Passive vortex vibration control device and method based on combination of collision type tuned mass damper and synthetic jet

Abstract

The invention belongs to the field of structural engineering and fluid mechanics, and particularly relates to a passive vortex vibration control device and method based on a collision type tuned mass damper and synthetic jet flow combination. The control device comprises a piston cylinder arranged in the bluff body structure, a piston capable of doing reciprocating motion is arranged in the piston cylinder, through holes are formed in the surfaces, located on the two sides of the piston cylinder, of the bluff body structure, and the two ends of the piston cylinder are communicated with the through holes through fluid pipelines. When vortex-induced vibration happens to the bluff body structure, the piston is driven by structural vibration to reciprocate in the piston cylinder, on one hand, the damping control effect of the tuned mass damper is generated, vibration energy is dissipated through gas compression and expansion, on the other hand, fluid is driven to flow in the fluid pipeline, periodic zero-mass synthetic jet is generated at the position of the through hole, and the zero-mass synthetic jet is generated. The interference vortex falls off, and the fluid load is reduced. According to the invention, through two cooperative physical mechanisms of damping control and flow control, the vortex vibration of the structure is jointly and efficiently inhibited from two aspects of energy dissipation and energy absorption.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of structural engineering and fluid mechanics, and particularly relates to a passive vortex vibration control device and method based on a combination of a collision type tuned mass damper and synthetic jet. BACKGROUND

[0002] In civil, marine and aerospace engineering, when a bluff body structure (such as a bridge cable, a bridge girder, a high-rise bridge tower, a marine platform riser, a building mast, etc.) is subjected to a fluid (such as wind or water flow) perpendicular to its axis, the fluid boundary layer will separate and periodically alternate shedding, forming two rows of vortices with opposite rotation directions and regular arrangement, i.e. the famous "Karman vortex street". This periodic vortex shedding will generate an alternating excitation force perpendicular to the flow direction, which will excite the structure to vibrate when the excitation force frequency is close to or coincides with the natural frequency of the structure. This phenomenon is called vortex-induced vibration (VIV), which is one of the key factors leading to structural fatigue damage and even instability failure.

[0003] In order to suppress or eliminate vortex-induced vibration of the structure, the engineering and academic circles have proposed various control methods, which can be mainly divided into flow control method and damping control method according to the working principle. The flow control method starts from the source of fluid-structure interaction, and intervenes in the vortex shedding process; the damping control method starts from the structural response, and limits the structural amplitude by consuming energy.

[0004] The core idea of the flow control method is to change the flow field characteristics around the structure, interfere with the regularity of vortex shedding, and thus reduce the periodic excitation force applied to the structure. This method can be divided into passive and active forms. Passive flow control usually achieves by changing the shape of the structure or adding specific devices, such as installing spiral stripes, guide plates, stabilizing plates, guide covers on the surface of the structure, or optimizing the aerodynamic shape of the structure. However, the above methods usually have poor adaptability to external flow field changes, resulting in insufficient control effect. At the same time, the external additional devices change the aerodynamic / hydrodynamic shape of the structure, thus changing the lift and drag coefficients and loads of the structure, affecting the overall aesthetics of the structure. Active flow control is more precise, such as active air suction and blowing method, which changes the vortex separation characteristics through boundary layer momentum adjustment mechanism to suppress vortex shedding; and plasma excitation method, which generates directional wall jet by ionizing air to actively disturb the flow field and destroy the formation of large-scale vortices. The above active flow control can be adjusted in real time according to the fluid state, has high control precision, and usually has good control effect. However, its system is relatively complex, requires additional energy input and control system, and has high cost.

[0005] The damper control method does not directly intervene in vortex shedding, but dissipates vibration energy by increasing the damping of the structural system or adding a dynamic vibration absorber, thereby limiting the amplitude. Common measures include installing a tuned mass damper (TMD) in the structure. For example, the damper control is often used for cable vibration of a cable-stayed bridge, and the TMD is used for wind vibration suppression of a super high-rise building structure. The above method is like "strengthening the constitution", so that the structure is not easy to produce large vibration when it is excited, but the damper control method only controls vibration from the perspective of vibration energy dissipation of the structure, and cannot reduce the load acting on the structure.

