CN112199907B - Analysis method for multi-index ventilation effect of hydropower station underground powerhouse based on CFD - Google Patents
Analysis method for multi-index ventilation effect of hydropower station underground powerhouse based on CFD Download PDFInfo
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Abstract
The invention discloses a CFD-based analysis method for multi-index ventilation effect of an underground powerhouse of a hydropower station, which comprises the steps of establishing a three-dimensional model of chambers of each level of a main powerhouse of the hydropower station, and carrying out grid division and attribute setting on the three-dimensional model; preprocessing the grid file, and setting the boundary condition of the three-dimensional model by using each index data at the measuring point measured off-line or on-line; performing analog calculation on the index data, selecting a corresponding equation set to perform iterative calculation until a convergence condition is met, and outputting a three-dimensional flow field simulation model; and analyzing the three-dimensional flow field simulation model through post-processing to obtain flow field simulation results of the velocity field, the temperature field and the humidity field at each cross section of the space, and finishing the judgment of the ventilation effect under the current working condition through the flow field simulation results. The invention analyzes the effect of the ventilation system of the underground powerhouse through multiple indexes, and can more comprehensively analyze whether the current fan working condition meets the requirements of normal production and life of the hydropower station.
Description
Technical Field
The invention relates to the technical field of hydromechanics, in particular to a CFD-based analysis method for multi-index ventilation effect of an underground powerhouse of a hydropower station.
Background
With the continuous maturity of hydroelectric power generation technology, the construction level of large-scale hydroelectric engineering and the construction process of water turbine units in China are in the forefront of the world. The vigorous development of hydropower stations not only is an effective measure for solving the energy shortage and promoting the ecological environment construction, but also is an important means for shortening the urban and rural gap and promoting green economy, and the capacity and income creating effect of the hydropower stations cannot be ignored. However, the hydropower station is often exposed to the environment in the normal operation process, because water needs to be introduced from a high position of a river or a reservoir, the hydropower station is usually arranged at a position of tens of meters underground, the whole hydropower station is surrounded by thick underground rocks, the ventilation effect and the heat dissipation condition are far inferior to those of ground buildings, the underground hydropower station is very easy to be wet, stuffy and hot along with the change of seasons and weather, and the phenomena of water seepage and condensation even occur in partial levels of the hydropower station, which undoubtedly causes great hidden troubles to the normal operation of equipment and the normal life of personnel. At the moment, the ventilation system of the underground powerhouse of the hydropower station plays an important role, and the ventilation effect of the ventilation system influences a plurality of index factors related to production and life safety, including wind speed, temperature, humidity, oxygen concentration and the like.
Disclosure of Invention
This section is for the purpose of summarizing some aspects of embodiments of the invention and to briefly introduce some preferred embodiments. In this section, as well as in the abstract and title of the application, simplifications or omissions may be made to avoid obscuring the purpose of the section, the abstract and the title, and such simplifications or omissions are not intended to limit the scope of the invention.
The present invention has been made in view of the above-mentioned conventional problems.
Therefore, the invention provides a CFD-based analysis method for the multi-index ventilation effect of the underground powerhouse of the hydropower station, which can intuitively reflect the distribution condition of each index in time and space, can more comprehensively reflect the multi-index parameter change rule of the whole powerhouse compared with single data of local measuring points and single humidity analysis, and is convenient to determine the position ranges of a heat source, a wet source and a low oxygen concentration area, thereby determining the most suitable wind speed condition under each working condition and establishing the specific position of a dehumidification device.
In order to solve the technical problems, the invention provides the following technical scheme: establishing a three-dimensional model and a flow field simulation model of each layer of cavern of a main plant of a hydropower plant, and performing grid division and attribute setting on the three-dimensional model; preprocessing a grid file, and setting boundary conditions of the three-dimensional model by using each index data at the measuring points measured off-line or on-line; performing simulation calculation on the index data, selecting a corresponding equation set to perform iterative calculation until a convergence condition is met, and outputting a three-dimensional flow field simulation model; and analyzing the three-dimensional flow field simulation model through post-processing to obtain flow field simulation results of the velocity field, the temperature field and the humidity field at each cross section of the space, and finishing the judgment of the ventilation effect under the current working condition through the flow field simulation results.
