A large-span split three-box beam structure wind-induced vibration active control system

Abstract

The application discloses a wind-induced vibration active control system of a large-span split three-box beam structure, which controls large-amplitude vortex vibration of the large-span split three-box beam. The system comprises an air suction pump, an air blowing pump, a real-time flowmeter, a hot-wire anemometer and a main control computer. A slit is arranged at a flow characteristic point on the surface of the box beam, wherein the flow separation point is set as air suction control, and the laminar shear layer roll-up point and the vortex collision point are set as air blowing control, so that the control effects of inhibiting flow separation on the surface of the box beam, preventing the surface shear layer from rolling up and interacting, and avoiding the collision between the vortex and the box beam are achieved, the flow around the whole structure of the split three-box beam is more stable, the system has high practicability, and the control effect is obvious.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wind-induced vibration control, and particularly relates to a wind-induced vibration active control system for a large-span split three-box girder structure. BACKGROUND

[0002] Compared with the traditional truss main girder and closed single-box girder, the application of split three-box girder bridge section type can further break through the limit span, improve the flutter stability and limit design wind speed of the large-span bridge. However, unlike the flow around the single-box girder, due to the existence of the gap between the adjacent box girders of the split three-box girder, the vortex in the flow field can collide with the box girder surface, which makes the vortex dynamics behavior in the flow field more complex, the stability of the flow around is reduced, the downstream box girder will not only be subjected to the unsteady action caused by the flow separation of the wake flow, but also be subjected to the direct action of the gap vortex collision of the upstream, and finally can be induced to a large amplitude vortex-induced vibration at low wind speed, which causes the fatigue damage of the bridge deck structure member and the discomfort of the driver on the bridge, and lays a safety hidden danger for major traffic accidents. Therefore, it is necessary to adopt an effective method to control the wind-induced vibration of the large-span split three-box girder. SUMMARY

[0003] Based on the above problems, the purpose of the present application is to provide a wind-induced vibration active control system for a large-span split three-box girder structure, which solves the problem of wind-induced vibration of the large-span split three-box girder.

[0004] To achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: an active control system for wind-induced vibration of a large-span split three-box girder structure, comprising an air suction pump, an air blowing pump, a real-time flow meter, a hot wire anemometer and a main control computer, wherein air suction and blowing slits are arranged based on the flow characteristic points on the box girder surface, and ten slits are opened on the box girder along its entire length for blowing or suctioning, and the positions of the slits are as follows: the first slit: the corner position of the front edge of the windward surface of the upstream box girder; the second slit: the upper position of the shear layer rolling up on the leeward side of the upstream box girder; the third slit: the lower position of the shear layer rolling up on the leeward side of the upstream box girder; the fourth slit: the upper position of the vortex collision point on the windward side of the middle box girder; the fifth slit: the lower position of the vortex collision point on the windward side of the middle box girder; the sixth slit position: the upper position of the vortex collision point on the leeward side of the middle box girder; the seventh slit: the lower position of the vortex collision point on the leeward side of the middle box girder The 8th slit is located at the upper part of the vortex collision point on the leeward side of the downstream box girder; the 9th slit is located at the lower part of the vortex collision point on the leeward side of the downstream box girder; the 10th slit is located at the corner of the trailing edge of the leeward side of the downstream box girder; the 1st and 10th slits are suction slits, and the 1st to 9th slits are blowing slits. The 1st slit is connected to the 1st suction pump through the 1st suction pipe, and the 2nd and 3rd slits are connected to the 2nd blowing pipe through the 2nd blowing pipe. The 4th slit and the 5th slit are connected to the 3rd air pump through the 3rd air pipe, the 6th slit and the 7th slit are connected to the 4th air pump through the 4th air pipe, the 8th slit and the 9th slit are connected to the 5th air pump through the 5th air pipe, and the 10th slit is connected to the 6th suction pump through the 6th air pipe. A hot wire anemometer is set at the mouth of each slit to measure the flow field wind speed U1~U 10 Real-time collection is performed, and then the collected flow field wind speed U1~U 10 The data is input into the main control computer, and the wind speed U1~U 10 To control the power of different suction or blowing pumps, get the given suction or blowing average speed U at different slits sj , where j = 1-10, thereby controlling the wind-induced vibration of the entire box girder.

