Device for flexible adjustment of model torsional frequency in wind tunnel tests

Abstract

The application provides a device for flexibly adjusting a model torsional frequency in a wind tunnel test, comprising two symmetrical slide rails arranged at two ends of the model, two counterweight assemblies and a detection assembly; the slide rails are installed on the end face of the model; the two counterweight assemblies are respectively provided with two sliding parts which slide along the extension direction of the corresponding slide rail, and the two sliding parts in the same counterweight assembly symmetrically slide about the central axis of the model length direction; the detection assembly is installed on the model, and is used for detecting the displacement of the sliding part and the vibration frequency of the model. The device for flexibly adjusting the model torsional frequency in the wind tunnel test provided by the application can change the mass inertia moment by adjusting the distance between the sliding part and the central axis of the model, continuously and efficiently adjust the torsional frequency of the bridge section model, does not change the spring stiffness of the suspension system, and ensures that only the torsional frequency is adjusted in the elastic suspension section model test.

Description

Technical Field

[0001] This application belongs to the field of wind tunnel testing technology, specifically relating to a device for flexibly adjusting the torsional frequency of a model during wind tunnel testing. Background Technology

[0002] Wind-induced torsional vibration is a dynamic response that bridge structures are prone to under natural wind loads. Flutter, for example, is a destructive divergent vibration involving pure torsion or bending-torsion coupling. Wind tunnel testing is the most commonly used method for evaluating wind-induced torsional vibration of bridges. Therefore, accurately and efficiently simulating and adjusting the torsional frequencies of bridge segment models to reproduce the torsional vibration of actual bridges in real-world environments is crucial for wind-resistant bridge design.

[0003] In existing wind tunnel tests, there are two main methods for adjusting the torsional frequency: First, changing the spring stiffness of the elastic suspension system directly adjusts the torsional stiffness, thereby regulating the model's torsional frequency. Second, manually moving the end weights of the model indirectly regulates the torsional frequency. Both methods have shortcomings. The first method changes the model's vertical bending frequency, making it unsuitable for adjusting the torsional frequency. The second method has the following problems: First, limited accuracy: moving the weights is discontinuous, resulting in discrete frequencies that easily miss the target value; second, time-consuming and labor-intensive: after each weight movement, the frequency needs to be measured immediately, and if the target value is not reached, it needs to be moved and measured again, requiring repeated movements and tests per test; finally, the weights are often attached to the model with tape, and repeated attachment and removal can easily damage the model. Summary of the Invention

[0004] This application provides a device for flexibly adjusting the torsional frequency of a model in wind tunnel tests, aiming to solve the technical problems in the prior art where adjusting the torsional frequency of a model in wind tunnel tests would affect other parameters, and manually adjusting the model's counterweight would be time-consuming and laborious.

[0005] To achieve the above objectives, the technical solution adopted in this application is as follows:

[0006] A device is provided for flexibly adjusting the torsional frequency of a model during wind tunnel testing, comprising:

[0007] Two symmetrical slide rails are provided at both ends of the model. The slide rails are installed on the end faces of the model and the extension direction of the slide rails is perpendicular to the length direction of the model.

[0008] Two counterweight components, each having two sliding parts, slide along the extension direction of the corresponding slide rail, and the two sliding parts within the same counterweight component slide symmetrically about the central axis of the model's length direction; and

[0009] A detection component is mounted on the model and is used to detect the displacement of the sliding part and the vibration frequency of the model.

[0010] In one possible implementation, the counterweight component further includes:

[0011] A driving component is installed inside the model, and the driving component has rotation output ends on both sides;

[0012] Two support frames, installed inside the model and located on either side of the drive component; and

[0013] Two screws are respectively connected to the support frame and the corresponding rotary output end. The two screws are located on both sides of the drive member, and the two screws have opposite directions of rotation.

[0014] The side of the model is provided with a clearance groove corresponding to the screw;

[0015] The sliding part has a mating block extending into the clearance groove on its side. The mating block has a through threaded groove, and the two screws are respectively threaded into the corresponding threaded groove.

