CN114021278A - Full-automatic internal flow analysis method for hydraulic mechanical transition process - Google Patents
Full-automatic internal flow analysis method for hydraulic mechanical transition process Download PDFInfo
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Abstract
The invention discloses a full-automatic internal flow analysis method in a hydraulic mechanical transition process, which comprises the following steps: s1, acquiring a fluid domain of the hydraulic machine, and performing three-dimensional modeling and network division based on the fluid domain to acquire network node information; s2, screening based on the network node information to obtain a value of a first parameter; s3, calculating based on the values of the related parameters to obtain values of a second parameter; and S4, changing boundary conditions after preprocessing by changing the network node information, and completing hydraulic mechanical transition and full-automatic flow analysis. The method accurately predicts the change rule of the rotating speed in the transition process of the hydraulic machine, increases the calculation accuracy of the transition process, can also process the internal flow change diagram of each step in the start-stop transition of the hydraulic machine in batches, is convenient and quick, and enables the internal flow change in the transition process to be more visual; and according to different computing requirements, input and output parameters and visual contents are customized in a personalized mode.
Description
Technical Field
The invention relates to the field of hydraulic machinery calculation, in particular to a full-automatic internal flow analysis method for a hydraulic machinery transition process.
Background
The transition process refers to the process that the unit undergoes when the unit transits from one steady state to another. A large number of engineering practices prove that accidents of hydropower stations and pump stations often occur in the transition process of the units. In the actual operation process, various transition processes of the hydraulic machine are in unstable operation under the non-design working condition, and the variable factors are more and difficult to control. In recent years, with the continuous increase of the power and the size of a pump station unit, the problems of the hydraulic transition process of the pump station are more and more, and the appearance of the problems leads people to pay more attention to the hydraulic mechanical transition process of the pump station. Such as: in the power-off transition process of the hydraulic machine, after sudden power-off, the impeller is only influenced by water flow, the internal flow state is obviously changed in a very short time, and great potential safety hazards exist; in the runaway transition process of the hydraulic machine, when the hydraulic machine is in a runaway working condition, the rotating speed is far higher than the design rotating speed, the safety of a rotor component is threatened, and an internal flow passage component is easy to damage due to the unstable hydraulic phenomenon and easily damages a unit. Therefore, the transition process is predicted in advance by using a numerical simulation method, so that the aims of avoiding the generation of dangerous transition process and skillfully coping with the emergency in the transition process are fulfilled.
There are two main types of simulation of the transition process: the method is characterized in that firstly, the variable factors of the transition process in numerical simulation calculation, such as boundary conditions of rotating speed, pressure and the like, are manually adjusted. The method has the advantages that the calculated working condition points are fewer, the calculation time is shorter, but the calculation of the transition process is discontinuous due to the fact that only a few working condition points are selected, the change in the transition process is difficult to accurately and completely predict, and the purpose of actual simulation is difficult to achieve. And secondly, artificially fitting a certain boundary condition in the transition process through empirical judgment. The transition of this method is continuous, but human experience is not applicable to all hydraulic machines, and the method is less versatile. At present, data processing in the transition process is generally carried out in post-processing software by adopting manual adjustment, and the mode not only occupies long time, but also has high requirement on the storage space of a hard disk.
Aiming at the problems of discontinuous and inaccurate calculation of the transition process of the current hydraulic machinery, the invention provides a continuous and universal calculation method of the transition process. Aiming at the problems of large data quantity and large occupied storage space in the transition process calculation, the invention provides a numerical simulation calculation method for the transition process of the hydraulic machine, and the data is processed in the calculation process, so that a large amount of manpower and financial resources are saved.
Disclosure of Invention
The invention aims to provide a full-automatic internal flow analysis method in a hydraulic mechanical transition process, which aims to solve the problems in the prior art, improve the calculation precision and reduce the calculation cost.
In order to achieve the purpose, the invention provides the following scheme: the invention provides a full-automatic internal flow analysis method for a hydraulic mechanical transition process, which comprises the following steps:
s1, acquiring a fluid domain of the hydraulic machine, and performing three-dimensional modeling and network division based on the fluid domain to acquire network node information;
s2, screening based on the network node information to obtain a value of a first parameter;
s3, calculating based on the values of the related parameters to obtain values of a second parameter;
and S4, changing boundary conditions after preprocessing by changing the network node information, and finishing the transition process of the hydraulic machine.
Optionally, the obtaining of the network node information in S1 includes: and dividing the fluid domain into grid node information, and calculating the simulation process of the grid node information to obtain the network node information.
Optionally, the grid node information comprises flow, head, torque, speed, turbulence energy.
