Wind tunnel test device

Abstract

To provide a wind tunnel test device capable of easily setting vibration characteristics of a building and evaluating vibration response of the building caused by wind.SOLUTION: A wind tunnel test device 1 comprises a frame 10 capable of supporting a building model 2 and a wind blowing device 20 that blows wind toward the building model 2. The frame 10 is configured to include: a gimbal 11 to which the building model 2 is fixed; a frame body 12 that swingably supports the gimbal 11; a plurality of coil springs 30 that biases the gimbal 11 horizontally toward the frame body 12; and a vibration measurement device 16 that is provided on the frame body 12 and measures vibration response caused by the wind of the gimbal 11. Each coil spring 30 is provided with a connecting fixture 31 that connects both end portions of a predetermined section P in a length direction of the coil spring 30. By preventing expansion and contraction between both end portions of the predetermined section P of the coil spring 30 by means of the connecting fixture 31, rigidity of the gimbal 11 can be set to a predetermined value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a wind tunnel testing device for measuring the vibration response of a building model due to wind. [Background technology]

[0002] BACKGROUND ART Structures for changing the spring constant of a coil spring have been proposed (see Patent Documents 1 and 2). Patent Document 1 discloses a vibration control device for a structure. The vibration control device comprises an added mass, a laminated rubber that supports the added mass so that it can oscillate, a coil spring that biases the laminated rubber, and a natural period adjustment mechanism that adjusts the natural period of the coil spring. The natural period adjustment mechanism comprises an engaging member with which the other end of the coil spring engages, a support that supports the engaging member, and a bolt that connects the engaging member to the support. The spring constant of the coil spring is changed by engaging a part of the coil spring with the spiral groove of the engaging member.

[0003] Patent Document 2 discloses a vibration suppression device for floors, etc., for suppressing vibration of floors, etc. The vibration suppression device for floors, etc., includes a mounting base provided on the floor, a swing base provided on the mounting base, a swing lever swingably connected to the swing base, an elastic body provided between the swing lever and the mounting base, and a solidifying material provided on the elastic body to adjust the spring constant of the elastic body. In this vibration suppression device for floors, etc., the spring constant of the elastic body is adjusted by burying a portion of the elastic body in the solidifying material. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 8-334148 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-315093 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a wind tunnel testing device that can easily set the vibration characteristics of a building and evaluate the vibration response of the building to wind. [Means for solving the problem]

[0006] A wind tunnel testing apparatus (for example, wind tunnel testing apparatus 1 described later) according to a first aspect of the present invention is a wind tunnel testing apparatus for measuring the vibration response of a building model (for example, building model 2 described later), which is caused by wind, and includes a base (for example, base 10 described later) capable of supporting the building model, and a blower (for example, blower 20 described later) for blowing air to the building model, and the base includes a gimbal (for example, gimbal 11 described later) to which the building model is fixed, a base body (for example, base body 12 described later) for supporting the gimbal so that it can swing, and a force acting on the gimbal in a horizontal direction toward the base body. and a vibration measuring device (for example, vibration measuring device 16 described later) provided on the base body for measuring the vibration response of the gimbal due to wind. The coil springs are provided with connecting devices (for example, connecting device 31 described later) that connect both ends of a predetermined section in the length direction of the coil springs (for example, predetermined section P described later), and the connecting devices prevent expansion and contraction between both ends of the predetermined section of the coil springs, making it possible to set the rigidity of the gimbal to a predetermined value.

[0007] According to this invention, the stand supporting the building model is composed of a gimbal, a stand body, a coil spring, and a vibration measuring device, and by using a connecting device to prevent expansion and contraction between both ends of a specified section of the coil spring, the rigidity, or vibration characteristics, of the gimbal, or the building model, are set to a specified value. In order to evaluate the vibration response of a building due to wind, wind tunnel tests (aerodynamic vibration tests) are conducted using an elastic model that mimics the vibration characteristics of the building. Specifically, by blowing wind onto the elastic model and measuring the vibration response, wind loads can be calculated in building design, and the habitability of the building and unstable vibration of the building can be examined. This elastic model uses coil springs to model the rigidity and vibration characteristics of the building. By attaching connecting devices to the coil springs, the rigidity of the building model can be easily set and the vibration response of the building due to wind can be evaluated. In addition, the rigidity (vibration characteristics) of the building model can be easily changed simply by appropriately changing the attachment position of the connecting device on the coil spring.

