completing the acquisition of the current angle point, the model attitude moves to the next level angle, and the same steps are repeated until the entire angle sequence has been traversed.

[0073] Step 105 enables the system to acquire complete aerodynamic response data under controlled variable conditions, providing a raw data foundation for subsequent material performance analysis, modeling of aerodynamic effects on the model surface, and calculation of aerodynamic coefficients.

[0074] Step 106: Perform dimensionless processing on the aerodynamic force and torque data to obtain the aerodynamic force coefficient and torque coefficient.

[0075] Since the raw data collected in the wind tunnel is a voltage signal output from a force balance, it cannot be directly used for engineering analysis or comparison between different operating conditions. Therefore, after collecting aerodynamic and torque data at all attitude angles, these raw voltage data can be converted into standard aerodynamic and torque coefficients by performing coordinate transformation, balance formula conversion, and dimensionless processing. This yields the aerodynamic and torque coefficients for each attitude, thus accurately reflecting the influence of the capsule material on aerodynamic performance.

[0076] In this step, the aerodynamic coefficient is a dimensionless quantity obtained by dividing the aerodynamic forces acting on the model in three directions by the product of the dynamic pressure and the reference area, respectively. It is used to measure the magnitude of the aerodynamic force generated per unit area. The torque coefficient is obtained by dividing the torque signal by the product of the dynamic pressure, the reference area, and the reference length, representing the aerodynamic torque response per unit scale. These dimensionless parameters can be used to compare experimental results under different sizes and Reynolds numbers, and have wide applicability.

[0077] In terms of specific implementation, the raw voltage signals acquired under each test attitude are first analyzed. Using a pre-calibrated balance matrix, the voltage values ​​are converted into aerodynamic forces (Fx, Fy, Fz) and moments (Mx, My, Mz) in three directions for the model. Subsequently, based on the model's reference area, reference length, and dynamic pressure during the test, the aerodynamic coefficients (e.g., lift coefficient Cl, drag coefficient Cd) and moment coefficients (e.g., pitch moment coefficient Cm, roll moment coefficient Cl, yaw moment coefficient Cn) for each component are calculated. During the conversion process, coordinate axis transformation and zero-point correction are performed on all component data to ensure consistency with the model's body coordinate system and to eliminate systematic deviations caused by balance drift, installation errors, etc.

[0078] Step 106 transforms the raw physical signals obtained from the wind tunnel force measurement experiment into standardized aerodynamic performance parameters through mathematical conversion. By acquiring aerodynamic coefficients and moment coefficients under different angles of attack or sideslip angles, the drag reduction performance of the capsule material and its practical effect in flow control can be systematically evaluated. The converted results provide quantitative basis for subsequent performance comparison, material selection optimization, and numerical simulation verification, significantly enhancing the engineering application value of the experimental data.

[0079] In one possible implementation, refer to Figure 6 , Figure 6 This is the second flowchart of the test method for the aerodynamic characteristics test model of the drag-reducing capsule material of the airship provided by the present invention. Step 102 specifically includes steps 201 to 203: Step 201: According to the scaling ratio, the capsule material is cut into two-dimensional membranes along the axial direction.

[0080] Step 202: Weld the two-dimensional diaphragm to form a sleeve structure with a connecting seam that can be opened and closed along the axial direction.

[0081] Step 203: Using a removable adhesive layer, attach the capsule material to the outer surface of the main body through the connecting seam, and then close the connecting seam.

[0082] The airship test model is a streamlined three-dimensional structure. Forcibly covering it directly with a single piece of flexible membrane material can easily lead to surface wrinkles, tensile deformation, or poor adhesion, affecting airflow adhesion and boundary layer development during the test and causing errors in aerodynamic data. Therefore, to process the capsule material into a suitable covering structure for the scaled-down test model and meet the requirements for geometric matching, surface fit, and assemblability in wind tunnel testing, the three-dimensional shape is unfolded into a two-dimensional membrane, and then segmented and welded along the axial direction to form a sleeve structure. This allows for better control of the material's geometric accuracy and adhesion flatness. Simultaneously, retaining the axial connection seam and using a detachable adhesive method facilitates rapid replacement and repeated testing of the capsule material model.