[0005] Furthermore, the given suction or blowing rate U sj The calculation formula is as follows:

[0006] A s =αHL

[0007] Q c1 =β1U1·πD 2 / 4

[0008] Q c2 =β2{U2,U3} max ·πD 2 / 4

[0009] Q c3 = β3{U4, U5} max · πD 2 / 4

[0010] Q c4 = β4{U6, U7} max · πD 2 / 4

[0011] Q c5 = β5{U8, U9} max · πD 2 / 4

[0012] Q c6 = β6{U 10} max · πD 2 / 4

[0013] In the formula, A s is the slit area, α is the slit height ratio coefficient, α = 0.05-0.1, H and L are the height and length of the three box beams respectively, {·} max indicates the maximum value of all variables in the brackets, β i is the empirical coefficient of the pipeline flow, β1=1.0-1.2, β2=0.6-1.0, β3=1.0-1.5, β4=0.6-1.0, β5=1.0-1.4, β6=0.8-1.2.

[0014] Further, the flow meter is used to measure the real-time gas flow Q ci (t) of each pipeline, i = 1-6, and the real-time gas flow Q ci (t) data is fed back to the host computer, and the host computer uses PID control on the suction or blowing pump to gradually eliminate the deviation, so that the actual suction or blowing rate U sj (t) at each slit port reaches the given suction or blowing rate U sj as soon as possible. The specific calculation formula is as follows:

[0015]

[0016] e(t) = U sj -U sj (t)

[0017] In the formula, t is each time; K p is the proportional coefficient, K p = 0.02; K i=0.06; K d =0.001; e(t) is the error between each moment and the expected target.

[0018] Furthermore, the height of the slit is 0.05 to 0.1 times the center height of the split three-box girder.

[0019] Furthermore, an inner baffle is installed on the slit, and the inner baffle is closed when not actively controlled.

[0020] Advantages and beneficial effects of the present invention: Under a specific suction and blowing rate, the present invention will induce a series of antisymmetric small-scale secondary vortices in the area between adjacent suction and blowing holes on the box girder surface, which can effectively prevent the rolling up and interaction of the upper and lower surface separation shear layers of the box girder gap flow field and the near-wake flow field, and due to the presence of the blowing slit on the windward side of the box girder, the shedding vortex in the wake of the upstream box girder cannot collide with the surface of the downstream box girder, the overall structure of the split three-box girder has more stable flow, high feasibility, and obvious control effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the slit location of the large-span split three-box girder structure.

[0022] Figure 2 Schematic diagram of the structure of an active control system for wind-induced vibration of a large-span split three-box girder structure according to Example 1 of the present invention.

[0023] Figure 3 Schematic diagram of the working principle of the active control method for wind-induced vibration of a large-span split three-box girder structure.

[0024] Figure 4 Figure 1 shows the spanwise vorticity diagram of the flow field around the split three-box girder under uncontrolled and controlled conditions using Example 1 of the present invention. (a) shows the spanwise vorticity diagram of the flow field around the split box girder under uncontrolled conditions; (b) shows the spanwise vorticity diagram of the flow field around the split box girder under controlled conditions.

[0025] Figure 5 The following are time-varying curves of the unsteady aerodynamic coefficients of the split three-box girder as a whole and for each individual box girder under uncontrolled and controlled conditions according to Example 1 of the present invention. (a) is a time-varying curve of the drag coefficient under uncontrolled conditions; (b) is a time-varying curve of the lift coefficient under uncontrolled conditions; (c) is a time-varying curve of the drag coefficient under controlled conditions; and (d) is a time-varying curve of the lift coefficient under controlled conditions.

[0026] Figure 6The time-averaged flow streamlines and turbulent kinetic energy diagrams for the box girder gap flow field and the near-wake flow field under uncontrolled conditions using Example 1 of the present invention are shown. (a) shows the time-averaged flow streamlines and turbulent kinetic energy diagram for the box girder gap flow field; (b) shows the time-averaged flow streamlines and turbulent kinetic energy diagram for the near-wake flow field.

