CN110688718A - Method for designing beam-type bridge of air cooling fan under conditions of beam-type bridge parameters and vibration amplitude - Google Patents
Method for designing beam-type bridge of air cooling fan under conditions of beam-type bridge parameters and vibration amplitude Download PDFInfo
- Publication number
- CN110688718A CN110688718A CN201910931895.3A CN201910931895A CN110688718A CN 110688718 A CN110688718 A CN 110688718A CN 201910931895 A CN201910931895 A CN 201910931895A CN 110688718 A CN110688718 A CN 110688718A
- Authority
- CN
- China
- Prior art keywords
- bridge
- fan
- vibration
- eccentric
- formula
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims abstract description 25
- 238000001816 cooling Methods 0.000 title claims abstract description 18
- 238000004458 analytical method Methods 0.000 claims abstract description 25
- 238000012360 testing method Methods 0.000 claims abstract description 15
- 230000009471 action Effects 0.000 claims abstract description 13
- 238000013461 design Methods 0.000 claims abstract description 8
- 229910000831 Steel Inorganic materials 0.000 claims description 22
- 239000010959 steel Substances 0.000 claims description 22
- 238000006073 displacement reaction Methods 0.000 claims description 17
- 230000008569 process Effects 0.000 claims description 10
- 230000001133 acceleration Effects 0.000 claims description 9
- 238000009434 installation Methods 0.000 claims description 9
- 238000004364 calculation method Methods 0.000 claims description 6
- 230000003068 static effect Effects 0.000 claims description 6
- 230000005483 Hooke's law Effects 0.000 claims description 2
- NAWXUBYGYWOOIX-SFHVURJKSA-N (2s)-2-[[4-[2-(2,4-diaminoquinazolin-6-yl)ethyl]benzoyl]amino]-4-methylidenepentanedioic acid Chemical compound C1=CC2=NC(N)=NC(N)=C2C=C1CCC1=CC=C(C(=O)N[C@@H](CC(=C)C(O)=O)C(O)=O)C=C1 NAWXUBYGYWOOIX-SFHVURJKSA-N 0.000 claims 1
- 238000011160 research Methods 0.000 abstract description 4
- 238000011002 quantification Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 5
- 239000003638 chemical reducing agent Substances 0.000 description 4
- 238000012938 design process Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 230000005484 gravity Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 238000005452 bending Methods 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003245 coal Substances 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 230000005284 excitation Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011835 investigation Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000004445 quantitative analysis Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
Images
Landscapes
- Bridges Or Land Bridges (AREA)
Abstract
A method for designing a beam-type bridge of an air cooling fan under the conditions of beam-type bridge parameters and vibration amplitudes belongs to the field of structural performance research, and the vibration of the bridge caused by fan eccentricity is found through field test on the vibration of the beam-type fan bridge, and the vibration amplitudes of the fan bridge are related to the eccentric mass and the vertical rigidity of two main beams. In order to analyze the vibration relation between the eccentric mass and the fan bridge, the action of the eccentric force caused by the eccentric mass under different working conditions on the bridge is solved, a beam type bridge rigidity analysis model under the action of the eccentric force is established, the magnitude of the fan eccentric mass is indirectly estimated by measuring the vibration amplitude values on the main beams at the two sides of the bridge, and a quantification formula of the influence of the eccentric mass on the vibration of the bridge is deduced. The relation between the fan eccentric mass and the beam type bridge parameters and the vibration amplitude is established, and a basis is provided for avoiding bridge vibration caused by fan eccentricity in the design of the beam type bridge.
Description
Technical Field
The invention relates to a method for designing a beam-type bridge structure of an air cooling fan, belongs to the field of structural performance research, and particularly relates to a method for simplifying the structure of the fan bridge structure by analyzing the eccentric action of the fan, and finally designing a bridge design formula under the eccentric mass by deducing under the conditions of beam-type bridge parameters and vibration amplitude values.
Background
The direct air cooling system is an important component of an air cooling type thermal power plant, and adopts a large-diameter axial flow fan as an air driving device, so that exhaust steam of a steam turbine is cooled and condensed into water through air. With the development of industry and the improvement of human living standard, the demand of water resources is increasing day by day, and in addition, the influence of a plurality of factors such as water resource shortage caused by environmental pollution, the direct air cooling technology for saving water is rapidly developed at home and abroad. In northern areas of China, coal resources are rich, but water resources are short, and the application of the direct air cooling technology in a thermal power plant in the area generates obvious environmental and economic benefits.