[0006] Therefore, it is of great significance to develop a vortex vibration control device and method which are simple in structure, low in cost, do not require external energy, have little influence on the original structure appearance, and are stable in vibration suppression effect. SUMMARY

[0007] To overcome the above defects, the purpose of the present application is to provide a passive vortex vibration control device and method based on the combination of a collision type tuned mass damper and a synthetic jet.

[0008] To achieve the above purpose, the technical scheme adopted by the present application is as follows: A passive vortex vibration control device based on the combination of a collision type tuned mass damper and a synthetic jet, comprising a piston cylinder arranged inside a bluff body structure, a reciprocating piston arranged inside the piston cylinder, a through hole opened on the surface of the bluff body structure on both sides of the piston cylinder, and a fluid pipeline connected between both ends of the piston cylinder and the through hole.

[0009] Preferably, the movement direction of the piston is the same as the vortex vibration direction of the bluff body structure.

[0010] Preferably, the reciprocating frequency of the piston is close to or coincides with the vortex vibration frequency of the bluff body structure.

[0011] Preferably, a plurality of through holes are arranged.

[0012] Preferably, the fluid pipeline comprises a main pipeline and a plurality of branch pipelines, the main pipeline is connected with the piston cylinder and each branch pipeline, and each branch pipeline is connected with each through hole.

[0013] A passive vortex vibration control method based on the combination of a collision type tuned mass damper and a synthetic jet, comprising the following steps: S1, setting the mass of the piston, the stroke of the piston cylinder, and the damping coefficient of the piston cylinder wall, so that the reciprocating frequency of the piston is tuned to the vortex vibration frequency of the bluff body structure; S2, when vortex-induced vibration occurs in the bluff body structure, driving the piston to reciprocate in the piston cylinder, and exciting damping dissipation at the same time; S3, by reciprocating motion of the piston in the piston cylinder, a zero mass synthetic jet is generated at the through hole, the boundary layer separation is regulated, the vortex shedding is interfered, and the fluid load is reduced.

[0014] The positive beneficial effects of the present application are: The present application firstly sets the mass of the piston, the stroke of the piston cylinder and the damping coefficient of the piston cylinder wall, so that the reciprocating motion frequency of the piston is consistent with the vortex vibration frequency of the bluff body structure, so that when the bluff body structure occurs vortex-induced vibration, the piston is driven by the structure vibration to reciprocate in the piston cylinder, on the one hand, the damping control effect of the tuned mass damper is generated, the vibration energy is dissipated through fluid compression and expansion, on the other hand, the fluid is driven to flow in the fluid pipeline, a periodic zero mass synthetic jet (output momentum is not zero but output mass is zero) is generated at the through hole, the vortex shedding is interfered, the fluid load is reduced, and the vortex-induced vibration is cooperatively suppressed from the aspects of damping control and flow control.

[0015] The piston, the piston cylinder and the fluid constitute a typical impact tuned damper (PTMD) in the present application, and the existing PTMD achieves energy dissipation by setting an energy absorption device at the impact end, the present application does not set an energy absorption device at both ends of the piston cylinder, and the piston impacts the end of the piston cylinder close to elastic impact, and the system energy consumption is mainly the energy consumption generated in the repeated compression and expansion process of the fluid in the piston cylinder and the fluid pipeline. Meanwhile, the piston, the piston cylinder, the fluid pipeline and the through hole constitute a typical synthetic jet system in the present application, and the existing synthetic jet system is all active control, and needs to provide energy externally, such as a gas pump, a piezoelectric sheet and the like, and the system is complex, the synthetic jet system of the present application is driven by the piston, and the piston is driven by the structure vibration, so that no external energy input and additional control system are needed. Therefore, the piston is driven by the structure vibration in the present application, the motion frequency of the piston is consistent with the structure vibration frequency, the basic working principle of the tuned mass damper is met, and a part of the vibration control effect is provided from the aspect of structural damping; meanwhile, the fluid is driven to generate a synthetic jet, and the frequency of the synthetic jet is also consistent with the structure vibration frequency, at this time, the vortex shedding frequency is locked by the structure vibration frequency, so that the vortex shedding frequency is close to or coincides with the synthetic jet frequency, and the control condition of the synthetic jet is met, and another part of the vibration control effect is provided from the aspect of flow control.

