A joint analysis and calculation method for offshore operation of land-based generator sets

Abstract

The present invention discloses a joint analysis and calculation method for offshore operation of land-based generator sets. 1. Use Patran to establish a joint analysis finite element model consisting of a hull structure, a vibration isolator, an equipment base, and a generator set equipment; the equipment is replaced by a mass unit simulation applied on MPC, the equipment base is simulated by a plate unit, the vibration isolator is simulated by a BUSH unit, and the hull structure is simulated by a plate unit and a beam unit; after the structure is modeled, the center of gravity is adjusted; 2. Combine working conditions according to load information such as wave direction, acceleration, and wind load; 3. Perform modal and vibration type analysis on the finite element model to ensure that the fundamental frequency of the model in all directions is far away from the equipment operating frequency; 4. Perform static analysis according to the working condition combination, solve the static displacement and verify it; 5. Determine the disturbance force value of each bearing support point, perform dynamic analysis, solve the dynamic displacement and verify it. This method can accurately simulate the offshore operation conditions of the generator set, and can provide assistance for the design and selection of offshore operation of land-based generator sets.

Description

Technical Field

[0001] The present invention belongs to the technical field of finite element analysis of hull deformation, and relates to a vibration deformation simulation analysis method for land-based generators operating at sea, and in particular to a joint analysis and calculation method for land-based generator sets operating at sea. Background Art

[0002] The operating conditions of land-based generator sets at sea are quite different from those on land. The existing analysis and calculation methods for land-based generator sets operating at sea cannot accurately simulate the operating conditions of generator sets at sea. At present, land-based generator sets are basically operated on land, and the pile foundations and foundation loads and boundary conditions that play a supporting role are relatively easy to determine; however, when land-based generator sets are operating at sea, only a local model of the generator set support base is established for analysis. The loads and boundary conditions generated by waves and hulls are difficult to accurately simulate (such as hull mass and stiffness distribution, hull three-dimensional deformation, etc.), and the calculation method may have a large safety factor, resulting in a large design redundancy and increased production costs. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a joint analysis and calculation method for the offshore operation of land-based generator sets that can more accurately simulate the offshore operating conditions of the generator sets, in order to solve the problem of the offshore operation of land-based generator sets.

[0004] The objective of the present invention is achieved through the following technical solutions:

[0005] The present invention is a method for simulating and analyzing the vibration deformation of a land-based generator set during offshore operation. The method is based on a processing method for jointly modeling a generator set and its supporting base (equipment base), a spring isolator, and a hull structure, and the deformation and vibration of the generator shaft system are calculated under this processing method.

[0006] The present invention provides a joint analysis and calculation method for offshore operation of a land-based generator set, comprising the following steps:

[0007] Step 1: Use MSC.Patran to establish a joint analysis finite element model consisting of the hull structure, spring isolators, equipment base, and generator set equipment;

[0008] The generator set equipment is replaced by the mass unit applied on the MPC for simulation, the equipment base is simulated by plate units, the spring isolator is simulated by BUSH units, and the hull structure is simulated by plate units and beam units. After the structural modeling is completed, the weight center of gravity is adjusted to ensure that the error between the model weight center of gravity and the actual value is within 1%.

[0009] Step 2: Refer to standard specifications and combine working conditions according to load information such as wave direction, acceleration, wind load, etc.

[0010] Step 3: Perform modal and vibration type analysis on the finite element model to ensure that the fundamental frequency of the model in all directions is far away from the operating frequency of the equipment.

[0011] Step 4: Perform static analysis based on the working condition combination, solve the static displacement, and verify whether it meets the static requirements.

[0012] Step 5: Determine the disturbance force value of each bearing support point, perform dynamic analysis, solve the dynamic displacement, synthesize the vibration displacement, and verify whether it meets the dynamic requirements.