As a preferable scheme of the analysis method for the multi-index ventilation effect of the hydropower station underground powerhouse based on the CFD, the method comprises the following steps: the three-dimensional model comprises a three-dimensional modeling according to a plant design drawing of the hydraulic power plant, the overall size of the plant, the size of the ventilation opening and the air outlet, the size of the porch and the size of the generator set, and the three-dimensional model structurally comprises a generator layer, a bus layer, an excitation variable layer, a water turbine layer and a volute layer.
The invention relates to a preferable scheme of a CFD-based hydropower station underground powerhouse multi-index ventilation effect analysis method, wherein the method comprises the following steps: the grid division comprises the step of carrying out grid division on the three-dimensional model by adopting ICEM-CFD software, wherein grid parameters of different positions of the plant follow a setting mode from a local part to the whole part; respectively carrying out grid division on the areas of the air supply outlet and the air exhaust outlet; carrying out grid encryption processing on an area with large flow field change near the generator set; and then integrating and merging the processed grids into a global grid so as to obtain a grid model of each level of the main workshop.
The invention relates to a preferable scheme of a CFD-based hydropower station underground powerhouse multi-index ventilation effect analysis method, wherein the method comprises the following steps: the attribute setting comprises setting the attribute of the air supply port as a speed inlet, setting the attribute of the air exhaust port as a static pressure outlet, and setting the pressure value as an atmospheric pressure.
The invention relates to a preferable scheme of a CFD-based hydropower station underground powerhouse multi-index ventilation effect analysis method, wherein the method comprises the following steps: the pre-processing comprises the steps of importing the grid file into Fluent and establishing a unit and a node group set.
As a preferable scheme of the analysis method for the multi-index ventilation effect of the hydropower station underground powerhouse based on the CFD, the method comprises the following steps: the index data includes PM2.5 concentration, supply-air outlet wind speed, temperature, humidity, and oxygen concentration.
The invention relates to a preferable scheme of a CFD-based hydropower station underground powerhouse multi-index ventilation effect analysis method, wherein the method comprises the following steps: the boundary condition setting comprises that each layer of air supply outlet is set to be 'velocity-inlet'; the air outlet is set to be 'pressure-output'; the right side wall in the boundary type of wall radiation heat exchange is set as 'semi-transparent'.
As a preferable scheme of the analysis method for the multi-index ventilation effect of the hydropower station underground powerhouse based on the CFD, the method comprises the following steps: the equation set comprises that in the multi-index analysis, the heat exchange flow condition of the fluid needs to be considered, the air supply transmitted by a factory building is regarded as the incompressible fluid, and a standard k-epsilon turbulence dual equation model is selected for iteration; the selection of the multi-component transport equation is required in relation to the velocity field, the humidity field and the oxygen concentration.
The invention relates to a preferable scheme of a CFD-based hydropower station underground powerhouse multi-index ventilation effect analysis method, wherein the method comprises the following steps: the convergence condition includes that the speed residual value is stabilized at 10 -3 Residual values of oxygen and moisture content stabilized at 10 -7 。
The invention relates to a preferable scheme of a CFD-based hydropower station underground powerhouse multi-index ventilation effect analysis method, wherein the method comprises the following steps: and the flow field simulation result comprises a wind speed vector diagram, a temperature distribution cloud diagram, a humidity distribution cloud diagram and an oxygen concentration change cloud diagram of the underground plant obtained by establishing longitudinal and transverse sections.
