CN111507030B - Hydraulic steel gate flow-induced vibration analysis method based on large vortex simulation - Google Patents

Hydraulic steel gate flow-induced vibration analysis method based on large vortex simulation Download PDF

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CN111507030B
CN111507030B CN202010201324.7A CN202010201324A CN111507030B CN 111507030 B CN111507030 B CN 111507030B CN 202010201324 A CN202010201324 A CN 202010201324A CN 111507030 B CN111507030 B CN 111507030B
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郭博文
鲁立三
高玉琴
宋力
王荆
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Yellow River Institute of Hydraulic Research
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Abstract

The invention discloses a hydraulic steel gate flow-induced vibration analysis method based on large vortex simulation, which comprises the steps of establishing a water body finite element model and a steel gate solid finite element model of front and rear runners according to the structural characteristics of a hydraulic steel gate, sequentially carrying out hydrodynamic calculation and solid mechanical calculation on the water body finite element model and the steel gate solid finite element model of the front and rear runners based on ADINA finite element analysis software, and integrally evaluating the structural safety of the hydraulic steel gate from qualitative and quantitative angles. The invention provides a numerical simulation analysis method based on large vortex simulation, aiming at the problems in the current flow-induced vibration calculation analysis of hydraulic steel gates, the method not only can capture the falling of small-scale vortices under high-speed water flow, but also can effectively solve the defects of difficult determination of similar scale, high manufacturing cost and the like in a physical model test, and can provide corresponding basis and reference for the design and the operation of the hydraulic steel gates.

Description

Hydraulic steel gate flow-induced vibration analysis method based on large vortex simulation
Technical Field
The invention relates to a flow-induced vibration analysis method for a hydraulic steel gate, in particular to a flow-induced vibration analysis method for a hydraulic steel gate based on large vortex simulation.
Background
The gate is used as a movable water retaining structure, is an important component in buildings such as water drainage and water diversion, has the functions of adjusting water levels of upstream and downstream, draining, discharging and transporting ships, wooden rafts and bamboo rafts, removing silt, floaters and the like, ensures the safe operation of a water conservancy hub, and gives consideration to the benefits of flood control, irrigation, navigation and water diversion and power generation. The gates are classified into a working gate, a maintenance gate and an accident gate according to the working property of the gates; the gate can be divided into a plane gate, a radial gate, a miter gate, an arch gate, a spherical gate, a cylinder gate, etc. according to the shape of the gate. At present, steel gates are more in various types of gates, and the flat steel gates and arc steel gates are widely applied, particularly the flat steel gates are adopted in accident gates.
The interaction between water flow and the gate is necessarily existed in the operation process of the gate, the water flow acts on the gate to cause the vibration of the gate, and the vibration of the gate in turn influences the distribution of the surrounding flow field, and the phenomenon is called flow-induced vibration. The gate flow-induced vibration is a phenomenon of exciting extremely complex fluid and structure interaction, and belongs to a typical fluid-solid coupling phenomenon. Research finds that a large amount of gate failures at home and abroad are caused by flow-induced vibration, for example, a fixed-wheel working gate of a flood discharge tunnel of a hydropower station of a Si-Chuan-Shi beach adopts flat-bottom water stopping, when the gate is subjected to first-time gate-off water storage after construction, the gate is strongly vibrated, the vibration of the gate is still strong in the opening and closing process, and after the gate is lifted for about one minute, the vibration is weakened, but the gate cannot be partially opened; the Liu's gorge hydropower station sluice gate is found to have strong vibration after being formally put into use in 1969 summer, the observation shows that the gate not only has large overall vibration, but also has large structural stress, and forms a potential damage factor for the gate, and the research shows that the flow-induced vibration of the gate is caused by poor water stopping of the gate; the flat gate with 14 m height of the U.S. bang-pinch Weier overflow dam generates strong self-excited vibration when the opening degree is small; the Barkley dam 15.2m 16.8m arc gate generates 30Hz strong vibration when the opening degree is small; when the Harenfnet radial gate is locally opened, vibration with the amplitude of 2mm and the frequency of 2.5Hz is generated; when the gate of a certain meter hole house type in Japan is in test operation, the gate is suddenly damaged, the bent frame of the whole support arm is unstably bent, the support is broken, and the gate is flushed to the position 130m downstream.
