CN106644357A - Active grating device for generating vertical pulsation airflow - Google Patents

Abstract

The invention discloses an active grid device for generating vertical pulsating airflow, which comprises a support frame fixed on the wall of a wind tunnel, and the support frame is sequentially hinged with a plurality of horizontally arranged vibrating wing grids at intervals from top to bottom; the lower part of the support frame There is a first transmission rod arranged horizontally, and a driving device for driving the first transmission rod to move up and down; a second transmission rod vertically arranged is hinged on the upper part of the supporting frame, and the lower end of the second transmission rod is connected with the first transmission rod hinged, and the second transmission rod is hinged with each vibrating wing grid. The present invention generates vertical pulsating airflow by guiding the airflow through the vibrating wing grid, and has better airflow controllability. The combination of servo motor and digital control system can generate vertical pulsating airflow characterized by single-frequency harmonics, multi-frequency combined harmonics and random vibration with controllable spectrum characteristics in the wind tunnel, which has strong applicability.

Description

An active grille device that generates vertically pulsating airflow

technical field

The invention belongs to the technical field of wind tunnel experiments, and in particular relates to an active grid device for generating vertical pulsating airflow.

Background technique

In the wind tunnel test research of long-span bridge structures, long-span roof structures and similar structures, the characteristics of vertical fluctuating airflow are important factors affecting wind-induced response and wind load, so careful simulation is required in boundary layer wind tunnel tests. However, the existing wind tunnel test technology is generally realized by passive simulation methods such as horizontal and vertical grid bars, or multiple separated triangular wedges, and there is still a lack of active control simulation methods that can set target parameters.

For long-span bridge structures and long-span roof structures, the vertical fluctuating airflow is the most important wind field fluctuation component, and the simulation of the vertical fluctuating component is the key to the success of many wind tunnel tests. However, in the field of existing wind tunnel test technology, passive simulation devices are mainly vertically arranged sharp wedges, and can be assisted by horizontally arranged grid bars when necessary. It is difficult for this type of simulation method to generate sufficient The vertical wind spectrum is required, and the wind spectrum generated by it will change with the change of position in the wind tunnel. At the same time, the aerodynamic admittance function of structural buffeting force theory is initially inferred by the assumption of a single harmonic fluctuating wind, so the generation of a single harmonic fluctuating wind in a wind tunnel is of great significance to the study of buffeting theory. In addition, the characteristic wake of structures is often a periodic fluctuating flow with certain spectral characteristics, which can be expressed by multi-order Fourier series, while the wind spectrum of natural wind is often a random fluctuating flow with certain spectral characteristics flow.

At present, the means to generate the above three types of characteristic pulsating flow in the wind tunnel are very scarce. As far as the inventor knows, such general-purpose equipment has not yet appeared in China. Practical engineering applications are of great significance.

This invention is jointly funded by the National Natural Science Foundation of China (No.51478181, U1534206).

Contents of the invention

In view of the above problems, the present invention aims to provide an active grid that can generate vertical pulsating airflow in a wind tunnel, and can generate single-frequency harmonics and multi-frequency combined harmonics downstream of the grid by controlling the operation of the active grid Vertical fluctuating airflow characterized by random vibration with controllable spectral characteristics.

The technical solution to the problem of the present invention is: an active grille device for generating vertical pulsating airflow, including a support frame fixed on the wind tunnel wall, characterized in that the support frame is hinged at intervals from top to bottom The vibrating wing grid set horizontally;

The lower part of the support frame is provided with a first transmission rod arranged horizontally, and a driving device for driving the first transmission rod to move up and down in translation;

The upper part of the support frame is hinged with a vertically arranged second transmission rod, the lower end of the second transmission rod is hinged with the first transmission rod, and the second transmission rod is hinged with each vibrating wing grid.

In the above solution, the driving device drives the first transmission rod to move up and down in translation, and drives the second transmission rod to move up and down, and the second transmission rod guides the vibrating wing grid to swing up and down with a controllable spectrum characteristic in the wind field, so that in the downstream wind field The vertical pulsating airflow that produces the corresponding spectral characteristics.

Specifically, the driving device includes a servo motor fixed at the bottom of the supporting frame, an eccentric wheel arranged on the rotating shaft of the servo motor, and a motion frame fitted outside the eccentric wheel, and the first transmission rod is horizontally fixed on the top of the motion frame, The motion frame can move up and down in translation driven by the eccentric wheel.

In the above solution, the servo motor drives the eccentric wheel to rotate in the motion frame, and a certain gap is reserved between the eccentric wheel and the left and right inner walls of the motion frame, so that the left and right side movements are released during the movement of the eccentric wheel, and only the motion frame is guided to move in the up and down direction. Driven by the eccentric wheel, the motion frame moves up and down in translation, thereby causing the first transmission rod to move up and down in translation.

The eccentric wheel can be designed as a component with a vertical movement displacement of 10mm, 20mm, 30mm, etc., and the turbulence degree of the vertical pulsating airflow can be changed by adjusting the vertical amplitude of the vibrating wing grid to meet different experimental needs.

Preferably, the support frame is divided into at least two regional frames from left to right, each regional frame is hinged with a plurality of horizontally arranged vibrating wing grids at intervals from top to bottom, and each regional frame is provided with at least one A second transmission rod, each second transmission rod is hinged with the first transmission rod.

Notable effect of the present invention is:

1. The vertical pulsating airflow is generated by the guidance of the vibrating wing grid to the airflow. The period of the vertical pulsation of the airflow is the same as the movement period of the vibrating wing grid. The turbulence degree of the pulsating wind field can be adjusted according to the needs of the experiment, and it has better airflow controllability characteristic.

