Three-dimensional synchronous coordinate device and test method for ship model flow field SPIV test in wind tunnel

Abstract

The present application relates to a kind of three-dimensional synchronous coordinate device and test method of ship model flow field SPIV test in wind tunnel.The device includes wind tunnel test section, ship model assembly and positioning assembly;Wherein, positioning assembly has linear drive mechanism along the first horizontal direction, and three independently controllable movable parts are configured on the linear drive mechanism, each movable part is connected installation part by three-dimensional adjusting frame, and two cameras and laser sheet light source are respectively fixed on each installation part, to form the SPIV optical path system that can be integrally synchronously moved;The test method includes: after initial calibration, the relative position of each component of positioning assembly is fixed, the three installation parts are synchronously moved in three-dimensional space with same displacement vector, the optical path is translated to different test section as a whole, and multiple-section continuous measurement is realized.The present application fundamentally avoids the optical path uncertainty and random error caused by repeated disassembly and re-calibration, and significantly improves the efficiency, precision and data confidence of multi-section flow field test.

Description

Technical Field

[0001] This invention relates to the field of experimental testing technology, and in particular to a three-dimensional synchronous coordinate device and test method for SPIV flow field tests of ship models in wind tunnels. Background Technology

[0002] With the development of experimental testing technology, particle image velocimetry (PIV) technology and its derivative, stereoscopic particle image velocimetry (SPIV), have emerged. This type of technology involves scattering tracer particles into a flow field, illuminating the measured cross-section with a pulsed laser sheet, and recording particle images two or more times consecutively with a camera. The images are then processed using algorithms such as cross-correlation to obtain the planar velocity field. Building upon this, SPIV technology employs two cameras to simultaneously observe the same flow field from different perspectives, reconstructing the spatial displacement of particles using the principle of perspective. This allows for the acquisition of three-dimensional velocity vectors that traditional planar PIV cannot measure. Based on these characteristics, in wind tunnel ship model flow field testing, SPIV measurement devices have gradually been developed, consisting of two cameras, a laser sheet light source, and a calibration target, to achieve the measurement of the three-component velocities of the ship model around the flow field.

[0003] In related technologies, when conducting SPIV (Split-In-Video) tests of multi-section flow fields on ship models in a wind tunnel using the aforementioned device, one common approach is as follows: First, a calibration target is installed in the wind tunnel to calibrate the spatial geometric relationship between the camera and the laser sheet light source, obtaining the mapping relationship between pixel distance and physical distance. After calibration, the poses of the camera and laser sheet light source must remain strictly unchanged; if the optical path changes, recalibration is necessary. When it is necessary to measure different sections around the ship model sequentially, the test personnel must repeatedly disassemble and reassemble the calibration target, camera, and laser sheet light source, and readjust the spatial position and angle of each component. Another approach is to fix the camera and laser sheet light source in place, and only move the test model via a longitudinal sliding rail to change the longitudinal relative position of the model and the optical path, thereby achieving flow field measurements at different longitudinal profiles.

[0004] However, the aforementioned methods or devices all have significant shortcomings: Repeated disassembly, assembly, and recalibration are not only extremely time-consuming and labor-intensive, but also make it very difficult to guarantee that the relative positions and angles between the two cameras and between the camera and the laser sheet can be perfectly reproduced after each installation, easily introducing additional measurement uncertainties. Especially in large closed wind tunnels, when a large number of test sections with a wide spatial distribution are needed to comprehensively obtain the flow details in different areas around the ship model, this repeated adjustment and calibration work places extremely high demands on the equipment verification capabilities of the test personnel. As for moving the test model, its drawback is that it can only change the longitudinal position of the test section, and cannot change the lateral and vertical positions. However, the main body of the ship model is wide and tall, and the appendages such as the rudder, propeller, deck, and conning tower have significant differences in spatial distribution. Simply relying on longitudinal movement cannot meet the test requirements for flow field measurement in different spatial areas. At the same time, releasing the longitudinal degree of freedom of the bottom support rod of the model may cause the model to be unstable or vibrate under high Reynolds number and high wind speed conditions, affecting test safety and data quality. Summary of the Invention

[0005] To address the shortcomings of existing production technologies, this applicant provides a three-dimensional synchronous coordinate device and testing method for SPIV tests on ship model flow fields in a wind tunnel. This ensures the relative positional relationship between the camera and the laser sheet in optical space, enabling the optical path to meet the requirements of SPIV testing. It avoids the problems of low efficiency and uncontrollable errors in manual adjustment, while greatly expanding the testing range of the flow field space.