The damage or even the accident of the gate not only can lead to the waste of water resources, but also can seriously affect the safe reliability of the operation of the whole hub. Although the gate forms and the vibration causes are different in the above-described flow-induced vibration examples, the mechanism for inducing gate vibration is similar, but the mechanism of such flow-induced vibration has not been known so far. Some students study gate flow-induced vibration by using a vortex-induced vibration theory, but a karman vortex street phenomenon is not observed when the gate vibrates in many times, and the vortex-induced vibration phenomenon only occurs on the gate under the conditions of a certain opening degree and a certain reduced flow rate, so that the vortex-induced vibration theory cannot be completely used for explaining the fluid-induced gate vibration; however, the flow excitation vibration at a small opening degree of the gate does not accord with the basic assumption of the galloping theory, so that the gate flow excitation vibration phenomenon cannot be completely explained by the galloping theory. The gate flow-induced vibration process is a typical fluid-solid coupling phenomenon, namely, fluid and solid have strong coupling action, and a single subject cannot meet the requirement. Aiming at the complexity of a steel gate flow-induced vibration mechanism and the multiple occurrence of the steel gate flow-induced vibration in the actual engineering, in order to ensure the normal operation of the steel gate in a complex water flow state, the problem of flow-induced vibration of a hydraulic steel gate structure needs to be analyzed, but the analysis is inaccurate and incomplete at present, and the requirement cannot be met.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to provide a hydraulic steel gate flow-induced vibration analysis method based on large vortex simulation, and solves the problems that the current hydraulic steel gate flow-induced vibration analysis is inaccurate and incomplete.
The technical scheme is as follows: the invention relates to a hydraulic steel gate flow-induced vibration analysis method based on large vortex simulation, which comprises the following steps of:
(1) Respectively establishing a steel gate solid finite element model and water body finite element models of the front runner and the rear runner according to the specific sizes of the steel gate and the front runner and the rear runner of the steel gate;
(2) Importing the established front and rear runner water body finite element models into ADINA finite element analysis software, selecting a standard Smagorinsky large vortex model, inputting preset material parameters, boundary conditions and flow rate, and carrying out fluid mechanics calculation based on the ADINA finite element analysis software to obtain pulsating pressure at each position of the steel gate under the high-speed water flow;
(3) Fourier variation is carried out on the pulsating pressure obtained in the step (2), and the main frequency of the pulsating pressure at each position of the steel gate is obtained;
(4) Importing the steel gate solid finite element model established in the step (1) into ADINA finite element analysis software, simulating the action of the hydrodynamic pressure of the water body in front of and behind the steel gate by adopting a potential fluid unit, inputting preset material parameters and boundary conditions, and analyzing the self-vibration characteristics of the steel gate result to obtain the self-vibration frequency and vibration mode of each order of the steel gate structure;
(5) Comparing the pulsating pressure dominant frequency at each position of the steel gate obtained in the step (3) with the first-order natural vibration frequency of the steel gate structure obtained in the step (4), and judging whether the possibility of resonance exists according to a comparison result;
(6) Leading the steel gate solid finite element model established in the step (1) into ADINA finite element analysis software, applying pulsating pressure at each position of the steel gate obtained in the step (2) as known load to the steel gate solid finite element model, inputting preset material parameters and boundary conditions, performing dynamic calculation on the steel gate solid finite element model to obtain displacement response and stress response of the steel gate, judging whether the maximum deflection of the steel gate exceeds the requirement according to the displacement response result, and judging whether the maximum tensile stress of the steel gate exceeds the tensile allowable stress according to the stress response result;
(7) And (5) judging the structural safety of the steel gate under the high-speed water flow according to the results of the steps (5) and (6).
In the step (1), the potential fluid unit is adopted by the solid finite element model to simulate the action of additional pulsating pressure in the front and back of the steel gate, the dimension of the water body grid near the steel gate in the water body finite element models of the front and back runners is dense enough, and the grid tensile rate is smaller than 1.1.
The material parameters in the step (2) are gravity acceleration, water density, viscosity, a Prandtl constant and a sub-lattice model constant.