The invention has the beneficial effects that: when the method is applied to the analysis process of the underground powerhouse of the hydropower station, the judgment on the ventilation effect is not only limited to the temperature or the humidity, but also has a wider coverage range, the effect of the ventilation system of the underground powerhouse is analyzed through multiple indexes, whether the current fan working condition meets the requirement of normal production and life of the hydropower station or not is analyzed more comprehensively, the potential safety hazard of production is eliminated, and greater economic benefit is brought to the hydropower station.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced 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 based on these drawings without inventive exercise. Wherein:
fig. 1 is a schematic flow chart illustrating a method for analyzing the multi-index ventilation effect of an underground powerhouse of a hydropower station based on CFD according to a first embodiment of the invention;
fig. 2 is a schematic layout diagram of the wind outlets of the generator layer of the main power house according to the method for analyzing the multi-index ventilation effect of the underground power house of the hydropower station based on CFD according to the first embodiment of the invention;
FIG. 3 is a cloud diagram of humidity distribution of generator levels of a main power plant at a typical setting of a CFD-based analysis method for multi-index ventilation effect of an underground power plant of a hydropower station according to a second embodiment of the invention;
fig. 4 is a schematic diagram of velocity field distribution of a generator layer of a main power station of a hydropower station underground power station multi-index ventilation effect analysis method based on CFD according to a second embodiment of the invention;
fig. 5 is a cross-sectional and longitudinal-sectional temperature distribution cloud chart of a generator layer of a main power station based on a CFD analysis method for multi-index ventilation effect of an underground power station of a hydropower station according to a second embodiment of the invention;
fig. 6 is a cloud diagram of the humidity distribution of the transverse and longitudinal sections of the generator layer of the main power station house according to the analysis method of the multi-index ventilation effect of the underground power station house based on the CFD according to the second embodiment of the present invention;
fig. 7 is a cloud diagram of the distribution of oxygen concentration in the cross-section and the longitudinal section of the generator layer of the main power station based on the analysis method of the multi-index ventilation effect of the underground power station of the hydropower station based on CFD according to the second embodiment of the invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, specific embodiments accompanied with figures are described in detail below, and it is apparent that the described embodiments are a part of the embodiments of the present invention, not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without making creative efforts based on the embodiments of the present invention, shall fall within the protection scope of the present invention.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced in other ways than those specifically described and will be readily apparent to those of ordinary skill in the art without departing from the spirit of the present invention, and therefore the present invention is not limited to the specific embodiments disclosed below.
Furthermore, reference herein to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the invention. The appearances of the phrase "in one embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments.
The present invention will be described in detail with reference to the drawings, wherein the cross-sectional views illustrating the structure of the device are not enlarged partially in general scale for convenience of illustration, and the drawings are only exemplary and should not be construed as limiting the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in the actual fabrication.
Meanwhile, in the description of the present invention, it should be noted that the terms "upper, lower, inner and outer" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the present invention and simplifying the description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation and operate, and thus, cannot be construed as limiting the present invention. Furthermore, the terms first, second, or third are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
The terms "mounted, connected and connected" in the present invention are to be understood broadly, unless otherwise explicitly specified or limited, for example: can be fixedly connected, detachably connected or integrally connected; they may be mechanically, electrically, or directly connected, or indirectly connected through intervening media, or may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
Example 1
Referring to fig. 1 to 2, a first embodiment of the present invention provides a method for analyzing a multi-index ventilation effect of an underground powerhouse of a hydropower station based on CFD, including:
s1: and establishing a three-dimensional model of each layer of cavern of the main plant of the hydropower plant, and carrying out grid division and attribute setting on the three-dimensional model.
And performing three-dimensional modeling according to the plant design drawing of the hydraulic power plant, the overall size of the plant, the sizes of the ventilation opening and the exhaust opening, the size of the porch and the size of the generator set.
Specifically, as shown in fig. 2, the heights of the air supply outlet and the air exhaust outlet from the ground and the length, width and geometric dimensions of the air supply outlet and the air exhaust outlet are marked in the figure, the marked heights and the length of the factory building and the width and the height of the corridor are also marked, a model of the factory building is established by using three-dimensional modeling software SolidWorks, a cartesian coordinate system is used as a global coordinate system, the west direction of the factory building is defined as the x-axis direction, the south direction is defined as the y-axis direction, and the height direction is defined as the z-axis direction. The model structure comprises a generator layer, a bus layer, an excitation variable layer, a water turbine layer, a volute layer and other hierarchical caverns. And the three-dimensional model is properly simplified, so that the post CFD pretreatment work is facilitated.