[0016] In one possible implementation, the sliding part includes a counterweight block, the bottom of which is provided with a pulley that slides in cooperation with the slide rail. The counterweight block is provided with a docking block on one side near the model, and the sliding directions of the two counterweight blocks in the same counterweight assembly are opposite.

[0017] In one possible implementation, the slide rail is provided with a guide bar, and the bottom of the sliding part is provided with a guide groove corresponding to the guide bar, and the guide groove slides in cooperation with the guide bar.

[0018] In one possible implementation, the top of the counterweight is provided with a fixed post, and the sliding part further includes a plurality of weight-adding blocks, which are respectively inserted into the fixed post and stacked sequentially on top of the counterweight in the vertical direction.

[0019] In one possible implementation, the detection component includes:

[0020] A vibration sensor, mounted on the model, is used to detect the vibration frequency of the model; and

[0021] A displacement sensor is mounted on the sliding part, and the displacement sensor is used to detect the displacement of the sliding part.

[0022] In one possible implementation, the slide rail includes:

[0023] A connecting plate includes a support plate and a fixing plate that are perpendicular to each other, the fixing plate being connected to the side of the model, and the upper surface of the support plate being parallel to the horizontal direction; and

[0024] The guide rail body is mounted on the upper surface of the support plate, and the sliding part is slidably engaged with the guide rail body.

[0025] In one possible implementation, the sliding part includes:

[0026] A sliding seat, slidably connected to the slide rail; and

[0027] A water tank is installed on the sliding seat, and the water tank contains a certain amount of water.

[0028] In one possible implementation, the sliding part further includes:

[0029] The water storage tank is equipped with an outlet pipe and an inlet pipe. The outlet pipe is connected to the top of the water tank, and the inlet pipe is connected to the bottom of the water tank. A flow valve is installed on the outlet pipe.

[0030] In one possible implementation, the water tank is equipped with an air bladder, and the side wall of the water tank has an air inlet and outlet that communicate with the air bladder to change the air volume inside the air bladder.

[0031] The device provided in this application for flexibly adjusting the torsional frequency of a model in wind tunnel testing, compared with existing technologies, firstly involves symmetrically installing two slide rails on the end faces of the model, ensuring that the extension direction of the slide rails is perpendicular to the length direction of the model; then, the sliding part of the counterweight assembly is assembled onto the slide rails, ensuring that the two sliding parts within the same counterweight assembly can slide symmetrically around the central axis of the model; next, a detection component is installed and adjusted to normal working condition; during the test, according to the target torsional frequency, the distance between the sliding part and the central axis of the model is adjusted by moving the sliding part, and the detection component provides real-time feedback on the displacement and current vibration frequency; based on the feedback data, the position of the sliding part is continuously fine-tuned until the model vibration frequency meets the test requirements, thus completing the torsional frequency adjustment. By only adjusting the distance between the sliding part and the central axis of the model to change the moment of inertia, the vertical vibration stiffness of the model is not changed, avoiding the drawbacks of synchronous changes in vertical bending frequency, ensuring that only the torsional frequency is adjusted during the test, thus restoring the authenticity of the torsional vibration of an actual bridge; compared with the manual adjustment of the counterweight, this device achieves continuous adjustment of the torsional frequency through the symmetrical sliding of the sliding part, which can accurately adapt to the test requirements. The detection components monitor displacement and vibration frequency in real time, allowing operators to monitor the adjustment effect immediately, significantly improving adjustment accuracy and speed. The sliding adjustment of the sliding part eliminates the need for frequent pasting and removal of counterweights, making operation convenient and efficient. The symmetrical arrangement of the two slide rails and counterweight components ensures the force balance of the model, avoids uneven loading of the model during adjustment, further improves the reliability of test data, and provides a more accurate basis for bridge wind-resistant design. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application 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 only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a front view schematic diagram of a device for flexibly adjusting the torsional frequency of a model in a wind tunnel test, provided in an embodiment of this application.

