Sound wave control method for inhibiting vortex vibration of engineering structure

Abstract

The invention discloses a sound wave control method for inhibiting vortex-induced vibration of an engineering structure, which utilizes sound waves generated by sound excitation equipment to change the characteristics of an external flow field of the structure and influence the coupling effect of the external flow field and the vibration of the structure, thereby inhibiting the vortex-induced vibration of the engineering structure. The invention discloses a method for determining parameters and an arrangement position of acoustic excitation equipment on the surface of an engineering structure, and the acoustic excitation equipment is used for generating specific sound waves to interfere an external flow field so as to weaken the aerodynamic strength of the surface of the engineering structure and finally achieve the purpose of inhibiting vortex vibration of the structure. When the sound wave control method is applied, the equipment can be hidden in the structure, so that the sound excitation equipment is tightly attached to the surface of the structure without changing the original aerodynamic configuration and structural integrity of the structure, and the original appearance design of the structure is kept.

Description

Technical Field

[0001] The invention belongs to the field of vortex vibration control of engineering structures, and in particular relates to a sound wave control method for suppressing vortex vibration of engineering structures. Background Art

[0002] Vortex-induced vibration is a self-limited wind-induced vibration phenomenon with both forced and self-excited properties caused by the regular shedding of vortices generated when air flows around the surface of the structure. The vortex shedding, drift and its unsteady evolution process determine the aerodynamic force on the cross-section surface and its phase relationship with the structural motion, realizing the conversion of wind energy into vibration energy, which in turn leads to the structural vortex-induced vibration response. When the aerodynamic energy input and the structural damping specific energy consumption reach an energy balance, the vortex-induced vibration limit cycle vibration phenomenon occurs. This structural wind vibration phenomenon at low wind speeds is particularly common in bridges. Vertical vortex vibration has occurred in the Xihoumen Bridge in Zhoushan, the Yingwuzhou Bridge in Wuhan and the Humen Bridge in Guangdong. In addition to vertical vortex vibration, torsional vortex vibration has been observed on site, such as the Kessock Bridge in Scotland and the Hongguang Bridge in Liuzhou, China. Although vortex-induced vibration does not cause divergence like flutter or galloping, it can affect driving safety and even induce other types of aerodynamic instability problems such as cable parameter resonance.

[0003] When vortex-induced vibration occurs in existing engineering structures, various vibration reduction measures can be considered. At present, vibration reduction control measures can be divided into two categories: structural vibration control measures and aerodynamic flow control measures. Aerodynamic flow control measures are a control method based on the flow field, which can be divided into active flow control and passive flow control.

[0004] The traditional means of structural vibration control is to apply damping to the structure, including passive and active tuned mass dampers (TMD, AMD). By adjusting their own mass, stiffness and damping system, the energy of structural vibration is transferred to TMD and AMD, thereby achieving the purpose of reducing or suppressing structural vibration. However, TMD and AMD have heavy mass, which will undoubtedly increase the dead load of engineering structures; their vibration suppression effect is highly dependent on the matching degree between the natural frequency and the structural vibration frequency, and the change of structural vibration frequency will reduce the vibration suppression effect; their design and use require accurate control of parameters such as mass, stiffness, and damping, and the sensitivity to parameters makes the subsequent inspection and maintenance costs high; the limited space in the engineering structure will also affect the further application of TMD and AMD. In addition, for most engineering structures, vortex-induced vibrations in different modes often occur, and TMD and AMD can generally only produce a good control effect on the response of a certain order vibration mode. This feature will seriously limit the application of TMD and AMD in multi-modal vortex-induced vibration control of engineering structures. Such as patents (CN202311277609.9) (CN202223514095.8).

[0005] Active flow control applies external energy to the flow field, directly injects appropriate disturbance modes into the flow environment, and couples with the internal modes of the system to achieve the control purpose, including wall vibration drag reduction method, bubble method, blowing and suction method, momentum injection method, traveling wave wall bionic control method, plasma synthetic jet control method, etc. The above active flow control methods have structural measures such as opening and truncation on the surface of the structure that affect the shape and integrity of the structure, which adds unnecessary influencing factors in actual application and limits the application conditions. Such as patents (CN202410348890.9)(CN202311864207.9)(CN202210231759.5).