[0013] The present invention provides a joint analysis and calculation method for offshore operation of a land-based generator set, which specifically includes the following steps:

[0014] Step 1: Use MSC.Patran to establish a joint analysis finite element model consisting of the hull structure, spring isolators, equipment base, and generator set equipment;

[0015] 1) The generator set equipment (mechanical equipment) is a rigid body with 6 degrees of freedom, which can be equivalent to a node unit with the node located at the center of mass, and is replaced by a mass unit applied on the MPC for simulation;

[0016] 2) The equipment base is simulated using plate elements;

[0017] 3) The spring isolator is simulated by BUSH unit and connected with the generator set equipment and hull structure by MPC. BUSH unit can define complex spring-damper system. By defining the spring stiffness of the 6 degrees of freedom of the isolator and the structural damping coefficient, the spring isolator can be simulated more accurately.

[0018] 4) The hull structure is simulated by plate elements and beam elements, and other equipment on the hull structure is also simulated by mass elements applied on MPC;

[0019] 5) After the structural modeling is completed, adjust the weight center of gravity;

[0020] Step 2: Refer to standard specifications and combine working conditions according to load information such as wave direction, acceleration, wind load, etc.

[0021] Step 3: According to the requirements of standards and specifications, perform modal and vibration type analysis on the finite element model to ensure that the fundamental frequency of the model in all directions is much lower than the rated operating frequency of the generator set equipment to avoid resonance.

[0022] Step 4: Perform static analysis based on the operating condition combination determined in step 2, solve the static displacement, and compare it with the manufacturer's required value.

[0023] Step 5: According to the standard design method of power machinery, determine the disturbance force value of each bearing support point at any speed, and perform dynamic analysis respectively;

[0024] Step 6: Solve the dynamic displacement corresponding to each disturbance force; then synthesize the vibration displacement according to the standard design method of the power machine, and verify whether it meets the manufacturer's requirements.

[0025] Furthermore, in step 2) of the first step, the device base is simulated using plate units, and the opening information on the device base is approximately processed according to the actual situation.

[0026] Furthermore, in step 5) of the first step, after the structural modeling is completed, the weight center of gravity is adjusted to ensure that the error between the model weight center of gravity and the actual value is within 1%.

[0027] Furthermore, in the third step, according to the requirements of standard specifications, the finite element model is subjected to modal and vibration type analysis to ensure that the fundamental frequency of the model in all directions is much lower than 80% of the rated operating frequency of the generator set equipment.

[0028] Furthermore, in the third step, the fundamental frequencies of the model in each direction include the fundamental frequencies in the horizontal direction and the fundamental frequencies in the vertical direction.

[0029] Furthermore, in the third step, the rated operating frequency of the generator set equipment is 50 Hz.

[0030] Furthermore, in the fourth step, the static displacement is solved using the programmed program.

[0031] Furthermore, in the sixth step, the dynamic displacement corresponding to each disturbance force is solved using the programmed program.

[0032] Beneficial effects of the present invention:

[0033] Aiming at the problem of land-based generator sets operating at sea, the present invention proposes a joint analysis and calculation method, which can more accurately simulate the operating conditions of the generator sets at sea and provide assistance for the design and selection of land-based generator sets operating at sea.

[0034] The joint analysis and calculation method for the offshore operation of land-based generator sets of the present invention jointly models and analyzes the land-based generator sets, supporting bases, spring isolators and hull structures. The isolators use BUSH units to simulate real properties, and there is no need to make separate assumptions about the interaction between the isolators and the hull structure (when a local model is used, there will be a large safety margin for boundary conditions and load assumptions based on specifications and engineering experience). The analysis can be completed by loading according to actual working conditions, which can improve the accuracy of numerical simulation.

[0035] The key technical points and advantages of the combined analysis and calculation method for offshore operation of land-based generator sets of the present invention are:

[0036] 1. The BUSH unit is a six-degree-of-freedom spring unit. The parameters that can be defined include the spring stiffness of the six degrees of freedom, the damping coefficient in the six degrees of freedom directions, the structural damping coefficient, the stress recovery coefficient and the strain recovery coefficient. By adjusting and setting the parameters of the BUSH unit, the performance of the vibration isolator can be simulated more accurately.