[0034] Figure 2 This is a schematic diagram of the counterweight component used in one embodiment of this application;

[0035] Figure 3 This is a top view of the assembly of the counterweight components and model used in an embodiment of this application;

[0036] Figure 4 This is a side view of the slide rail used in one embodiment of this application;

[0037] Figure 5This is a schematic diagram of the counterweight component used in another embodiment of this application;

[0038] Figure 6 This is a schematic diagram of the structure of the counterweight component used in another embodiment of this application;

[0039] Figure 7 This is a structural side view of the counterweight component used in another embodiment of this application.

[0040] Explanation of reference numerals in the attached figures:

[0041] 1. Model;

[0042] 2. Slide rail; 21. Guide bar; 22. Connecting plate; 23. Guide rail body;

[0043] 3. Counterweight components;

[0044] 31. Sliding part; 311. Counterweight; 312. Pulley; 313. Connecting block; 314. Weight-adding block; 315. Fixed column; 316. Sliding seat; 317. Water tank; 318. Water storage tank; 3181. Inlet pipe; 3182. Outlet pipe; 319. Inflatable bladder;

[0045] 32. Driving component; 33. Support frame; 34. Screw;

[0046] 4. Detection components; 41. Vibration sensor; 42. Displacement sensor. Detailed Implementation

[0047] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. The following description of at least one exemplary embodiment is actually illustrative only and is in no way intended to limit this application or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0049] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0050] It should be noted that the terms "length," "width," "height," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "head," and "tail," 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 invention and simplifying the description, and do not 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 on the application. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0051] It should also be noted that, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "linking," "fixing," and "setting" 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. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0052] 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 one or more of that feature. Additionally, "multiple" and "several" mean two or more, unless otherwise explicitly specified.

[0053] In the existing technology, wind-induced torsional vibration is a dynamic response that bridge structures are very likely to experience under natural wind loads, and the vortex-induced vibration phenomenon that frequently occurs in bridges also belongs to torsional vibration.

[0054] Please refer to the following: Figures 1 to 7 The present application describes the device for flexibly adjusting the torsional frequency of a model during wind tunnel testing. The device includes two slide rails 2 symmetrically positioned at both ends of a model 1, two counterweight components 3, and a detection component 4. The slide rails 2 are mounted on the end faces of the model 1, with their extension direction perpendicular to the length direction of the model 1. Each of the two counterweight components 3 has two sliding parts 31, which slide along the corresponding extension direction of the slide rail 2. The two sliding parts 31 within the same counterweight component 3 slide symmetrically about the central axis of the model 1's length direction. The detection component 4 is mounted on the model 1 and is used to detect the displacement of the sliding parts 31 and the vibration frequency of the model 1.

[0055] It should be noted that the two sliding parts 31 inside the counterweight assembly 3 are symmetrical along the bridge axis, and the two sliding parts 31 move simultaneously.

[0056] It should be noted that the working principle of this application is as follows: the sliding part 31 of the counterweight component 3 slides symmetrically along the slide rail 2, changing the distance between the sliding part 31 and the central axis of the model 1, thereby adjusting the mass moment of inertia of the model 1, and ultimately achieving flexible adjustment of the torsional frequency. The detection component 4 collects the displacement of the sliding part 31 and the vibration frequency data of the model 1 in real time, providing accurate basis for adjustment and avoiding blind adjustment.

[0057] In practice, firstly, two slide rails 2 are symmetrically installed on the end faces of the model 1, ensuring that the extension direction of the slide rails 2 is perpendicular to the length direction of the model 1; then, the sliding part 31 of the counterweight component 3 is assembled onto the slide rail 2, ensuring that the two sliding parts 31 within the same counterweight component 3 can slide symmetrically around the central axis of the model 1; then, the detection component 4 is installed and adjusted to normal working condition; during the test, according to the target torsional frequency, the distance between the sliding part 31 and the central axis of the model 1 is adjusted by moving the sliding part 31, and the detection component 4 provides real-time feedback on the displacement and the current vibration frequency; based on the feedback data, the position of the sliding part 31 is continuously fine-tuned until the vibration frequency of the model 1 reaches the test requirements, thus completing the torsional frequency adjustment.