[0006] Passive flow control does not consume external energy, does not rely too much on control machinery, and mainly achieves flow control purposes through boundary conditions, pressure gradients, etc. The most common method is to adjust and optimize the aerodynamic shape of the structure, thereby interfering with the flow pattern of the wind field around the structure to affect the aerodynamic force in order to suppress or reduce the structural vibration response, including diverter plates, central slots, and bridge accessories (pedestrian railings, crash railings, maintenance vehicle tracks, etc.) shape and position optimization. Passive control measures are generally permanent, have poor universality, and to a certain extent destroy the aesthetic design of the original engineering structure. At the same time, the installation position of aerodynamic measures is relatively fixed, and it is difficult to adjust in real time according to the characteristics of the incoming wind. Summary of the invention

[0007] To solve the above problems, we proposed an acoustic wave control method for suppressing vortex vibration of engineering structures.

[0008] The technical solution of the present invention is as follows:

[0009] A method for controlling an acoustic wave for suppressing vortex vibration of an engineering structure comprises the following steps:

[0010] Step 1: Test the amplitude change of the structural vortex vibration of the target engineering structure at different wind speeds in a wind tunnel test or on-site measurement to determine the position of the vibration lock zone;

[0011] Step 2, arranging the first acoustic excitation device and the second acoustic excitation device at different positions of the target engineering structure where the structure shape suddenly changes;

[0012] Step 3: Take the acoustic wave parameter combination of the first acoustic excitation device and the second acoustic excitation device as the variable to be solved, simulate the amplitude of the target engineering structure under the preset wind speed using the first acoustic excitation device and the second acoustic excitation device with different acoustic wave parameter combinations, take the obtained structural amplitude as the fitness value, use the genetic algorithm to update the acoustic wave parameter combination value of the first acoustic excitation device and the second acoustic excitation device, and obtain the optimal acoustic wave parameter combination value of the first acoustic excitation device and the second acoustic excitation device by minimizing the fitness value;

[0013] Step 4: Set the first acoustic excitation device and the second acoustic excitation device according to the optimal sound wave parameter combination value. When the incoming wind speed is monitored to enter the vortex vibration locking zone of the target engineering structure, start the first acoustic excitation device and the second acoustic excitation device to suppress the vortex vibration of the target engineering structure.

[0014] Furthermore, in step 3, the sound wave parameters include three parameters: sound wave frequency, amplitude and wavelength.

[0015] Furthermore, in step 3, a first acoustic excitation device is arranged at the bending corners of the top plate and the bottom plate of the main beam of the target engineering structure, and a second acoustic excitation device is arranged at the lower part of the anti-collision guardrail and the upper part of the maintenance track.

[0016] The present invention has the following beneficial technical effects:

[0017] Compared with the traditional control method, the acoustic control method adopted by the present invention has the advantages of light weight, small size, simple installation, flexible regulation, wide frequency band and fast response. Therefore, when the anemometer detects that the incoming wind enters the vortex vibration locking range, real-time feedback adjustment can be made, which is more efficient.

[0018] From the perspective of flow field, the present invention uses acoustic wave excitation to directly inject appropriate disturbance modes into the flow environment, and couples with the internal mode of the system to achieve the control purpose. Acoustic wave excitation can be adjusted in real time according to the characteristics of the incoming wind, and is suitable for vortex-induced vibrations under different modes.

[0019] From a structural perspective, the acoustic wave control method of the present invention can hide the device inside the structure when applied, so that the acoustic excitation device is close to the surface of the structure without changing the original aerodynamic shape and structural integrity of the structure, thereby maintaining the original appearance design of the structure.

[0020] From the control perspective, when the acoustic excitation device of the present invention generates sound waves, the frequency, wave velocity, amplitude, propagation direction and other parameters of the sound waves can be precisely controlled, and specific sound waves can be generated as required, and the physical mechanism of the interaction between the sound waves and the air is clear. The method of using sound waves to act on the flow field to change the flow field characteristics has higher control accuracy and more stable effect, and can more quickly and effectively suppress the vortex vibration of the engineering structure.