[0006] The technical solution adopted in this invention is as follows: This invention provides a three-dimensional synchronous coordinate device for SPIV test of ship model flow field in wind tunnel. The device includes a wind tunnel test section, which is defined with a first horizontal direction, a second horizontal direction, and a height direction that are perpendicular to each other based on the structure of the wind tunnel test section. The ship model assembly is disposed inside the wind tunnel test section along the first horizontal direction; A positioning component is disposed on one side of the wind tunnel test section in the second horizontal direction; the positioning component is equipped with a first camera, a second camera, and a laser sheet light source; The wind tunnel test section is equipped with glass portholes on both sides of the second horizontal direction, and the first camera, the second camera, and the laser sheet light source are directed toward the ship model assembly through the glass portholes; The positioning component includes: a base; a first linear drive mechanism disposed on the base along the first horizontal direction; three first movable parts disposed at intervals and independently on the first linear drive mechanism for controlled movement along the first horizontal direction; and mounting parts, each of the first movable parts being connected to a mounting part via a three-dimensional adjustment frame, wherein the first camera, the second camera, and the laser light source are respectively mounted on the three mounting parts; the three-dimensional adjustment frame is used to drive the mounting parts to move along the second horizontal direction and the height direction, so that the three mounting parts can achieve synchronous or independent position adjustment in three-dimensional space.

[0007] Its beneficial effects are as follows: By integrating a positioning component, two cameras and one laser sheet light source, which originally needed to be installed and calibrated independently and repeatedly in wind tunnel tests, are integrated into a common platform that can be controlled for three-dimensional spatial position adjustment. This is completely different from the existing technical approach of either "fixing the optical path and moving the model" or "disassembling and calibrating section by section." It creatively proposes the technical concept of "fixing the model and moving the optical path synchronously as a whole." By setting three independently driveable first movable parts and equipping each with a three-dimensional adjustment frame that drives its movement in the second horizontal and vertical directions, it achieves for the first time three-dimensional... In the Cartesian coordinate system, the overall attitude of the SPIV measurement system (two cameras and a laser sheet light source) can be accurately and repeatably reconstructed. Its fundamental advantage lies in the fact that once the relative spatial geometric relationships (i.e., optical paths) between the components are established through a single calibration, these relationships are completely solidified by the positioning components using a rigid mechanical structure. When switching to test sections at different spatial locations around the ship model, simply controlling the three mounting parts to execute identical displacement vectors in three-dimensional space is sufficient to "translate" the entire optical path to the new test area. The relative positions and angles between the two cameras, and between the cameras and the laser sheet light, remain physically unchanged. This fundamentally eliminates the uncertainty and random errors caused by repeated disassembly and manual adjustments, ensuring the consistency of all test section data on the spatial reference. This significantly improves the accuracy, efficiency, and data confidence of multi-section, large-scale flow field measurements in large wind tunnels.

[0008] As a further improvement, the three-dimensional adjustment frame includes a second linear drive mechanism and a third linear drive mechanism; one end of the second linear drive mechanism is fixedly connected to the first movable part, and it is arranged along the height direction, with a second movable part that moves along the height direction disposed thereon; one end of the third linear drive mechanism is fixedly connected to the second movable part, and it is arranged along the second horizontal direction, with a third movable part that moves along the second horizontal direction disposed thereon; the mounting part is fixedly connected to the third movable part.

[0009] Its beneficial effects are as follows: the structure clearly and orthogonally deconstructs the drive layout required for three-dimensional spatial movement. By connecting the second and third linear drive mechanisms in series, which are responsible for driving in the height and second horizontal directions respectively, a cantilevered three-dimensional adjustment arm with controllable precision and good rigidity is formed. This layout not only meets the basic function of three-dimensional spatial position adjustment, but more importantly, the movement in each direction is independent and orthogonal. This makes the control logic extremely simple and reliable when "synchronous movement" is required. Only equal displacement commands in the three directions need to be issued, providing a structural foundation for the high-precision synchronous control of the system.