[0058] The device for flexibly adjusting the torsional frequency of a model in wind tunnel testing provided in this embodiment, compared with the prior art, only changes the moment of inertia of the mass by adjusting the distance between the sliding part 31 and the central axis of the model 1, without changing the vertical vibration stiffness of the model 1. This avoids the drawback of synchronous changes in vertical bending frequency, ensuring that only the torsional frequency is adjusted during the test, thus restoring the authenticity of the actual torsional vibration of the bridge. Compared with the manual addition or removal of counterweights, this device achieves continuous adjustment of the torsional frequency through the symmetrical sliding of the sliding part 31, which can accurately adapt to the test requirements under different design stages and construction conditions. The detection component 4 detects the displacement and vibration frequency in real time, allowing operators to monitor the adjustment effect in real time, greatly improving the adjustment accuracy and speed. The sliding adjustment of the sliding part 31 does not require frequent pasting and removal of counterweights, making the operation convenient and efficient. The symmetrical arrangement of the two slide rails 2 and the counterweight component 3 ensures the force balance of the model 1, avoids the model 1 from being unbalanced during the adjustment process, further improves the reliability of the test data, and provides a more accurate basis for the wind-resistant design of bridges.

[0059] In some embodiments, see Figure 3 The counterweight assembly 3 also includes a drive component 32, two support frames 33, and two screws 34. The drive component 32 is installed inside the model 1, and has rotating output ends on both sides. The two support frames 33 are installed inside the model 1 and are located on both sides of the drive component 32. The two screws 34 are respectively connected to the support frames 33 and the corresponding rotating output ends. The two screws 34 are located on both sides of the drive component 32, and the two screws 34 have opposite directions of rotation. The side of the model 1 is provided with clearance grooves corresponding to the screws 34. The side of the sliding part 31 is provided with a mating block 313 that extends into the clearance groove. The mating block 313 has a through threaded groove, and the two screws 34 are threadedly engaged with the corresponding threaded grooves.

[0060] In this embodiment, the screw 34 is rotatably connected to the corresponding support frame 33, and the driving component 32 drives the two screws 34 to rotate. The driving component 32 is a rotary motor, which can be a stepper motor or a servo motor, as long as it can drive the screws 34 to rotate.

[0061] This embodiment achieves automated symmetrical adjustment of the sliding part 31 through the threaded engagement of the drive component 32, screw 34, and mating block 313. The drive component 32 provides stable power, eliminating the need for manual pushing of the sliding part 31 and avoiding problems such as uneven force and displacement deviation caused by manual operation. The two screws 34 rotate in opposite directions, and with the fixed support of the support frame 33, the two sliding parts 31 within the same counterweight assembly 3 can slide synchronously in opposite directions along the slide rail 2 after the drive component 32 is activated, always maintaining symmetry about the central axis of model 1 and avoiding loss of control over the torsional frequency adjustment due to the offset of the sliding part 31. The clearance groove on the side of model 1 provides movement space for the mating block 313, ensuring smooth threaded engagement between the screw 34 and the mating block 313 and preventing structural interference. By controlling the rotation angle of the drive component 32, precise control of the displacement of the sliding part 31 is achieved, further improving the adjustment accuracy of the torsional frequency. Meanwhile, both the drive component 32 and the screw 34 are installed inside the model 1, which is compact and does not affect the overall aerodynamic shape of the model 1. This avoids interference from the external drive structure with the airflow field in the wind tunnel test and ensures the authenticity of the test environment.

[0062] In some embodiments, see Figure 2 The sliding part 31 includes a counterweight 311, and a pulley 312 is provided at the bottom of the counterweight 311. The pulley 312 is slidably engaged with the slide rail 2. A docking block 313 is provided on one side of the counterweight 311 near the model 1. The sliding directions of the two counterweights 311 in the same counterweight component 3 are opposite.