The air cooling fan mainly comprises a motor, a speed reducer, a fan shaft, fan blades and a bridge, wherein the fan bridge is fixed on the air cooling platform. The fan takes a motor as a power source and is driven by the output torque of the reduction gearbox. In the running process of the fan, the fan bridge generates large vibration. The safety and reliability of the fan bridge frame are the precondition for ensuring the normal operation of the fan and the normal work of the air cooling system. According to investigation, many power plants such as the Tokto power plant, the Huaian power plant, the Dongsheng power plant and the like have been damaged by the equipment such as the motor, the speed reducer, the fan and the like due to the overlarge vibration amplitude of the fan bridge, and potential safety hazards are caused to the supporting structure, and the condition is continuous. The shore charm aims at the vibration problem of a bridge frame of a certain petrochemical F1059 direct air cooling unit, vibration tests and modal analysis are carried out on a wind turbine bridge frame, resonance is generated when the natural frequency of the bridge frame is close to the passing frequency of blades, and meanwhile, unbalanced force when a wind turbine runs is indicated to be one of the reasons for causing the vibration of the bridge frame. The sinus Ruijie carries out a series of experimental researches on a 1:1 experimental model of the fan system, and analyzes the distribution rule of the acceleration along the bridge when the fan runs. The drogue and the like adopt a dynamic strain test technology to test the strain of a fan shaft under working conditions, and the result shows that 4 disturbance forces are generated in the running process of the fan. The vibration source of the fan bridge vibration is analyzed comprehensively, mass eccentricity is proposed to be one of the reasons for causing the bridge vibration, and due to the fact that the mass center of a fan rotor deviates from the axis of a fan in the manufacturing and mounting processes, eccentric force is generated in the running process of the fan, and therefore the vibration frequency of the vibration caused by the eccentric force is equal to the rotation frequency of a fan shaft. But the main analysis is the vortex excitation effect on the fan blades and the influence on the bridge frame vibration. The research preliminarily analyzes the bridge vibration caused by the eccentric force when the fan operates, and does not have a quantitative analysis result, but in the bridge design process, the bridge needs to be designed according to a quantitative result.
Therefore, it is very important to provide a quantitative formula of the influence of the eccentric mass of the fan on the vibration of the bridge, and the quantitative formula is also the core of the patent.
Disclosure of Invention
The method is based on the vibration condition of the beam type fan bridge of the direct air cooling system measured actually, and under the conditions of beam type bridge parameters and vibration amplitude values, a quantitative formula of the influence of eccentric mass on bridge vibration is deduced. The method is mainly characterized in that after the vibration source of the fan bridge is analyzed, the bridge is simplified into a simply supported beam model, a design formula of the bridge under the eccentric mass is deduced, a complex finite element analysis process in the bridge design process is omitted, and a convenient method is provided for designing the beam bridge.
The invention is realized by adopting the following technical means:
1. the acceleration sensor is used for carrying out real-ground vibration test on the fan bridge, and the vibration influence of the fan eccentricity on the fan bridge is researched.
2. In order to analyze the vibration relationship between the eccentric mass and the fan bridge, the action of the eccentric force caused by the eccentric mass on the bridge under different working conditions needs to be solved, and then a rigidity model of the bridge is established, so that an equation of the eccentric mass of the fan and the amplitude of the bridge can be deduced. Based on the model, the eccentric mass is indirectly estimated by testing the amplitude of the bridge frame. Namely, the wind turbine bridge is estimated through a finite element model.
3. And designing the rigidity of the bridge according to the mass-diameter product of the eccentric mass allowed by the fan and the vibration amplitude allowed by the bridge. In order to facilitate engineering application, a fan bridge model is simplified, a design formula of the bridge under the eccentric mass is deduced, a complex finite element analysis process in the bridge design process is omitted, and a convenient method is provided for designing the beam type bridge.