[0027] Figure 7 The time-averaged flow streamlines and turbulent kinetic energy diagrams for the box girder gap flow field and the near-wake flow field under controlled conditions using Example 1 of the present invention are shown. (a) shows the time-averaged flow streamlines and turbulent kinetic energy diagram for the box girder gap flow field; (b) shows the time-averaged flow streamlines and turbulent kinetic energy diagram for the near-wake flow field. DETAILED DESCRIPTION

[0028] The present invention will be further described below with reference to the accompanying drawings and examples.

[0029] Example 1

[0030] like Figures 1-2 As shown, an active control system for wind-induced vibration of a large-span split three-box girder structure includes an air suction pump 21, an air blowing pump 22, a real-time flow meter 23, a hot-wire anemometer 25, and a main control computer 24. Air suction and air blowing slits are arranged based on the flow characteristic points on the box girder surface. Ten slits are opened on the box girder along its entire length for blowing or suction. The positions of the slits are as follows: the first slit 1: at the corner of the windward front edge of the upstream box girder; the second slit 2: at the upper The upper position of the shear layer roll-up on the leeward side of the upstream box girder; the third slit 3: the lower position of the shear layer roll-up on the leeward side of the upstream box girder; the fourth slit 4: the upper position of the vortex collision on the windward side of the middle box girder; the fifth slit 5: the lower position of the vortex collision on the windward side of the middle box girder; the sixth slit position 6: the upper position of the vortex collision on the leeward side of the middle box girder; the seventh slit 7: the lower position of the vortex collision on the leeward side of the middle box girder; the eighth slit 8: the vortex collision on the leeward side of the downstream box girder The 9th slit 9 is located at the upper part of the vortex collision point on the leeward side of the downstream box girder; the 10th slit 10 is located at the corner of the trailing edge of the leeward side of the downstream box girder. The height of the slit is 0.05 to 0.1 times the center height of the split three-box girder. The 1st and 10th slits are suction slits, and the 1st to 9th slits are blowing slits. The 1st slit is connected to the 1st suction pump through the 1st suction pipe, and the 2nd and 3rd slits are connected through the 1st suction pipe. The 2nd blowing pipe is connected to the 2nd blowing pump, the 4th slit and the 5th slit are connected to the 3rd blowing pump through the 3rd blowing pipe, the 6th slit and the 7th slit are connected to the 4th blowing pump through the 4th blowing pipe, the 8th slit and the 9th slit are connected to the 5th blowing pump through the 5th blowing pipe, and the 10th slit is connected to the 6th suction pump through the 6th blowing pipe. A hot wire anemometer is set at the mouth of each slit to measure the flow field wind speed U1~U 10 Real-time collection is performed, and then the collected flow field wind speed U1~U 10The data input to the host computer, according to the flow field wind speed U1~U 10 The power of different suction or blowing pumps is controlled to obtain the given suction or blowing average speed U of the slits sj Wherein, j=1-10, so as to control the wind-induced vibration of the whole box girder. The given suction or blowing rate U sj The calculation formula is as follows:

[0031] A s =αHL

[0032] Q c1 =β1U1·πD 2 / 4

[0033] Q c2 =β2{U2,U3} max ·πD 2 / 4

[0034] Q c3 =β3{U4,U5} max ·πD 2 / 4

[0035] Q c4 =β4{U6,U7} max ·πD 2 / 4

[0036] Q c5 =β5{U8,U9} max ·πD 2 / 4

[0037] Q c6 =β6{U 10} max ·πD 2 / 4

[0038] In the formula, As is the slit area, α is the slit height ratio coefficient, α=0.05~0.1, H and L are the height and length of the whole three box girders respectively, {·} max Indicates the maximum value of all variables in the parentheses, β i is the empirical coefficient of pipe flow, which is related to the position of the slit distribution on the surface of the box girder and the setting of the suction and blowing control mode, β1=1.0~1.2, β2=0.6~1.0, β3=1.0~1.5, β4=0.6~1.0, β5=1.0~1.4, β6=0.8~1.2. The flow meter is used to measure the real-time gas flow Q of each pipeci (t) Measurements are taken, i = 1-6, and real-time gas flow Q ci (t) Data is fed back into the main computer, which uses PID control to eliminate the deviation amount step by step, so that the actual suction and blowing rate U sj (t) The given suction and blowing rate U sj is reached as soon as possible

[0039]

[0040] e(t) = U sj - U sj (t)

[0041] In the formula, t is each time; K p is the proportional coefficient, K p = 0.02; K i = 0.06; K d = 0.001; e(t) is the error amount at each time from the expected target.