[0063] In this embodiment, the sliding friction between the sliding part 31 and the slide rail 2 is converted into rolling friction through the cooperation of the pulley 312 and the slide rail 2, which greatly reduces the motion resistance and makes the sliding of the counterweight 311 smoother and more stable. This avoids adjustment jamming or displacement deviation caused by excessive frictional resistance and ensures that the drive component 32 can accurately control the movement distance of the counterweight 311. The two counterweights 311 in the same counterweight assembly 3 slide in opposite directions and cooperate with the screw 34 rotating in opposite directions to achieve symmetrical and synchronous adjustment of the counterweights 311 around the central axis of the model 1. This ensures the symmetry and stability of the change in mass moment of inertia and avoids the imbalance of force on the model 1 caused by unilateral adjustment, which would affect the accuracy of torsional frequency detection. The adjustment process does not affect the vertical bending frequency of the model 1, taking into account both the targeting and accuracy of the adjustment, and providing more reliable structural support for the experiment.

[0064] In some embodiments, see Figure 2 The slide rail 2 is provided with a guide bar 21, and the bottom of the sliding part 31 is provided with a guide groove corresponding to the guide bar 21. The guide groove and the guide bar 21 are slidably engaged.

[0065] The guide bar 21 is arranged along the extension direction of the slide rail 2 and fits into the guide groove at the bottom of the sliding part 31. This effectively restricts the movement direction of the sliding part 31, preventing lateral deviation or wobbling during sliding and ensuring that the sliding part 31 always moves along the preset trajectory, thus guaranteeing the accuracy of the displacement of the sliding part 31. The cooperation between the guide groove and the guide bar 21 can share the force on the sliding part 31, reduce local wear between the sliding part 31 and the slide rail 2, extend the service life of the slide rail 2 and the sliding part 31, and reduce the maintenance cost of the device.

[0066] As one embodiment of the guide strip 21, the guide strip is a long strip structure with a square cross-section.

[0067] As another implementation of the guide bar 21, the guide bar 21 is a long strip structure with a T-shaped cross-section.

[0068] In some embodiments, see Figure 5 The counterweight 311 has a fixed post 315 at its top, and the sliding part 31 also includes several weight-adding blocks 314. These weight-adding blocks 314 are inserted into the fixed post 315 and are sequentially stacked on top of the counterweight 311 in a vertical direction. The weight-adding blocks 314 are assembled via an insertion method, making installation and disassembly convenient and eliminating the need for cumbersome pasting or connecting operations, thus saving adjustment time. The weight-adding blocks 314 can be stacked sequentially, allowing for flexible increases or decreases in number according to experimental needs, changing the total counterweight. While meeting the vertical bending frequency of the model, the distance between the sliding part 31 and the central axis of model 1 can be adjusted, achieving multi-dimensional adjustment of the moment of inertia and significantly expanding the adjustment range of the torsional frequency. This adapts to the experimental needs of bridge models 1 with different spans and structural types. By adding or removing individual weight-adding blocks 314, minute changes in the counterweight can be achieved, thereby enabling fine-tuning of the torsional frequency and improving experimental accuracy.

[0069] In some embodiments, see Figure 2 The detection component 4 includes a vibration sensor 41 and a displacement sensor 42. The vibration sensor 41 is mounted on the model 1 and is used to detect the vibration frequency of the model 1; the displacement sensor 42 is mounted on the sliding part 31 and is used to detect the displacement of the sliding part 31.

[0070] It should be noted that the detection component 4 achieves real-time linkage monitoring of displacement and frequency. The vibration sensor 41 is directly installed on the model 1, which can accurately collect the current vibration frequency of the model 1 in real time, allowing the operator to intuitively grasp the actual state of the torsional frequency. The displacement sensor 42 is installed on the sliding part 31, which can accurately capture the displacement of the sliding part 31 and determine the real-time distance between the sliding part 31 and the central axis of the model 1, providing accurate data support for the calculation of the moment of inertia.