[0037] 2. Establishing the hull structure, land-based generator sets, equipment bases, spring isolators and other components in the same model can avoid boundary and load errors caused by multi-interface conversion, and can more accurately simulate the interaction between the hull structure and land-based generator sets, equipment bases, spring isolators, and improve the accuracy of the numerical simulation model. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of a joint analysis and calculation method for offshore operation of a land-based generator set according to the present invention;

[0039] Figure 2 is a schematic diagram of a wave load condition in an embodiment of the present invention;

[0040] Figure 3 is a schematic diagram of static displacement calculation results in an embodiment of the present invention;

[0041] Figure 4 Schematic diagram of vibration displacement calculation results in an embodiment of the present invention. DETAILED DESCRIPTION

[0042] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0043] Example

[0044] like Figure 1 As shown, the present invention provides a joint analysis and calculation method for offshore operation of land-based generator sets, which includes the following steps:

[0045] Step 1: Use MSC.Patran to establish a joint analysis finite element model consisting of the hull structure, spring isolators, equipment base, and generator set equipment;

[0046] 1) The generator set equipment (mechanical equipment) is a rigid body with 6 degrees of freedom, which can be equivalent to a node unit with the node located at the center of mass, and is replaced by a mass unit applied on the MPC for simulation;

[0047] 2) The equipment base is simulated with plate units, and the opening information on the equipment base is approximately processed according to the actual situation;

[0048] 3) The spring isolator is simulated by BUSH unit and connected with the generator set equipment and hull structure by MPC. BUSH unit can define complex spring-damper system. By defining the spring stiffness of the 6 degrees of freedom of the isolator and the structural damping coefficient, the spring isolator can be simulated more accurately.

[0049] 4) The hull structure is simulated by plate elements and beam elements, and other equipment on the hull structure is also simulated by mass elements applied on MPC;

[0050] 5) After the structure modeling is completed, the weight center of gravity is adjusted to ensure that the error between the model weight center of gravity and the actual value is within 1%.

[0051] Step 2: Refer to the "DNVGL-OS-C102 Structural design of offshore ship-shaped units" specification and combine the working conditions according to load information such as wave direction, acceleration, wind load, etc.

[0052] In this embodiment, the wave load condition is as follows: Figure 2 shown.

[0053] Step 3: According to the requirements of the "DIN4024 machine foundations" specification, perform modal and vibration type analysis on the finite element model to ensure that the fundamental frequency of the model in all directions (horizontal and vertical directions) is far lower than 80% of the rated operating frequency of the equipment (50Hz) to avoid resonance.

[0054] Step 4: Perform static analysis based on the working condition combination determined in step 2, obtain the calculation results, and generate the f06 result file. Write a python code program to extract the vertical static displacement values ​​of the target node (indicated by X in the figure) and a series of nodes near it by querying keywords, solve the static displacement, and compare it with the manufacturer's required value.

[0055] In this embodiment, the static displacement calculation results are as follows: Figure 3 shown.

[0056] Step 5: According to the standard design method in Section 4.1.7 of GB 50040-2020 Basic Design Standard for Power Machinery, determine the disturbance force value of each bearing support point at any speed and perform dynamic analysis respectively;

[0057] Step 6: According to the dynamic analysis in step 5, the calculation results are obtained and the f06 result file is generated. A python code program is written to extract the vertical dynamic displacement values ​​of the target node and a series of nodes near it in the frequency range of 0-110Hz (interval 1Hz) by querying keywords, and solve the dynamic displacement corresponding to each disturbance force at the target node; then, according to the standard design method in Section 4.1.8 of "GB 50040-2020 Basic Design Standard for Power Machinery", the vibration displacement is synthesized and verified to see whether it meets the manufacturer's requirements.

[0058] In this embodiment, the vibration displacement calculation results are as follows: Figure 4 shown.