Drawings
Fig. 1 fan bridge and structure
FIG. 2 Fan bridge model and measurement Point layout
FIG. 31 and FIG. 3 are frequency domain diagrams of sensors
Figure 4 bridge three-dimensional model
FIG. 5 illustrates the first three-order mode of the bridge
FIG. 6 force analysis diagram
FIG. 71, No. 3 sensor experiment data fitting
FIG. 8 gantry statics analysis
Detailed Description
Step one, researching influence of eccentricity of a fan on a bridge
The vibration condition of the bridge at different rotating speeds is tested by testing the air cooling fan bridge of a waste heat power generation project of Shanxi Xiaoxiayi, and as shown in a fan bridge and a structure diagram in figure 1, the fan parameters are shown in a table 1. In order to test the vibration condition of the middle part of the bridge girder, and the vibration of the bridge caused by the eccentric force mainly comes from the fan shaft, therefore, the measuring sensor is mainly arranged in the middle of the middle part of the bridge girder in the vertical direction (Z direction), and the schematic diagram of the sensor arrangement is shown in FIG. 1. According to the working range of the fan, the rotating speed of the fan is divided into 12 working conditions from low speed to high speed, and therefore, frequency domain analysis is carried out on effective data collected under the working conditions of the fan. In the vertical direction (i.e. Z direction), the data analysis results of sensors No. 1 and 3 are shown in fig. 3, table 2 shows the relevant parameters corresponding to the test conditions and the fan, and the test results show that: the corresponding frequency of the peak point is equal to the rotating frequency of the fan shaft, and the frequency is continuously increased along with the increase of the rotating speed of the fan, so that the overlarge vibration amplitude of the bridge caused by the eccentric mass of the fan is proved.
TABLE 1 Fan parameters
TABLE 2 Fan Condition parameters
Step two, fan bridge dynamic analysis
2.1 bridge three-dimensional model
A three-dimensional model of the bridge is established according to an engineering drawing, the bridge is mainly formed by two H-shaped steels serving as main beams, and a bearing fan, a speed reducer and a motor are arranged in the middle of the bridge and are supported by a fan bottom plate. As shown in fig. 4, which is a bridge frame equipped with a speed reducer and a simplified model of a motor, the weight of a fan blade is placed on a fan shaft at a blade mounting position in a mass element manner.
2.2 bridge Modal analysis
And after the bridge is modeled, grid division is carried out, and then modal analysis is carried out on the bridge. The front three-order mode of the bridge is shown in fig. 5, and the natural frequency is shown in table 3.
TABLE 3 inherent frequency of the first third order of bridge
From the results of the modal analysis it can be seen that: the maximum frequency value of the bridge vibration caused by the eccentric mass is 2.9HZ, the frequency is far away from the natural frequency of the bridge and cannot resonate with the bridge, so that the vibration caused by the eccentric mass is only related to the static rigidity of the fan bridge. When analyzing the vibration relation between the eccentric mass and the fan bridge, only the static rigidity of the bridge can be considered.
Step three fan eccentricity analysis
In order to analyze the vibration relation between the eccentric mass and the fan bridge, the action of the eccentric force caused by the eccentric mass on the bridge under different working conditions needs to be solved, and then a rigidity model of the bridge is established, so that an equation of the amplitude of the fan eccentric mass and the bridge can be deduced. Based on the model, the eccentric mass is indirectly estimated by testing the amplitude of the bridge frame.
Step 3.1 Fan eccentricity theoretical analysis
In the running process of the fan, the magnitude of the eccentric force F generated by the blades is unchanged under the same rotating speed, and when the eccentric force F in the horizontal plane acts on the fan shaft in the direction vertical to the axes of the two main beams (namely the X direction), the vibration generated by the main beams at the two sides of the bridge frame is the largest, so the stress of the fan at the moment is taken as an example for calculation. After the eccentric force F is converted to the center of the bridge, the bridge bears a force F vertical to the bridge in the connecting direction (namely the X direction) of the two main beams5Acts to simultaneously generate a torque. The torque can be converted into a couple F in the vertical direction (i.e. Z direction)1The moment of couple generated. Due to the couple, the couple F on both sides1Equal in size and opposite in direction. Couple F1Causing bending deformation of the middle part of the bridge girder in the vertical direction, the deformation amount is | X |, as shown in fig. 6.
From the above torque conversion relationship: the eccentric force F is in direct proportion to a couple F1, and the relation between the eccentric force F and the deformation | X | of the bridge girder in the vertical (namely Z direction) direction can be determined according to Hooke's law:
F＝K·|X| (1)
in the formula: f is the eccentric force, K is the rigidity value of the bridge girder, and | X | is the vibration displacement amplitude of the middle part of the bridge girder in the vertical direction.
The relationship between the displacement amplitude and the acceleration amplitude is as follows:
in the formula: and | A | is the vibration acceleration amplitude of the middle part of the bridge girder, ω is the vibration frequency of the middle part of the bridge girder, and | X | is the vibration displacement amplitude of the middle part of the bridge girder in the vertical direction.