In the step (2), the sub-lattice stress in the standard Smigorinsky large vortex model is
Figure BDA0002419490870000031
In the formula, τ ij The stress is sub-lattice stress, and represents the turbulence effect of the turbulence with the mesoscale smaller than the filtration scale; tau. kk Is sub-lattice turbulent kinetic energy;
Figure BDA0002419490870000032
is the shear deformation tensor; v is t Sub-lattice turbulent viscosity; delta ij Is a unit tensor;
for v t The following equation should be satisfied:
Figure BDA0002419490870000033
l s ＝C s Δ
Figure BDA0002419490870000034
/>
wherein l s Is a sub-lattice vortex scale; c s Is a model constant; delta is the filtration scale of the large vortex model; delta x ，Δ y ，Δ z Calculating the scales of the grid in the x, y and z directions;
in addition, the flow field inlet applies the boundary condition of incoming flow speed, the upper part, the lower part and the contact part with the steel gate apply the solid wall boundary, and the outlet applies the boundary condition, so that the free outflow is realized.
In the step (4), the potential fluid unit is adopted to simulate the action of the hydrodynamic pressure of the front and rear water bodies of the steel gate, and the control equation is as follows:
Figure BDA0002419490870000035
wherein P represents the pressure of the flowing water, c is the speed of the sound wave in the water,
Figure BDA0002419490870000036
is Laplace operator, is->
Figure BDA0002419490870000037
The method is characterized in that a fluid-solid coupling boundary is set between a water body and a steel gate for the second derivative of the hydrodynamic pressure to time, so as to simulate the energy transfer between the water body and the steel gate, and the method comprises the following steps:
Figure BDA0002419490870000041
in the formula, n is the external normal direction of the fluid domain on the fluid-solid coupling surface;
Figure BDA0002419490870000042
the absolute acceleration along the normal direction on the fluid-solid coupling surface; rho is the density of the water body.
And (5) judging whether resonance is possible to occur according to whether the fluctuating pressure main frequency at each position of the steel gate floats up and down in a 10% floating interval of the first-order natural frequency value of the steel gate structure.
In the step (6), when the steel gate is subjected to dynamic calculation, the water body is regarded as a uniform, non-viscous and non-rotational potential fluid, and a system finite element equation set is subjected to gradual time integration by adopting an overall solution method based on a generalized Newmark-beta method to obtain the dynamic response of the steel gate under the action of pulsating water pressure, wherein the fluid-solid coupling system finite element equation set is as follows:
Figure BDA0002419490870000043
Figure BDA0002419490870000044
in the formula, M is a steel gate mass matrix; d is a steel gate damping matrix, rayleigh proportional damping is adopted, D = alpha M + beta K, and alpha and beta are Rayleigh proportional damping coefficients; k is a steel gate rigidity matrix; u, u,
Figure BDA0002419490870000045
Respectively a steel gate displacement vector, a speed vector and an acceleration vector; p is the pressure of the hydraulic pressure before and after the brake; rho represents the density of the water body; f 0 The pulsating pressure acts on the steel gate; g is a mass matrix of the fluid; q is the stiffness matrix of the fluid; h is a damping matrix of the fluid; s is a fluid-solid coupling coefficient matrix; s T Is the transpose of the fluid-solid coupling coefficient matrix.
Has the advantages that: the invention provides a numerical simulation analysis method based on large vortex simulation, aiming at the problems in the current flow-induced vibration calculation analysis of the hydraulic steel gate, the method not only can capture the falling of small-scale vortex under high-speed water flow, but also can effectively solve the defects of difficult determination of a similar scale, high manufacturing cost and the like in a physical model test, can accurately and comprehensively analyze, and provides corresponding basis and reference for the design and the operation of the hydraulic steel gate.