[0042] In combination Figure 3 , the active control system will cause a series of anti-symmetric small-scale secondary vortices between the adjacent slits on the surface of the box girder at the given suction and blowing rate U sj . This can effectively prevent the interaction of the upper and lower surface separation shear layers of the gap flow field and the near wake flow field between the box girders, and because of the presence of the blowing slits on the windward surface of the box girder, the shedding vortices in the upstream box girder wake do not collide with the surface of the downstream box girder, and the overall surface flow around the box girder is more stable. An inner baffle is installed on the slit, and when the wind-induced vibration control of the split three-box girder structure is not needed, the inner baffle is closed.

[0043] Secondly, through high-precision numerical simulation, the surrounding flow field of the split three-box girder structure before and after the suction and blowing slits are arranged is reproduced and visually analyzed, as shown in Figure 4 (a) shows that under the condition of no control, the shear layer on the trailing edge surface of the upstream box girder rolls up, large-scale vortices are formed alternately on the upstream gap flow field, and after colliding with the intermediate box girder, they continue to act on the windward surface of the downstream box girder at the downstream gap, and finally form an alternating vortex pair in the near wake flow area of the box girder. While under the condition of control, as shown in Figure 4 (b), due to the presence of the slits, the shear layer on the surface of each position box girder is elongated and no longer rolls up, so no large-scale vortices are observed in the upstream and downstream gap flow fields, but only vortices are produced in the wake field away from the box girder, but the formation length is significantly increased compared to the condition without control, similar to two vortex bands, and roughly symmetric shedding.

[0044] NextFigure 5 The uncontrolled conditions ( Figure 5 (a)) and under controlled conditions ( Figure 5 (b)) The unsteady aerodynamic conditions of the split three-box girder. By comparison, it can be seen that under active suction and blowing control, the pulsation of the overall aerodynamic coefficient of the split box girder is significantly suppressed. The unsteady aerodynamic coefficient of the upstream box girder is almost stable under the combined action of headwind blowing and leeward blowing, and is approximately a constant. In addition, the average drag coefficient is greatly reduced. This is mainly attributed to the fact that the middle box girder successfully avoids collision with the upstream gap vortex under the action of headwind blowing, and is thus not subject to additional vortex forces. The magnitude and pulsation of the drag coefficient are greatly suppressed. Finally, within the same time range, the number of periodic changes in the aerodynamic force of the box girder under controlled conditions is less than that under uncontrolled conditions. This shows that suction and blowing control also plays a role in delaying the vortex shedding phenomenon in the flow field, reducing the frequency of vortex shedding.

[0045] Figure 6 The time-averaged streamlines and turbulent kinetic energy distributions of the box girder gap flow field and the near-wake flow field under uncontrolled conditions are shown. The results show that the gap flow fields upstream and downstream of the box girder under uncontrolled conditions exhibit high turbulent kinetic energy amplitudes, with large shed vortices forming close to the box girder surface. Turbulent pulsation effects are evident in the gap flow field. The near-wake recirculation region is smaller, indicating a shorter vortex formation length and closer proximity of the shed vortices to the cable structure wall. The peak turbulent kinetic energy is larger, indicating significant turbulent pulsation effects in the wake region and an unstable wake.