[0008] The wind tunnel testing apparatus of the second invention is characterized in that the connecting device comprises a pair of adjustment plates (e.g., adjustment plate 33 described below) attached to both ends of a predetermined section of the coil spring and having through holes (e.g., through hole 32 described below) formed therein, and bolts (e.g., bolt 34 described below) and nuts (e.g., nut 35 described below) inserted into the through holes of the adjustment plates to connect the adjustment plates to each other.

[0009] According to this invention, the connecting device is made up of an adjusting plate, a bolt, and a nut, which makes the connecting device simple in structure and allows the connecting device to be manufactured at low cost. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a wind tunnel testing device that can easily set the vibration characteristics of a building and evaluate the vibration response of the building due to wind. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing the configuration of a wind tunnel testing device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a vertical cross-sectional view of a stand that constitutes the wind tunnel testing equipment. [Figure 3] FIG. 3 is a cross-sectional view of the frame taken along line AA in FIG. 2. [Figure 4] FIG. 3 is a BB cross-sectional view of the frame of FIG. 2. [Figure 5] FIG. 10 is a side view of a coil spring with a coupling device attached. [Figure 6] 6 is a cross-sectional view of the coupling device of FIG. 5 along CC. [Figure 7] FIG. 10 is a diagram showing a state in which the coil spring connecting device is not attached. [Figure 8] 4A and 4B are diagrams for explaining dimensions of a coil spring that constitutes the stiffness setting device. [Figure 9] FIG. 10 is a diagram showing dimensions of an adjustment plate that constitutes the stiffness setting device. [Figure 10] 10 is a flowchart of a procedure for attaching a connecting device to a coil spring. [Figure 11] This is an explanatory diagram of the procedure for attaching a connecting device to a coil spring (Part 1, showing the state in which the adjustment plate is inserted into the coil spring). [Figure 12] This is an explanatory diagram of the procedure for attaching a connecting device to a coil spring (part 2, with bolts and nuts attached to the adjustment plate). [Figure 13] FIG. 10 is a diagram for explaining the operation of a stand that constitutes the wind tunnel testing equipment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of a wind tunnel testing device 1 according to one embodiment of the present invention. The wind tunnel testing device 1 measures the vibration response of a building model 2 due to wind. The wind tunnel testing device 1 includes a stand 10 on which the building model 2 is supported, and a blower 20 that blows wind to the building model 2.

[0013] The air blowing device 20 includes a cylindrical wind tunnel 21 extending horizontally, and an air blower 22 provided at one end of the wind tunnel 21 to blow air to the other end of the wind tunnel 21. The wind tunnel 21 includes a diffuser drum 23 connected to the air blower 22, a flow straightener drum 24 connected to the diffuser drum 23, a contraction drum 25 connected to the flow straightener drum 24, and a measurement drum 26 connected to the contraction drum 25. A flow straightening mesh 27 and a flow straightening honeycomb 28 are provided inside the flow straightening drum 24. A building model 2 supported by a stand 10 is placed on the tip side of the measuring barrel 26. In this blower device 20, when the blower 22 is driven, the air sent from the blower 22 is straightened as it passes through the diffusion barrel 23, the straightening barrel 24, the contraction barrel 25, and the measuring barrel 26, and hits the side of the building model 2.