It should be noted that, in the process of model simplification, the whole plant is surrounded by underground rocks, so that the wall thickness of the plant wall is neglected, and other objects with small influence on simulation analysis in the plant are simplified, thereby reducing the complexity of calculation. In a specific implementation process, sundries accumulated at corners of a generator layer of a main plant and part of control cabinets are removed, part of corner parts in geometric characteristics of the plant are simplified, places with extending parts such as porch channels are subjected to sealing treatment, only the ventilation performance of porches is reserved, and the extended channel space is not considered; overhead crane equipment is installed above the generator layer cavern, is close to the wall surface, has small influence on gas flow at high altitude, is regarded as an open area, and is removed in model simplification, and plant columns, lighting equipment, workers and mechanical parts are ignored.
Furthermore, the ICEM-CFD software is adopted to carry out meshing on the three-dimensional model, the setting of the parameters of meshes at different positions of a factory building is different, and the meshing is carried out according to the setting mode from local to integral. And respectively carrying out grid division on the air supply outlet, the air exhaust outlet and each wall surface of the plant main body, setting the minimum size of a grid to be 0.1m and the maximum grid to be 0.3m, carrying out grid encryption treatment on an area with large flow field change near the generator set, and finally integrating and combining the global grids to obtain a grid model of each level of the main plant.
Still further, the attribute of the air supply port is set as a speed inlet, the attribute of the air exhaust port is set as a static pressure outlet, and the pressure value is set to be one atmospheric pressure.
S2: and preprocessing the grid file, and setting the boundary condition of the three-dimensional model by using each index data of the measuring points measured off-line or on-line.
And importing the grid file into Fluent to establish a unit and node group set.
The method comprises the following steps of utilizing test data of indexes at measuring points of each air supply outlet of a factory building, which are measured by a series of instruments such as a handheld wind speed tester, a temperature and humidity tester and the like, collecting the data in a manual off-line measuring mode before each sensor is not installed and debugged, and collecting the measuring point data by an on-line collecting method after an intelligent ventilation collecting system is complete:
table 1: list of off-line test instruments.
For the solid particle type index, volume parameters of the collected solid particles and concentration in the air supply are also needed.
In the embodiment, a generator layer of a main plant is used as an example for expansion, the space of the layer is large, the ground is flush with a generator cover plate, the layer is wide and flat, the air circulation flow is smooth, and during testing, an independent measuring point is arranged at each air supply outlet of the layer to collect PM2.5 concentration, air speed, temperature, humidity and oxygen concentration of the air supply outlet, as shown in table 2.
Table 2: and measuring a data table at each measuring point.
| |
1 | 2 | 3 | 4 | 5 | 6 |
| Temperature of | 14.6 | 14.5 | 14.4 | 14.5 | 14.2 | 14.2 |
| Humidity% | 54.5 | 54.6 | 54.6 | 54.6 | 54.7 | 54.7 |
| PM2.5ug/m3 | 9 | 9 | 7 | 7 | 7 | 7 |
| Wind speed m/s | 1.11 | 1.20 | 1.62 | 1.65 | 0.30 | 0.32 |
| O 2 Concentration% | 20.6 | 20.6 | 20.5 | 20.5 | 20.5 | 20.5 |
Further, boundary conditions are set for the three-dimensional model. Setting air supply ports of all layers as 'velcro-inlets', setting air exhaust ports as 'pressure-outlets', simultaneously setting heat dissipation of the top, side walls and the ground of a plant, considering one side of a main control room of the plant, the glass wall surface occupies a larger area, setting right side wall of a boundary type of wall radiation heat exchange as 'semi-transparent', setting the top surface and side heat dissipation surfaces of a generator set, setting the average temperature of all side wall surfaces of a generator layer in winter to be 17 ℃ according to actual measurement data of the plant in winter, and performing the same setting treatment on the top wall of the plant.