[0010] As a further improvement, the first linear drive mechanism, the second linear drive mechanism, and the third linear drive mechanism are all electrically connected to the controller via cables to achieve centralized or independent control of position.

[0011] Its beneficial effects are as follows: integrated control through a unified controller is a key technological guarantee for achieving "three-dimensional synchronization". It can ensure that when switching test sections, the controller can simultaneously issue precise and synchronized motion commands to a total of nine drive axes corresponding to the three mounting sections, enabling the core function of "fixed optical path and overall translation" to be realized, eliminating manual adjustment and significantly improving the level of test automation and repeatability.

[0012] As a further improvement, the first linear drive mechanism, the second linear drive mechanism, and / or the third linear drive mechanism are any one of a gear and rack mechanism, a timing belt mechanism, or a lead screw and slider mechanism.

[0013] Its beneficial effects are: it provides diverse implementation methods for the drive mechanism, offers open choices, and enhances the adaptability and configurability of the invention in engineering practice.

[0014] As a further improvement, the first camera and the second camera are symmetrically arranged on both sides of the laser sheet light source in the first horizontal direction.

[0015] Its beneficial effects are as follows: This symmetrical layout is a classic optical path configuration for SPIV measurement, which can capture particle images from both sides at approximately equal angles with the laser sheet optical plane as the center; this is conducive to obtaining good three-dimensional particle image perspective effect and high measurement accuracy of out-of-plane velocity components, and is especially suitable for measurement scenarios where the flow field structure is relatively regular and requires symmetrical observation.

[0016] As a further improvement, the first camera and the second camera are arranged together on the same side of the laser sheet light source in the first horizontal direction.

[0017] Its advantages are as follows: This asymmetrical layout provides another important and flexible configuration option for SPIV measurements; when the observation window or space on one side is blocked due to wind tunnel models, supports, or other obstacles, making it impossible to place the camera, this asymmetrical layout becomes the only feasible technical solution. It greatly enhances the system's adaptability to complex and constrained wind tunnel testing environments.

[0018] As a further improvement, the ship model assembly includes a ship model guide rail, a slider, a connecting plate, and a ship model body; the ship model guide rail is fixed along the first horizontal direction; the slider is slidably fitted onto the ship model guide rail; the bottom end of the connecting plate is fixedly connected to the slider, and the top end extends along the height direction and is fixedly connected to the ship model body.

[0019] Its beneficial effects are as follows: This structure endows the ship model with the ability to independently adjust along a first horizontal direction (usually the wind tunnel axis) in the wind tunnel. Combined with the ability of the positioning component in this invention to move the optical path in three-dimensional space, it achieves the decoupling and combination of the functions of "large-range longitudinal adjustment of the model" and "fine three-dimensional scanning of the optical path." This provides extremely high flexibility for testing, allowing for both individual adjustment of the model's longitudinal position to quickly change the test cross-section, and, after the model is fixed, using optical path scanning to complete fine measurements of the three-dimensional space surrounding the model.

[0020] This invention also provides a method for SPIV testing of a ship model flow field based on the above-mentioned device, comprising the following steps: mounting a first camera, a second camera, and a laser sheet light source on three mounting parts of a positioning assembly; independently adjusting the three-dimensional spatial positions of the three mounting parts through the positioning assembly, and manually adjusting the camera shooting angle and the laser illumination plane angle to make the laser plane coincide with the current flow field section to be measured, and the camera field of view meet the SPIV shooting requirements, and then completing the SPIV system calibration; after calibration, keeping the positions of all movable parts on the positioning assembly fixed, and performing flow field measurement of the current test section; when it is necessary to switch to the next test section, controlling the laser sheet light source to move to the spatial position corresponding to the next test section through the positioning assembly, and synchronously controlling the first camera and the second camera to move synchronously in three-dimensional space with the same displacement vector, so that the relative positions and angles between the three remain unchanged before and after the movement; repeating the flow field measurement and synchronous movement steps until the measurement of all predetermined test sections is completed.