Drawings
FIG. 1 is a solid finite element model of a steel gate;
FIG. 2 is a finite element model of the fluid in the front and rear flow channels of the steel gate;
FIG. 3 is an enlarged view of a portion of a fluid finite element model;
FIG. 4 is a velocity cloud (m/s) of the flow field at a time;
FIG. 5 is a pressure cloud (Pa) at a time in the flow field;
FIG. 6 is a schematic diagram of the positions of feature points in a finite element model of a flow field;
FIG. 7 is a time course curve of pulsating pressure at characteristic points of a flow field;
FIG. 8 is a pulsating pressure spectrum plot at a flow field feature point;
FIG. 9 shows the displacement (m) of the steel gate in the water flow direction at a certain time;
FIG. 10 is a first principal stress (Pa) at a time of the steel gate;
FIG. 11 is a schematic diagram of the position of a steel gate displacement and stress feature point;
FIG. 12 is a displacement time-course curve along the water flow direction at the displacement characteristic point of the steel gate;
fig. 13 is a first principal stress time course curve at a stress characteristic point of the steel gate.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
The invention discloses a hydraulic steel gate flow-induced vibration analysis method based on large vortex simulation, which comprises the following steps of:
(1) Measuring the specific dimensions of the steel gate and the front and rear runners of the gate, and respectively establishing a solid finite element model of the steel gate and a water body finite element model of the front and rear runners according to the specific dimensions of the steel gate and the front and rear runners of the gate, wherein in consideration of the fact that the steel gate generates displacement deformation under the action of high-speed water flow to cause additional pulsating pressure on a water body adjacent to the structure, in the solid finite element model, a potential fluid unit is adopted to simulate the action of the additional pulsating pressure on the front and rear sides of the steel gate; in the finite element model of the water body with the front and the rear channels, the grid size of the water body near the steel gate needs to be dense enough, and the grid tensile rate needs to be less than 1.1, so that the pulsating pressure of water flow near the steel gate can be accurately simulated.
(2) Leading the front and rear runner water body finite element models established in the step 1 into ADINA finite element analysis software, selecting a standard Smagorinsky large vortex model from the ADINA finite element analysis software, inputting preset material parameters such as gravity acceleration, water body density, viscosity, prandtl constant and sub-grid model constant, boundary conditions and flow speed, carrying out fluid mechanics calculation based on the ADINA finite element analysis software to obtain pulsating pressure at each position of the steel gate under high-speed water flow, wherein the sub-grid stress in the standard Smagorinsky large vortex model is
Figure BDA0002419490870000051
In the formula, τ ij The stress of the sub-lattice represents the turbulence effect of the turbulence with the scale smaller than the filtration scale; tau is kk Is sub-lattice turbulent kinetic energy;
Figure BDA0002419490870000052
is the shear deformation tensor; v is t Sub-lattice turbulent viscosity; delta ij Is the unit tensor.
For v t The following equation should be satisfied:
Figure BDA0002419490870000061
l s ＝C s Δ
Figure BDA0002419490870000062
wherein l s Is a sub-lattice vortex scale; c s Is a model constant; delta is the filtration scale of the large vortex model; delta x ，Δ y ，Δ z Calculating the dimension of the grid in the x, y and z directions; c s The value of the (A) is different with the property of the fluid, and is taken as 0.1 in the calculation, in addition, an incoming flow velocity boundary condition is applied to the inlet of the flow field, a solid wall boundary is applied to the upper part, the lower part and the contact part with the steel gate, and a boundary condition is applied to the outlet to ensure free outflow;
(3) In ADINA finite element analysis software, carrying out Fourier change on the pulsating pressure obtained in the step 2 to obtain the main frequency of the pulsating pressure at each position of the steel gate;
(4) Leading the steel gate solid finite element model established in the step 1 into ADINA finite element analysis software, adopting a potential fluid unit to simulate the action of the front and back water body dynamic water pressure of the steel gate, inputting preset material parameters and boundary conditions, carrying out self-vibration characteristic analysis on the steel gate result, adopting the potential fluid unit to simulate the action of the front and back water body dynamic water pressure of the steel gate, and having the following control equation:
Figure BDA0002419490870000063
wherein P represents the pressure of the flowing water, c is the speed of the sound wave in the water,
Figure BDA0002419490870000064
is Laplace operator, is->
Figure BDA0002419490870000065
The second derivative of the hydrodynamic pressure with respect to time. Meanwhile, a fluid-solid coupling boundary is arranged between the water body and the structure so as to simulate energy transfer between the water body and the structure, and the method comprises the following specific steps:
Figure BDA0002419490870000066
in the formula, n is the external normal direction of the fluid domain on the fluid-solid coupling surface;
Figure BDA0002419490870000067
the absolute acceleration along the normal direction on the fluid-solid coupling surface; rho is the density of the water body.