[0021] The control method of the acoustic wave to suppress vortex vibration adopted by the present invention is based on the consideration of application to the main beam of the bridge. Compared with the traditional control means, it is more suitable for application to the bridge structure due to its advantages such as small size, light weight, low cost, easy installation, real-time regulation according to the characteristics of the incoming wind, wide range of vibration modes, fast and flexible regulation, stable and high control accuracy, no change to the original aerodynamic shape of the structure, and no damage to the integrity of the structure. At the same time, the control method of the acoustic wave to suppress vortex vibration adopted by the present invention has no obvious usage scenario restrictions in practical applications, and can be applied to the vortex vibration response control of almost all engineering structures (large-span bridges, high-rise buildings, tower mast structures, etc.) and achieve good suppression effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the vertical bending vortex vibration response of the cross section;

[0023] Figure 2 It is a schematic diagram of the layout of the acoustic excitation equipment;

[0024] Figure 3 This is the working diagram of device A;

[0025] Figure 4 This is the working diagram of device B;

[0026] Figure 5 Schematic diagram of pressure variation on the structure surface;

[0027] Figure 6 It is a schematic diagram of the process of controlling the acoustic wave parameters;

[0028] Figure 7 This is a comparison diagram of the flow field when the device is turned off and on;

[0029] Figure 8 This is a comparison chart of the vortex vibration response when the equipment is turned off and on. DETAILED DESCRIPTION

[0030] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0031] The following is a detailed technical solution for acoustic wave suppression of vortex vibration, taking a typical bridge section as an example. (The control method for acoustic wave suppression of vortex vibration, when acting on the flow field to change the flow field characteristics, includes but is not limited to the following three action mechanisms, which are only used to introduce the technical solution and are not the entire content protected by this patent application).

[0032] In this embodiment, the main beam section width (B) is 1.9m, the height (D) is 0.178m, the vertical bending frequency (fb) is 3.32Hz, the vertical bending damping ratio (ξb) is 0.35%, and the wind attack angle (the angle difference between the incoming flow direction and the horizontal direction of the section) is +3°.

[0033] Figure 1 The figure shows the change in the amplitude of the cross-section vortex vibration at different wind speeds in the wind tunnel test. In the figure, U is the incoming wind speed and A is the vortex vibration amplitude. As the wind speed increases, the frequency of vortex shedding no longer changes much at a certain wind speed, and this frequency is close to the fundamental frequency of the main beam, causing resonance. Therefore, the cross-section vibration amplitude shows a significant change in a certain wind speed range, which is called vortex vibration. Such a wind speed range is called the vortex vibration locking zone. Figure 1 As shown in the figure, three vortex-vibration locking zones appear in the cross section of this example at low wind speed. In practical applications, when the incoming wind speed is detected to enter the vortex-vibration locking zone, the active control system starts to work and controls the acoustic excitation device to generate specific sound waves to change the flow field around the structure.

[0034] In practical applications, acoustic excitation equipment is placed at the sudden change of the structure shape in order to affect the key complex flow field area. In this example, the acoustic excitation equipment is arranged near the bending corners of the top and bottom plates of the main beam, the lower part of the anti-collision guardrail and the upper part of the maintenance track. The specific locations are as follows: Figure 2 as shown in .

[0035] The pressure longitudinal waves generated by the acoustic excitation equipment adjust the pressure gradient of the boundary layer on the surface of the structure, thereby controlling the flow separation process at the boundary layer position; the sound waves generated by the acoustic excitation equipment drive the air outside the surface of the structure to vibrate, thereby preventing the detached vortex from attaching to the main beam surface again; the acoustic wave excitation is used to add appropriate disturbances to the external flow field on the surface of the engineering structure, and real-time feedback adjustment is made according to the characteristics of the incoming wind. The added acoustic wave disturbance meets specific parameters, including wavelength, wave speed, amplitude, frequency and propagation direction.

[0036] In the figure, A and B represent the first acoustic excitation device and the second acoustic excitation device respectively. The acoustic excitation device A mainly plays the role of controlling the boundary layer separation, and the acoustic excitation device B mainly plays the role of preventing the separation vortex generated by the leading edge from attaching to the main beam surface again. The process of injecting a suitable disturbance mode into the external flow field of the engineering structure to weaken the aerodynamic force on the surface of the structure is controlled by the coordinated action of the acoustic excitation devices A and B.

[0037] When the airflow passes over the main beam surface, due to the adhesion between the wall and the air and the viscosity of the air, a boundary layer air velocity gradient is formed as shown in the figure (the air tangential velocity at the wall is 0, and the air tangential velocity along the wall normal gradually increases and eventually equals the incoming wind speed). Figure 3 As shown in (a), a relatively stable and continuous boundary layer is formed on the main beam surface. When the sound source device A is turned on, Figure 3 As shown in (b), it generates a series of dense and sparse longitudinal pressure waves. The pressure waves couple with the velocity gradient of the boundary layer to produce an adverse pressure gradient to induce the boundary layer to separate at a suitable position.

