Method, system and storage medium for identifying coherence function of buffeting force of complex linear slender structure based on force measurement method

Abstract

The present invention discloses a method for identifying the flutter force coherence function of a complex linear slender structure based on a force measurement method, comprising the following steps: step one: constructing a mathematical model of a strip bucket flutter lift power spectrum and a mathematical model of a strip flutter lift coherence function; step two: obtaining a turbulence power spectrum and a turbulence span-wise coherence function according to an isotropic turbulence spectrum model in a grid turbulent flow field; step three: using a force balance and a segment model force measurement method to obtain a segment flutter lift coherence function and a segment flutter lift spectrum under a specific segment length of the linear slender structure; step four: establishing a conversion relationship between lift coherence functions acting on segments and strips, fitting the overall lift coherence function experimental data, and identifying the fitting parameters in the strip flutter lift coherence function model; step five: using the identified fitting parameters, combined with the segment flutter lift spectrum, calculating a joint receiver function on the segment, and obtaining the strip lift spectrum.

Description

Technical Field

[0001] The present invention belongs to the technical field of wind load testing, and specifically relates to a method, system and storage medium for identifying a coherence function of a complex linear slender structure buffeting force based on a force measurement method. Background Art

[0002] The span-wise coherence function is a very important aerodynamic parameter in the current large-span bridge buffeting analysis method. Traditional large-span bridge buffeting analysis methods are generally based on linear quasi-steady theory and aerodynamic strip theory. However, due to the small wavelength and high frequency turbulent components, they are not uniform in space and time, and they show incomplete spatial correlation along the width and height directions of the bridge cross section. Therefore, the traditional large-span bridge buffeting analysis method considers the non-steadiness and incomplete correlation of turbulence in time and space on the basis of using quasi-steady buffeting forces. For complex sections such as truss bridges, it is difficult to arrange pressure measuring holes in the wind tunnel to identify the coherence function between strips. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a method, system and storage medium for identifying the flutter force coherence function of a complex linear slender structure based on the force measurement method, and to use a force measuring balance to identify the span-wise coherence function of a complex section, thereby solving the problem of identifying the lift coherence function of a complex section.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A method for identifying a buffeting force coherence function of a complex linear slender structure based on a force measurement method comprises the following steps:

[0006] Step 1: Construct the mathematical model of the strip bucket vibration lift power spectrum and the mathematical model of the strip buffeting lift coherence function;

[0007] Step 2: According to the isotropic turbulence spectrum model in the grid turbulence field, the turbulence power spectrum and the turbulence span-wise coherence function are obtained;

[0008] Step 3: Use the segment model force measurement method to obtain the segment buffeting lift coherence function of the linear slender structure at a specific segment length through a force balance and segmental buffeting lift spectrum

[0009] Step 4: Establish the conversion relationship between the lift coherence functions acting on the segments and strips, fit the experimental data of the overall lift coherence function, and identify the fitting parameters in the strip buffeting lift coherence function model;

[0010] Step 5: Using the identified fitting parameters and the segment buffeting lift spectrum, the joint receiver function on the segment is calculated to obtain the strip lift spectrum.

[0011] Furthermore, in the step 1, the mathematical model of the blade bucket vibration lift power spectrum is constructed as follows:

[0012]

[0013] Where: ρ represents air density; U represents average wind speed; b represents the half width of the linear slender structure, and b = B / 2, B is the width of the linear slender structure; C L Indicates lift coefficient; C D Indicates the drag coefficient; C' L represents the lift coefficient derivative; |χ L (k1)| 2 is the lift aerodynamic admittance; S u (k1) and S w (k1) are the turbulence power spectra in the downwind and vertical directions respectively.

[0014] Further, the step 2 includes the following steps:

[0015] 11) Using wind field data and turbulence power spectrum to fit the turbulence integral scale in the downwind and vertical directions and Solve for the turbulent power spectrum:

[0016]

[0017]

[0018] Where: and represent the turbulence integral scales along the wind and vertical directions respectively; σ u and σ w represent the RMS values ​​of the pulsation components along the wind and vertical wind directions respectively;

[0019] 12) Using the turbulent Jakobsen coherence function model to fit the vertical wind turbulence span coherence function, the parameters to be fitted in the Jakobsen coherence function are obtained to solve the turbulent span coherence function;

[0020] The turbulent spanwise coherence function is expressed as:

[0021] Coh Jw (k1,Δy)=exp(-2πA J Δy)

[0022]

[0023] In the formula: Coh Jw (k1, Δy) is the turbulent spanwise coherence function; k1 represents the wave number, and k1 = n i / U,n iis the frequency, i=1, 2 represent the downwind direction and span direction respectively; c1, c2 and c3 are all parameters to be fitted; Δy is the spacing between two span-wise strips of the linear slender structure.