(5) Comparing the pulsating pressure main frequency at each position of the steel gate obtained in the step 3 with the first-order natural frequency of the steel gate structure obtained in the step 4, and judging whether the possibility of proving resonance exists or not, evaluating the safety of the steel gate structure from a qualitative angle, wherein if the pulsating pressure main frequency at each position of the steel gate is in a floating interval which is 10% above and below the first-order natural frequency value of the steel gate structure, the steel gate is likely to resonate under high-speed water flow;
(6) Leading the steel gate solid finite element model established in the step 1 into ADINA finite element analysis software, applying pulsating pressure at each position of the steel gate obtained in the step 2 as known load to the steel gate solid finite element model in the ADINA finite element analysis software, inputting preset material parameters and boundary conditions, performing dynamic calculation on the steel gate solid finite element model to obtain displacement response and stress response of the steel gate, judging whether the maximum deflection of the steel gate exceeds the requirement according to the displacement response result, and judging whether the maximum tensile stress of the steel gate exceeds the allowable tensile stress according to the stress response result; if the two are not exceeded, the steel gate is safe, if one is exceeded, potential safety hazards exist, and the structural safety of the steel gate is evaluated from the quantitative angle; and when the steel gate is subjected to dynamic calculation, the fluid-solid coupling effect of the front and rear water bodies and the steel gate is considered, the water bodies are regarded as uniform, non-viscous and non-rotational potential fluids, and the system finite element equation set is subjected to gradual time integration by adopting an integral solution method based on a generalized Newmark-beta method, so that the dynamic response of the steel gate under the action of the pulsating water pressure is obtained. The fluid-solid coupling system finite element equation set is as follows:
Figure BDA0002419490870000071
Figure BDA0002419490870000072
in the formula, M is a steel gate mass matrix; d is a steel gate damping matrix, rayleigh proportional damping is adopted to assume that D = AlM + beta K, and alpha and beta are Rayleigh proportional damping coefficients; k is a steel gate rigidity matrix; u, u,
Figure BDA0002419490870000073
Respectively a steel gate displacement vector, a speed vector and an acceleration vector; p is the pressure of the hydraulic pressure before and after the brake; s is a fluid-solid coupling coefficient matrix; rho represents the density of the water body; f 0 Pulsating pressure acting on the steel gate; g is the 'mass matrix' of the fluid; q is the 'stiffness matrix' of the fluid; h is a 'damping matrix' of the fluid; s is a fluid-solid coupling coefficient matrix; s T Is the transpose of the fluid-solid coupling coefficient matrix.
(7) And (4) combining qualitative and quantitative evaluation results to perform overall evaluation on the structural safety of the steel gate under the high-speed water flow.
When the method is used for specific analysis, a flood discharge bottom hole of a certain hydropower station is a plane steel gate, and a steel gate solid finite element model under the opening degree of 10% and water body finite element models of front and rear runners are respectively established according to specific sizes of the plane steel gate and the front and rear runners of the gate, wherein the specific models are shown in figures 1 and 2. In order to accurately simulate the pulsating pressure of water flow near the steel gate, the grid dimension near the steel gate in the fluid finite element model is dense enough, and the grid stretching ratio is less than 1.1, as shown in fig. 3.
The steel gate in the calculation is Q345B steel, and the density is 7850kg/m 3 The elastic modulus is 206GPa, the Poisson ratio is 0.30, and the water density is 1000kg/m 3 Viscosity coefficient of 0.001 pas and gravitational acceleration of 9.81m/s 2 。
The front and rear runner water body finite element models established as shown in fig. 2 are led into ADINA finite element analysis software, and in the ADINA finite element analysis software, a standard Smagorinsky large vortex model is adopted, preset material parameters, boundary conditions and flow rate are input, and the established fluid finite element models are calculated and analyzed. Wherein, the inlet of the flow field applies boundary condition of incoming flow speed, the speed is 1.0m/s, the upper part, the lower part and the contact part with the steel gate apply solid wall boundary, the outlet applies boundary condition to ensure free outflow.
For the standard Smagorinsky large vortex model, the subgrid stress is:
Figure BDA0002419490870000081
in the formula, τ ij The stress of the sub-lattice represents the turbulence effect of the turbulence with the scale smaller than the filtration scale; tau is kk Is sub-lattice turbulent kinetic energy;
Figure BDA0002419490870000082
is the shear deformation tensor; v is t Sub-lattice turbulent viscosity; delta. For the preparation of a coating ij Is the unit tensor.