[0083] In the specific implementation process, firstly, based on the determined scale of the experimental model, the three-dimensional geometric data of the model's outer surface is extracted, and then the three-dimensional surface is unfolded into a two-dimensional planar region through projection mapping. Based on the unfolded pattern, operators use an automatic cutting machine to precisely cut the flexible capsule material, obtaining multiple two-dimensional membranes of corresponding shapes. The arrangement direction of the membranes is consistent with the model's axis to ensure that the load-bearing fibers or microstructure textures of the material are distributed along the airflow direction, avoiding flow interference caused by directional misalignment.

[0084] Subsequently, the cut membrane pieces are welded together, divided into multiple sections such as the head, middle, and tail sections according to the model's axial structure. These sections are then heat-welded sequentially to ultimately form a sleeve-like structure with a complete three-dimensional form. During the welding process, an axial connecting seam is maintained around the perimeter. This seam can be opened during assembly to facilitate the sleeve being inserted axially from the head of the model. After welding, the sleeve material precisely matches the shape of the main body of the model, exhibiting good flexibility and maneuverability.

[0085] Finally, the processed capsule material sleeve is assembled onto the surface of the test model body through the pre-reserved connecting seams. During the bonding process, a removable adhesive layer is placed between the capsule material sleeve and the metal model, preferably using double-sided adhesive material, to ensure both a firm bond and easy removal. The bonding operation should begin from the front of the model and proceed gradually along the axial direction, ensuring that the material is flat, free of air bubbles and wrinkles during the bonding process. After bonding is completed, the axial connecting seams are closed to form a continuous and closed sleeve structure.

[0086] In one possible implementation, refer to Figure 7 , Figure 7 This is the third flowchart of the test method for the aerodynamic characteristics test model of the drag-reducing capsule material of the airship provided by the present invention. Step 105 specifically includes steps 301 to 302: Step 301: During the longitudinal test, fix the sideslip angle and dynamic pressure and adjust the angle of attack in sequence, and collect the aerodynamic force and torque data of the test model after each adjustment is stable.

[0087] Step 302: During the lateral test, fix the angle of attack and dynamic pressure and adjust the sideslip angle in sequence, and collect the aerodynamic force and torque data of the test model after each adjustment is stable.

[0088] During actual flight, airships are often subjected to different windward conditions. Testing a single attitude in the wind tunnel on a model cannot fully reflect the aerodynamic adaptability of the envelope material. Therefore, after the model is attached and installed, longitudinal and lateral tests need to be conducted separately to obtain the mechanical response of the envelope material under different aerodynamic attitudes. To this end, one type of attitude angle (angle of attack or sideslip angle) should be fixed in the wind tunnel according to a predetermined angle adjustment sequence, and another type of angle should be gradually adjusted. After stabilization at each angle point, the aerodynamic force and torque data of the model should be collected to obtain a complete curve of the material's aerodynamic response, providing a basis for subsequent assessment of the material's drag reduction performance.

[0089] In specific implementation, during the longitudinal test, the sideslip angle and dynamic pressure of the model are first fixed to set values ​​using the tail boom angle control system. Then, the angle of attack is adjusted step-by-step according to a predetermined angle-of-attack sequence. After each angle of attack is adjusted to the target angle, the model's attitude is stabilized to ensure that the wind speed, dynamic pressure, and aerodynamic force signals all reach a steady state before data acquisition. The acquired data includes the six-component balance signal (i.e., aerodynamic forces in three directions and moments in three directions), angle of attack, dynamic pressure, and other synchronous signals. The sampling frequency and time are executed according to preset values ​​(e.g., 100Hz, lasting 10 seconds). After completing one set of angle-of-attack data, the test continues with the next lower angle of attack until the entire angle-of-attack sequence has been traversed.

[0090] During the lateral test, the angle of attack and dynamic pressure were fixed at the set values ​​using the same method. Then, the model attitude was gradually adjusted according to a predetermined sideslip angle sequence, and the above data acquisition process was repeated. By keeping the wind speed constant, the control of variables ensured that the data obtained from each set were comparable.