[0071] The vibration sensor 41 and displacement sensor 42 provided in this embodiment are combined to form a closed-loop monitoring system. The operator can accurately determine the adjustment direction and amount based on the frequency data fed back by the vibration sensor 41 and the displacement information of the displacement sensor 42, avoiding blindly moving the sliding part 31. The real-time monitoring data can be recorded and archived synchronously, providing complete raw data for the traceability of the test process and subsequent data analysis, which facilitates researchers to conduct in-depth analysis of the wind-induced vibration response law of bridge model 1 under different torsional frequencies.

[0072] In some embodiments, see Figure 4 The slide rail 2 includes a connecting plate 22 and a guide rail body 23. The connecting plate 22 includes a support plate and a fixing plate that are perpendicular to each other. The fixing plate is connected to the side of the model 1, and the upper surface of the support plate is parallel to the horizontal direction. The guide rail body 23 is installed on the upper surface of the support plate, and the sliding part 31 is slidably engaged with the guide rail body 23.

[0073] In this embodiment, the connecting plate 22 consists of a support plate and a fixing plate that are perpendicular to each other. The fixing plate is connected to the side of the model 1, increasing the contact area with the model 1 and improving the connection's firmness. This prevents the slide rail 2 from loosening or shifting due to vibration or the force of the sliding part 31 during the test. The upper surface of the support plate remains horizontal, ensuring that the guide rail body 23 is in a horizontal state after installation. This provides a guarantee for the smooth sliding of the sliding part 31 and avoids uneven force or displacement deviation of the sliding part 31 due to guide rail tilt. The guide rail body 23 is independently installed on the support plate. The structural design is simple, facilitating processing, manufacturing, and subsequent maintenance and replacement. If the guide rail body 23 is worn, it can be replaced separately without disassembling the entire slide rail 2, reducing maintenance costs. The slide rail 2 can stably support the weight of the sliding part 31 and the counterweight, preventing deformation of the slide rail 2 and ensuring the precise sliding trajectory of the sliding part 31, thereby ensuring the accuracy of the torsional frequency adjustment.

[0074] In some embodiments, see Figure 6 and Figure 7 The sliding part 31 includes a sliding seat 316 and a water tank 317; the sliding seat 316 is slidably connected to the slide rail 2; the water tank 317 is installed on the sliding seat 316 and contains a certain amount of water.

[0075] It should be noted that the overall weight of the water tank 317 is changed by altering the volume of the water.

[0076] In this embodiment, water in the water tank 317 is used as a counterweight. The weight can be precisely controlled by adding or subtracting water, allowing for minute adjustments to the counterweight. While meeting the vertical bending frequency requirements of the bridge segment model, the distance of the water tank 317 can be adjusted to meet the needs for fine-tuning the torsional frequency. The water tank 317 is mounted on the sliding seat 316, ensuring structural stability. The water has good fluidity during the test, preventing the counterweight's center of gravity from shifting due to vibration, thus ensuring the stability of the moment of inertia and avoiding problems such as loosening or displacement that may occur with the solid counterweight 311. Water is widely available and inexpensive, significantly reducing the manufacturing cost of the device compared to a customized solid counterweight 311. The water tank 317 has a simple structure, is easy to clean, and can be quickly emptied after use, facilitating the storage and maintenance of the device. The uniform weight distribution of the water allows for more balanced force distribution on the sliding part 31, reducing localized wear on the slide rail 2 and extending the device's service life.

[0077] In some embodiments, see Figure 7 The sliding part 31 also includes a water storage tank 318, which is equipped with an outlet pipe 3182 and an inlet pipe 3181. The outlet pipe 3182 is connected to the top of the water tank 317, and the inlet pipe 3181 is connected to the bottom of the water tank 317. A flow valve is provided on the outlet pipe 3182.

[0078] Specifically, the outlet pipe 3182 and the inlet pipe 3181 are made of flexible hoses, which do not affect the vibration of model 1. After the required water is injected, the outlet pipe 3182 and the inlet pipe 3181 can be disconnected from the water tank 317, and a sealing device, such as a sealing cap or a cork stopper, can be installed at the opening.