[0021] Its beneficial effects are as follows: It proposes a brand-new experimental process of "one-time calibration, overall optical path translation, and continuous measurement of multiple sections". The core advantage of this process is that it completely simplifies the time-consuming and error-inducing "disassembly-fine-tuning-calibration" cycle that must be repeated for each new section in the traditional method into a controlled "synchronous movement" action executed by the controller. This not only improves the efficiency of multi-section testing, but more importantly, it ensures from a physical mechanism that the optical path system that determines the essential accuracy of SPIV measurement remains consistent throughout the entire test, eliminating the deviation of the data system between sections caused by differences in human installation. This makes the flow field data obtained from different spatial locations highly correlated and comparable, providing a high-quality data foundation for the refined analysis and verification of complex flow phenomena.

[0022] As a further improvement, the step of "synchronously controlling the first camera and the second camera to move synchronously in the three-dimensional space with the same displacement vector" specifically involves: controlling the first camera and the second camera to move the same distance in the first horizontal direction, the second horizontal direction, and the height direction based on the displacement of the laser sheet light source.

[0023] Its beneficial effects are as follows: it defines the operational connotation of "synchronous movement"—that is, performing equal displacements in three orthogonal directions of the Cartesian coordinate system; the control logic is clear in this way, it is easy to program and implement, the motion trajectory is highly predictable, and it is the most reliable method to ensure that the principle of "light path invariance" is faithfully realized at the physical level.

[0024] As a further improvement, the SPIV system calibration steps include: placing a calibration target in the wind tunnel test section, adjusting the calibration plane of the calibration target to coincide with the laser plane generated by the laser chip light source, and removing the calibration target after calibration is completed.

[0025] Its beneficial effects are as follows: This step clearly defines the physical reference for the calibration operation, that is, establishing a direct mapping relationship between the calibration target coordinate system and the laser illumination plane; this is the premise for the entire "one-time calibration, universal applicability" technical concept. Through a precise overlap adjustment, a coordinate transformation model from image pixel space to physical world space can be established. Because the optical path remains unchanged in subsequent measurements, this model will be effectively applicable to all cross-sections measured after translation based on this optical path, ensuring the accuracy of the measurement. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the test for the present invention.

[0027] Figure 2 In order to be in Figure 1 The diagram shows the interior of the wind tunnel test section hidden in the design.

[0028] Figure 3 This is a schematic diagram of the positioning component of the present invention.

[0029] Figure 4 This is a schematic diagram showing the cooperation between the linear guide rail and the first connecting part in the positioning component of the present invention.

[0030] Figure 5 This is a schematic diagram of a symmetrical arrangement in one embodiment of the present invention.

[0031] Figure 6 This is a schematic diagram of an asymmetric arrangement in another embodiment of the present invention.

[0032] Among them: 100, wind tunnel test section; 200, glass porthole; 300, ship model assembly; 400, positioning assembly; 500, first camera; 600, second camera; 700, laser sheet light source; 310. Ship model guide rail; 320. Slider; 330. Connecting plate; 340. Ship model body; 410. Base; 420. First linear module; 430. First moving part; 440. First connecting part; 450. Second linear module; 460. Second connecting part; 470. Third linear module; 480. Mounting part; 421. Gear rack; 441. Moving gear; 442. Moving plate; 443. Extension plate. Detailed Implementation

[0033] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In the description of the present invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0035] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0036] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0037] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0038] Example 1 This embodiment provides a three-dimensional synchronous coordinate device for SPIV flow field tests of ship models in a wind tunnel. The device integrates a positioning component 400 that can be controlled to achieve precise adjustment of the three-dimensional spatial position into a rigid or kinematically integral system, which constitutes the first camera 500, the second camera 600, and the laser sheet light source 700 constituting the SPIV measurement optical path. After calibration, the measurement section can be switched by overall translation, fundamentally avoiding changes in the relative relationship of the optical path.

[0039] like Figure 1 and Figure 2 As shown, the main body of the device of the present invention is arranged in the area where the wind tunnel test section 100 is located.

[0040] For ease of explanation, based on the physical structure of the wind tunnel test section 100, a three-dimensional Cartesian coordinate system is defined: the direction of the incoming flow or the axis of the wind tunnel test section 100 is taken as the first horizontal direction, the direction perpendicular to the first horizontal direction in the horizontal plane is taken as the second horizontal direction, and the vertical direction is taken as the height direction.