The formula for calculating the eccentric force F is as follows:
F＝4π2mrf2(3)
in the formula: f is eccentric force, m is eccentric mass, r is eccentric radius, and F is fan shaft rotation frequency.
Because the fan is at the operation in-process, the vibration frequency in crane span structure girder middle part equals with fan axle rotational frequency, and f equals omega, so substitutes equation (1), (2) into equation (3) and gets:
in the formula: and | A | is the vibration acceleration amplitude of the middle part of the bridge girder, ω is the vibration frequency of the middle part of the bridge girder, m is the eccentric mass, r is the eccentric radius, and K is the rigidity value of the bridge girder.
Step 3.2 fitting of Experimental data
From equation (4) it follows: the acceleration and the frequency are in a 4-power relation, and then peak points, namely | A, in the frequency domain graphs of the sensors No. 1 and No. 3 are extracted1|、|A3And performing power exponent fitting by using MATLAB, wherein peak points of sensors 1 and 3 and a fitting curve are shown in FIG. 7. The fitted curve equations are respectively:
|A1|＝0.135ω4(5)
|A3|＝0.15ω4(6)
in the formula: | A1I is peak point data in the frequency domain diagram of sensor No. 1, | A2And | is peak point data in the frequency domain diagram of the No. 2 sensor, and ω is the vibration frequency of the middle part of the bridge girder.
Step 3.3 eccentric mass estimation
Because the eccentric force of the fan acts on the fan shaft, in order to obtain the static rigidity of the two main beams of the bridge, negative X-direction force is exerted on the fan shaft, and the deformations | X | of the bridge main beam in the vertical direction (namely the Z direction) are X | respectively under the action of torque3＝0.185mm、X10.181mm, as shown in fig. 8. The eccentric force and the rigidity K of the two main beams are respectively known by a rigidity calculation formula: k3＝12356.76N/mm、K1＝12629.83N/mm。
Combining the experimental results and combining the formulas (4), (5) and (6) and finite element analysis results to obtain a mass-diameter product [ mr ] of the eccentric mass of the fan, wherein the mass-diameter product [ mr ] is as follows:
[mr1]＝0.135K1＝1705.03(kg·mm) (7)
[mr3]＝0.15K3＝1853.51(kg·mm) (8)
in the formula: [ mr ] of1]Mass product at point No. 1, [ mr ]3]Is the mass product at the No. 3 test point, K1Is the stiffness value at test point No. 1, K3The value of the rigidity at the measurement point No. 3.
It can be seen that the results of estimating the fan mass-diameter products respectively according to the vibration at the two measuring points are approximately equal. The slight difference between the two results is mainly due to the difference between the theoretical design and the actual structure in the structure manufacturing process.
Step four, designing the bridge frame for the eccentricity of the fan
Step 4.1 Main Beam stress analysis
The eccentric force F of the fan acts on the fan shaft, a torque M is generated in the direction (namely the X direction) perpendicular to the main beam in the horizontal plane, and the component force of the eccentric force F in the direction perpendicular to the main beam in the horizontal plane is periodically changed due to the continuous change of the direction of the eccentric force F, so that a couple F in the vertical direction (namely the Z direction) is converted1Also, a periodic change occurs when F1When the maximum value is reached, the eccentric force is perpendicular to the bridge girder in the horizontal plane, as shown in fig. 4. The torque generated by the eccentric force F can be equivalently converted into a couple F1The moment of couple is generated so that the moment of couple is equal to the converted torque.
Eccentric force F and couple F1The relationship of (1) is:
M＝F·L (9)
in the formula: f is eccentric force, and L is the distance from the installation position of the fan blade to the middle point of the section of the H-shaped steel.
Couple F1The moment of couple generated is:
M＝F1·L1(10)
in the formula: f is eccentric force, L is the distance from the installation position of the fan blade to the middle point of the section of the H-shaped steel, and F1Couple, L, produced in the vertical direction of the two main beams for eccentric forces1The distance between the central axes of the two main beams of the bridge frame.
Simultaneous (9) and (10) to obtain the eccentric force F and the couple F1The relationship of (1) is:
F·L＝F1·L1(11)
in the formula: f1Couple, L, produced in the vertical direction of the two main beams for eccentric forces1The distance between the central axes of the two main beams of the bridge frame.
In the vertical direction, the rigidity of a single main beam is K according to Hooke's law2And the displacement of the main beam under the action of unit force is calculated according to the formula:
F1＝K2·|X| (12)
in the formula: f1Couple, K, produced in the vertical direction of the two main beams for eccentric forces2The rigidity of the middle part of the bridge girder is shown, and | X | is the vibration displacement amplitude of the middle part of the bridge girder in the vertical direction.