Preferably, after data testing in a certain season is finished, the data are measured again under the same working condition at intervals, taking a generator layer as an example, the data such as wind speed, temperature and humidity among generator groups are measured, then the data are compared with simulation result data of a fluent same place, if the comparison error range exceeds +/-15%, the grids in the area are encrypted, the number and density of the grids in the area are improved, and the accuracy of data measurement is guaranteed.
S3: and (4) simulating and calculating index data, selecting a corresponding equation set to perform iterative calculation until a convergence condition is met, and outputting a three-dimensional flow field simulation model.
In the multi-index data simulation analysis, the conditions such as heat exchange flow of fluid are considered, the air supply transmitted by a factory building is regarded as incompressible fluid, a standard k-epsilon turbulence two-way model is selected, the model has reasonable speculation on the problem of large-scale turbulence, and the model is widely used for the simulation analysis of industrial fluid flow and heat transfer, and is shown as the following formula:
wherein, C μ ＝0.09、C 1ε ＝1.44、C 2ε Each of =1.92 is a turbulence constant, σ k ＝1.0、σ ε =1.3 is turbulent Plantt number, custom source term S k 、S ε Is set to 0.
The velocity field, the humidity field, the oxygen concentration and the PM2.5 are related to select a multi-component transport equation, and the equation is used for deducing the viscosity coefficient, the diffusion coefficient and the thermal conductivity of oxygen molecules, water molecules and the like in the transport process, and is as follows:
wherein, C f Is the volume concentration of component f; d f Is the diffusion coefficient of component f.
In addition, a continuity equation, a mass conservation equation and an energy conservation equation are added to ensure that a mass conservation law and an energy conservation law are followed in the simulation process; before simulation analysis is carried out on a humidity field and oxygen concentration, the influence of gravity factors needs to be considered according to reality so as to improve the authenticity of a simulation result, and a continuity equation, a mass conservation equation and an energy conservation equation are respectively as follows:
wherein S is u ＝F x +S X ，S v ＝F y +S y ，S w ＝F z +S z Fx, fy and Fz represent the stress conditions of the infinitesimal body in three spatial directions, the vertical upward direction of the model is set to be the positive direction of the Z axis in the early stage, and Fx =0, fy =0, fz = - ρ g under the condition of only considering the action of gravity;
when analyzing the speed field, the humidity field and the oxygen concentration, selecting the gradient when setting the Cell Zone Conditions part, wherein i and j can take the values of 1, 2 and 3 to represent three space coordinates.
Through the simplification to hydropower station underground factory building three-dimensional model in earlier stage, the barrier that mainly exists in the factory building is the generating set, but the geometric proportion compares whole factory building influence less, can ignore this part from the wind pressure change of supply-air outlet transmission air supply to promote the iterative operation in later stage.
Further, the solution of the above equation set is solved through iterative calculation until the speed residual value is stabilized at 10 -3 Residual values of oxygen and moisture content stabilized at 10 -7 And outputting an iteration result, namely the three-dimensional flow field simulation model.
Preferably, the low-speed incompressible flow process can be determined based on the air supply speed of the ventilation system of the underground powerhouse of the hydropower station, and the solver is based on a pressure solver. In each level cavern of an underground factory building, the space of a generator layer is maximum, the longitudinal height of the generator layer is far higher than that of other level caverns, the ground surface area is larger, a direct solution for discrete solution commonly used in the smaller cavern is not applicable, the generator layer is large in area, more in nodes and complex in grids, an iteration method is adopted in the operation of each index of the generator layer, a SIMPLE equation is selected for the nonlinear equation set to be discretely solved, the stability is kept, meanwhile, a raw Square Cell Based method is selected for the Gradient option block of a solver to control the central Gradient of a control body, and the precision is more accurate than that of a Green-Gauss Node central Gradient control method.
Preferably, for the setting of the grid discrete format, in the "differentiation" version in the cell interface, "Momentum", "turbolent Kinetic Energy" and "turbolent dispersal Rate" are all set to "Second Order update", that is, the Second-Order windward gradient is higher in precision, and the simulated spatial distribution rule of each index is more specific.