[0041] The ship model assembly 300 is fixedly installed in the interior space of the wind tunnel test section 100 along the first horizontal direction. The bow and stern lines of its ship model body 340 are usually aligned with the first horizontal direction to simulate the state of the ship in actual navigation.

[0042] The wind tunnel test section 100 is equipped with glass portholes 200 on each of the opposite side walls in the second horizontal direction.

[0043] The glass porthole 200 not only serves as an optical observation window, but its transparent physical properties also allow laser beams to be transmitted to illuminate the flow field cross section, while also allowing the first camera 500 and the second camera 600 to capture images of the particles inside from the outside.

[0044] The positioning component 400 is set on the outside of one side of the wind tunnel test section 100 in the second horizontal direction. Using the glass porthole 200 on this side, the optical paths of the first camera 500, the second camera 600 and the laser sheet light source 700 installed on the positioning component 400 are guided without obstruction and cover the flow field area to be tested around the ship model component 300.

[0045] The following is combined Figure 3 and Figure 4 A detailed description of the positioning component 400 is provided below: The positioning component 400 includes a base 410 for providing a stable support foundation.

[0046] A first linear module 420 extending along a first horizontal direction is disposed on the base 410.

[0047] The first linear module 420 is the basis for realizing the large-stroke, high-precision independent or synchronous motion of three loads in the first horizontal direction.

[0048] In this embodiment, the first linear module 420 adopts a gear and rack drive mechanism, and a rack 421 extending along the first horizontal direction is provided inside it.

[0049] On the first linear module 420, three structurally similar but independently controllable first moving parts 430 are slidably arranged. Each first moving part 430 integrates a drive motor and a gear meshing with a rack 421. When the motor is rotated under control, it drives itself and the load it carries to move linearly along the first horizontal direction through the gear and rack meshing principle.

[0050] Each first moving part 430 is fixedly connected to a first connecting part 440. The function of the first connecting part 440 is to transmit the movement in the first horizontal direction to the subsequent two-dimensional adjustment components and to bear the overturning moment generated by the subsequent cantilever structure. To ensure the smoothness and high guiding accuracy of the movement of the first connecting part 440 in the first horizontal direction, this embodiment additionally provides a movable gear 441 that can roll on the rack 421 at the bottom of the first connecting part 440. The movable gear 441 not only acts as a driven support wheel to share the load, but also forms a forced linear guide with the precise meshing of the rack 421, effectively suppressing the yaw and torsion that may occur in the first connecting part 440 during movement.

[0051] The main body of the first connecting part 440 includes a vertical movable plate 442 for fixed connection with the first movable part 430, and an extension plate 443 extending from the top of the movable plate 442 in the height direction; the design of the extension plate 443 increases its installation area and structural rigidity in the height direction, providing more stable support for subsequent connections.

[0052] A second linear module 450 is fixedly installed on the extension plate 443 of the first connecting part 440.

[0053] The guide rail of the second linear module 450 is set along the height direction, and a second movable part that can be controlled to move along the height direction is slidably arranged on it; a second connecting part 460 is fixedly connected to the second movable part.

[0054] A third linear module 470 is fixedly mounted on the second connecting part 460; the guide rail of the third linear module 470 is set along the second horizontal direction, and a third movable part that can be controlled to move along the second horizontal direction is slidably arranged on it. Finally, a mounting part 480 is fixedly connected to the third movable part.

[0055] Thus, starting from the first moving part 430, the first connecting part 440, the second linear module 450, the second connecting part 460, and the third linear module 470 are connected in sequence, finally reaching the mounting part 480, forming a complete three-dimensional adjustment frame; the three-dimensional adjustment frame provides each mounting part 480 with the ability to move independently and controllably in three orthogonal directions.

[0056] The mounting section 480 is an L-shaped integral molded component. Its vertical section is used to firmly connect with the third movable part, while its horizontal section serves as the final execution end, used to directly support and mount the first camera 500, the second camera 600, or the laser light source 700.