Substituting the eccentric force formula (3) and the calculation formula (12) of the rigidity of the single main beam into the formula (11) to obtain the relation between the rigidity and the eccentric mass
In the formula: omega is the vibration frequency of the middle part of the bridge girder, L1Is the distance between the central axes of two main beams of the bridge, L is the distance from the installation position of the fan blade to the middle point of the section of the H-shaped steel, E is Q235 elastic modulus, m is the eccentric mass, r is the eccentric radius, K is the distance between the central axes of the two main beams of the bridge2The rigidity of the middle part of the bridge girder is shown, and | X | is the vibration displacement amplitude of the middle part of the bridge girder in the vertical direction.
Step 4.2 calculation of theoretical stiffness of girder
The wind turbine bridge is a truss structure, the middle part of the wind turbine bridge is provided with a supporting structure, but in the gravity direction, the wind turbine bridge is almost in a plane. Therefore, the main beam of the bridge can be simplified into a simple beam model. The main beam is H-shaped steel and has a length of L27901mm (the width of the platform supporting beam is removed), the middle part of the beam is acted by concentrated force, and the rigidity of the middle part is obtained. The deflection W of the middle part of the main beam under the concentrated acting force can be obtained according to the following formula.
In the formula: f2For concentrated force, W is the deflection of the middle part of the main beam,e is Q235 elastic modulus, I is H-shaped steel inertia moment, L2Is the bridge length.
Two girders of the bridge are H-shaped steel, taking the H-shaped steel of the experimental bridge girder as an example, the specification is HM350x175x7x11, and the inertia moment is I-131234688.7 mm4。
According to the above partial formulas, the bridge girder on-force F is obtained2Under the action, the maximum deflection of the middle part of the main beam is W. The theoretical rigidity K of the middle part of the bridge girder in the vertical direction (namely the Z direction) is solved according to the formula (15)4＝5123.4N/mm。
In the formula: f2For concentrated force, W is the deflection of the middle of the main beam, K4The theoretical rigidity of the middle part of the bridge girder in the vertical direction is obtained.
Through statics analysis under the action of the eccentric force, the rigidity of the middle part of each main beam in the vertical direction (namely the Z direction) can be solved as follows: 5405.41N/mm, 5524.86N/mm. And comparing the theoretical calculation rigidity of the bridge girder with the finite element analysis result, wherein the two are basically consistent. Therefore, the bridge main beam can be simplified into a simple beam structure when rigidity analysis is carried out in the gravity direction.
In summary, since the theoretical stiffness of the simplified middle portion of the bridge girder is substantially equal to the finite element analysis stiffness of the middle portion of the bridge girder under the action of the eccentric force, the theoretical stiffness of the middle portion of the bridge girder can be used to replace the finite element analysis stiffness of the middle portion of the bridge girder in the bridge design process, i.e., K is the finite element analysis stiffness of the middle portion of the bridge girder2＝K4And further simplifies the analysis process of the bridge.
Step 4.3 bridge design formula
According to the allowable vibration amplitude of the bridge frame, the rigidity of the bridge frame can be deduced, and H meeting the design requirement of the bridge frame is selected
Section steel. The vibration control value of the fan bridge is considered as a speed quantity. The relationship between the vibration velocity amplitude and the displacement amplitude is as follows:
|V|＝ω·|X| (16)
in the formula: and | V | is the vibration speed of the middle part of the bridge girder, omega is the vibration frequency of the middle part of the bridge girder, and | X | is the vibration displacement amplitude of the middle part of the bridge girder in the vertical direction.
Substituting simplified bridge rigidity formulas (12), (13) and (14) into a formula (11), the bridge H-shaped steel needs to meet the following requirements:
wherein I is the inertia moment of H-shaped steel, [ V ]]Amplitude of vibration speed, omega, allowed for the middle of bridgemaxFor maximum vibration frequency, L, of the middle part of the bridge girder2Is the length of the bridge frame, L1The distance between the central axes of two main beams of the bridge is L, the distance from the installation position of the fan blade to the middle point of the section of the H-shaped steel is L, E is the elastic modulus, m is the eccentric mass, and r is the eccentric radius;
in conclusion, based on a method for designing the beam-type bridge of the air cooling fan under the conditions of beam-type bridge parameters and vibration amplitude, the type of the bridge is selected according to the formula.