S4: and analyzing the three-dimensional flow field simulation model through post-processing to obtain flow field simulation results of the velocity field, the temperature field and the humidity field at each cross section of the space, and finishing the judgment of the ventilation effect under the current working condition through the flow field simulation results.
After the operation convergence of the early-stage steps, a three-dimensional flow field simulation model obtained by Fluent operation is guided into CFD-Post for Post-processing analysis, and a longitudinal cutting and transverse cutting section is established to obtain an underground factory building wind speed vector diagram, a temperature distribution cloud diagram, a humidity distribution cloud diagram and an oxygen concentration change cloud diagram, wherein the transverse cutting section with the distance of 1.7m from the ground is established by considering the flow of ground personnel and equipment arrangement, the height is the average height of power station workers, and various parameters such as temperature and humidity at the height level have direct influence on the healthy production life of the personnel; the main power house generator layer is provided with a crown block crane at the position 11m away from the ground, so that a cross section at the position 11m away from the ground is established, and temperature and humidity parameters at the height have direct influence on maintenance of crown block parts; and (3) setting a longitudinal section at the central line of the plant, and judging the quality of the ventilation effect under the current working condition by observing the distribution rule of each index in a vertical space, thereby providing effective support for optimizing the ventilation system and improving the air supply speed in the later period.
Example 2
In order to verify and explain the technical effects adopted in the method, the embodiment selects a traditional simulation method and adopts the method to perform comparison test, and compares the test results by means of scientific demonstration to verify the real effect of the method.
The traditional simulation method has the disadvantages that the operation and calculation time is long, the requirement on the configuration performance of a computer is high, the generally configured computer is difficult to meet the operation requirement under the method, the accurate simulation result of data such as temperature, humidity and wind speed in a factory space cannot be obtained, and the judgment on the ventilation effect is limited to humidity.
In order to verify that the method has a wider coverage range compared with the traditional method, the ventilation effect of the underground powerhouse of the hydraulic power plant is analyzed and compared in real time by adopting the traditional simulation method and the method respectively.
And (3) testing environment: a CPU: intel Core i7-4712MQ CPU 2.3GHz; memory:8GB; and OS: win10 bit; a simulation platform: ANSYS simulation platform.
The simulation of the method takes 8 hours, and the simulation of the traditional method takes 11 hours. The ventilation effect of 6 measuring points of the underground powerhouse of the hydraulic power plant is analyzed by respectively adopting a traditional simulation method and a simulation result graph obtained by the method.
As shown in fig. 3, compared with the second-order windward gradient adopted in fig. 6 (a), the humidity distribution cloud chart obtained by the conventional simulation method has an unobvious humidity distribution rule and cannot accurately reflect the position of the humidity source, so that the second-order windward gradient adopted in the embodiment has higher precision, and the simulated spatial distribution rule of each index is more specific.
As shown in FIG. 4, the velocity field distribution diagram of the generator layer of the main factory building obtained by the method can visually reflect whether the air supply is uniform on the generator layer or not according to the distribution change of the wind speed in the factory building, the air supply between 0.41m/s and 0.83m/s is provided in the extension area between the air supply outlet and the air outlet, the wind speed of the vent of No. 6 measuring point is 0.32m/s, although the wind speed is smaller than that of the vents of No. 1 and No. 3, the velocity field distribution diagram has obvious effect on sharing the ventilation and heat dissipation effects of the No. 3 generator set. The air delivered from each air supply outlet forms a backflow after passing through a channel between each power generator set, heat generated in the running process of the power generator sets is dispersed, an induced draft fan is used for completing effective circulation of ventilation and heat dissipation through each air outlet, according to the analysis of a speed distribution diagram obtained by CFD-Post treatment, high-wind-speed areas are concentrated in No. 2 and No. 3 power generator sets, the highest wind speed can reach 0.83m/s, and ventilation and heat dissipation in the running of the power generator sets are facilitated.