2. With the cooperation of servo motor and control software, vertical pulsating airflow with single frequency harmonics, vertical pulsating airflow with multi-frequency combined harmonics, and cyclically controllable random airflow targeted at a certain frequency spectrum can be generated in the wind tunnel. Vertical pulsating airflow, with strong applicability.

Description of drawings

The present invention will be further described below in conjunction with accompanying drawing.

Fig. 1 is the main assembly drawing of the present invention.

Fig. 2 is a sectional view of A-A in Fig. 1 .

Fig. 3 is a B-B sectional view in Fig. 1 .

Figure 4 is a large scale diagram of the vibrating wing grid.

Figure 5 is a large sample diagram of the motion frame.

In the figure: 1. supporting frame; 2. vibrating wing grid; 3. second transmission rod; 4. first transmission rod; 5. movement frame; 6. servo motor; 7. eccentric wheel.

detailed description

For the convenience of description, the description of the relative positional relationship of each component (such as: up, down, left, right, etc.) is described according to the layout direction of the drawings in the specification, and does not limit the structure of this patent.

As shown in Figures 1 to 5, an active grille device that generates vertical pulsating airflow includes a support frame 1 fixed on the wall of a wind tunnel, and the support frame 1 is hinged at intervals from top to bottom and has a plurality of horizontally arranged The vibrating wing grid 2.

The lower part of the support frame 1 is provided with a first transmission rod 4 arranged horizontally, and a driving device for driving the first transmission rod 4 to move up and down in translation. The driving device includes a servo motor 6 fixed on the bottom of the supporting frame 1 , an eccentric wheel 7 arranged on the rotating shaft of the servo motor 6 , and a motion frame 5 sleeved outside the eccentric wheel 7 . The first transmission rod 4 is horizontally fixed on the top of the motion frame 5 . The motion frame 5 can translate up and down under the drive of the eccentric wheel 7 .

The upper part of the support frame 1 is hinged with a vertically arranged second transmission rod 3 , the lower end of the second transmission rod 3 is hinged with the first transmission rod 4 , and the second transmission rod 3 is hinged with each vibrating wing grid 2 .

The eccentric wheel 7 can be designed as a component with a vertical movement displacement of 10mm, 20mm, and 30mm, and the turbulence degree of the vertical pulsating airflow can be changed by adjusting the vertical amplitude of the vibrating wing grid 2 to meet different experimental requirements.

In a preferred embodiment, the support frame 1 is divided into at least two area frames from left to right. There are a plurality of horizontally arranged vibrating wing grids 2 hinged at intervals from top to bottom in each area frame. At least one second transmission rod 3 is arranged in each area frame. Each second transmission rod 3 is hinged to the first transmission rod 4 .

The servo motor 6 drives the eccentric wheel 7 to rotate in the motion frame 5, and the motion frame 5 moves up and down in translation driven by the eccentric wheel 7, thereby causing the first transmission rod 4 to move up and down in translation. The first transmission rod 4 drives the second transmission rod 3 to move up and down, and the second transmission rod 3 guides the vibrating wing grid 2 to swing up and down with controllable spectral characteristics in the wind field, thereby generating a vertical vibration with corresponding spectral characteristics in the downstream wind field. Pulsating airflow.

The following three types of motion can be realized through the cooperation of the servo motor and the servo driver:

(1) Single harmonic frequency movement, movement displacement d1=A.sin(ωt), where movement frequency f=0.1～3Hz is adjustable, ω=2πf, t is time, A is movement displacement amplitude, according to grid design Initial condition setting.

(2) Multi-harmonic combined motion, motion displacement j=2～10 multi-order harmonic combinations can be selected according to needs, where ω=2πf, f is the motion frequency, a _n is the motion displacement amplitude, and t is time.

(3) Random motion, motion displacement d3 obtains the motion time history through FFT inverse transformation according to the target wind spectrum, and then obtains an acceptable operating curve for motor operation through peak smoothing processing technology.

The control goal is to achieve a vertically pulsating controllable airflow with three types of characteristics.

The motion of the servo motor 6 in the present invention adjusts the parameters through the software "grid operation control", thereby realizing multiple motion forms such as single-frequency harmonic motion, multi-frequency harmonic combined motion, and random vibration targeting a certain frequency spectrum. The "grid operation control" is the name of the existing software.

Claims (3)

1. An active grille device that generates vertical pulsating airflow, including a support frame (1) fixed on the wind tunnel wall, characterized in that: the support frame (1) is hinged at intervals from top to bottom with multiple Horizontally arranged vibrating wing grids (2); The lower part of the support frame (1) is provided with a first transmission rod (4) arranged horizontally, and a driving device for driving the first transmission rod (4) to move up and down; The upper part of the support frame (1) is hinged with a vertically arranged second transmission rod (3), the lower end of the second transmission rod (3) is hinged with the first transmission rod (4), and the second transmission rod (3) is connected to the Each vibrating wing grid (2) is hinged. 2. The active grille device for generating vertical pulsating airflow according to claim 1, characterized in that: the drive device includes a servo motor (6) fixed at the bottom of the supporting frame (1), and a servo motor (6) The eccentric wheel (7) on the rotating shaft of the eccentric wheel (7), the motion frame (5) set outside the eccentric wheel (7), the first transmission rod (4) is horizontally fixed on the top of the motion frame (5), and the motion frame (5) Driven by the eccentric wheel (7), it can move up and down in translation. 3. The active grille device for generating vertical pulsating airflow according to claim 1, characterized in that: the support frame (1) is divided into at least two area frames from left to right, and each area frame is self-contained. A plurality of horizontal vibrating wing grids (2) are hinged at intervals from top to bottom, and at least one second transmission rod (3) is arranged in each area frame, and each second transmission rod (3) is connected to the first The transmission rod (4) is hinged.