Claims (2)
1. A method for designing a beam-type bridge of an air cooling fan under the conditions of beam-type bridge parameters and vibration amplitude is characterized by comprising the following steps of:
1) carrying out real-ground vibration test on the fan bridge by using the acceleration sensor, and researching the vibration influence of the fan eccentricity on the fan bridge;
2) in the operation process, the action of the eccentric force caused by the eccentric mass on the bridge is solved, and then a rigidity model of the bridge is established, namely an equation of the eccentric mass of the fan and the amplitude of the bridge is deduced; based on the rigidity model, indirectly estimating the magnitude of the eccentric mass by testing the amplitude of the bridge, namely estimating the fan bridge by a finite element model;
3) designing the stiffness of the bridge according to the mass-diameter product of the eccentric mass allowed by the fan and the vibration amplitude allowed by the bridge, and specifically as follows:
wherein I is the inertia moment of H-shaped steel, [ V ]]The maximum value omega is taken for the vibration velocity amplitude allowed by the middle part of the bridge, omega is the vibration frequency of the middle part of the main beam of the bridgemax；L2Is the length of the bridge frame, L1The distance between the central axes of two main beams of the bridge is L, the distance from the installation position of the fan blade to the middle point of the section of the H-shaped steel is L, E is the elastic modulus, m is the eccentric mass, and r is the eccentric radius; [ mr ] of]Is the maximum of the mass-diameter product.
2. The method of designing a beam bridge of an air cooling fan under the conditions of beam bridge parameters and vibration amplitude as claimed in claim 1, wherein the process is as follows:
determining the relation between the eccentric force F and the vertical direction deformation | X | of the middle part of the bridge girder according to Hooke's law as follows:
F＝K·|X| (1)
in the formula: f is eccentric force, K is rigidity value of the bridge girder, and | X | is vibration displacement amplitude of the middle part of the bridge girder in the vertical direction;
the relationship between the displacement amplitude and the acceleration amplitude is as follows:
in the formula: the vibration displacement amplitude of the middle part of the bridge girder in the vertical direction is | A |, omega, and | X |;
the formula for calculating the eccentric force F is as follows:
F＝4π2mrf2(3)
in the formula: f is eccentric force, m is eccentric mass, r is eccentric radius, and F is fan shaft rotation frequency;
because the fan is at the operation in-process, the vibration frequency in crane span structure girder middle part equals with fan axle rotational frequency, and f equals omega, so substitutes equation (1), (2) into equation (3) and gets:
in the formula: the | A | is the vibration acceleration amplitude of the middle part of the bridge girder, the ω is the vibration frequency of the middle part of the bridge girder, the m is the eccentric mass, the r is the eccentric radius, and the K is the rigidity value of the bridge girder;
extracting peak points, namely | A |, in a frequency domain graph of a sensor in the middle of the bridge, and performing power exponent fitting by using MATLAB, wherein fitting curve equations are respectively as follows:
|A|＝T·ω4(5)
in the formula: | A | is peak point data in a sensor frequency domain graph, and T is the slope of a fitting curve;
because the eccentric force of the fan acts on the fan shaft, in order to obtain the static rigidity of the two main beams of the bridge, a finite element analysis is carried out on the built fan bridge model, and the deformation of the bridge main beam in the vertical direction under the action of torque is | X |; according to the formula (1), the rigidity values of the two main beams are K;
and (3) combining formulas (4) and (5) and a finite element analysis result to obtain a mass-diameter product [ mr ] of the eccentric mass of the fan, wherein the mass-diameter product [ mr ] is as follows:
[mr]＝T·K (6)
in the formula: [ mr ] is the mass-diameter product at the measuring point, T is the slope of the fitting curve, and K is the rigidity value of the bridge girder;
eccentric force F and couple F1The relationship of (1) is:
M＝F·L (7)
in the formula: f is eccentric force, and L is the distance from the installation position of the fan blade to the middle point of the section of the H-shaped steel;
couple F1The moment of couple generated is:
M＝F1·L1(8)
in the formula: f is eccentric force, L is the distance from the installation position of the fan blade to the middle point of the section of the H-shaped steel, and F1Couple, L, produced in the vertical direction of the two main beams for eccentric forces1The distance between the central shafts of the two main beams of the bridge frame is the distance between the central shafts of the two main beams of the bridge frame;