[0091] In one possible implementation, the method further includes the following steps: Record the zero-point data of the force balance in a windless state; the zero-point data is used to correct the aerodynamic force and torque data.

[0092] During the experiment, the voltage signal output by the force balance not only reflects the actual aerodynamic forces and torques experienced by the model, but may also include zero-bias errors caused by the initial state of the balance, installation stress, or electrical noise. Without prior calibration, this will directly lead to measured data deviating from the true physical quantities. Especially when conducting comparative experiments between different capsule materials, inconsistent zero-point data or systematic shifts will affect the comparability of different sets of data. Therefore, it is necessary to record the zero-point voltage values ​​of each channel of the balance before the experiment begins, with the wind tunnel un-aired, and use these values ​​as a benchmark for data correction.

[0093] In specific implementation, after the test model is installed and in its initial position, the wind tunnel is kept closed to ensure no airflow acts on the model within the test section. The data acquisition system is then activated to collect static voltage signals from the six component channels of the force balance. The system performs real-time filtering and statistical processing on the static voltage of each component, extracting its stable value as zero-point reference data. After acquisition, this zero-point data is saved in the test data file as a benchmark for subsequent wind tunnel measurement data processing, used to correct deviations in all aerodynamic force and torque data during the sampling process.

[0094] It should be noted that, to accurately assess the impact of different capsule materials on the aerodynamic performance of the airship, comparative tests should be conducted under the same test conditions, the same structural model, and the same force measurement settings. That is, after completing all aerodynamic characteristic tests based on the conventional capsule material model, to continue comparative measurements of the drag-reducing capsule material model under the same test conditions, it is necessary to change the material of the test model and ensure that the new material model is in a measurable state. This process includes restoring the model to its initial state, removing the conventional capsule material model, installing the drag-reducing material model, and smoothing the material welding transition area to ensure the application accuracy and data consistency of subsequent tests.

[0095] In addition, since the drag-reducing capsule material model is made of two materials with different surface morphologies welded together, there may be small steps or unevenness on the surface of the connection transition area. If not treated, it may cause local flow separation or interference, affecting the accuracy of aerodynamic measurement. Therefore, auxiliary bonding treatment needs to be implemented at the welding interface.

[0096] In terms of specific implementation, the test model is first unloaded from the wind tunnel test section and detached from the test platform via the tail support structure. Operators restore the model to its initial position and remove the conventional capsule material attached to its surface. During removal, the material is removed by peeling off the double-sided adhesive layer, while residual adhesive residue is cleaned to ensure a clean and smooth surface, preparing for the next round of application.

[0097] Subsequently, the drag-reducing material model is applied to the main body surface. This model is pre-assembled from two capsule-shaped material sheets welded together; the front section is made of a material with low surface roughness, while the rear section is a drag-reducing material with a microstructure. During application, double-sided adhesive is used as a removable bonding layer, applied sequentially from the front to the rear of the model. At the interface formed by the welded joint of the two material sheets, the operator uses flexible tape to cover the interface area, creating a continuous, smooth outer surface and effectively avoiding flow interference caused by variations in weld thickness or local undulations.

[0098] After the coating is completed, the pre-reserved weld openings on the model are closed, and the bonding quality and axial alignment of the material surface are checked again. Once confirmed to be correct, the model is reinstalled in the wind tunnel test section, and the aforementioned angle of attack or sideslip angle adjustment and aerodynamic data acquisition process is repeated to complete the test measurement of the drag-reducing material under operating conditions.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A test model for the aerodynamic properties of a drag-reducing capsule material for an airship, characterized in that, include: Main body, bladder material sleeve and tail support connector; The main body is streamlined, and a tail fin is provided at the rear end of the main body; The capsule material sleeve is a sleeve-type structure, and the capsule material sleeve is attached to the outer surface of the main body by a detachable adhesive layer; the capsule material sleeve is welded together from one or more capsule material sheets with different surface morphologies; the capsule material sleeve is composed of segmented structures along the axial direction of the main body, and each segmented structure is welded together in the circumferential direction of the main body to form a whole, and a connecting seam is formed in the circumferential direction for opening and closing in the axial direction during assembly; The tail support connector is fixed to the tail section of the main body and is used to support and install the test model in the wind tunnel.