[0057] Three completely independent three-dimensional adjustment frame systems share the same base 410 and guide rail body of the first linear module 420, thus forming the overall structure of the positioning component 400; this enables the three loads, namely the first camera 500, the second camera 600 and the laser sheet light source 700, to be accurately positioned and adjusted independently in the second horizontal and vertical directions on the basis of a shared one-dimensional long stroke.

[0058] To achieve automated and precise synchronous control, all drive motors integrated within the first linear module 420, the second linear module 450, and the third linear module 470 are electrically connected to a central controller via cables. This controller can execute preset control algorithms, either independently sending commands to the motors of each module to achieve independent position adjustment of the three mounting parts 480 to meet the initial installation positioning and optical path construction, or synchronously sending equal displacement commands to all motors to achieve overall translation of the three mounting parts 480 in three-dimensional space.

[0059] It should be noted that this embodiment exemplarily uses a gear and rack mechanism, but in other specific applications with different cost and precision requirements, any or all of the above linear modules can be flexibly replaced with commonly used linear drive mechanisms such as synchronous belt mechanisms or lead screw and slider mechanisms, and all of these should fall within the protection scope of this invention.

[0060] like Figure 5 As shown, a preferred arrangement of the camera and light source in this device is a symmetrical arrangement.

[0061] Specifically, in the first horizontal direction, the laser sheet light source 700 is arranged in the middle position, and the first camera 500 and the second camera 600 are symmetrically arranged on both sides of the laser sheet light source 700. This arrangement allows the two cameras to take pictures from both sides of the laser sheet light plane with a roughly symmetrical perspective, which is very beneficial for obtaining high-precision out-of-plane velocity components and reconstructing the three-dimensional flow field structure. It is especially suitable for measurement scenarios where the flow field structure is relatively regular and the space is not limited.

[0062] Example 2 This embodiment provides a three-dimensional synchronous coordinate device with an asymmetric layout. Its main structure and working principle are basically the same as those of Embodiment 1. The main difference lies in the relative spatial arrangement of the first camera 500, the second camera 600 and the laser sheet light source 700.

[0063] like Figure 6As shown, in this embodiment, the first camera 500 and the second camera 600 are not located on opposite sides, but are arranged together on the same side of the laser sheet light source 700 in the first horizontal direction. The technical significance of this asymmetrical layout is that it greatly improves the adaptability and survivability of the device when facing complex testing environments.

[0064] In actual wind tunnel tests, the ship model and its support system (such as sword supports and stern supports) often obstruct one side of the observation window or internal light path. In this case, a symmetrical arrangement cannot be implemented. However, the asymmetrical layout in this embodiment allows the test personnel to concentrate all optical observation equipment on the unobstructed side, ensuring the smooth progress of the test. With this layout, despite different camera perspective angles, the three-dimensional velocity field can still be accurately reconstructed through a precise SPIV calibration algorithm.

[0065] Based on the apparatus of any of the above embodiments, the present invention provides a SPIV test method for ship model flow field, the core of which lies in "one calibration, multiple synchronous translational measurements". The specific steps of the method are as follows: Step 1, Initial Installation and Configuration: Based on the geometric features of the main body 340 of the ship model under test and the testing requirements, the testers decided to adopt either the symmetrical arrangement of Embodiment 1 or the asymmetrical arrangement of Embodiment 2. After selection, the first camera 500, the second camera 600 and the laser sheet light source 700 were firmly installed on the horizontal sections of the three mounting parts 480 of the positioning component 400 using fasteners such as bolts.

[0066] Step 2, Initial optical path construction and adjustment: The controller, electrically connected to the positioning component 400, is activated. First, the positions of the three first moving parts 430 on the first linear module 420 are independently controlled to coarsely adjust the spacing between the camera and the sheet light source in the first horizontal direction. Then, the positions of each mounting part 480 in the height and second horizontal directions are precisely adjusted by independently controlling the second linear module 450 and the third linear module 470 in each three-dimensional adjustment frame. Through this series of independent single-axis movements, the laser plane emitted by the laser sheet light source 700 is made to approximately coincide with the current first cross-section of the flow field to be measured. Subsequently, the experimenter can manually fine-tune the camera gimbal (not shown in the figure) and the sheet light angle adjustment mechanism of the laser sheet light source 700 mounted on the mounting part 480 to finely optimize the shooting angle of the first camera 500 and the second camera 600 as well as the direction of the laser plane, ensuring that the field of view of the two cameras can clearly and completely capture the particle image illuminated by the laser, and meet the geometric requirements of the SPIV measurement for the viewing angle.