[0024] Furthermore, in the step 1, the double exponential lift coherence function model is used as the strip buffeting lift coherence function mathematical model, and the constructed strip buffeting lift coherence function mathematical model is:

[0025]

[0026]

[0027] In the formula: Coh L (k1,Δy) is the overall bucket lift coherence function; a1, a2 and a3 are all parameters to be fitted.

[0028] Furthermore, in step 5, the conversion relationship between the segment bucket vibration lift coherence function and the overall bucket vibration lift coherence function is:

[0029]

[0030] Combining the mathematical model of the strip buffeting lift coherence function, we get:

[0031] get:

[0032]

[0033] α1=1-2πA J ,γ1=1-2πλ Lexp

[0034] Where: is the lift coherence function of the segment under the aspect ratio of δ; δ = L / B is the aspect ratio of the segment; L is the segment length, B is the bridge width; y1, y2 are two points on the upper span of the segment.

[0035] Further, in step 5, the lift power spectrum of the strip bucket vibration is:

[0036]

[0037]

[0038] Where: |Joint| 2 is the joint receiving function; It is the lift force spectrum of segment bucket vibration.

[0039] The present invention also proposes a complex linear slender structure vibration force coherence function identification system based on force measurement method, including a memory, a processor and a computer program stored in the memory and executable on the processor, and the processor implements the method described above when executing the program.

[0040] The present invention also proposes a storage medium, wherein a computer program is stored on the computer-readable storage medium, and when the computer program is executed by a processor, the steps of the above method are implemented.

[0041] The beneficial effects of the present invention are:

[0042] The present invention is based on a method for identifying the flutter force coherence function of a complex linear slender structure using the force measurement method. Through a large number of wind tunnel experiments, the conversion relationship between the segment lift span coherence function and the strip lift coherence function is studied. Based on the double exponential lift coherence function and the turbulent Jakobsen coherence function, the analytical form of the conversion relationship is obtained. For complex sections where it is not convenient to arrange pressure measuring holes, the present invention can directly identify the lift span coherence function through a force balance, solving the difficulty of identifying the coherence function of complex sections. The strip lift self-spectrum can be calculated from the segment lift self-spectrum identified by the force balance, providing a solid basis for the subsequent linear length structure response calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration:

[0044] Figure 1 It is a flow chart of the method for identifying the coherence function of the buffeting force of a complex linear slender structure based on the force measurement method of the present invention;

[0045] Figure 2 It is the top view of the segmental force measurement model;

[0046] Figure 3 This is the front view of the segmental force measurement model;

[0047] Figure 4 It is the downwind wind spectrum;

[0048] Figure 5 It is the vertical wind direction wind spectrum;

[0049] Figure 6 It is the Jakobsen span coherence function diagram in the downwind and vertical wind directions;

[0050] Figure 7 is the segment lift coherence function when the segment aspect ratio is 0.2;

[0051] Figure 8 is the strip lift coherence function;

[0052] Fig. 9 is the self-power spectrum of segment lift;

[0053] Fig.10 is the strip lift self-power spectrum. DETAILED DESCRIPTION

[0054] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it, but the embodiments are not intended to limit the present invention.

[0055] like Figure 1 As shown, the method for identifying the coherence function of the flutter force of a complex linear slender structure based on the force measurement method in this embodiment includes the following steps.

[0056] Step 1: Construct the mathematical model of the strip bucket vibration lift power spectrum and the mathematical model of the strip buffeting lift coherence function.

[0057] In this embodiment, the constructed mathematical model of the strip bucket lift power spectrum is:

[0058]

[0059] Where: ρ represents air density; U represents average wind speed; b represents the half width of the linear slender structure, and b = B / 2, B is the width of the linear slender structure; C L Indicates lift coefficient; C D Indicates the drag coefficient; C' L represents the lift coefficient derivative; |χ L (k1)| 2 is the lift aerodynamic admittance; S u (k1) and S w (k1) are the turbulence power spectra in the downwind and vertical directions respectively.

[0060] In this embodiment, a double exponential lift coherence function model is used as a strip buffeting lift coherence function mathematical model, and the constructed strip buffeting lift coherence function mathematical model is:

[0061]

[0062]

[0063] In the formula: Coh L (k1,Δy) is the overall bucket lift coherence function; a1, a2 and a3 are all parameters to be fitted.