Optionally, the screening process in S2 includes: and selecting corresponding data parameters for the network node information to obtain the numerical value of the first parameter.
Optionally, the process of calculating in S3 includes: and calculating the value of the first parameter, verifying and simulating to obtain the value of the second parameter.
Optionally, the preprocessing in S4 includes: and acquiring relevant data of the numerical value of the second parameter, and performing visualization processing on the acquired relevant data to obtain a calculation result of the hydraulic mechanical transition process.
Optionally, the visualization processing includes calculating a law of conservation of momentum for the relevant data, where the expression of angular momentum difference is:
wherein J-rotor moment of inertia (kg. m)2) Omega-rotor angular velocity (rad/s), MRActive water moment (N.m), MG-load moment (N · m), Δ t being the time interval.
Optionally, the boundary conditions in S4 include: inlet pressure, outlet pressure, moment of inertia; the process of changing the boundary condition includes: and measuring the torque in real time, observing the change of the rotating speed of the impeller, and controlling the inlet pressure, the outlet pressure and the rotational inertia.
The invention discloses the following technical effects:
1) the method realizes the calculation of the starting and stopping transition process of the hydraulic machinery, and obviously improves the calculation efficiency of the transition process;
2) the method accurately predicts the change rule of the rotating speed in the transition process of the hydraulic machine, and increases the calculation accuracy in the transition process;
3) the method can be used for processing the internal flow change diagram of each step in the starting and stopping transition process of the hydraulic machinery in batches, is convenient and quick, and enables the internal flow change in the transition process to be more visual;
4) the invention can customize input and output parameters and visual contents according to different calculation requirements.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a flowchart of the overall scheme of the present embodiment;
FIG. 2 is a schematic diagram illustrating the variation of the rotation speed during the power-off transition process according to the present embodiment;
FIG. 3 is a schematic diagram illustrating torque variation during a power-off transition according to the present embodiment;
fig. 4 is a schematic diagram of the main component inflow at different times during the power-off transition process according to this embodiment.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
As shown in fig. 1 to 4, the present invention provides a full-automatic internal flow analysis method for a hydromechanical transition process, comprising the following steps:
s1, acquiring a fluid domain of the hydraulic machine, and performing three-dimensional modeling and network division based on the fluid domain to acquire network node information;
s2, screening based on the network node information to obtain a value of a first parameter;
s3, calculating based on the values of the related parameters to obtain values of a second parameter;
and S4, changing boundary conditions after preprocessing by changing the network node information, and finishing the transition process of the hydraulic machine.
Optionally, the obtaining of the network node information in S1 includes: and dividing the fluid domain into grid node information, and calculating the simulation process of the grid node information to obtain the network node information.
Optionally, the grid node information comprises flow, head, torque, speed, turbulence energy.
Optionally, the screening process in S2 includes: and selecting corresponding data parameters for the network node information to obtain the numerical value of the first parameter.
Optionally, the process of calculating in S3 includes: and calculating the value of the first parameter, verifying and simulating to obtain the value of the second parameter.
Optionally, the preprocessing in S4 includes: and acquiring relevant data of the numerical value of the second parameter, and performing visualization processing on the acquired relevant data to obtain a calculation result of the hydraulic mechanical transition process.
Optionally, the visualization processing includes calculating a law of conservation of momentum for the relevant data, where the expression of angular momentum difference is:
wherein J-rotor moment of inertia (kg. m)2) Omega-rotor angular velocity (rad/s), MRActive water moment (N.m), MGLoad moment (N m), Δ t being the time interval。
Optionally, the boundary conditions in S4 include: inlet pressure, outlet pressure, moment of inertia; the process of changing the boundary condition includes: and measuring the torque in real time, observing the change of the rotating speed of the impeller, and controlling the inlet pressure, the outlet pressure and the rotational inertia.
Example one
The method comprises the following steps: and carrying out three-dimensional modeling and meshing on the fluid domain of the mixed flow pump.
Step two: and introducing a mixed flow pump fluid domain divided into grids in a CFX Per module of ANASYS software, and adding a ccl language file to form a calculation file. Wherein, writing in Output Control makes the calculation file generate a backup file (. bak file) every calculation step.
Step three: and calculating the case set in the step two in a CFX Solver module in ANASYS software, and storing the generated backup file (. bak file) in a folder with the suffix of.dir. The backup file comprises information of each grid node in the mixed flow pump power-off transition process calculation, wherein the information comprises flow, lift, torque, rotating speed and turbulent kinetic energy.
Step four: and importing the backup file (. bak file) into a CFX Post module of ANASYS, wherein the module can read the information stored in the backup file (. bak file).