[0067] Step 3, SPIV system calibration: With the initial optical path constructed, the crucial step determining measurement accuracy—calibration—takes place. A precision-machined calibration target is placed at the corresponding position on the main body 340 of the ship model inside the wind tunnel test section 100. Further fine-tuning of the positioning component 400, particularly the three-dimensional adjustment frame corresponding to the laser light source 700, ensures that the laser plane precisely coincides with the calibration plane on the calibration target. At this point, the known geometric pattern on the calibration target is illuminated, and the first camera 500 and the second camera 600 simultaneously capture calibration images. Through a calibration algorithm, an accurate mapping relationship is established between the pixel coordinate systems of the two cameras and the world physical coordinate system, completing the calibration. After calibration, the calibration target is removed, and the positions of all moving parts of the linear modules on the positioning component 400, representing the current optical path, are locked, making it a fixed, standard SPIV measurement optical path reference.

[0068] Step 4, First cross-section measurement: Start the wind tunnel flow field and testing system, perform flow field measurements at the current test section, and acquire particle image data.

[0069] Step 5, synchronize the translation of the entire optical path: After the current cross-section measurement is completed, the test system is shut down. For the next cross-section to be measured, the controller is activated. Based on the preset or newly input spatial displacement vector from the current cross-section to the next cross-section, the controller calculates the required displacement components in the first horizontal direction, the second horizontal direction, and the height direction. Then, a synchronization control command is sent to the positioning component 400 to control the first moving part 430 corresponding to the laser sheet light source 700 and its three-dimensional adjustment frame to move to the target position of the next cross-section; simultaneously, the first moving part 430 corresponding to the first camera 500 and the second camera 600 and their three-dimensional adjustment frames are controlled to perform the same displacement vectors as the laser sheet light source 700 in the three orthogonal directions of three-dimensional space. This is analogous to treating the entire SPIV optical path composed of three sets of devices as a rigid body and precisely "moving" it from one position to another. During this process, the core parameters of the optical path, such as the relative position, angle, and attitude between the two cameras and between the cameras and the laser plane, do not undergo any physical changes.

[0070] Step 6, cyclic measurement: After synchronous movement is complete, no recalibration is required. The component position can be locked directly, and the test system can be run to complete the new cross-sectional measurement. Repeat steps 5 and 6 until all predetermined test cross-sections have been measured.

[0071] In the entire test process of this invention, by changing the tedious manual "disassembly-adjustment-calibration" cycle to a programmed control operation of "one-time calibration-overall synchronous translation", not only is the efficiency of multi-section testing improved, but more importantly, the consistency and comparability of long-cycle, multi-section measurement data on the spatial reference are guaranteed from the principle level, which significantly improves the quality and confidence of test data.

[0072] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The embodiments described above are merely illustrative of implementation methods of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A three-dimensional synchronous coordinate device for SPIV flow field tests of ship models in a wind tunnel, characterized in that, include: The wind tunnel test section (100) has a first horizontal direction, a second horizontal direction, and a height direction that are perpendicular to each other, based on the structural definition of the wind tunnel test section (100); The ship model assembly (300) is disposed inside the wind tunnel test section (100) along the first horizontal direction; A positioning component (400) is disposed on one side of the wind tunnel test section (100) in the second horizontal direction; The positioning component (400) is equipped with a first camera (500), a second camera (600), and a laser sheet light source (700); The wind tunnel test section (100) is equipped with glass portholes (200) on both sides of the second horizontal direction, and the first camera (500), the second camera (600) and the laser sheet light source (700) face the ship model assembly (300) through the glass portholes (200); The positioning component (400) includes: Base (410); A first linear drive mechanism is disposed on the base (410) along the first horizontal direction; Three first movable parts are spaced apart and independently arranged on the first linear drive mechanism to move in a controlled manner along the first horizontal direction; Mounting part (480), each of the first movable parts is connected to the mounting part (480) via a three-dimensional adjustment frame, the first camera (500), the second camera (600) and the laser sheet light source (700) are respectively mounted on the three mounting parts (480); The three-dimensional adjustment frame is used to drive the mounting part (480) to move along the second horizontal direction and the height direction, so that the three mounting parts (480) can achieve synchronous or independent position adjustment in three-dimensional space, so as to achieve one calibration, overall optical path translation, and continuous measurement of multiple sections; The three-dimensional adjustment frame includes a second linear drive mechanism and a third linear drive mechanism; one end of the second linear drive mechanism is fixedly connected to the first movable part, and it is arranged along the height direction, with a second movable part that moves along the height direction disposed thereon; one end of the third linear drive mechanism is fixedly connected to the second movable part, and it is arranged along the second horizontal direction, with a third movable part that moves along the second horizontal direction disposed thereon; the mounting part (480) is fixedly connected to the third movable part.