[0079] In this embodiment, the coordinated design of the water storage tank 318, inlet and outlet pipes 3182, and flow valve enables automated and precise adjustment of the water counterweight. The water storage tank 318 serves as a water reserve unit, supplying water to the holding tank 317 via the outlet pipe 3182. The inlet pipe 3181 facilitates the return of water from the holding tank 317, forming a closed-loop water circulation system. This eliminates the need for manual addition or emptying of water, avoiding errors and cumbersome procedures associated with manual operation and saving experimental time. The flow valve on the outlet pipe 3182 precisely controls the water flow rate and supply volume. Based on the required vibration frequency, the required counterweight weight can be accurately calculated, and the volume of water injected into the holding tank 317 can be adjusted via the flow valve to achieve precise control of the counterweight, significantly improving the accuracy of torsional frequency adjustment. This automated water supply structure allows for faster response times in counterweight adjustment, quickly adapting to different experimental conditions. Simultaneously, the closed-loop water circulation system reduces water waste and prevents pollution of the experimental environment, maintaining its cleanliness. This structure allows for counterweight adjustment without disassembling the water tank 317, avoiding disturbance to the device structure during adjustment and ensuring the continuity and stability of the experiment.

[0080] In some embodiments, see Figure 7 The water tank 317 is equipped with an air bladder 319. The side wall of the water tank 317 has an air inlet and outlet, which are connected to the air bladder 319 to change the air volume inside the air bladder 319.

[0081] Furthermore, in this embodiment, the inflatable bladder 319 and the water body jointly fill the space within the water tank 317. By changing the air volume within the inflatable bladder 319 through the air inlet and outlet, the effective space occupied by the water body within the water tank 317 can be indirectly adjusted, thereby changing the displaced volume of the water body and its actual counterweight. The operation of the inflatable bladder 319 is simple; adjustment can be made quickly by inflating or deflating the bladder, with a fast response speed. It eliminates the need to wait for water to be injected or discharged, shortening the adjustment time and improving experimental efficiency. Simultaneously, the inflatable bladder 319 is isolated from the water body, not affecting the stability of the water body and avoiding counterweight fluctuations caused by water flow. This gas adjustment method has no mechanical friction, reducing device wear and extending its service life. Moreover, the adjustment process does not generate noise or pollution, maintaining a quiet and clean experimental environment. Compared to traditional counterweight adjustment methods, the inflatable bladder 319 design allows for more flexible and precise adjustment of the torsional frequency. It enables a combination of "coarse adjustment + fine adjustment" control. First, the approximate counterweight is adjusted by adding or removing water, and then fine calibration is performed using the inflatable bladder 319. During the vibration test of Model 1, the water does not shake violently due to the occupancy effect of the inflatable bladder 319, ensuring that the torsional frequency accurately meets the test requirements. This provides a more reliable technical means for in-depth research on the wind-induced vibration characteristics of bridges.

[0082] The following are the acquisition and calculation principles of this embodiment:

[0083] Formula for torsional frequency in a single degree of freedom:

[0084]

[0085] f: Torsional natural frequency;

[0086] k: Torsional frequency;

[0087] I: Moment of inertia of the model about the torsion axis;

[0088] The formula for the moment of inertia of mass is:

[0089]

[0090] m: Mass of the sliding part;

[0091] l: The distance between the sliding part and the central axis of the model;

[0092] After adjusting the mass of the sliding part:

[0093] The initial moment of inertia was I;

[0094] The adjusted moment of inertia is ;

[0095] Difference in moments of inertia:

[0096]

[0097]