the torque generated by the eccentric force F is equivalently converted into a couple F1The generated moment of couple is obtained by combining (7) and (8), the eccentric force F and the couple F1The relationship of (1) is:
F·L＝F1·L1(9)
in the formula: f1Couple, L, produced in the vertical direction of the two main beams for eccentric forces1The distance between the central shafts of the two main beams of the bridge frame is the distance between the central shafts of the two main beams of the bridge frame;
in the vertical direction, the rigidity of a single main beam is K according to Hooke's law2And the displacement of the main beam under the action of unit force is calculated according to the formula:
F1＝K2·|X| (10)
in the formula: f1Couple, K, produced in the vertical direction of the two main beams for eccentric forces2The rigidity of the middle part of the bridge girder is shown, and | X | is the vibration displacement amplitude of the middle part of the bridge girder in the vertical direction;
substituting the eccentric force formula (3) and the calculation formula (10) of the rigidity of the single main beam into the formula (9) to obtain the relation between the rigidity and the eccentric mass as follows:
in the formula: omega is the vibration frequency of the middle part of the bridge girder, L1Is the distance between the central axes of two main beams of the bridge, L is the distance from the installation position of the fan blade to the middle point of the section of the H-shaped steel, E is the elastic modulus, m is the eccentric mass, r is the eccentric radius, K2The rigidity of the middle part of the bridge girder is shown, and | X | is the vibration displacement amplitude of the middle part of the bridge girder in the vertical direction;
simplifying the main beam of the bridge frame into a simple beam model; obtaining the deflection W of the middle part of the main beam under the concentrated acting force according to the following formula;
in the formula: f2For concentrated force, W is the deflection of the middle part of the main beam, E is the elastic modulus, I is the inertia moment of steel, L2Is the length of the bridge;
solving the theoretical rigidity K of the middle part of the bridge girder in the vertical direction according to the formula (13)4；
In the formula: f2For concentrated force, W is the deflection of the middle of the main beam, K4The theoretical rigidity of the middle part of the bridge girder in the vertical direction is obtained;
deducing the rigidity of the bridge frame according to the allowable vibration amplitude of the bridge frame, and selecting H-shaped steel meeting the design requirement of the bridge frame; considering the vibration control value of the fan bridge as a speed quantity; the relationship between the vibration velocity amplitude and the displacement amplitude is as follows:
|V|＝ω·|X| (14)
in the formula: the vibration displacement amplitude of the middle part of the bridge girder in the vertical direction is | V | is the vibration speed of the middle part of the bridge girder, omega is the vibration frequency of the middle part of the bridge girder, and | X | is the vibration displacement amplitude of the middle part of the bridge girder in the vertical direction;
substituting simplified bridge rigidity formulas (12), (13) and (14) into a formula (11), the bridge H-shaped steel needs to meet the following requirements:
wherein I is the inertia moment of H-shaped steel, [ V ]]Amplitude of vibration speed, omega, allowed for the middle of bridgemaxFor maximum vibration frequency, L, of the middle part of the bridge girder2Is the length of the bridge frame, L1The distance between the central axes of two main beams of the bridge is L, the distance from the installation position of the fan blade to the middle point of the section of the H-shaped steel is L, E is the elastic modulus, m is the eccentric mass, and r is the eccentric radius;
in conclusion, based on a method for designing the beam-type bridge of the air cooling fan under the conditions of beam-type bridge parameters and vibration amplitude, the type of the bridge is selected according to the formula.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910931895.3A CN110688718B (en) | 2019-09-27 | 2019-09-27 | Method for designing beam bridge of air cooling fan under beam bridge parameters and vibration amplitude conditions |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910931895.3A CN110688718B (en) | 2019-09-27 | 2019-09-27 | Method for designing beam bridge of air cooling fan under beam bridge parameters and vibration amplitude conditions |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110688718A true CN110688718A (en) | 2020-01-14 |
| CN110688718B CN110688718B (en) | 2024-02-02 |
Family
ID=69111031