[0046] at last, Figure 7 The time-averaged streamlines and turbulent kinetic energy distributions of the box girder gap flow field and the near-wake flow field under controlled conditions are shown. The results show that the peak turbulent kinetic energy in the gap flow field is weakened, the turbulent pulsation effect is suppressed, and the flow becomes more stable. This is primarily due to the formation of small-scale vortex pairs at the slots on the box girder surface. This prevents the formation of large-scale vortices caused by flow separation on the leeward sides of the upstream and intermediate box girders, thus preventing the interaction between the vortices in the gap flow field and the box girder structure. Secondly, although the near-wake region still exhibits a significant turbulent distribution, the turbulent kinetic energy close to the downstream box girder surface is almost completely suppressed compared to the uncontrolled condition. These results demonstrate that the active control system for wind-induced vibration of a split three-box girder structure based on slots arranged at surface flow characteristic points can make the split three-box girder aerodynamic characteristics closer to those of a streamlined closed box girder, effectively reducing the unsteady aerodynamic forces acting on the split three-box girder structure and suppressing its pulsation. It also reduces the vortex shedding frequency in the wake of the split three-box girder, thereby suppressing its wind-induced vibration.

Claims

1. A large-span split three-box girder structure wind-induced vibration active control system, comprising an air suction pump, an air blowing pump, a real-time flow meter, a hot-wire anemometer and a host computer, and air suction and blowing slits are arranged based on the characteristic points of the girder surface flow, characterized in that: Ten slits are opened on the box girder along its spanwise length for blowing or suction, the positions of the slits are as follows: the first slit is located at the upstream box girder windward face front edge corner position; the second slit is located at the upstream box girder leeward face shear layer rolling up upper position; the third slit is located at the upstream box girder leeward face shear layer rolling up lower position; the fourth slit is located at the intermediate box girder windward face vortex collision upper position; the fifth slit is located at the intermediate box girder windward face vortex collision lower position; the sixth slit is located at the intermediate box girder leeward face vortex collision upper position; the seventh slit is located at the intermediate box girder leeward face vortex collision lower position; the eighth slit is located at the downstream box girder leeward face vortex collision upper position; the ninth slit is located at the downstream box girder leeward face vortex collision lower position; the tenth slit is located at the downstream box girder leeward face tail edge corner position; the first slit and the tenth slit are suction slits, the first slit to the ninth slit are blowing slits, the first slit is connected with the first suction pump through the first suction pipe, the second slit and the third slit are connected with the second blowing pump through the second blowing pipe, the fourth slit and the fifth slit are connected with the third blowing pump through the third blowing pipe, the sixth slit and the seventh slit are connected with the fourth blowing pump through the fourth blowing pipe, the eighth slit and the ninth slit are connected with the fifth blowing pump through the fifth blowing pipe, and the tenth slit is connected with the sixth suction pump through the sixth blowing pipe; hot wire anemometers are arranged at each slit opening, and the flow field wind speeds at the ten slits are collected in real time , then the collected flow field wind speed data is input into the host computer, the flow field wind speeds at different positions are used to control the power of different suction or blowing pumps, different given suction or blowing average speeds at the slits are obtained , and the wind-induced vibration of the whole box girder is controlled , wherein j=1-10. Wherein, the given suction or blowing average speed The calculation formula is as follows: ， ， ， ， ， ， ， wherein is the slit area; is the slit height ratio coefficient, ; H and L are the height and length of the whole three-box girder, respectively; denotes the maximum value of all variables in the parentheses; is the empirical coefficient of pipeline flow, = 1.0~1.2, = 0.6~1.0, = 1.0~1.5, = 0.6~1.0, = 1.0~1.4, = 0.8~1.2; Among them, the real-time gas flow of each pipeline is measured by flow meter. Perform measurement, i=1-6, and send real-time gas flow Feedback is sent to the main control computer, which uses PID control on the suction or blowing pump to gradually eliminate the deviation so that the actual suction and blowing rate at each slit is Reach a given average suction or blowing speed as quickly as possible , the specific calculation formula is as follows: ， ， where t is the time at each time instant; is a proportionality coefficient, ; ; ; is the error amount from the expected target at each time instant.

2. The wind-induced vibration active control system for a long-span split three-box girder structure according to claim 1, characterized in that: The height of the slit is 0.05-0.1 times the center height of the split three-box girder.

3. The wind-induced vibration active control system for a long-span split three-box girder structure according to claim 1 or 2, characterized in that: An inner baffle is mounted on the slit, and the inner baffle is closed when not actively controlled.

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