For v t The following equation should be satisfied:
Figure BDA0002419490870000083
l s ＝C s Δ
Figure BDA0002419490870000084
wherein l s Is a sub-lattice vortex scale; c s Is a model constant; delta is the filtration scale of the large vortex model; delta of x ，Δ y ，Δ z Calculating the scales of the grid in the x, y and z directions; c s The value of (2) is different with the property of the fluid, and is taken as 0.1 in the calculation.
Fig. 4 and 5 respectively show a speed distribution cloud chart and a pressure distribution cloud chart of a flow field at a certain time, and it can be seen that the falling of vortices under high-speed water flow can be captured by adopting a standard Smagorinsky large vortex model. Meanwhile, in order to analyze the calculation result, a certain node in the fluid finite element is selected as a characteristic point to be analyzed, and the specific position of the node is shown in fig. 6.
Fig. 7 shows a pulse pressure time-course curve at the characteristic point, and the pulse pressure time-course curve is subjected to fourier transform, so that a pulse pressure frequency distribution at the position can be obtained, and as shown in fig. 8, it can be seen that a main frequency of a pulse frequency of water flow at 10% opening is about 1.12HZ.
The steel gate solid finite element model shown in fig. 1 is led into ADINA finite element analysis software, the potential fluid unit is adopted to simulate the action of the hydrodynamic pressure of the front and rear water bodies of the steel gate, preset material parameters and boundary conditions are input, and the steel gate is subjected to natural vibration analysis by using a structural natural vibration characteristic analysis method. Wherein, fixed constraint is exerted on the top of the steel gate and two sides of a downward 10% region, and a control equation of potential fluid is as follows:
Figure BDA0002419490870000091
wherein P represents the pressure of the flowing water, c is the speed of the sound wave in the water,
Figure BDA0002419490870000092
is Laplace operator, is->
Figure BDA0002419490870000093
The second derivative of the hydrodynamic pressure with respect to time. Meanwhile, a fluid-solid coupling boundary is arranged between the water body and the structure so as to simulate energy transfer between the water body and the structure, and the method comprises the following specific steps: />
Figure BDA0002419490870000094
In the formula, n is the external normal direction of the fluid domain on the fluid-solid coupling surface;
Figure BDA0002419490870000095
is fluid-solid couplingAbsolute acceleration on the surface along the normal; rho is the density of the water body.
TABLE 1 comparison of 2-order natural vibration frequency before steel gate under water and water-free working conditions
Order of mode Frequency of vibration (Hz) Frequency of natural vibration with water (Hz)
1 54.59 36.24
2 327.9 253.5
The comparison shows that the natural vibration frequency of the steel gate is reduced by the presence of water bodies in front of and behind the gate, wherein the first-order natural vibration frequency is reduced by about 33.6 percent compared with the anhydrous working condition, and the natural vibration frequency cannot be ignored in calculation and analysis. As can be seen from Table 1, the first-order natural vibration frequency of the steel gate is respectively 54.59Hz and 36.24Hz under the working conditions of no water and water, and far exceeds the water flow pulsation frequency, so the possibility of resonance phenomenon is low.
The method comprises the steps of introducing a steel gate solid finite element model shown in figure 1 into ADINA finite element analysis software, applying pulsating pressure at each position of the steel gate obtained by calculation as known load to the steel gate in the ADINA finite element analysis software, inputting preset material parameters and boundary conditions, adopting a potential fluid unit to consider the fluid-solid coupling effect of front and rear water bodies and the steel gate, adopting an integral solution method based on a generalized Newmark-beta method to carry out power calculation on the steel gate solid finite element model to obtain displacement response and stress response of the steel gate, judging whether the maximum deflection of the steel gate exceeds the requirement according to the displacement response result, and judging whether the maximum tensile stress of the steel gate exceeds the tensile allowable stress according to the stress response result; if both of the two are not exceeded, the operation is safe, and if one of the two is exceeded, the potential safety hazard exists; wherein, fixed constraint is exerted on the top of the steel gate and two sides of a downward 10% region, and a finite element equation system of the fluid-solid coupling system is as follows:
Figure BDA0002419490870000096
Figure BDA0002419490870000097
in the formula, M is a steel gate mass matrix; d is a steel gate damping matrix, rayleigh proportional damping is adopted to assume that D = AlM + beta K, and alpha and beta are Rayleigh proportional damping coefficients; k is a steel gate rigidity matrix; u, u,
Figure BDA0002419490870000101
Respectively a steel gate displacement vector, a speed vector and an acceleration vector; p is the pressure of the hydraulic pressure before and after the brake; s is a fluid-solid coupling coefficient matrix; ρ represents the density of the water body; f 0 The pulsating pressure acts on the steel gate; g is the 'mass matrix' of the fluid; q is the 'stiffness matrix' of the fluid; h is a 'damping matrix' of the fluid; s is a fluid-solid coupling coefficient matrix; s T Is the transpose of the fluid-solid coupling coefficient matrix.