[0064] Step 2: According to the isotropic turbulence spectrum model in the grid turbulence field, the turbulence power spectrum and the turbulence span-wise coherence function are obtained. Specifically, the steps include:

[0065] 11) Using wind field data and turbulence power spectrum to fit the turbulence integral scale in the downwind and vertical directions and Solve for the turbulent power spectrum:

[0066]

[0067]

[0068] Where: and represent the turbulence integral scales along the wind and vertical directions respectively; σ u and σ w represent the RMS values ​​of the pulsation components along the wind and vertical wind directions respectively;

[0069] 12) Using the turbulent Jakobsen coherence function model to fit the vertical wind turbulence span coherence function, the parameters to be fitted in the Jakobsen coherence function are obtained to solve the turbulent span coherence function;

[0070] The turbulent spanwise coherence function is expressed as:

[0071] Coh Jw (k1,Δy)=exp(-2πA J Δy)

[0072]

[0073] In the formula: Coh Jw (k1, Δy) is the turbulent spanwise coherence function; k1 represents the wave number, and k1 = n i / U,n i is the frequency, i=1, 2 represent the downwind direction and span direction respectively; c1, c2 and c3 are all parameters to be fitted; Δy is the spacing between two span-wise strips of the linear slender structure.

[0074] Step 3: Use the segment model force measurement method to obtain the segment buffeting lift coherence function of the linear slender structure at a specific segment length through a force balance and segmental buffeting lift spectrum

[0075] Step 4: Establish the conversion relationship between the lift coherence functions acting on the segments and strips, fit the experimental data of the overall lift coherence function, and identify the fitting parameters in the strip buffeting lift coherence function model.

[0076] Specifically, the conversion relationship between the segment bucket vibration lift coherence function and the overall bucket vibration lift coherence function is:

[0077]

[0078] Combining the mathematical model of the strip buffeting lift coherence function, we get:

[0079] get:

[0080]

[0081] α1=1-2πA J ,γ1=1-2πλ Lexp

[0082] Where: is the lift coherence function of the segment under the aspect ratio of δ; δ = L / B is the aspect ratio of the segment; L is the segment length, B is the bridge width; y1, y2 are two points on the upper span of the segment.

[0083] Step 5: Using the identified fitting parameters and the segment buffeting lift spectrum, the joint receiver function on the segment is calculated to obtain the strip lift spectrum.

[0084] The lift power spectrum of the strip bucket vibration is:

[0085]

[0086]

[0087] Where: |Joint| 2 is the joint receiving function; It is the lift force spectrum of segment bucket vibration.

[0088] This embodiment also proposes a complex linear slender structure vibration force coherence function identification system based on force measurement method, including a memory, a processor and a computer program stored in the memory and executable on the processor. When the processor executes the program, the method described above in this embodiment is implemented.

[0089] This embodiment further provides a storage medium, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the method described above in this embodiment are implemented.

[0090] The specific implementation of the method of the present invention is described below with reference to examples.

[0091] like Figure 2-3 The figure shows the top view and front view of the slender structure tested in the example. The force balance is installed directly below the center of the force measuring section, and the entire model is erected on a rigid bracket. The Cobra anemometer is installed 1.2m in front of the slender structure to test the turbulent von Kármán wind spectrum. The slender structure used in this example is a separated double box beam section with a section width of 0.25m and a segment length of 0.05m.

[0092] According to the basic parameters of the experimental wind field, the geometric von Kármán downwind and vertical turbulence power spectrum S u (k1) and S w (k1), and the Jakobsen transverse coherence function Coh of the vertical component of turbulence Jw (k1,Δy), as shown below:

[0093]

[0094]

[0095] Coh Jw (k1,Δy)=exp(-2πA J Δy)

[0096]

[0097] Where: c1, c2, c3 are the parameters to be fitted. The downwind wind spectrum results are as follows: Figure 4 The vertical wind spectrum results are shown as follows: Figure 5 The Jakobsen coherence function model obtains the vertical wind direction coherence function result, such as Figure 6 Show.

[0098] The analytical model for defining the strip double exponential lift coherence function is as follows:

[0099]

[0100]

[0101] In the formula, Coh L (k1,Δy) is the strip lift coherence function; Lexp In the equation, a1, a2, and a3 are the parameters to be fitted.

[0102] The segment lift coherence function under a certain segment length is measured through wind tunnel experiments. Figure 7 The coherence function of the segment lift at different span distances for a segment with an aspect ratio of 0.2 is shown. Calculate the segmental one-wavenumber lift autopower spectrum like Figure 8 Show.