Fig. 5 shows a cross-sectional and longitudinal-sectional temperature distribution cloud chart of a generator layer of a main plant obtained by simulation of the method, wherein (a) is a cross section of 1.7m, (b) is a cross section of 11m, and (c) is a longitudinal tangent of a central line; the position and the specific temperature of a heat source in a high-temperature area in a plant can be judged according to the temperature value of each area, the clearance channels of each unit have temperature zones lower than those of other areas, the average temperature is 15.85 ℃, the fluctuation is smaller compared with the initial temperature of an air supply outlet, the high-temperature area appears on the edge side of a wall, the highest temperature reaches 18 ℃, and the temperature fluctuation relative to the air supply outlet is larger; in the top space of the factory building, high-temperature areas are mainly concentrated on two sides of the factory building, areas above a main control room and a traffic hole, the temperature distribution of the middle area is gentle and uniform, the temperature of the whole area is kept at 15.25 ℃, and the highest temperature of the edge area is 17.45 ℃.
Fig. 6 shows a cloud chart of humidity distribution in the cross section and the longitudinal section of the generator layer of the main plant obtained by simulation in the method, wherein (a) is a cross section of 1.7m, (b) is a cross section of 11m, and (c) is a longitudinal tangent of a central line; the method is used as a basis to judge that the wet source of the starting motor layer is positioned in the gallery between the No. 2 and No. 3 engine groups, and in the section of the No. 6 measuring point 1.7m away from the ground, the front extension area of the air supply opening is measured, namely, the channels on the two sides of the No. 1 engine group have higher humidity areas, the highest humidity is 54.64 percent, the area is mainly concentrated in the front area of the leftmost ventilation opening, the humidity meets the relevant requirements for the normal operation of machinery, and the humidity change tends to disperse and the numerical value is reduced along with the retraction from the air outlet. The No. 2 unit is just opposite to the air supply outlets of the No. 3 and No. 4 measuring points, the air speed of the No. 2 air supply outlet is 1.62m/s, the humidity distribution around the No. 2 unit is uniform, the humidity range is 54.55% -54.57%, and the variation range is small; the humidity of the No. 3 unit is always kept at a lower level under the combined action of the vents of the No. 1 and No. 2 measuring points, and the humidity fluctuates slightly from 54.50% -54.52% in the range from the No. 3 unit to the traffic hole, so that the influence can be ignored. For a plant headspace at a height of 10m from the ground, the humidity is 54.63% at the position where the overhead crane is deployed, and is slightly higher than that in other areas, but the overall humidity environment fluctuates about 54.6%.
Fig. 7 shows the oxygen concentration distribution cloud of the cross section and the longitudinal section of the generator layer of the main plant obtained by the simulation of the method, wherein (a) is a cross section of 1.7m, (b) is a cross section of 11m, and (c) is a longitudinal tangent of a central line; the distribution condition of the oxygen concentration is directly related to the operation condition of a ventilation system, the distribution condition of the oxygen concentration is influenced by the working conditions of a blower and an exhaust fan, the distribution condition of the oxygen concentration also changes along with the distribution condition, a region with higher oxygen content under the working condition is concentrated between a traffic tunnel and a machine set No. 3, the average oxygen concentration reaches 20.59 percent, and a region close to one side of a main control room has slightly poor air circulation effect because the air speed of a ventilation opening of a measuring point No. 3 is small, but the oxygen content can also reach 20.50 percent, no obvious difference exists, the oxygen concentration is important for ensuring the health of working personnel of a power plant, and the quality of the ventilation effect can be visually judged through the distribution diagram of the oxygen concentration.
The method integrates the multiple indexes to carry out development analysis on the ventilation effect of the hydropower station underground powerhouse, is more comprehensive and specific than the traditional simulation method, can provide effective suggestion and feedback for optimization of the ventilation system of the underground powerhouse, and guarantees safety of production and life.
It should be noted that the above-mentioned embodiments are only for illustrating the technical solutions of the present invention and not for limiting, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, which should be covered by the claims of the present invention.