[0059] The key technical points and advantages of this embodiment are:

[0060] 1. The BUSH unit is a six-degree-of-freedom spring unit. The parameters that can be defined include the spring stiffness of the six degrees of freedom, the damping coefficient in the six degrees of freedom directions, the structural damping coefficient, the stress recovery coefficient and the strain recovery coefficient. By adjusting and setting the parameters of the BUSH unit, the performance of the vibration isolator can be simulated more accurately.

[0061] 2. Establishing the hull structure, land-based generator sets, equipment bases, spring isolators and other components in the same model can avoid boundary and load errors caused by multi-interface conversion, and can more accurately simulate the interaction between the hull structure and land-based generator sets, equipment bases, spring isolators, and improve the accuracy of the numerical simulation model.

Claims

1. A joint analysis and calculation method for offshore operation of land-based generator sets, characterized in that: The steps include: Step 1: Use MSC.Patran to establish a joint analysis finite element model consisting of the hull structure, spring isolators, equipment base, and generator set equipment; 1) Generator equipment is replaced by the mass unit applied on MPC for simulation; 2) The equipment base is simulated using plate elements; 3) The spring isolator is simulated by BUSH unit and connected with the generator set equipment and hull structure by MPC; 4) The hull structure is simulated using plate elements and beam elements; 5) After the structural modeling is completed, adjust the weight center of gravity; Step 2: Refer to standard specifications and combine working conditions according to wave direction, acceleration and wind load information; Step 3: Perform modal and vibration type analysis on the finite element model to ensure that the fundamental frequency of the model in all directions is much lower than the rated operating frequency of the generator set equipment; Step 4: Perform static analysis based on the working condition combination determined in step 2, solve the static displacement, and verify whether it meets the static requirements; Step 5: According to the standard design method of power machinery, determine the disturbance force value of each bearing support point at any speed, and perform dynamic analysis respectively; Step 6: Solve the dynamic displacement corresponding to each disturbance force; synthesize the vibration displacement and verify whether it meets the dynamic requirements.

2. The combined analysis and calculation method for offshore operation of land-based generator sets according to claim 1, characterized in that: In step 2) of the first step, the equipment base is simulated using plate units, and the opening information on the equipment base is approximated according to the actual situation.

3. The combined analysis and calculation method for offshore operation of land-based generator sets according to claim 1, characterized in that: In step 4) of the first step, other equipment on the hull structure is also simulated using MPC applied mass elements.

4. The combined analysis and calculation method for offshore operation of land-based generator sets according to claim 1, characterized in that: In step 5) of the first step, after the structure modeling is completed, the weight center of gravity is adjusted to ensure that the error between the model weight center of gravity and the actual value is within 1%.

5. The combined analysis and calculation method for offshore operation of land-based generator sets as claimed in claim 1, 2, 3 or 4, characterized in that: In the third step, according to the requirements of standard specifications, the finite element model is subjected to modal and vibration type analysis to ensure that the fundamental frequency of the model in all directions is far lower than 80% of the rated operating frequency of the generator set equipment.

6. The combined analysis and calculation method for offshore operation of land-based generator sets as claimed in claim 1, 2, 3 or 4, characterized in that: In the third step, the fundamental frequencies of the model in each direction include the fundamental frequencies in the horizontal direction and the fundamental frequencies in the vertical direction.

7. The combined analysis and calculation method for offshore operation of land-based generator sets as claimed in claim 1, 2, 3 or 4, characterized in that: In the third step, the rated operating frequency of the generator set equipment is 50Hz.

8. The combined analysis and calculation method for offshore operation of land-based generator sets as claimed in claim 1, 2, 3 or 4, characterized in that: In the fourth step, use the written program to solve the static displacement.

9. The combined analysis and calculation method for offshore operation of land-based generator sets as claimed in claim 1, 2, 3 or 4, characterized in that: In the sixth step, the written program is used to solve the dynamic displacement corresponding to each disturbance force.

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