[0103] The conversion relationship between the segment lift coherence function and the strip coherence function is established as follows:

[0104]

[0105] Where δ = L / B is the length-to-width ratio of the segment; L is the segment length, and B is the bridge width. L Substituting the (k1,Δy) model into the above formula, we can get:

[0106]

[0107]

[0108] α1=1-2πA J ,γ1=1-2πλ Lexp

[0109] Based on the buffeting lift coherence function model, the experimental data of the overall lift coherence function in the second step are fitted, and the fitting parameters in the strip buffeting lift coherence function model are directly identified. Fig. 9 The lift coherence function results of the strip at different span distances using the identified fitting parameters are shown and compared with the lift coherence function results obtained using the pressure measuring valve. The identified results are in good agreement.

[0110] According to the segment lift self-spectrum and the joint receiving equation calculated by the identified strip coherence function, the strip lift self-power spectrum S is obtained. L (k1), the calculation results are as follows Fig.10 shown.

[0111]

[0112]

[0113] In the formula, |Joint| 2 is the joint receiver function. The lift spectrum of the identified strip is in good agreement with the result of using the pressure measuring valve.

[0114] The above-described embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Equivalent substitutions or changes made by those skilled in the art based on the present invention are within the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A method for identifying the coherence function of the buffeting force of a complex linear slender structure based on force measurement, characterized in that: The steps include: Step 1: Construct the mathematical model of the strip bucket vibration lift power spectrum and the mathematical model of the strip buffeting lift coherence function; Step 2: According to the isotropic turbulence spectrum model in the grid turbulence field, the turbulence power spectrum and the turbulence span-wise coherence function are obtained; Step 3: Use the segment model force measurement method to obtain the segment buffeting lift coherence function of the linear slender structure at a specific segment length through a force balance and segmental buffeting lift spectrum Step 4: Establish the conversion relationship between the lift coherence functions acting on the segments and strips, fit the experimental data of the overall lift coherence function, and identify the fitting parameters in the strip buffeting lift coherence function model; Step 5: Using the identified fitting parameters and the segment buffeting lift spectrum, the joint receiver function on the segment is calculated to obtain the strip lift spectrum; In the step 1, the constructed mathematical model of the strip bucket lift power spectrum is: Where: ρ represents air density; U represents the average wind speed; b represents the half width of the linear elongated structure, and b = B / 2, where B is the width of the linear elongated structure; C L Indicates lift coefficient; C D Indicates the drag coefficient; C' L represents the lift coefficient derivative; |χ L (k1)| 2 is the lift aerodynamic admittance; S u (k1) and S w (k1) are the turbulence power spectra in the downwind and vertical directions respectively; The step 2 includes the following steps: 11) Using wind field data and turbulence power spectrum to fit the turbulence integral scale in the downwind and vertical directions and Solve for the turbulent power spectrum: Where: and represent the turbulence integral scales along the wind and vertical directions respectively; σ u and σ w They represent the RMS values ​​of the pulsation components along the wind direction and vertical wind direction respectively; 12) Using the turbulent Jakobsen coherence function model to fit the vertical wind turbulence span coherence function, the parameters to be fitted in the Jakobsen coherence function are obtained to solve the turbulent span coherence function; The turbulent spanwise coherence function is expressed as: Coh Jw (k1,Δy)=exp(-2πA J Δy) In the formula: Coh Jw (k1, Δy) is the turbulent spanwise coherence function; k1 represents the wave number, and k1 = n i / U,n i is the frequency, i=1, 2 represent the downwind direction and span direction respectively; c1, c2 and c3 are all parameters to be fitted; Δy is the spacing between two span-wise strips of the linear slender structure; In the step 1, a double exponential lift coherence function model is used as a strip buffeting lift coherence function mathematical model, and the constructed strip buffeting lift coherence function mathematical model is: In the formula: Coh L (k1,Δy) is the overall bucket lift coherence function; a1, a2 and a3 are all parameters to be fitted; In step 5, the conversion relationship between the segment bucket vibration lift coherence function and the overall bucket vibration lift coherence function is: Combining the mathematical model of the strip buffeting lift coherence function, we get: get: α1=1-2πA J ,γ1=1-2pl Lexp Where: is the lift coherence function of the segment under the aspect ratio of δ; δ = L / B is the aspect ratio of the segment; L is the segment length, B is the bridge width; y1, y2 are two points on the upper side of the segment in the span direction; In step 5, the strip bucket lift power spectrum is: Where: |Joint| 2 is the joint receiving function; It is the lift force spectrum of segment bucket vibration.

2. A complex linear slender structure buffeting force coherence function identification system based on force measurement, characterized by: The method comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the method according to claim 1 is implemented when the processor executes the program.

3. A storage medium, characterized in that: The storage medium stores a computer program, which implements the steps of the method as claimed in claim 1 when executed by a processor.

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