[0016] In summary, the present application proposes a passive vortex vibration control device based on the combination of the impact tuned mass damper and the synthetic jet, and the following positive beneficial effects are generated by the improved impact tuned damper and the synthetic jet system: 1. The control effect is remarkable: through a simple structure, the comprehensive control effect of the combination of the damping control and the flow control is realized, the former enhances the energy dissipation of the structure vibration by improving the equivalent damping ratio of the structure, the latter reduces the fluid load of the structure from the perspective of the flow field, and the two mechanisms jointly produce a stronger control effect.

[0017] 2. Efficient vortex suppression synergy: The present application is a passive vortex control mechanism that combines a collision tuned mass damper with a synthetic jet. The working frequency of the damper and the synthetic jet is affected by the piston drive, which is exactly consistent with the vibration frequency of the structure and the shedding frequency of the vortex. Both control modes are in the best control parameter state, achieving maximum control efficiency.

[0018] 3. No external energy input required: Unlike the complex energy supply and control system of traditional synthetic jets, the present application does not require external energy input, but cleverly relies on the energy generated by the structure vibration to in turn suppress the vibration of the structure.

[0019] 4. Little impact on the aerodynamic / hydrodynamic shape of the bluff body structure: Since the control device is located inside the bluff body structure, it does not significantly change the aerodynamic / hydrodynamic shape of the structure like external additional devices such as spiral stripes and fairings, so it does not change the average damping coefficient and static force of the structure, and does not affect the overall aesthetics of the structure.

[0020] 5. Simple structure, low cost, and high reliability: The core component of the present application is only the passive vortex control device that combines a collision tuned mass damper with a synthetic jet. The material and processing technology requirements are not high, it is easy to achieve standardized production and installation, the production and installation cost is low, the structure is simple, easy to maintain, durable, and the life cycle cost is low. Self-adaptive control with zero energy consumption, with very high working reliability.

[0021] 6. Wide applicability: The structure of the present application is flexible and easy to install. It can be directly designed for use in new projects, and it can also be easily retrofitted to existing bluff body structures, with a wide range of applications. BRIEF DESCRIPTION OF DRAWINGS

[0022] Fig. 1 is a side view of the control device of the present application; Fig. 2 is a front view of the control device of the present application; Fig. 3 is a top view of the control device of the present application; In the figure: 1 - piston, 2 - piston cylinder, 3 - fluid pipeline, 31 - main pipeline, 32 - branch pipeline, 4 - through hole, 5 - bluff body structure. DETAILED DESCRIPTION

[0023] The present application will be further described in conjunction with some specific embodiments.

[0024] Example 1 A passive vortex control device based on the combination of a collision tuned mass damper and a synthetic jet, taking a bluff body structure cylindrical pipe as an example, see Figs. 1-3The control device comprises a piston cylinder 2 arranged inside a bluff body structure 5, a reciprocating piston 1 arranged inside the piston cylinder 2, and through holes 4 arranged on the surfaces of the bluff body structure 5 located on both sides of the piston cylinder 2, and the piston cylinder 2 is connected to the through holes 4 through fluid pipes 3 arranged at both ends of the piston cylinder 2.

[0025] Further, the reciprocating piston 1 has the same direction as the vortex vibration direction of the bluff body structure 5, and there is a phase difference between the reciprocating piston 1 and the bluff body structure 5. The reciprocating piston 1 is driven by the structural vibration to reciprocate in the piston cylinder 2, thereby achieving the vortex vibration suppression from the damping control and the flow control.

[0026] Further, the reciprocating frequency of the reciprocating piston 1 is close to or coincides with the vortex vibration frequency of the bluff body structure 5, thereby satisfying the basic working principle of the tuned mass damper, and the synthetic jet frequency is matched with the vortex shedding frequency, thereby satisfying the control condition of the synthetic jet and achieving the adaptive optimization of the control parameters.

[0027] Further, three through holes 4 are arranged on the surfaces of the bluff body structure 5 located on both sides of the piston cylinder 2. The through holes are arranged on the surfaces of the bluff body structure and located on both sides of the piston cylinder 2, which are the boundary layer separation points. The reciprocating piston 1 drives the fluid to form a zero-mass synthetic jet at the through holes, thereby regulating the boundary layer separation, interfering with the vortex shedding, and reducing the fluid load.

[0028] Further, the fluid pipes 3 comprise a main pipe 31 and three branch pipes 32. The main pipe 31 is connected to the piston cylinder 2 and each branch pipe 32. Each branch pipe 32 is connected to each through hole 4. The through holes are arranged at the boundary layer separation points on the surfaces of the bluff body structure located on both sides, thereby enabling the zero-mass synthetic jet to directly act on the vortex formation area and optimizing the flow control effect.