[0038] The separation vortex generated upstream attaches to the main beam surface again and drifts along the main beam surface, which causes the pressure change on the main beam surface and is the main reason for inducing vortex vibration. Figure 4 As shown in (a), when the sound source device is not working, the separation vortex generated upstream will attach to the main beam surface again, which will generate a pressure wave that directly acts on the main beam surface. The periodic change of pressure generated by the movement of the pressure wave and the vortex along the incoming flow direction will induce vortex vibration of the main beam. Figure 4 As shown in (b), when the sound source device B is turned on, the sound waves it generates will drive the air outside the main beam surface to vibrate. The diffuse vibration toward the outside can prevent the detached vortex from attaching to the main beam surface again, thereby weakening or even cutting off the direct interaction between the separation vortex and the main beam surface.

[0039] By coordinating the acoustic excitation devices A and B, appropriate disturbances can be injected into the external flow field of the engineering structure. Figure 5 As shown in , after injecting appropriate disturbances into the external flow field through acoustic waves, the aerodynamic force distribution on the surface of the engineering structure shows a weakening effect from the solid line to the dotted line. Both the acoustic wave parameters and the aerodynamic force weakening effect of the surface distribution of the engineering structure can be precisely controlled through coordinated control between acoustic excitation devices, thereby generating a suitable disturbance pattern to reduce the aerodynamic force that is unfavorable to the vortex vibration of the main beam caused by the original flow field.

[0040] The dominant pressure wave action mode on the main beam surface is extracted, and acoustic wave disturbances of specific wavelength, frequency, and amplitude are generated through acoustic excitation devices A and B. The acoustic wave disturbance mode is coupled with the aerodynamic force of the structure surface distribution with the dominant pressure wave on the main beam surface as the core, so that the pressure pulsation value acting on the main beam surface is greatly reduced, thereby achieving the purpose of reducing the vortex vibration of the main beam. The surface pressure in the time domain can be converted to the frequency domain by Fourier transforming the surface pressure data obtained from the main beam experiment or numerical simulation, so that the dominant frequency of the pulsating pressure can be determined, and the spatial distribution of the pulsating pressure phase on the main beam surface at the dominant frequency can be obtained, and then the dominant pressure wave wavelength is determined by the main beam width and the phase difference at both ends. The wavelength and wave velocity of the dominant pressure wave are determined by the above method, which can provide a basis for the parameter control of generating a suitable acoustic wave disturbance mode using acoustic excitation equipment.

[0041] The working condition of this example is the wind speed corresponding to the third vortex-vibration locking zone. The initial sound wave parameters (frequency, amplitude, wavelength) of the active acoustic wave control system are referenced to the optimal solution obtained by numerical simulation determined by the genetic algorithm. The genetic algorithm mainly has the following process: first determine the number of initial sound wave parameter groups, and then randomly generate a set of initial parameter groups, each of which represents a possible solution to the set target. The structural amplitude is used as the fitness to measure the adaptability of the parameter group to the target. The parameter group with high fitness has a higher probability of being selected in subsequent operations. Select parameter groups from the set according to a certain probability, select some parameter groups for two-to-two crossover, and exchange some of their parameters to generate new parameter groups. Mutate some parameters of the parameter group with a lower probability to increase the diversity of parameters and avoid the algorithm from converging to the local optimal solution too early. Repeat the fitness evaluation, selection, crossover and mutation operations on the newly generated set. After multiple generations of evolution, the fitness of the parameter groups in the set will gradually increase until the structural vortex vibration amplitude limit is met.

[0042] The initial value of the acoustic wave parameter is determined by the optimal parameter group under the set target obtained by the genetic algorithm. The initial value is taken near the optimal parameter group. The acoustic wave control system further determines the optimal value of the acoustic wave parameter in the actual environment through actual application. The acoustic wave control system carefully controls the three parameters of acoustic wave frequency, amplitude, and wavelength respectively, and monitors the changes in the amplitude of the structure after control to guide the next control. The specific control process is as follows Figure 6 as shown in .