[0014] Fig. 2 is a vertical cross-sectional view of the gantry 10. Fig. 3 is a cross-sectional view of the gantry 10 of Fig. 2 taken along line AA. Fig. 4 is a cross-sectional view of the gantry 10 of Fig. 2 taken along line BB. The mount 10 comprises a gimbal 11 to which the building model 2 is fixed, a mount body 12 that supports the gimbal 11 so that it can swing horizontally, a rotation device 13 that is provided on the floor surface 3 and supports the mount body 12 so that it can rotate, a stiffness setting device 14 that sets the stiffness of the gimbal 11, a vibration damping device 15 that damps the vibration of the gimbal 11, and a vibration measuring device 16 that is provided on the mount body 12 and measures the vibration response of the gimbal 11 due to wind. The rotation device 13 rotates the base body 12 as needed, so that the wind from the blower 22 can be directed at the building model 2 from any direction. The stiffness setting device 14 includes four coil springs 30 that urge the gimbal 11 horizontally toward the mount body 12, and four connecting devices 31 that connect both ends of a predetermined section P in the longitudinal direction of each coil spring 30.

[0015] The vibration damping device 15 is a permanent magnet provided in the mount body 12. At least the lower end of the gimbal 11 is made of metal, and the vibration of the gimbal 11 is damped by attracting the lower end of the gimbal 11 with the magnetic force of the permanent magnet. The vibration measuring device 16 is composed of two laser displacement meters 17 that measure the position of the gimbal 11 from two intersecting directions (X direction and Y direction) in a horizontal plane. Each laser displacement meter 17 measures the horizontal position of the gimbal 11 by irradiating a side surface of the gimbal 11 with laser light and receiving the laser light reflected by the side surface of the gimbal 11.

[0016] 5 is a side view of the coil spring 30 attached with the connecting device 31. FIG. 6 is a cross-sectional view of the connecting device 31 of FIG. The connecting device 31 includes a pair of adjustment plates 33 attached to both ends of the predetermined section P of the coil spring 30 and having through holes 32 formed therein, and bolts 34 and nuts 35 that connect the adjustment plates 33 together. A pair of through holes 32 is formed in each adjustment plate 33, sandwiching the coil spring 30 therebetween, and bolts 34 are inserted into the through holes 32 of these adjustment plates 33 and nuts 35 are fastened to them. The stiffness setting device 14 prevents expansion and contraction between both ends of the predetermined section P of the coil spring 30 using the connecting device 31, thereby making it possible to set the stiffness of the gimbal 11 to a predetermined value.

[0017] For springs, the following equation (1) holds true (Hooke's law): k=P / δ (1) Here, k is the spring constant, P is the load on the spring, and δ is the deflection of the spring. In addition, in the case of a compression spring, the following formula (2) holds true. k=P / δ=G d 4 / (8·Na·D 3 ) ···(2) Here, G is the modulus of transverse elasticity (68500 for stainless steel (SUS302)), Na is the effective number of turns, D is the average coil diameter, and d is the wire diameter. Therefore, it is clear that the spring constant can be set to any value by changing the number of effective turns of the coil spring. For example, if the number of effective turns of a coil spring is 12 as shown in Figure 7, by attaching a connecting device to this coil spring, the number of effective turns becomes 5 as shown in Figure 5, and the spring constant becomes 5 / 12.

[0018] As shown in FIG. 8, the coil spring 30 is made of stainless steel, has a diameter of 2.5 mm or less, an outer diameter of 5 mm or more (an opening of 2 mm or more width is provided at the end of the spring to allow it to pass through the gimbal), a free length of 45 mm to 55 mm, and a maximum length of 70 mm or more. 9, the adjustment plate 33 is made of stainless steel (SUS304) and has a size of 13 mm×45 mm and a thickness of 1 mm. The bolt 34 is, for example, an M3 bolt.

[0019] The procedure for attaching the connecting device 31 to the coil spring 30 will be described below with reference to the flowchart of FIG. In step S1, as shown in FIG. 11, a tensile force is applied to the coil spring 30 to stretch the coil spring 30. In step S2, as shown in FIG. 11, the adjustment plates 33 are inserted into both ends of the predetermined section P of the coil spring 30 while the coil spring is stretched. In step S3, as shown in FIG. 12, the tension is released and the coil spring 30 returns to its original state. In step S4, as shown in FIG. 12, the bolt 34 and the nut 35 are attached to the adjustment plate 33 in a state where no tension is applied to the coil spring 30.