[0029] Embodiment 2 A passive vortex vibration control method based on the combination of the collision type tuned mass damper and the synthetic jet by using the control device of embodiment 1, comprising the following steps. S1, setting the mass of the piston, the stroke of the piston cylinder, and the damping coefficient of the piston cylinder wall, so that the reciprocating frequency of the piston is tuned to the vortex vibration frequency of the bluff body structure; S2, when the bluff body structure has vortex-induced vibration, driving the piston to reciprocate in the piston cylinder, and exciting the damping dissipation at the same time; S3, generating a zero-mass synthetic jet at the through holes by the reciprocating motion of the piston in the piston cylinder, thereby regulating the boundary layer separation, interfering with the vortex shedding, and reducing the fluid load.

[0030] The control method sets the piston mass, the piston cylinder stroke and the piston cylinder wall damping coefficient, so that the frequency of the reciprocating motion of the piston is close to or coincides with the structural vortex vibration frequency, when the structure occurs vortex-induced vibration, the piston is driven by the structure, and asynchronous same frequency reciprocating vibration will occur, the fluid provides damping dissipation in the vibration process, forming the control effect of the optimal impact tuned mass damper; meanwhile, the through hole is arranged on the upper and lower surfaces of the structure, which is the boundary layer separation point, the piston drives the internal fluid (such as gas) of the cylinder to enter / extract the fluid pipeline, and the zero mass synthetic jet is formed at the through hole, since the vortex shedding frequency is locked by the structural vortex vibration frequency, and the synthetic jet frequency is equal to the piston motion frequency, that is, equal to the structural vortex vibration frequency, therefore the synthetic jet frequency is equal to the vortex shedding frequency at this time, and the optimal synthetic jet control effect can be achieved. The control device of the application controls the structural vortex-induced vibration based on the double control structure of the impact tuned mass damper principle and the synthetic jet principle, that is, through the two cooperative physical mechanisms of damping control and flow control, the structural anti-vortex vibration performance is optimized from the aspects of energy dissipation and energy absorption, so as to efficiently suppress vortex vibration.

[0031] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application, and other modifications or equivalent replacements to the technical solutions of the present application made by those skilled in the art should be covered in the scope of the claims of the present application, as long as they do not deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A passive vortex-induced vibration control device based on a combination of a collision-type tuned mass damper and a synthetic jet, characterized in that, The invention includes a piston cylinder disposed inside a blunt body structure, wherein a reciprocating piston is disposed inside the piston cylinder, and through holes are opened on the surfaces of the blunt body structure on both sides of the piston cylinder, and the two ends of the piston cylinder are connected to the through holes through fluid pipelines.

2. The passive vortex vibration control device based on the combination of a collision-type tuned mass damper and a synthetic jet as described in claim 1, characterized in that, The piston's motion direction is the same as the vortex vibration direction of the blunt body structure.

3. The passive vortex vibration control device based on the combination of a collision-type tuned mass damper and a synthetic jet as described in claim 2, characterized in that, The reciprocating frequency of the piston is close to or coincides with the vortex vibration frequency of the blunt body structure.

4. The passive vortex vibration control device based on the combination of a collision-type tuned mass damper and a synthetic jet as described in claim 1, characterized in that, Multiple through holes are provided.

5. The passive vortex vibration control device based on the combination of a collision-type tuned mass damper and a synthetic jet as described in claim 4, characterized in that, The fluid pipeline includes a main pipeline and several branch pipelines. The main pipeline is connected to the piston cylinder and each branch pipeline, and the branch pipelines are connected to each through hole.

6. A passive vortex-induced vibration control method based on a combination of a collision-type tuned mass damper and a synthetic jet, using the control device described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Set the piston mass, piston cylinder stroke and piston cylinder wall damping coefficient to tune the piston reciprocating motion frequency to the vortex vibration frequency of the blunt body structure. S2. When the blunt body structure undergoes vortex-induced vibration, it drives the piston to reciprocate within the piston cylinder, thereby stimulating damping dissipation. S3. By reciprocating the piston within the piston cylinder, a zero-mass synthetic jet is generated at the through-hole, which regulates boundary layer separation, interferes with vortex shedding, and reduces fluid load.

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