2. The three-dimensional synchronous coordinate device for SPIV test of ship model flow field in wind tunnel according to claim 1, characterized in that: The first, second, and third linear drive mechanisms are all electrically connected to the controller via cables to achieve centralized or independent control of position.

3. The three-dimensional synchronous coordinate device for SPIV test of ship model flow field in wind tunnel according to claim 1, characterized in that: The first linear drive mechanism, the second linear drive mechanism, and / or the third linear drive mechanism are any one of the following: a gear and rack mechanism, a timing belt mechanism, or a lead screw and slider mechanism.

4. The three-dimensional synchronous coordinate device for SPIV test of ship model flow field in wind tunnel according to claim 1, characterized in that: The first camera (500) and the second camera (600) are symmetrically arranged on both sides of the laser sheet light source (700) in the first horizontal direction.

5. The three-dimensional synchronous coordinate device for SPIV test of ship model flow field in wind tunnel according to claim 1, characterized in that: The first camera (500) and the second camera (600) are arranged together on the same side of the laser sheet light source (700) in the first horizontal direction.

6. The three-dimensional synchronous coordinate device for SPIV test of ship model flow field in wind tunnel according to claim 1, characterized in that: The ship model assembly (300) includes a ship model guide rail (310), a slider (320), a connecting plate (330), and a ship model body (340); the ship model guide rail (310) is fixed along the first horizontal direction; the slider (320) is slidably fitted on the ship model guide rail (310); the bottom end of the connecting plate (330) is fixedly connected to the slider (320), and the top end extends along the height direction and is fixedly connected to the ship model body (340).

7. A method for SPIV test of a ship model flow field based on the apparatus described in any one of claims 1-6, characterized in that, Includes the following steps: The first camera (500), the second camera (600), and the laser sheet light source (700) are respectively mounted on the three mounting parts (480) of the positioning assembly (400); The three-dimensional spatial positions of the three mounting parts (480) are independently adjusted by the positioning component (400), and the camera shooting angle and laser irradiation plane angle are manually adjusted to make the laser plane coincide with the current flow field section to be measured, and the camera field of view meets the SPIV shooting requirements. Then the SPIV system calibration is completed. After calibration, keep the positions of all movable parts on the positioning component (400) fixed and perform flow field measurement of the current test section; When it is necessary to switch to the next test section, the positioning component (400) controls the laser sheet light source (700) to move to the spatial position corresponding to the next test section, and simultaneously controls the first camera (500) and the second camera (600) to move synchronously in three-dimensional space with the same displacement vector, so that the relative position and angle between the three remain unchanged before and after the movement. Repeat the flow field measurement and synchronous movement steps until all predetermined test sections have been measured.

8. The test method according to claim 7, characterized in that, The step of "synchronously controlling the first camera (500) and the second camera (600) to move synchronously in the three-dimensional space with the same displacement vector" specifically involves controlling the first camera (500) and the second camera (600) to move the same distance in the first horizontal direction, the second horizontal direction, and the height direction based on the displacement of the laser sheet light source (700).

9. The test method according to claim 7, characterized in that, The SPIV system calibration steps include: placing a calibration target in the wind tunnel test section (100), adjusting the calibration plane of the calibration target to coincide with the laser plane generated by the laser chip light source (700), and removing the calibration target after calibration is completed.

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