Fig. 9 and 10 show the downstream displacement distribution and the first principal stress distribution cloud chart of the steel gate at a certain time. In order to facilitate the analysis of the displacement and the stress state of the steel gate, a displacement analysis characteristic point and a stress analysis characteristic point are respectively selected, and are specifically shown in fig. 11.
Fig. 12 and 13 respectively show a time-course change curve of a displacement characteristic point and a time-course change curve of a stress characteristic point, and it can be seen that, under the action of high-speed water flow, the displacement of the steel gate along the water flow direction is smaller, the maximum value is about 0.96mm, the ratio of the maximum deflection to the calculated width is 1/2083.3, which is smaller than 1/750 specified in the design specification of the steel gate for hydraulic and hydro-power engineering (SL 74-2013), and the safety requirement is met; meanwhile, the maximum tensile stress of the steel gate under the action of water flow is 37.1MPa, which is less than the allowable tensile stress of the Q345B steel, namely 220MPa, so that the safety requirement is met.
In conclusion, the overall structure of the steel gate under the opening degree of 10% meets the safety requirement by combining the qualitative and quantitative evaluation results.

Claims (7)

1. A hydraulic steel gate flow-induced vibration analysis method based on large vortex simulation is characterized by comprising the following steps:
(1) Respectively establishing a steel gate solid finite element model and water body finite element models of the front runner and the rear runner according to the specific sizes of the steel gate and the front runner and the rear runner of the steel gate;
(2) Leading the established water body finite element models of the front runner and the rear runner into ADINA finite element analysis software, selecting a standard Smigorinsky large vortex model, inputting preset material parameters, boundary conditions and flow rate, and carrying out fluid mechanics calculation based on the ADINA finite element analysis software to obtain pulsating pressure at each position of the steel gate under the high-speed water flow;
(3) Fourier variation is carried out on the pulsating pressure obtained in the step (2), and the main frequency of the pulsating pressure at each position of the steel gate is obtained;
(4) Importing the steel gate solid finite element model established in the step (1) into ADINA finite element analysis software, simulating the action of hydrodynamic pressure of water in front of and behind the steel gate by adopting a potential fluid unit, inputting preset material parameters and boundary conditions, and analyzing the self-vibration characteristics of the steel gate result to obtain the self-vibration frequency and vibration mode of each order of the steel gate structure;
(5) Comparing the pulsating pressure main frequency at each position of the steel gate obtained in the step (3) with the first-order natural vibration frequency of the steel gate structure obtained in the step (4), and judging whether the possibility of resonance exists according to the comparison result;
(6) Leading the steel gate solid finite element model established in the step (1) into ADINA finite element analysis software, applying pulsating pressure at each position of the steel gate obtained in the step (2) as known load to the steel gate solid finite element model, inputting preset material parameters and boundary conditions, performing dynamic calculation on the steel gate solid finite element model to obtain displacement response and stress response of the steel gate, judging whether the maximum deflection of the steel gate exceeds the requirement according to the displacement response result, and judging whether the maximum tensile stress of the steel gate exceeds the tensile allowable stress according to the stress response result;
(7) And (5) judging the structural safety of the steel gate under the high-speed water flow according to the results of the steps (5) and (6).