Claims (5)
1. A multi-index ventilation effect analysis method for hydropower station underground powerhouse based on CFD is characterized by comprising the following steps: comprises the steps of (a) preparing a mixture of a plurality of raw materials,
establishing a three-dimensional model of each layer of cavern of a main plant of the hydropower plant, and performing grid division and attribute setting on the three-dimensional model;
preprocessing the grid file, and setting the boundary condition of the three-dimensional model by using each index data at the measuring point measured off-line or on-line;
performing analog calculation on the index data, selecting a corresponding equation set to perform iterative calculation until a convergence condition is met, and outputting a three-dimensional flow field simulation model;
analyzing the three-dimensional flow field simulation model through post-processing to obtain flow field simulation results of a velocity field, a temperature field and a humidity field at each cross section of the space, and finishing the judgment of the ventilation effect under the current working condition through the flow field simulation results;
the three-dimensional model comprises a three-dimensional modeling according to a plant design drawing of the hydraulic power plant, the overall size of the plant, the sizes of an air supply outlet and an air exhaust outlet, the size of a porch and the size of a generator set, and the three-dimensional modeling structurally comprises a generator layer, a bus layer, an excitation transformation layer, a water turbine layer and a volute layer;
the grid division comprises the step of carrying out grid division on the three-dimensional model by adopting ICEM-CFD software, wherein grid parameters of different positions of the plant follow a setting mode from a local part to an integral part;
respectively carrying out grid division on the areas of the air supply outlet and the air exhaust outlet; setting the minimum size of the grid to be 0.1m and the maximum grid to be 0.3m;
carrying out grid encryption processing on an area with large flow field change near the generator set;
then, integrating and combining the processed grids into a global grid so as to obtain a grid model of each layer of the main plant;
the index data includes, for example,
PM2.5 concentration, air outlet air speed, temperature, humidity and oxygen concentration;
the setting of the boundary conditions includes that,
each layer of air supply outlet is set as 'velocity-inlet';
the air outlet is set to be 'pressure-output';
the right side wall in the boundary type of wall radiation heat exchange is set as 'semi-transparent';
after data testing in a certain season is finished, measuring again under the same working condition at intervals, comparing with fluent same-place simulation result data, and if the comparison error range exceeds +/-15%, encrypting the grids in the area;
the flow field simulation results include that,
obtaining a wind speed vector diagram, a temperature distribution cloud diagram, a humidity distribution cloud diagram and an oxygen concentration change cloud diagram of the underground plant by establishing longitudinal and transverse cross sections; a transverse section 1.7m away from the ground is set up, a transverse section at the height of 11m away from the ground is set up, and a longitudinal section at the center line of the workshop is set up.
2. The analysis method for the multi-index ventilation effect of the hydropower station underground powerhouse based on the CFD according to claim 1, is characterized in that: the setting of the properties may include,
setting the attribute of the air supply outlet as a speed inlet, setting the attribute of the air exhaust outlet as a static pressure outlet, and setting the pressure value as one atmospheric pressure.
3. The analysis method for the multi-index ventilation effect of the hydropower station underground powerhouse based on the CFD according to claim 2, is characterized in that: the pre-treatment comprises the steps of,
and importing the grid file into the Fluent to establish a unit and node group set.
4. The analysis method for the multi-index ventilation effect of the hydropower station underground powerhouse based on the CFD according to claim 3, is characterized in that: the system of equations includes the set of equations,
in the multi-index analysis, the heat exchange flow condition of the fluid needs to be considered, the air supply transmitted by a factory building is regarded as incompressible fluid, and a standard k-epsilon turbulence dual-equation model is selected for iteration;
the selection of the multi-component transport equation is required in relation to the velocity field, the humidity field and the oxygen concentration.
5. The analysis method for the multi-index ventilation effect of the hydropower station underground powerhouse based on the CFD according to claim 4, is characterized in that: the convergence condition includes a condition of a convergence of the image,
the speed residual value is stabilized at 10 -3 The residual values of oxygen and moisture contents stabilized at 10 -7 。
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