Method and system for simulating gas-liquid heat transfer mechanism of water conveying pipeline

Abstract

The invention discloses a simulation method and system for a gas-liquid heat transfer mechanism of a water delivery pipeline, and the method comprises the steps: dividing a target pipeline, and obtaining a plurality of pipeline nodes; judging pipeline filling states at two ends of the to-be-detected node in the pipeline to obtain a current state of the to-be-detected node; based on the current state of the to-be-tested node, performing calculation through a control algorithm adaptive to the current state to obtain target state data of the to-be-tested node; wherein the control algorithm comprises a gas column control algorithm based on gas thermodynamic characteristics; and solving the control algorithm based on the moving wave value solving format to obtain target state data of corresponding nodes in the target pipeline. According to the method, the change rule mechanism of the gas thermodynamic characteristics in the rapid change process of the water flow is fully considered, and the hydraulic data is calculated through three control algorithms, so that the checking accuracy of the hydraulic safety problem of the engineering pipeline of the water delivery system is improved, possible engineering hidden dangers are pre-judged, and the safety of the engineering design of the water delivery system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydraulic numerical simulation calculation, and particularly to a simulation method and system for the gas-liquid heat transfer mechanism in a water conveyance pipeline. Background Art

[0002] As an important infrastructure to ensure the rational distribution and utilization of water resources, the safety and reliability of the design, construction, and operation of water conveyance systems have received increasing attention. In these systems, pipelines are the key components for transporting liquids, and hydraulic safety issues are directly related to the stability and efficiency of the entire system. To ensure the reliable operation of water conveyance systems, it is necessary to accurately simulate and predict the dynamic behavior of the fluid inside the pipeline. In the past few decades, with the development of computational fluid dynamics (CFD), numerical simulation technology has become an important tool for analyzing and solving complex hydraulic problems.

[0003] However, the pipeline systems in actual engineering often involve complex operating conditions and different pipeline states. Currently, when checking the hydraulic safety issues of engineering pipelines in water conveyance systems, the commonly used method in the industry is to ignore the influence of the gas column existing in the pipeline on the liquid flow and simply regard the fluid inside the pipeline as a continuous and complete pressurized water column for numerical simulation. Another method is to assume that the gas column in the pipeline is an ideal gas and not consider any heat exchange process to simplify the model and estimate the possible pressure peaks. Although these two methods can provide useful information about the maximum pressure level of the system to a certain extent, they cannot accurately capture the detailed pressure changes and periodic fluctuation characteristics during the entire fluctuation process. There is a certain gap between this simplified treatment method and the actual situation. Especially in the face of multiple working conditions, it may underestimate or overestimate the dynamic characteristics of the actual pressure wave, thus affecting the accuracy of the assessment of the true performance of the system. Therefore, for further improving the simulation accuracy and better understanding the complex fluid phenomena in water conveyance systems, more refined and comprehensive modeling methods are needed. Summary of the Invention

[0004] In view of the above existing problems, the present invention is proposed.

[0005] Therefore, the present invention provides a simulation method and system for the gas-liquid heat transfer mechanism in a water conveyance pipeline to solve the problems that the existing technology cannot accurately capture the complete pressure changes and fluctuation periods during the entire fluctuation process, there is a certain gap from the actual situation, and it underestimates or overestimates the dynamic characteristics of the actual pressure wave.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] In a first aspect, the present invention provides a method for simulating the gas-liquid heat transfer mechanism of a water conveyance pipeline, including: dividing a target pipeline to obtain a plurality of pipeline nodes;

[0008] Judging the filling states of the pipelines at both ends of a node to be measured in the pipeline to obtain the current state of the node to be measured;

[0009] Based on the current state of the node to be measured, calculating through a control algorithm adapted to the current state to obtain the target state data of the node to be measured; wherein, the control algorithm includes a gas column control algorithm based on the gas thermodynamic characteristics;

[0010] Solving the control algorithm based on the moving wave numerical solution format to obtain the target state data of the corresponding nodes in the target pipeline.

[0011] As a preferred scheme of the method for simulating the gas-liquid heat transfer mechanism of the water conveyance pipeline according to the present invention, wherein: the current state of the node to be measured includes:

[0012] The first state, in which the water bodies fill the two side pipe sections connected to the node to be measured;

[0013] The second state, in which the gases fill the two side pipe sections connected to the node to be measured;

[0014] The third state, in which one side of the two side pipe sections connected to the node to be measured is gas and the other side is water body.

[0015] As a preferred scheme of the method for simulating the gas-liquid heat transfer mechanism of the water conveyance pipeline according to the present invention, wherein: calculating through a control algorithm adapted to the current state based on the current state of the node to be measured to obtain the target state data of the node to be measured, including:

[0016] When the node to be measured is in the first state, calculating the water pressure and flow rate at the node through a pipe flow liquid control algorithm to obtain the first target pressure and the first target flow rate of the node to be measured.

[0017] As a preferred scheme of the method for simulating the gas-liquid heat transfer mechanism of the water conveyance pipeline according to the present invention, wherein: calculating through a control algorithm adapted to the current state based on the current state of the node to be measured to obtain the target state data of the node to be measured, including:

[0018] When the node to be measured is in the second state, calculating the gas pressure at the node through a gas column control algorithm based on the gas thermodynamic characteristics to obtain the second target pressure of the node to be measured;

[0019] The gas column control algorithm based on the gas thermodynamic characteristics is expressed as:

[0020]

[0021] Among them, H a is the second target pressure of the gas column in the target pipeline, C p is the specific heat capacity at constant pressure of the gas column, C v is the specific heat capacity at constant volume of the gas column, V a is the volume of the gas column in the pipeline, α is the thermodynamic coefficient of the gas column, A a is the total contact area between the gas column and the pipe wall, T in is the internal temperature of the target pipeline, T ex is the external ambient temperature, t is the calculation time, s; d is the derivative symbol; dHa / dt is the derivative of the gas pressure with respect to time; dVa / dt is the derivative of the gas flow rate with respect to time.

[0022] As a preferred scheme of the simulation method for the gas-liquid heat transfer mechanism of the water conveyance pipeline described in the present invention, among them: based on the current state of the node to be measured, calculate through a control algorithm adapted to the current state to obtain the target state data of the node to be measured, and further include:

[0023] When the node to be measured is in the third state, calculate the water body, gas pressure and water flow rate at the node through the gas-liquid boundary control algorithm to obtain the third target pressure and third target flow rate of the node to be measured;

[0024] The gas-liquid boundary control algorithm is expressed as:

[0025]

[0026] H wa = H a

[0027] Among them, x w is the target distance from the gas-liquid boundary position at time t+△t to the most upstream node, x w0 is the distance from the gas-liquid boundary position at time t to the most upstream node, v c is the liquid velocity at time t, H wa is the liquid pressure at time t, d is the derivative symbol.

[0028] As a preferred scheme of the simulation method for the gas-liquid heat transfer mechanism of the water conveyance pipeline described in the present invention, among them: solve the control algorithm based on the moving wave numerical solution format to obtain the target state data of the corresponding nodes in the target pipeline, including:

[0029] Construct a moving wave numerical solution format, expressed as:

[0030]

[0031] Among them, A1 is the first characteristic parameter of pipeline node A, and B1 is the first characteristic parameter of pipeline node B; A2 is the second characteristic parameter of pipeline node A, and B2 is the second characteristic parameter of pipeline node B; pipeline node A is the upstream node of the node to be measured P, and pipeline node B is the downstream node of the node to be measured P; H P is the target pressure, and Q P is the target flow rate.

[0032] As a preferred solution of the simulation method for the gas-liquid heat transfer mechanism of the water conveyance pipeline described in the present invention, wherein: when in the first state, the water level of the upstream reservoir is the initial first target pressure, and the initial first target flow rate is obtained by combining the pipe flow liquid control algorithm; and the first target state data of the corresponding node is updated in real time based on the moving wave numerical solution format;

[0033] When in the third state, according to the third target flow rate of the node to be measured obtained at the previous moment and the node position where the gas-liquid interface is located, the updated third target pressure is obtained by combining the gas-liquid interface control algorithm, and the flow rate at the water-gas interface is the product of the liquid velocity at the water-gas interface at time t in the gas-liquid interface control algorithm and the cross-sectional area of the pipeline; and the third target state data of the corresponding node is updated in real time based on the moving wave numerical solution format.

[0034] In a second aspect, the present invention provides a simulation system for the gas-liquid heat transfer mechanism of a water conveyance pipeline, including:

[0035] A division module for dividing the target pipeline to obtain a plurality of pipeline nodes;

[0036] A judgment module for judging the filling state of the pipelines at both ends of the node to be measured in the pipeline to obtain the current state of the node to be measured;

[0037] A first calculation module for calculating the target state data of the node to be measured based on the current state of the node to be measured through a control algorithm adapted to the current state; wherein, the control algorithm includes a gas column control algorithm based on the thermodynamic characteristics of the gas;

[0038] A second calculation module for solving the control algorithm based on the moving wave numerical solution format to obtain the target state data of the corresponding node in the target pipeline.

[0039] In a third aspect, the present invention provides an electronic device, including:

[0040] A memory and a processor;

[0041] The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions. When the computer-executable instructions are executed by the processor, the steps of the simulation method for the gas-liquid heat transfer mechanism of the water conveyance pipeline are implemented.

[0042] In a fourth aspect, the present invention provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the simulation method for the gas-liquid heat transfer mechanism in the water conveyance pipeline.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows: Based on the three possible operating conditions in the pipeline, the present invention fully considers the variation law mechanism of the gas thermodynamic characteristics during the rapid change of the water flow rate. Through three control algorithms, especially the gas column control algorithm and the gas-liquid interface control algorithm based on the gas thermodynamic characteristics, the hydraulic data is calculated, thus greatly improving the accuracy of checking the hydraulic safety problems of the pipeline in the water conveyance system project, helping to predict and anticipate possible engineering hazards in advance during the engineering design stage, and improving the safety of the water conveyance system project design. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0045] Figure 1 It is a schematic diagram of the overall process of the simulation method for the gas-liquid heat transfer mechanism in the water conveyance pipeline according to an embodiment of the present invention;

[0046] Figure 2 It is a schematic diagram of the pipeline node division in the simulation method for the gas-liquid heat transfer mechanism in the water conveyance pipeline according to an embodiment of the present invention;

[0047] Figure 3 It is a schematic diagram of the experimental platform in the simulation method for the gas-liquid heat transfer mechanism in the water conveyance pipeline according to an embodiment of the present invention;

[0048] Figure 4 It is a comparison diagram of the gas column pressure fluctuation curves of the experiment and numerical simulation under the first operating condition in the simulation method for the gas-liquid heat transfer mechanism in the water conveyance pipeline according to an embodiment of the present invention;

[0049] Figure 5 It is a comparison diagram of the gas column pressure fluctuation curves of the experiment and numerical simulation under the first and second operating conditions in the simulation method for the gas-liquid heat transfer mechanism in the water conveyance pipeline according to an embodiment of the present invention;

[0050] Figure 6 It is a schematic diagram of the system structure in the simulation method for the gas-liquid heat transfer mechanism in the water conveyance pipeline according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] To make the above objects, features, and advantages of the present invention more apparent and understandable, the following provides a detailed description of the specific embodiments of the present invention in conjunction with the accompanying drawings of the specification. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0052] Embodiment 1

[0053] Referring to Figure 1 , for an embodiment of the present invention, a simulation method for the gas-liquid heat transfer mechanism of a water conveyance pipeline is provided, including:

[0054] S100: Divide the target pipeline to obtain multiple pipeline nodes;

[0055] S200: Judge the filling state of the pipeline at both ends of the node to be measured in the pipeline to obtain the current state of the node to be measured;

[0056] S300: Based on the current state of the node to be measured, calculate through a control algorithm adapted to the current state to obtain the target state data of the node to be measured; wherein, the control algorithm includes a gas column control algorithm based on the thermodynamic characteristics of the gas;

[0057] S400: Solve the control algorithm based on the moving wave numerical solution format to obtain the target state data of the corresponding nodes in the target pipeline.

[0058] It should be noted that when currently checking the hydraulic safety problem of the pipeline in the water conveyance system project, generally, the influence of the gas column in the pipeline on the liquid is ignored, and it is regarded as a complete pressurized water column for numerical simulation, or the gas column in the pipeline is regarded as an ideal gas without any heat exchange for simulation. Although it has a certain accuracy in simulating the possible pressure peaks in the pipeline, it cannot accurately capture the complete pressure change and fluctuation period in the entire fluctuation process.

[0059] Therefore, through the steps of S100 - S400 above, considering the change in the temperature of the gas, a control algorithm in the gas direction is constructed, regarding the gas temperature as a new variable to optimize and improve the accuracy of the overall model calculation, and based on the entire control algorithm, the accurate simulation of the target pressure and target flow of the whole process and all nodes of the operating state of the water conveyance pipeline is realized through a program. A moving wave numerical solution format for grid division in the spatial domain and time domain is established to ensure the smooth operation of the iterative calculation program.

[0060] Embodiment 2

[0061] Referring to Figure 1 - Figure 2, which is an embodiment of the present invention. Based on the above embodiment, a simulation method for the gas-liquid heat transfer mechanism of a water conveyance pipeline is provided.

[0062] In the embodiment of the present application, in step S100, the target pipeline is divided to obtain a plurality of pipeline nodes, including: setting a division spacing based on the total length of the pipeline to obtain N pipeline nodes; specifically, the following possible spacing division methods are included:

[0063] In an implementable manner, according to historical experience, when the pipeline length exceeds 100 m, the spacing is preset to 5 m or 10 m, and 20 or 10 pipe segments can be obtained. The starting connection of each pipe segment is regarded as a pipeline node. Therefore, there are 21 or 11 pipeline nodes in total; when ensuring that the number of pipeline nodes exceeds 10, relatively stable, accurate and efficient calculation results can be obtained;

[0064] In another implementable manner, if there is no requirement for calculation efficiency and a higher requirement for the accuracy of calculation results, the spacing can be set to 1 m, and 101 pipeline nodes are obtained at this time.

[0065] In the embodiment of the present application, the current state of the node to be measured in step S200 includes:

[0066] The first state, where the first state is that the two pipe segments connected to the node to be measured are filled with water.

[0067] Specifically, for the pipeline nodes obtained in step S100, there is a state where the two pipe segments connected to the node to be measured are filled with water, that is: the first state; in this state, the water pressure and flow rate at the node of this pipe segment can be calculated through the following pipe flow liquid control algorithm to obtain the first target pressure and the first target flow rate of the node to be measured.

[0068] The second state, where the second state is that the two pipe segments connected to the node to be measured are filled with gas.

[0069] Specifically, for the pipeline nodes obtained in step S100, there may also be another state where the two pipe segments connected to the node to be measured are filled with gas, that is: the second state; in this state, the gas pressure at the node of this pipe segment can be calculated through the following gas column control algorithm to obtain the second target pressure of the node to be measured.

[0070] The third state, where the third state is that one side of the two pipe segments connected to the node to be measured is gas and the other side is water.

[0071] Specifically, for the pipeline nodes obtained in step S100, there may also be a third state where one side of the two pipe segments connected to the node to be measured is gas and the other side is water body, that is: the third state. In this state, the water body and gas pressures, as well as the water body flow rate, at the pipeline node can be calculated through the following gas-liquid boundary control algorithm to obtain the third target pressure and the third target flow rate of the node to be measured.

[0072] It should be noted that for the overall target pipeline, when the pipeline is in the water conveyance operation process, the three states cover all states of each node to be measured at any moment. Therefore, by judging the water content of all nodes, their states can be determined, and corresponding algorithms can be applied to them, and finally, the calculation of the target pressure and target flow rate of all nodes in the pipeline can be realized.

[0073] In the embodiment of the present application, in step S300, based on the current state of the node to be measured, calculations are performed through a control algorithm adapted to the current state to obtain the target state data of the node to be measured, including:

[0074] When the node to be measured is in the first state, the water body pressure and flow rate at the node are calculated through the pipe flow liquid control algorithm to obtain the first target pressure and the first target flow rate of the node to be measured.

[0075] Specifically, the pipe flow liquid control algorithm is expressed as:

[0076]

[0077]

[0078] Among them, H is the pressure of the target pipeline, V is the liquid flow velocity, c is the velocity of the pipe flow wave propagation, and g is the acceleration due to gravity; combined with Figure 2 the horizontal axis and vertical axis shown, is the horizontal distance in the mathematical sense, is the time in the mathematical sense, D is the pipe diameter, f is the pipe friction coefficient, is the symbol for partial derivative;

[0079] After that, equations (1) and (2) are transformed into the ordinary differential form, expressed as:

[0080]

[0081]

[0082] Then, integrating it with respect to the time axis variable t can obtain the pipe flow liquid control algorithm, constructing a relationship equation between the parameters related to the liquid in the target pipeline, and finally expressed as:

[0083] H P′ =HA +XQ A -(X + Y|Q A |)Q P′ (5)

[0084] H P′ = H B -XQ B +(X + Y|Q B |)Q P′ (6)

[0085] Wherein, X and Y are constants, and their values can be found in the detailed description of specific embodiments. H A is the liquid pressure at pipeline node A, and H B is the liquid pressure at pipeline node B, and Q A is the liquid flow rate at pipeline node A, and Q B is the liquid flow rate at pipeline node B, and H P′ is the first target pressure of the node P to be measured, and Q P′ is the first target flow rate of the node P to be measured. Pipeline node A and pipeline node B are adjacent pipeline nodes to the node P to be measured, and || represents taking the absolute value.

[0086] In an alternative embodiment, when the node to be measured is in the first state in step S300, if there is a pump in the pipeline, a specific pumping system model can be used to predict the performance of the pump under given operating conditions, and then the pressure and flow rate at the node can be calculated.

[0087] In another alternative embodiment, when the node to be measured is in the first state in step S300, empirical formulas or charts can also be relied on to quickly estimate the pressure loss and flow rate. For example, the Darcy - Weisbach equation is used to calculate the frictional head loss along the pipeline.

[0088] In the embodiment of the present application, in step S300, based on the current state of the node to be measured, calculations are performed through a control algorithm adapted to the current state to obtain the target state data of the node to be measured, including:

[0089] When the node to be measured is in the second state, the gas pressure at the node is calculated through a gas column control algorithm based on the gas thermodynamic properties to obtain the second target pressure of the node to be measured.

[0090] In the embodiment of the present application, the gas column control algorithm based on the gas thermodynamic properties in step S300 is expressed as:

[0091]

[0092] Wherein, H a is the second target pressure of the gas column in the target pipeline, and Cp is the specific heat capacity at constant pressure of the gas column, C v is the specific heat capacity at constant volume of the gas column, V a is the volume of the gas column in the pipeline, α is the thermodynamic coefficient of the gas column, A a is the total contact area between the gas column and the pipe wall, T in is the internal temperature of the target pipeline, T ex is the external ambient temperature, t is the calculation time, s; d is the derivative symbol; dHa / dt is the derivative of the gas pressure with respect to time; dVa / dt is the derivative of the gas flow rate with respect to time.

[0093] It should be noted that based on this gas column control algorithm, the second target pressure can be calculated by derivation. In the traditional control algorithm, it is considered that the temperature of the gas never changes and there is no heat transfer, which does not conform to the actual situation; in the actual operation process, the gas temperature will not only rise sharply due to the collision and compression with the water body, but also change constantly due to the cooling effect of the pipe wall, so there is a large error, and this error will accumulate continuously with the extension of the pipeline operation time. The derived gas column algorithm fully considers the heat transfer between the gas, the pipe wall and the water body, and considers the thermodynamic characteristics of the gas, which can avoid the above errors.

[0094] In an alternative embodiment, when the node to be measured is in the second state in step S300, the pressure of the gas can also be indirectly inferred by measuring the speed of sound propagation in the pipeline. The speed of sound is related to the density of the medium, and the density is related to the pressure. In some cases, it can quickly provide a relatively accurate pressure estimate.

[0095] In another alternative embodiment, when the node to be measured is in the second state in step S300, if the pipeline contains a compressor, the state parameters of the gas, such as temperature, pressure and flow rate, can also be determined according to the working characteristics of the compressor.

[0096] In the embodiment of the present application, in step S300, based on the current state of the node to be measured, the target state data of the node to be measured is calculated by a control algorithm adapted to the current state, and further includes:

[0097] When the node to be measured is in the third state, the water body and gas pressure and water body flow rate at the node are calculated by the gas-liquid interface control algorithm to obtain the third target pressure and the third target flow rate of the node to be measured.

[0098] In the embodiment of the present application, the gas-liquid interface control algorithm in step S300 is expressed as:

[0099]

[0100] H wa = H a(9)

[0101] Among them, x w is the target distance from the gas-liquid interface position at time t+Δt to the most upstream node; x w0 is the distance from the gas-liquid interface position at time t to the most upstream node; v c is the liquid velocity at time t, which can be obtained from the third target flow rate at time t; H wa is the third target pressure at time t, and d is the derivative symbol.

[0102] In an alternative embodiment, when the node to be measured is in the third state in step S300, the target pressure and flow rate can also be calculated through a two-phase flow model, which can take into account bubble formation, rupture, and the interaction between liquid and gas, so as to more accurately predict the pressure and flow rate in the mixing region.

[0103] In another alternative embodiment, when the node to be measured is in the third state in step S300, a correction term introducing the buoyancy effect can also be added to the basic hydrodynamic equation to improve the calculation accuracy of the pressure and flow rate at the node, and it can be especially applied to vertical or inclined pipelines.

[0104] In the embodiment of the present application, in step S400, the target state data of the corresponding node in the target pipeline is obtained by numerically solving the control algorithm based on the moving wave numerical solution format, including:

[0105] As Figure 2 shown, a moving wave numerical solution format is constructed, expressed as:

[0106]

[0107] Among them, A1 is the first characteristic parameter of pipeline node A, B1 is the first characteristic parameter of pipeline node B; A2 is the second characteristic parameter of pipeline node A, B2 is the second characteristic parameter of pipeline node B; pipeline node A is the upstream node of the node to be measured P, and pipeline node B is the downstream node of the node to be measured P; H P is the target pressure, Q P is the target flow rate.

[0108] Furthermore, among them:

[0109] A1 = H A + XQ A ; B1 = H B - XQ B ; A2 = X + Y|Q A |; B2 = X + Y|Q B |.

[0110] It should be noted that the first characteristic parameter H Pmay refer to the target pressure H in the first state P′ or the target pressure H in the third state P″′ ; the second characteristic parameter Q P may refer to the target flow rate Q in the first state P′ or the target flow rate Q in the third state P″′ ; specifically defined according to the state, and used to solve and update the corresponding target data.

[0111] In the embodiment of the present application, in step S400, solving the control algorithm based on the moving wave numerical solution format to obtain the target state data of the corresponding nodes in the target pipeline further includes:

[0112] When in the first state, the upstream reservoir water level is the initial first target pressure, and the initial first target flow rate is obtained by combining the pipe flow liquid control algorithm; and the first target state data of the corresponding nodes is updated in real time based on the moving wave numerical solution format;

[0113] Specifically, for the upstream boundary of the water body, that is, the upstream reservoir connected to the end of the general pipeline, during the entire transient process, the upstream reservoir boundary condition can be expressed as:

[0114] H P = H u (12)

[0115] wherein, H P here is the target pressure H of the first node of the entire pipeline P′ , that is, the target pressure of the upstream reservoir node, m; H u is the upstream reservoir water level, m; substituting Equation (12) into Equation (6), the first target flow rate Q P′ , m3 / s, of the reservoir node can be obtained.

[0116] It should be noted that the upstream boundary here uses the reservoir boundary as an example for subsequent experimental verification (using a pressure tank to simulate the reservoir);

[0117] In another feasible embodiment, complex hydraulic components such as turbines, pumps, vent holes, gate wells, and surge chambers can also be added to simulate a more complex long-distance water pipeline system. Specifically, based on the principles of mass conservation (inflow equals outflow) and energy conservation (pressure drop equals head loss along the way), multiple branches, junctions, and different types of components (such as valves, pumps, etc.) can be processed.

[0118] When in the third state, according to the third target flow rate of the node to be measured obtained at the previous moment and the node position where the gas-liquid interface is located, the updated third target pressure is obtained by combining the gas-liquid interface control algorithm. The flow rate at the water-gas interface is the product of the liquid velocity at the t moment of the water-gas interface in the gas-liquid interface control algorithm and the cross-sectional area of the pipeline; and the third target state data of the corresponding node is updated in real time based on the moving wave numerical solution format.

[0119] Specifically, for the downstream boundary of the water body, that is, the water-gas interface boundary

[0120] H P =H wa (13)

[0121]

[0122] Among them, Q here P refers to the third target flow rate Q of this point obtained according to the previous moment P″′ , combined with the node position where the gas-liquid interface is located, substituting into equations (8) and (9) can obtain the third target pressure H at the water-gas interface boundary wa .

[0123] It should be noted that since the internal pressure of the gas is equal everywhere, H wa is also equal to the internal pressure of the gas. In addition, the flow rate at the water-gas interface can be regarded as the moving speed v of the water-gas interface in the gas-liquid interface control algorithm c multiplied by the cross-sectional area of the pipeline.

[0124] In general, during specific implementation, since there is a gas column in the pipeline to be measured relative to the target pipeline, first, according to the gas-liquid interface control algorithm, the gas-liquid interface position is determined; second, for the liquid part, according to the pipe flow liquid control algorithm, the liquid pressure and liquid flow rate are determined; third, for the gas column part, according to the gas column control algorithm, the target pressure and target flow rate of the gas column are finally determined; finally, for the gas-liquid interface part, a gas-liquid interface control algorithm is established to determine the pressure and flow rate at the gas-liquid interface.

[0125] It should be noted that the above solution improves the simulation accuracy in terms of pressure peak value, fluctuation period, pressure attenuation, etc. by considering the gas thermodynamic characteristics; based on this, the mechanism law of the gas column operation in the pipeline and its influence law on the pipeline are specifically studied, combined with the gas thermodynamic characteristic mechanism, to improve the accuracy of numerical simulation, and help to predict and anticipate possible engineering hidden dangers in advance during the engineering design stage, and improve the safety of the water conveyance system engineering design.

[0126] Embodiment 3

[0127] Refer to Figure 3 - Figure 5, based on the previous embodiment, this embodiment provides an effect case of a simulation method for the gas-liquid heat transfer mechanism of a water conveyance pipeline to illustrate the feasibility and beneficial effects of our solution.

[0128] The experimental results of the Hydraulics Laboratory of Hohai University are selected to verify the effectiveness of this application. The experimental system is as Figure 3 shown. The length of the horizontal pipeline is 8.382 m, the length of the vertical pipeline is 0.48 m, the inner diameter is 0.040 m, the average resistance coefficient of the target pipeline is 0.090, and the measured wave velocity of the pipe flow is 850 m / s. This application uses two working conditions with different boundary conditions for model verification.

[0129] In Working Condition 1, the upstream of the target pipeline is set as a pressure inlet boundary (pressure tank), the pressure is 0.08 MPa, and the initial gas column length in the pipeline is controlled to be 0.3 m. At the initial moment of the experiment, the ball valve is instantaneously opened, and the pipeline starts to be filled, and the liquid impacts the gas column in the vertical pipeline, resulting in a transient.

[0130] In Working Condition 2, the upstream of the target pipeline is set as a pressure inlet boundary, the pressure is 0.12 MPa, and the initial gas column length in the pipeline is controlled to be 0.3 m. At the initial moment of the experiment, the ball valve is instantaneously opened, and the pipeline starts to be filled, and the liquid impacts the gas column in the vertical pipeline, resulting in a transient.

[0131] By comparing the calculation results of this application with the experimental data results, a comparison curve graph of the pressure fluctuation of the gas column at the end of the pipeline is obtained. Figure 4 and Figure 5 respectively show that under the conditions of Working Condition 1 and Working Condition 2, the calculation results of the method proposed in this application are in excellent agreement with the experimental data, and the pressure change curves of the gas column at the end of the pipeline are basically the same. This application can well predict the fluctuation trend, period, and pressure peak of the pressure change curve of the gas column at the end of the pipeline.

[0132] In summary, according to the results, it can be seen that this application can better simulate and consider the transient flow problem of the water conveyance pipeline with the gas heat transfer mechanism model in terms of pressure peak, fluctuation period, pressure decay, etc.

[0133] Embodiment 4

[0134] The above is a schematic solution of a simulation method for the gas-liquid heat transfer mechanism of a water conveyance pipeline. It should be noted that the technical solution of the system for simulating the gas-liquid heat transfer mechanism of the water conveyance pipeline belongs to the same concept as the technical solution of the above simulation method for the gas-liquid heat transfer mechanism of the water conveyance pipeline. For the details not described in detail in the technical solution of the system for simulating the gas-liquid heat transfer mechanism of the water conveyance pipeline in this embodiment, reference can be made to the description of the technical solution of the above simulation method for the gas-liquid heat transfer mechanism of the water conveyance pipeline.

[0135] As Figure 6As shown in the figure, this embodiment also provides a system for simulating the gas-liquid heat transfer mechanism of a water conveyance pipeline, including:

[0136] A partitioning module 101 for partitioning a target pipeline to obtain a plurality of pipeline nodes;

[0137] A judgment module 102 for judging the filling state of the pipeline at both ends of a node to be measured in the pipeline to obtain the current state of the node to be measured;

[0138] A first calculation module 103 for calculating, based on the current state of the node to be measured, through a control algorithm adapted to the current state, to obtain the target state data of the node to be measured; wherein, the control algorithm includes a gas column control algorithm based on the thermodynamic characteristics of the gas;

[0139] A second calculation module 104 for solving the control algorithm based on the moving wave numerical solution format to obtain the target state data of the corresponding nodes in the target pipeline.

[0140] This embodiment also provides an electronic device applicable to the simulation of the gas-liquid heat transfer mechanism of a water conveyance pipeline, including: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the method for simulating the gas-liquid heat transfer mechanism of a water conveyance pipeline as proposed in the above embodiment.

[0141] This embodiment also provides a storage medium, on which a computer program is stored, and when the program is executed by a processor, it implements the method for simulating the gas-liquid heat transfer mechanism of a water conveyance pipeline as proposed in the above embodiment.

[0142] The storage medium proposed in this embodiment and the method for simulating the gas-liquid heat transfer mechanism of a water conveyance pipeline proposed in the above embodiment belong to the same inventive concept. For technical details not described in detail in this embodiment, reference can be made to the above embodiment, and this embodiment has the same beneficial effects as the above embodiment.

[0143] Through the above description of the embodiments, those skilled in the art can clearly understand that the present invention can be implemented by means of software and the necessary general hardware, and of course, it can also be implemented by hardware. Based on such an understanding, the technical solution of the present invention, in essence, or the part that makes a contribution to the prior art, can be embodied in the form of a software product, and this computer software product can be stored in a computer-readable storage medium, such as a floppy disk, read-only memory (ROM), random access memory (RAM), flash memory (FLASH), hard disk or optical disc of a computer, etc., including several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods of the various embodiments of the present invention.

[0144] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered by the scope of the claims of the present invention.

Claims

1. A method for simulating the gas-liquid heat transfer mechanism in a water pipeline, characterized in that: include: Divide the target pipeline to obtain multiple pipeline nodes; The pipeline filling status at both ends of the node to be tested in the pipeline is judged to obtain the current status of the node to be tested; Based on the current state of the node to be measured, the target state data of the node to be measured is obtained by calculating through a control algorithm adapted to the current state; wherein the control algorithm includes a gas column control algorithm based on the thermodynamic characteristics of the gas; The control algorithm is solved based on the moving wave numerical solution format to obtain the target state data of the corresponding nodes in the target pipeline.

2. The method for simulating the gas-liquid heat transfer mechanism of a water pipeline according to claim 1, characterized in that: The current state of the node to be tested includes: The first state is that the pipe sections on both sides connected to the node to be tested are filled with water; The second state is that the pipe sections on both sides connected to the node to be tested are filled with gas; The third state is that one side of the pipe sections on both sides connected to the node to be tested is gas and the other side is water.

3. The method for simulating the gas-liquid heat transfer mechanism of a water pipeline according to claim 1 or 2, characterized in that: Based on the current state of the node to be tested, the target state data of the node to be tested is obtained by calculation through a control algorithm adapted to the current state, including: When the node to be measured is in the first state, the water pressure and flow rate at the node are calculated by the pipe flow liquid control algorithm to obtain the first target pressure and the first target flow rate of the node to be measured.

4. The method for simulating the gas-liquid heat transfer mechanism of a water pipeline according to claim 1 or 2, characterized in that: Based on the current state of the node to be tested, the target state data of the node to be tested is obtained by calculation through a control algorithm adapted to the current state, including: When the node to be measured is in the second state, the gas pressure at the node is calculated by a gas column control algorithm based on the thermodynamic characteristics of the gas to obtain a second target pressure of the node to be measured; The gas column control algorithm based on gas thermodynamic characteristics is expressed as: Among them, H a is the second target pressure of the gas column in the target pipeline, C p is the constant pressure specific heat capacity of the gas column, C v is the constant volume specific heat capacity of the gas column, V a is the volume of the gas column in the pipe, α is the thermodynamic coefficient of the gas column, A a is the total contact area between the gas column and the tube wall, T in is the target pipe internal temperature, T ex is the external environment temperature, t is the calculation time, s; d is the derivative sign; dHa / dt is the derivative of gas pressure changing with time; dVa / dt is the derivative of gas flow rate changing with time.

5. The method for simulating the gas-liquid heat transfer mechanism of a water pipeline according to claim 1 or 2, characterized in that: Based on the current state of the node to be measured, the target state data of the node to be measured is obtained by calculating through a control algorithm adapted to the current state, and also includes: When the node to be tested is in the third state, the water and gas pressures and water flow at the node are calculated by the gas-liquid boundary control algorithm to obtain the third target pressure and the third target flow of the node to be tested; The gas-liquid boundary control algorithm is expressed as: H wa =H a Among them, x w is the target distance between the gas-liquid boundary position and the upstream node at time t+△t, x w0 is the distance between the gas-liquid boundary position and the most upstream node at time t, v c is the liquid velocity at time t, H wa is the liquid pressure at time t, and d is the sign of the derivative.

6. The method for simulating the gas-liquid heat transfer mechanism of a water pipeline according to claim 5, characterized in that: The control algorithm is solved based on the moving wave numerical solution format to obtain the target state data of the corresponding nodes in the target pipeline, including: Construct the moving wave numerical solution format, expressed as: Wherein, A1 is the first characteristic parameter of pipeline node A, B1 is the first characteristic parameter of pipeline node B; A2 is the second characteristic parameter of pipeline node A, B2 is the second characteristic parameter of pipeline node B; pipeline node A is the upstream node of the node to be tested P, and pipeline node B is the downstream node of the node to be tested P; H P is the target pressure, Q P The target flow.

7. The method for simulating the gas-liquid heat transfer mechanism of a water pipeline according to claim 6, characterized in that: When in the first state, the water level of the upstream reservoir is the initial first target pressure, and the initial first target flow rate is obtained by combining the pipe flow liquid control algorithm; and the first target state data of the corresponding node is updated in real time based on the moving wave numerical solution format; When in the third state, the updated third target pressure is obtained according to the third target flow of the node to be measured obtained at the previous moment and the node position of the gas-liquid boundary, combined with the gas-liquid boundary control algorithm. The flow of the water-gas interface is the product of the liquid velocity of the water-gas interface at time t in the gas-liquid boundary control algorithm and the cross-sectional area of ​​the pipeline; and the third target state data of the corresponding node is updated in real time based on the moving wave numerical solution format.

8. A system applied to the method for simulating the mechanism of gas-liquid heat transfer in a water pipeline according to any one of claims 1 to 7, characterized in that: include: A partitioning module, used for partitioning the target pipeline to obtain multiple pipeline nodes; A judgment module is used to judge the pipe filling status at both ends of the node to be tested in the pipe to obtain the current status of the node to be tested; A first calculation module is used to calculate the target state data of the node to be measured based on the current state of the node to be measured by a control algorithm adapted to the current state; wherein the control algorithm includes a gas column control algorithm based on the thermodynamic characteristics of the gas; The second calculation module is used to solve the control algorithm based on the moving wave numerical solution format to obtain the target state data of the corresponding node in the target pipeline.

9. An electronic device, comprising: Memory and processor; The memory is used to store computer executable instructions, and the processor is used to execute the computer executable instructions. When the computer executable instructions are executed by the processor, the steps of the method for simulating the gas-liquid heat transfer mechanism of a water pipeline as described in any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the steps of the method for simulating the gas-liquid heat transfer mechanism of a water pipeline as claimed in any one of claims 1 to 7.

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