2. The method for analyzing the flow-induced vibration of the hydraulic steel gate based on the large vortex simulation as claimed in claim 1, wherein the solid finite element model in the step (1) adopts a potential fluid unit to simulate the action of additional pulsating pressure at the front and the rear of the steel gate, the mesh sizes of the water bodies near the steel gate in the finite element models of the water bodies of the front and the rear runners are sufficiently dense, and the mesh tensile rate is less than 1.1.
3. The method for analyzing flow-induced vibration of the hydraulic steel gate based on the large vortex simulation as claimed in claim 1, wherein the material parameters in the step (2) are gravity acceleration, water density, viscosity, prandtl constant and sub-lattice model constant.
4. The method for analyzing flow-induced vibration of the hydraulic steel gate based on the large vortex simulation as claimed in claim 1, wherein in the step (2), the sub-lattice stress in the standard Smigorinsky large vortex model is as follows
Figure FDA0002419490860000021
In the formula, τ ij The stress is sub-lattice stress, and represents the turbulence effect of the turbulence with the mesoscale smaller than the filtration scale; tau. kk Is sub-lattice turbulent kinetic energy;
Figure FDA0002419490860000022
is the shear deformation tensor; v is t Sub-lattice turbulent viscosity; delta ij Is a unit tensor;
for v t The following equation should be satisfied:
Figure FDA0002419490860000023
l s ＝C s Δ
Figure FDA0002419490860000024
wherein l s Is a sub-lattice vortex scale; c s Is a model constant; delta is the filtration scale of the large vortex model; delta of x ，Δ y ，Δ z Calculating the dimension of the grid in the x, y and z directions;
in addition, the flow field inlet applies the boundary condition of incoming flow speed, the upper part, the lower part and the contact part with the steel gate apply the solid wall boundary, and the outlet applies the boundary condition, so that the free outflow is realized.
5. The method for analyzing the flow-induced vibration of the hydraulic steel gate based on the large vortex simulation as claimed in claim 1, wherein in the step (4), a potential fluid unit is used for simulating the hydrodynamic pressure action of the front and rear water bodies of the steel gate, and the control equation is as follows:
Figure FDA0002419490860000025
wherein P represents the hydrodynamic pressure, c is the sound wave velocity in water- 2 In order to be the laplacian operator,
Figure FDA0002419490860000026
for the second derivative of the hydrodynamic pressure to the time, a fluid-solid coupling boundary is arranged between the water body and the steel gate, so as to simulate the water body and the steel gateThe energy transfer between the doors is as follows:
Figure FDA0002419490860000027
in the formula, n is the external normal direction of the fluid domain on the fluid-solid coupling surface;
Figure FDA0002419490860000028
the absolute acceleration along the normal direction on the fluid-solid coupling surface; rho is the density of the water body.
6. The method for analyzing the flow-induced vibration of the hydraulic steel gate based on the large vortex simulation as claimed in claim 1, wherein in the step (5), whether resonance is possible to occur is determined according to whether the fluctuation of the pulsating pressure dominant frequency at each position of the steel gate in the first-order natural vibration frequency value of the steel gate structure is within a 10% fluctuation interval.
7. The method for analyzing flow-induced vibration of a hydraulic steel gate based on large vortex simulation as claimed in claim 1, wherein in the step (6), when the steel gate is subjected to dynamic calculation, the water body is regarded as a uniform, non-viscous and non-rotational potential fluid, and a generalized Newmark-beta method-based integral solution method is adopted to perform gradual time integration on a system finite element equation set so as to obtain the dynamic response of the steel gate under the action of pulsating water pressure, wherein the fluid-solid coupling system finite element equation set is as follows:
Figure FDA0002419490860000031
Figure FDA0002419490860000032
in the formula, M is a steel gate mass matrix; d is a steel gate damping matrix, rayleigh proportional damping is adopted to assume that D = alpha M + beta K, and alpha and beta are Rayleigh ratioDamping coefficient is adjusted; k is a steel gate rigidity matrix; u, u,
Figure FDA0002419490860000033
Respectively a steel gate displacement vector, a speed vector and an acceleration vector; p is the pressure of the hydraulic pressure before and after the brake; rho represents the density of the water body; f 0 The pulsating pressure acts on the steel gate; g is a mass matrix of the fluid; q is the stiffness matrix of the fluid; h is a damping matrix of the fluid; s is a fluid-solid coupling coefficient matrix; s T Is the transpose of the fluid-solid coupling coefficient matrix.
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