2. The aerodynamic characteristic test model of the airship drag reduction capsule material according to claim 1, characterized in that, The capsule material sleeve is formed by welding segments of the same capsule material sheet together along the axial direction of the main body. The capsule material sheet is continuously attached to the main body along the axial direction and has a consistent surface morphology and surface roughness throughout the attached area.

3. The aerodynamic characteristic test model of the airship drag reduction capsule material according to claim 1, characterized in that, The capsule material sleeve is formed by welding a first capsule material sheet and a second capsule material sheet together along the axial direction of the main body. The first capsule material sheet and the second capsule material sheet are made of different materials, and the first capsule material sheet and the second capsule material sheet are distributed sequentially along the axial direction of the main body.

4. The aerodynamic characteristic test model of the airship drag reduction capsule material according to claim 3, characterized in that, The first capsule material sheet is attached to the front portion of the axial length of the main body, and the second capsule material sheet is attached to the remaining portion of the axial length of the main body, and the surface roughness of the first capsule material sheet is less than that of the second capsule material sheet.

5. The aerodynamic characteristic test model of the airship drag reduction capsule material according to claim 1, characterized in that, The main body is made of aluminum alloy material in sections and is detachably connected by embedded screws. The sections include a blunt end section, a front section, a middle section, a middle second section, a rear section and a tail section in sequence. A balance connection seat is provided inside the middle section for the installation of the force balance.

6. The aerodynamic characteristic test model of the airship drag reduction capsule material according to claim 1, characterized in that, The tail fin has an X-shaped configuration.

7. A test method for an aerodynamic characteristic test model of a float-type drag-reducing capsule material according to any one of claims 1 to 6, characterized in that, include: Based on the dimensions of the wind tunnel test section, determine the scale of the test model and the axial length of the main body; The capsule material sleeve is processed according to the scale, and the capsule material sleeve is attached to the outer surface of the main body through a removable adhesive layer; The tail support connector is fixed to the tail section of the main body, and the test model is installed in the wind tunnel through the tail support connector; Set the airflow velocity in the wind tunnel, and adjust and fix the initial angle of attack and sideslip angle of the test model; According to the predetermined angle of attack or sideslip angle adjustment sequence, the angle of attack or sideslip angle of the test model is adjusted sequentially, and after the adjustment is stable, the aerodynamic force and torque data of the test model are collected. The aerodynamic force and torque data are processed in a dimensionless manner to obtain the aerodynamic force coefficient and torque coefficient.

8. The test method according to claim 7, characterized in that, The process of processing the capsule material sleeve according to the scaled-down version and attaching the capsule material sleeve to the outer surface of the main body via a removable adhesive layer includes: According to the scaling ratio, the capsule material sleeve is cut into two-dimensional membranes along the axial direction. The two-dimensional diaphragm is welded to form a sleeve-type structure with a connecting seam that can be opened and closed along the axial direction; The capsule material sleeve is attached to the outer surface of the main body through the connecting seam using a removable adhesive layer, and the connecting seam is then closed.

9. The test method according to claim 7, wherein the step of sequentially adjusting the angle of attack or sideslip angle of the test model according to a predetermined angle of attack or sideslip angle adjustment sequence, and collecting aerodynamic force and torque data of the test model after the adjustment is stable, includes: During the longitudinal test, the sideslip angle and dynamic pressure are fixed and the angle of attack is adjusted sequentially. After each adjustment is stabilized, the aerodynamic force and torque data of the test model are collected. During the lateral test, the angle of attack and dynamic pressure are fixed and the sideslip angle is adjusted sequentially. After each adjustment is stabilized, the aerodynamic force and torque data of the test model are collected.

10. The test method according to claim 7, characterized in that, Also includes: Record the zero-point data of the force balance under windless conditions; The zero-point data is used to correct the aerodynamic force and torque data.

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