[0098] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A device for flexibly adjusting the torsional frequency of a model during wind tunnel testing, characterized in that, include: Two slide rails (2) are symmetrically arranged at both ends of the model (1). The slide rails (2) are installed on the end face of the model (1). The extension direction of the slide rails (2) is perpendicular to the length direction of the model (1). Two counterweight components (3) each have two sliding parts (31), the sliding parts (31) slide along the extension direction of the corresponding slide rail (2), and the two sliding parts (31) in the same counterweight component (3) slide symmetrically about the central axis of the length direction of the model (1); as well as A detection component (4) is installed on the model (1). The detection component (4) is used to detect the displacement of the sliding part (31) and the vibration frequency of the model (1). The counterweight assembly (3) also includes: A drive unit (32) is installed inside the model (1), and the drive unit (32) has rotation output ends on both sides; Two support frames (33) are installed inside the model (1) and located on both sides of the drive element (32); and Two screws (34) are respectively connected to the support frame (33) and the corresponding rotary output end. The two screws (34) are located on both sides of the drive member (32), and the two screws (34) have opposite directions of rotation. The side of the model (1) is provided with a clearance groove corresponding to the screw (34); The sliding part (31) has a mating block (313) extending into the clearance groove on its side. The mating block (313) has a through threaded groove, and the two screws (34) are respectively threaded into the corresponding threaded groove.

2. The device for flexibly adjusting the torsional frequency of a model in wind tunnel testing as described in claim 1, characterized in that, The sliding part (31) includes a counterweight (311), and a pulley (312) is provided at the bottom of the counterweight (311). The pulley (312) is slidably engaged with the slide rail (2). The counterweight (311) has a docking block (313) on one side near the model (1). The sliding directions of the two counterweights (311) in the same counterweight assembly (3) are opposite.

3. The device for flexibly adjusting the torsional frequency of a model in wind tunnel testing as described in claim 1, characterized in that, The slide rail (2) is provided with a guide bar (21), and the bottom of the sliding part (31) is provided with a guide groove corresponding to the guide bar (21), and the guide groove slides in cooperation with the guide bar (21).

4. The device for flexibly adjusting the torsional frequency of a model in wind tunnel testing as described in claim 2, characterized in that, The counterweight (311) has a fixed post (315) at the top, and the sliding part (31) also includes several weight-adding blocks (314). The several weight-adding blocks (314) are respectively inserted and engaged with the fixed post (315), and the several weight-adding blocks (314) are stacked sequentially on top of the counterweight (311) in the vertical direction.

5. The device for flexibly adjusting the torsional frequency of a model in wind tunnel testing as described in claim 1, characterized in that, The detection component (4) includes: A vibration sensor (41) is mounted on the model (1), the vibration sensor (41) being used to detect the vibration frequency of the model (1); and A displacement sensor (42) is mounted on the sliding part (31) and is used to detect the displacement of the sliding part (31).

6. The device for flexibly adjusting the torsional frequency of a model in wind tunnel testing as described in claim 1, characterized in that, The slide rail (2) includes: A connecting plate (22) includes a support plate and a fixing plate perpendicular to each other, the fixing plate being connected to the side of the model (1), and the upper surface of the support plate being parallel to the horizontal direction; and The guide rail body (23) is mounted on the upper surface of the support plate, and the sliding part (31) slides in cooperation with the guide rail body (23).

7. The device for flexibly adjusting the torsional frequency of a model in wind tunnel testing as described in claim 1, characterized in that, The sliding part (31) includes: A sliding seat (316) is slidably connected to the slide rail (2); and A water tank (317) is installed on the sliding seat (316), and the water tank (317) contains a certain amount of water.

8. The device for flexibly adjusting the torsional frequency of a model in wind tunnel testing as described in claim 7, characterized in that, The sliding part (31) further includes: The water storage tank (318) is equipped with an outlet pipe (3182) and an inlet pipe (3181). The outlet pipe (3182) is connected to the top of the water tank (317), and the inlet pipe (3181) is connected to the bottom of the water tank (317). A flow valve is provided on the outlet pipe (3182).

9. The device for flexibly adjusting the torsional frequency of a model in wind tunnel testing as described in claim 7, characterized in that, The water tank (317) is equipped with an air bladder (319). The side wall of the water tank (317) has an air inlet and outlet, which are connected to the air bladder (319) to change the air volume inside the air bladder (319).

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