[0043] The essential reason why acoustic wave control can suppress bridge vortex vibration is that it produces a suitable acoustic wave disturbance mode on the flow field around the engineering structure by regulating the acoustic excitation equipment, and finally changes the aerodynamic characteristics of the main beam surface from the above three control angles. When the acoustic wave control device is turned off, there is a large-scale vortex drift evolution around the main beam, the pressure wave intensity on the main beam surface is large, and the vortex vibration response is obvious; when the acoustic wave control device is turned on, the acoustic wave disturbance changes the flow field characteristics around the engineering structure, there is no large-scale vortex drift evolution around the main beam, the pressure wave intensity on the main beam surface is reduced, and the vortex vibration response is significantly reduced. The acoustic wave control device takes the reduction of the intensity of the pressure wave acting on the main beam surface as the control target, which can achieve the effect of significantly reducing the vortex vibration of the bridge. Figure 7 The significant changes in the flow field around the main beam before and after the acoustic wave control device is turned on are shown. By comparing the difference in the structural vortex vibration amplitude when the acoustic wave control system is turned on and off in the wind tunnel test, it can be seen that the acoustic wave control system effectively suppresses the structural vortex vibration amplitude in the locking area. The specific suppression effect is as follows: Figure 8 As shown, it is proved that the acoustic wave method to control vortex vibration is practical and effective.

[0044] Working principle: Under normal conditions, the acoustic excitation active control system does not work. When the anemometer detects that the incoming wind enters the vortex vibration locking zone, the appropriate disturbance mode is directly injected into the flow environment through acoustic wave excitation, adding additional influence to the original flow field, thereby changing the flow field characteristics around the engineering structure, and ultimately achieving the purpose of suppressing vortex-induced vibration. After completing the autonomous control of the acoustic wave control system, the vibration amplitude value and change value of the structural section will be detected, and the positive and negative changes of the change value will guide the active control system to further adjust the control parameters of the acoustic excitation equipment to generate sound waves until the vibration amplitude of the structural section meets the requirements.

[0045] The present invention utilizes the sound waves generated by the acoustic excitation device to change the external flow field characteristics of the structure, affecting the coupling effect between the external flow field and the structural vibration, thereby suppressing the vortex-induced vibration of the engineering structure. A method for determining the dominant pressure wave on the surface of the engineering structure, and using the acoustic excitation device to inject a suitable disturbance mode into the flow field around the engineering structure to weaken the intensity of the pressure wave on the surface of the engineering structure, ultimately achieving the purpose of suppressing the vortex vibration of the structure. When the acoustic wave control method of the present invention is applied, the device can be hidden inside the structure, so that the acoustic excitation device is close to the surface of the structure without changing the original aerodynamic shape and structural integrity of the structure, thereby maintaining the original appearance design of the structure.

[0046] The above is an example of the best implementation of the present invention, and the parts not described in detail are common knowledge of ordinary technicians in the field. The protection scope of the present invention shall be based on the content of the claims, and any equivalent transformation based on the technical enlightenment of the present invention is also within the protection scope of the present invention.

Claims

1. A method for controlling acoustic waves for suppressing vortex vibration of an engineering structure, characterized in that: The following steps are involved: Step 1: testing the amplitude change of the structural vortex vibration of the target engineering structure at different wind speeds in a wind tunnel test or on-site measurement to determine the position of the vortex vibration locking zone; Step 2, arranging the first acoustic excitation device and the second acoustic excitation device at different positions of the target engineering structure where the structure shape suddenly changes; Step 3: Take the acoustic wave parameter combination of the first acoustic excitation device and the second acoustic excitation device as the variable to be solved, simulate the amplitude of the target engineering structure under the preset wind speed using the first acoustic excitation device and the second acoustic excitation device with different acoustic wave parameter combinations, take the obtained structural amplitude as the fitness value, use the genetic algorithm to update the acoustic wave parameter combination value of the first acoustic excitation device and the second acoustic excitation device, and obtain the optimal acoustic wave parameter combination value of the first acoustic excitation device and the second acoustic excitation device by minimizing the fitness value; Step 4: Set the first acoustic excitation device and the second acoustic excitation device according to the optimal sound wave parameter combination value. When the incoming wind speed is monitored to enter the vortex vibration locking zone of the target engineering structure, start the first acoustic excitation device and the second acoustic excitation device to suppress the vortex vibration of the target engineering structure.

2. The acoustic wave control method for suppressing vortex vibration of a target engineering structure according to claim 1, characterized in that: In step 3, the sound wave parameters include three parameters: sound wave frequency, amplitude and wavelength.

3. The acoustic wave control method for suppressing vortex vibration of a target engineering structure according to claim 1, characterized in that: In step 3, a first acoustic excitation device is arranged at the bending corners of the top plate and the bottom plate of the main beam of the target engineering structure, and a second acoustic excitation device is arranged at the lower part of the anti-collision guardrail and the upper part of the maintenance track.

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