[0020] The wind tunnel testing equipment 1 performs a wind tunnel test as follows. That is, the blower 22 is driven to blow wind against the side of the building model 2 from a predetermined direction. Then, as shown in FIG. 13 , the wind pressure causes the gimbal 11 of the frame 10 to swing and vibrate. At this time, the stiffness of the gimbal 11 is set by the stiffness setting device 14, and the vibration of the gimbal 11 is damped by the vibration damping device 15 and measured by the vibration measuring device 16.

[0021] According to this embodiment, the following effects are obtained. (1) The frame 10 supporting the building model 2 is composed of a gimbal 11, a frame body 12, a coil spring 30, and a vibration measuring device 16, and the rigidity, i.e., vibration characteristics of the gimbal 11, i.e., the building model 2, is set to a predetermined value by preventing expansion and contraction between both ends of a predetermined section P of the coil spring 30 using a connecting device 31. In order to evaluate the vibration response of a building due to wind, a wind tunnel test (aerodynamic vibration test) uses a building model 2 that models the rigidity and vibration characteristics of the building. A coil spring 30 is attached to the building model 2, and by attaching a connecting device 31 to this coil spring 30, the rigidity of the building model 2 can be easily set and the vibration response of the building due to wind can be evaluated. Furthermore, the rigidity (vibration characteristics) of the building model 2 can be easily adjusted simply by appropriately changing the attachment position of the connecting device 31 on the coil spring 30. In other words, the connecting device 31 has the function of adjusting the spring constant of the coil spring 30 and thereby adjusting the natural period of the elastic model of the building. Therefore, because buildings can be easily modeled, wind tunnel tests (aerodynamic vibration tests) can be carried out efficiently on various buildings, and calculations of wind loads and livability can be easily considered in building design.

[0022] (2) The connecting device 31 is composed of the adjusting plate 33, the bolt 34, and the nut 35. Therefore, the connecting device 31 has a simple structure and can be manufactured at low cost.

[0023] The present invention is not limited to the above-described embodiment, and modifications and improvements within the scope of achieving the object of the present invention are included in the present invention. [Explanation of symbols]

[0024] 1...Wind tunnel experiment equipment 2...Building model 3...Floor 10... Mounting base 11... Gimbal 12... Mounting base body 13... Rotation device 14... Stiffness setting device 15...Vibration damping device 16...Vibration measuring device 17...Laser displacement meter 20... Blower device 21... Wind tunnel 22... Blower 23... Diffusion drum 24... Flow straightening drum 25... Flow contraction drum 26... Measurement drum 27... Rectifying mesh 28... Rectifying honeycomb 30... Coil spring 31... Connecting device 32... Through hole 33...Adjustment plate 34...Bolt 35...Nut

Claims

1. A wind tunnel testing device for measuring the vibration response of a building model due to wind, a stand capable of supporting the building model; a blower for blowing air onto the building model, The mount includes a gimbal to which the building model is fixed; a base body that supports the gimbal so that the gimbal can swing; a plurality of coil springs that urge the gimbal horizontally toward the pedestal body; a vibration measuring device provided on the mount body for measuring a vibration response of the gimbal due to wind, The coil spring is provided with a connecting device that connects both ends of a predetermined section in the length direction of the coil spring, A wind tunnel testing device for a structure, characterized in that the rigidity of the gimbal can be set to a predetermined value by preventing expansion and contraction between both ends of a predetermined section of the coil spring using the connecting device.

2. The connecting device includes a pair of adjustment plates attached to both ends of a predetermined section of the coil spring and having through holes formed therein; 2. The wind tunnel testing apparatus according to claim 1, further comprising: bolts and nuts that are inserted into the through holes of the adjustment plates to connect the adjustment plates together.

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