Step five: reading data and images required in the mixed flow pump start-stop transition process stored in a backup file (. bak file) in a CFX Post module of ANASYS, mainly reading the rotating speed and the torque in the example, and carrying out visualization operation on the pressure distribution of the section in the impeller in the backup file (. bak) file. And records the process of reading data and visualization operation to generate a step reproduction file (. cse file). The data read out in this step is denoted as step 1 data.
Step six: calculating the read data according to an equation satisfying the law of conservation of momentum, such as an angular momentum difference equation:
wherein: j-moment of inertia of rotor (kg. M2), ω -rotor angular velocity (rad/s), MRActive water moment (N.m), MGLoad water moment (N.m) and Δ t is the time interval. In this example, the moment of inertia J of the rotor is 0.54kg m2Load water moment MGIs zero and the time interval Δ t is 0.00017 s. According to the formula and the active hydraulic moment M read in the step fiveRIs 721N m and the rotating speed omegai(i-1) calculating the second step rotation speed omega for-750 rad/si+1I.e. omega2Is-749.77 rad/s.
Step seven: the new rotating speed omega of the mixed flow pump calculated in the step six in the power-off transition process2And (4) importing-749.77 rad/s into the ccl language file to generate a new ccl language file.
Step eight: and (4) importing the generated ccl language file containing the new parameters into ANASYS software CFXSlever to replace the original ccl language file.
Step nine: and repeating the second step and the eighth step until the calculated starting and stopping transition process of the hydraulic machine reaches a stable state, wherein the stable state is that the torque vibrates near 0, and the rotating speed is basically kept unchanged.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.
Claims (8)
1. A full-automatic internal flow analysis method for a hydraulic mechanical transition process is characterized by comprising the following steps:
s1, acquiring a fluid domain of the hydraulic machine, and performing three-dimensional modeling and network division based on the fluid domain to acquire network node information;
s2, screening based on the network node information to obtain a value of a first parameter;
s3, calculating based on the values of the related parameters to obtain values of a second parameter;
and S4, changing boundary conditions after preprocessing by changing the network node information, and completing hydraulic mechanical transition and full-automatic flow analysis.
2. The full-automatic internal flow analysis method for the hydromechanical transition process according to claim 1, wherein the method comprises the following steps: the process of obtaining the network node information in S1 includes: and dividing the fluid domain into grid node information, and calculating the simulation process of the grid node information to obtain the network node information.
3. The full-automatic internal flow analysis method for the hydromechanical transition process according to claim 2, wherein the method comprises the following steps: the grid node information comprises flow, lift, torque, rotating speed and turbulence energy.
4. The full-automatic internal flow analysis method for the hydromechanical transition process according to claim 1, wherein the method comprises the following steps: the screening process in the step S2 comprises the following steps: and selecting corresponding data parameters for the network node information to obtain the numerical value of the first parameter.
5. The full-automatic internal flow analysis method for the hydromechanical transition process according to claim 1, wherein the method comprises the following steps: the process of calculating in S3 includes: and calculating the value of the first parameter, verifying and simulating to obtain the value of the second parameter.
6. The full-automatic internal flow analysis method for the hydromechanical transition process according to claim 1, wherein the method comprises the following steps: the preprocessing process in S4 includes: and acquiring relevant data of the numerical value of the second parameter, and performing visualization processing on the acquired relevant data to obtain a calculation result of the hydraulic mechanical transition process.
7. The full-automatic internal flow analysis method for the hydromechanical transition process according to claim 6, wherein the method comprises the following steps: the visualization processing comprises the calculation of momentum conservation law on the related data, wherein an angular momentum difference expression is as follows:
wherein, the moment of inertia (kg.m) of the J-rotor2) Omega-rotor angular velocity (rad/s), MRActive water moment (N M), MG-load moment (N · m), Δ t being the time interval.
8. The full-automatic internal flow analysis method for the hydromechanical transition process according to claim 1, wherein the method comprises the following steps: the boundary conditions in S4 include: inlet pressure, outlet pressure, moment of inertia; the process of changing the boundary condition includes: and measuring the torque in real time, observing the change of the rotating speed of the impeller, and controlling the inlet pressure, the outlet pressure and the rotational inertia.
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| CN103309727A (en) * | 2013-06-19 | 2013-09-18 | 江苏大学 | Vane pump cavitation numerical simulation automatic operation method based on ANSYS-CFX software |
| WO2017084106A1 (en) * | 2015-11-20 | 2017-05-26 | 田川 | System and method for numerical simulation of aircraft flow field |
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