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910931895.3A Active CN110688718B (en) | 2019-09-27 | 2019-09-27 | Method for designing beam bridge of air cooling fan under beam bridge parameters and vibration amplitude conditions |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110688718B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111914356A (en) * | 2020-07-30 | 2020-11-10 | 中车唐山机车车辆有限公司 | Vibration damping supporting device, rail vehicle and train floor area vibration isolation design method |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100242609A1 (en) * | 2009-03-26 | 2010-09-30 | Wei-Feng Lee | Bridge monitoring and safety evaluation method using a vibration technique |
| CN106777635A (en) * | 2016-12-07 | 2017-05-31 | 北京工业大学 | A kind of Air-Cooling Island fan bridge optimization method under fan parameter and motor rotation parameter known conditions |
| CN208071122U (en) * | 2018-03-30 | 2018-11-09 | 宁夏天地奔牛银起设备有限公司 | A kind of bridge crane main side beam joint device |
-
2019
- 2019-09-27 CN CN201910931895.3A patent/CN110688718B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100242609A1 (en) * | 2009-03-26 | 2010-09-30 | Wei-Feng Lee | Bridge monitoring and safety evaluation method using a vibration technique |
| CN106777635A (en) * | 2016-12-07 | 2017-05-31 | 北京工业大学 | A kind of Air-Cooling Island fan bridge optimization method under fan parameter and motor rotation parameter known conditions |
| CN208071122U (en) * | 2018-03-30 | 2018-11-09 | 宁夏天地奔牛银起设备有限公司 | A kind of bridge crane main side beam joint device |
Non-Patent Citations (3)
| Title |
|---|
| YANG LIJUN等: "《Measures aganist the adverse impact of natural wind on air-cooled condensers in power plant》", 《SCIENCE IN CHINA SERIES E:TECHNOLOGICAL SCIENCES》, vol. 53, no. 5 * |
| 晏红文等: "《大型风力发电机组传动链动力学分析与试验研究》", 《机械轻度》, vol. 37, no. 6 * |
| 窦瑞杰等: "《电厂直接空冷***风机桥强迫振动响应测试研究》", 《北方工业大学学报》, vol. 23, no. 1 * |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111914356A (en) * | 2020-07-30 | 2020-11-10 | 中车唐山机车车辆有限公司 | Vibration damping supporting device, rail vehicle and train floor area vibration isolation design method |
| CN111914356B (en) * | 2020-07-30 | 2023-08-08 | 中车唐山机车车辆有限公司 | Vibration reduction supporting device, railway vehicle and train floor area vibration isolation design method |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110688718B (en) | 2024-02-02 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101122541B (en) | Turbine blade vibration test method and device | |
| McLaren et al. | Measurement of high solidity vertical axis wind turbine aerodynamic loads under high vibration response conditions | |
| CN101949731B (en) | Method for testing high-order frequency of large wind-power blades | |
| CN105352713B (en) | The method for realizing detection blade fatigue crackle by detecting blade Static Correction | |
| CN101487756B (en) | Harmonic component rotational speed balancing method in rotating machinery vibration analysis | |
| CN102928222B (en) | Method for testing and identifying dynamic characteristic coefficients of sliding bearing | |
| Liu et al. | Influence of alternating loads on nonlinear vibration characteristics of cracked blade in rotor system | |
| Han et al. | Steady-state response of a geared rotor system with slant cracked shaft and time-varying mesh stiffness | |
| CN204423796U (en) | A kind of gas turbine scale-model experiment device | |
| CN110044625B (en) | Flywheel bearing dynamic stiffness measuring method | |
| CN110688718A (en) | Method for designing beam-type bridge of air cooling fan under conditions of beam-type bridge parameters and vibration amplitude | |
| CN111563342A (en) | Strain gauge measuring point layout optimization method for rotor blade | |
| Hoffmann et al. | Measured and simulated forced response of a rotating turbine disk with asymmetric and cylindrical underplatform dampers | |
| Al-Hadad et al. | Vibration characteristic responses due to transient mass loading on wind turbine blades | |
| KR100997810B1 (en) | Structural damage detection using a vibratory power | |
| CN114018480A (en) | Real-time diagnosis method for rotor unbalance fault of large-scale rotating machinery | |
| CN102650556A (en) | Bearing load identification method based on strain signals of three cross sections of rotating shaft | |
| Liu et al. | Dynamics of slant cracked rotor for a steam turbine generator system | |
| Chen et al. | Blade mass imbalance identification and estimation for three-bladed wind turbine rotor based on modal analysis | |
| CN102944334A (en) | Method for recognizing bearing distribution of bearings of turbo generator unit by bearing neck up-rising inclination distribution | |
| CN209513233U (en) | A kind of more load test devices of exhaust stage blade elongation | |
| Al‐Bedoor et al. | Blades condition monitoring using shaft torsional vibration signals | |
| CN106777635B (en) | Air cooling island fan bridge optimization method under known conditions of fan parameters and motor operation parameters | |
| Sunar et al. | Vibration measurement of rotating blades using a root embedded PZT sensor | |
| Abdulraheem et al. | Wind Turbine Blade Fault Detection Using Wavelet Power Spectrum and Experimental Modal Analysis |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |