Method and system for simplifying gas-liquid two-phase choked flow outlet based on CFD simulation

Abstract

The invention provides a method and system for simplifying a gas-liquid two-phase choking flow outlet based on CFD simulation, and relates to the technical field of nuclear energy engineering and liquid rockets. The method comprises the steps that firstly, an upstream fluid domain used for CFD simulation is constructed, a new pressure outlet of the upstream fluid domain is determined, and a new pressure outlet of the upstream fluid domain is determined; upstream incoming flow data, including temperature, flow and two-phase mass flow ratio, of the pressure reduction and flow limiting element in the CFD simulation process are obtained from the outlet through a self-defined module of simulation software; according to upstream incoming flow data, target pressure is obtained through iterative calculation of a two-phase flow calculation formula, and the target pressure is the pressure corresponding to the pressure outlet boundary condition formed by the upstream cross section. By means of the method, the technical problems that in the prior art, when CFD simulation is carried out, simulation calculation for the congestion area with the two-phase critical flow is complex and low in efficiency are solved, and the technical effects that calculation resource consumption is reduced, and time and cost are saved are achieved.

Description

Technical Field

[0001] The invention relates to the fields of nuclear energy engineering and liquid rocket technology, and in particular to a simplified method and system for a gas-liquid two-phase choked flow outlet based on CFD simulation. Background Art

[0002] When performing CFD simulation, the computational efficiency is limited by many factors, including the number of grids, Courant number, and model complexity. Taking the orifice plate, a common pressure reducing element in engineering, as an example, in the congestion area where two-phase critical flow occurs, the flow rate is high, the gas-liquid interface is complex, and there is currently no theoretical model that can accurately describe the process. In order to ensure the accuracy and convergence of the calculation, it is usually necessary to divide a finer grid in the orifice plate congestion area and use a very small time step. This processing method significantly increases the amount of calculation and calculation time.

[0003] That is to say, in the prior art, when performing CFD simulation, the simulation of the congestion area where the two-phase critical flow occurs has the technical problems of complex calculation and low calculation efficiency. Summary of the invention

[0004] The purpose of the present invention is to provide a simplified method and system for a gas-liquid two-phase blocked flow outlet based on CFD simulation, so as to alleviate the technical problems existing in the prior art of complex and inefficient simulation calculation of the blocked area where two-phase critical flow occurs.

[0005] In the first aspect, an embodiment of the present invention provides a simplified method for a gas-liquid two-phase blocked flow outlet based on CFD simulation, the method comprising: constructing an upstream fluid domain for CFD simulation, and determining a new pressure outlet of the upstream fluid domain; using a custom module of the simulation software to obtain the upstream flow data of the pressure reducing and limiting element during the CFD simulation from the new pressure outlet of the upstream fluid domain; the upstream flow data comprises: temperature, flow rate and two-phase mass flow ratio; based on the upstream flow data, the target pressure is iteratively calculated by a two-phase flow calculation formula; the target pressure is the corresponding pressure of the boundary condition of the new pressure outlet of the upstream fluid domain; the target pressure is used to return to the CFD simulation process as a simulation boundary condition.

[0006] In some optional implementations, an upstream fluid domain for CFD simulation is constructed, and a new pressure outlet of the upstream fluid domain is determined, including: when constructing the fluid domain, a pressure reducing limiting element where two-phase choked flow occurs is cut off at a preset distance upstream of the choked flow, and the generated truncation surface is used as a new upstream pressure outlet.

[0007] In some alternative implementations, based on the above upstream flow data, the target pressure is iteratively calculated through a two-phase flow rate calculation formula, including: by analyzing the correlations among flow rate, two-phase content, temperature, and pressure, determining the pressure corresponding to the boundary conditions at the outlet of the simplified two-phase choked flow based on the two-phase content, temperature, and two-phase mass flow rate of the above upstream flow data.

[0008] In some alternative implementations, the above two-phase flow rate calculation formula includes:

[0009]

[0010] where m1 is the two-phase mass flow rate; A is the flow area where choking occurs; x is the mass flow rate of the gas phase and the two-phase mass flow rate ratio; v g is the specific volume of the gas phase, and v f is the specific volume of the liquid phase, both of which are physical properties related to temperature and pressure; P is the pressure.

[0011] In some alternative implementations, by analyzing the correlations among flow rate, two-phase content, temperature, and pressure, determining the pressure corresponding to the boundary conditions at the outlet of the simplified two-phase choked flow based on the two-phase content, temperature, and two-phase mass flow rate of the above upstream flow data includes: determining the flow area where choking occurs, and the above flow area is the area of the cross-section of the above pressure-reducing and flow-limiting element for passing gas or liquid; obtaining the temperature and initial two-phase mass flow rate m0 of the upstream flow of the above pressure-reducing and flow-limiting element from the simulation; calculating the weighted average temperature and mass flow rate ratio of the two phases; determining the current assumed pressure P based on the upstream pressure or historical data.

[0012] In some alternative implementations, the above method further includes: calculating a first flow rate m1 using the two-phase flow rate calculation formula; determining whether ABS(m1 - m0) < Residual holds; where Residual is a pre-determined value.

[0013] In some alternative implementations, the above method further includes: if ABS(m1 - m0) < Residual holds, returning the current assumed pressure P to the simulation software as the boundary condition for the next iteration; if ABS(m1 - m0) < Residual does not hold, modifying the current assumed pressure P and re-executing the steps in the above alternative implementation method until ABS(m1 - m0) < Residual holds.

[0014] In the second aspect, an embodiment of the present invention provides a simplified system for a gas-liquid two-phase blocked flow outlet based on CFD simulation, the system comprising: a fluid domain construction module, used to construct an upstream fluid domain for CFD simulation and determine a new pressure outlet of the upstream fluid domain; a data acquisition module, used to obtain the upstream flow data of the pressure reducing and limiting element during the CFD simulation process from the new pressure outlet of the upstream fluid domain using a custom module of the simulation software; the above-mentioned upstream flow data comprises: temperature, flow rate and two-phase mass flow ratio; a calculation module, used to iteratively calculate the target pressure through a two-phase flow calculation formula according to the above-mentioned upstream flow data; the above-mentioned target pressure is the corresponding pressure of the boundary condition of the new pressure outlet of the upstream fluid domain; the above-mentioned target pressure is returned to the above-mentioned CFD simulation process as the boundary condition of the simulation.

[0015] In a third aspect, an embodiment of the present invention provides an electronic device, comprising a memory and a processor, wherein the memory stores a computer program executable on the processor, and when the processor executes the computer program, the steps of any one of the methods described in the first aspect are implemented.

[0016] In a fourth aspect, an embodiment of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium stores machine-executable instructions. When the computer-executable instructions are called and executed by a processor, the computer-executable instructions cause the processor to execute any method described in the first aspect.

[0017] The present invention provides a simplified method and system for gas-liquid two-phase congestion flow outlet based on CFD simulation, which relates to the technical field of nuclear energy engineering and liquid rockets. The method includes: firstly constructing an upstream fluid domain for CFD simulation, determining a new pressure outlet of the upstream fluid domain, and using a custom module of the simulation software to obtain the upstream incoming flow data of the pressure reducing and limiting element during the CFD simulation from the outlet, including temperature, flow rate and two-phase mass flow ratio; then according to the upstream incoming flow data, the target pressure is iteratively calculated by the two-phase flow calculation formula, and the target pressure is the corresponding pressure of the pressure outlet boundary condition formed by the upstream cross section. This method solves the technical problem that the simulation calculation of the congestion area where the two-phase critical flow occurs is complex and inefficient when performing CFD simulation in the prior art, and achieves the technical effect of reducing computing resource consumption, saving time and cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 A schematic flow chart of a simplified method for a gas-liquid two-phase blocked flow outlet based on CFD simulation provided in an embodiment of the present invention;

[0020] Figure 2 A comparison diagram of a fluid domain with a limited flow orifice plate and a simplified fluid domain provided in an embodiment of the present invention;

[0021] Figure 3 A schematic flow chart of another simplified method for a gas-liquid two-phase blocked flow outlet based on CFD simulation provided in an embodiment of the present invention;

[0022] Figure 4 A schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. Some embodiments of the present invention are described in detail below in conjunction with the drawings. The following embodiments and features in the embodiments can be combined with each other without conflict.

[0026] In a compressible fluid pipeline system, if the upstream flow conditions remain constant and the downstream outlet pressure gradually decreases, the flow rate will continue to increase as the downstream pressure decreases. However, when the downstream pressure drops to a certain value, the flow rate no longer increases despite the continued decrease in pressure, and reaches the maximum flow rate value. This phenomenon is called critical flow or choked flow. The corresponding maximum flow rate is called the critical flow rate, and the velocity of the fluid is called the critical flow velocity. In the field of gas dynamics, the theory and calculation methods of critical flow phenomena are already very mature.

[0027] For compressible two-phase flow, similar critical flow phenomena also occur and have been verified by experiments. In most actual working conditions, the critical velocity of two-phase flow is usually significantly lower than that of single-phase flow. In the safety analysis of modern nuclear power reactors, it is often necessary to study the transient process when liquid or gas-liquid mixture under high temperature and high pressure is discharged into a low-pressure environment. The discharge rate has a significant impact on the depressurization rate of the reactor, safe heat transfer, the pressure increase rate in the reactor containment, and the stress conditions of the reactor vessel, internal components and related pipelines.

[0028] For example, in the emergency cooling system of a nuclear power plant, a high-pressure cooling water mixture is released through a safety valve or other discharge device. When the coolant system is overpressured, the safety valve opens, allowing the high-pressure steam and water mixture to be discharged to the atmosphere through the pipe and orifice plate. In this process, the designer must calculate the choked flow of the orifice plate to ensure that the coolant can be discharged at a controlled rate under overpressure conditions, thereby avoiding equipment damage or leakage of radioactive materials.

[0029] Since the Three Mile Island nuclear power plant accident in 1979, small break loss of coolant accidents have received widespread attention and have become an important topic in reactor safety analysis. In addition, this type of research also has important practical application value for the design of chemical equipment, rocket engines and condensing ejectors. Experiments show that during the discharge stage of a reactor loss of coolant accident, it is in a two-phase critical flow state for a long time, and the critical flow rate is mainly controlled by the changes in the upstream operating conditions (i.e., the coolant state in the reactor system). Therefore, it is necessary to calculate the coolant loss process and system response in detail. In this case, more attention is usually paid to the impact of the discharge volume of the pressure reducing and limiting device on the pressure and residual amount of the upstream pipeline or container, while the changes in the choking point within microseconds are not considered in detail.

[0030] When performing CFD simulation, the computational efficiency is limited by many factors, including the number of grids, the Courant number, and the complexity of the model. Taking the orifice plate, a common pressure reducing element in engineering, as an example, in the congestion area where the two-phase critical flow occurs, the flow velocity is high, the gas-liquid interface is complex, and there is currently no theoretical model that can accurately describe the process. In order to ensure the accuracy and convergence of the calculation, it is usually necessary to divide the orifice plate into a finer grid and use a very small time step. This processing method significantly increases the amount of calculation and calculation time. In other words, when performing CFD simulation, the existing technology has technical problems such as complex calculations and low calculation efficiency for the simulation of the congestion area where the two-phase critical flow occurs.

[0031] Based on this, the embodiment of the present invention provides a simplified method and system for gas-liquid two-phase blocked flow outlet based on CFD simulation to solve the above problems. To facilitate understanding of this embodiment, the simplified method for gas-liquid two-phase blocked flow outlet based on CFD simulation disclosed in the embodiment of the present invention is first introduced in detail. Figure 1 FIG. 1 is a flow chart of a simplified method for a gas-liquid two-phase blocked flow outlet based on CFD simulation, which can be executed by an electronic device and mainly includes the following steps S110 to S130:

[0032] S110: construct an upstream fluid domain for CFD simulation and determine a new pressure outlet of the upstream fluid domain;

[0033] That is, when constructing the fluid domain, the pressure reducing limiting element where the two-phase choked flow occurs is cut off at a preset distance upstream of the choked flow, and the generated cut surface is used as a new pressure outlet upstream. The preset distance can be determined according to the actual application scenario.

[0034] S120: using a custom module of the simulation software to obtain upstream flow data of the pressure reducing flow limiting element during the CFD simulation from the new pressure outlet of the upstream fluid domain; the upstream flow data includes: temperature, flow rate and two-phase mass flow ratio;

[0035] The pressure reducing and flow limiting element may be a flow limiting orifice plate, a venturi tube or an orifice tube or other related device arranged in the pipeline to limit the flow and reduce pressure.

[0036] S130: According to the upstream flow data, the target pressure is iteratively calculated by the two-phase flow calculation formula; the target pressure is the corresponding pressure of the new pressure outlet boundary condition of the upstream fluid domain; the target pressure is used as a simulation boundary condition and returned to the CFD simulation process.

[0037] That is to say, the embodiment of the present invention provides a simplified method for gas-liquid two-phase blocked flow outlet based on CFD simulation, the method comprising: when constructing a fluid domain, the pressure reducing limiting element where the two-phase blocked flow occurs is cut off from a certain distance upstream of the blocked flow, and the formed cross-section is used as a new pressure outlet of the upstream fluid domain; the upstream incoming flow data, including temperature, flow rate, two-phase mass flow ratio, etc., are obtained from the new pressure outlet surface; then, according to the upstream incoming flow data, the target pressure is iteratively calculated by the two-phase flow calculation formula, and the target pressure is the corresponding pressure of the pressure outlet boundary condition formed by the upstream cross-section. This method solves the technical problem that the simulation calculation of the blocked area where the two-phase critical flow occurs is complex and inefficient when performing CFD simulation in the prior art, and achieves the technical effect of reducing computing resource consumption, saving time and cost.

[0038] In one embodiment, the above step S120 iteratively calculates the target pressure according to the upstream flow data through a two-phase flow calculation formula, including:

[0039] (S121) By analyzing the correlation between flow rate, two-phase content, temperature and pressure, the pressure corresponding to the boundary condition of the simplified two-phase congestion flow outlet is determined based on the two-phase content, temperature and two-phase mass flow of the upstream flow data.

[0040] In one embodiment, the two-phase flow calculation formula includes:

[0041]

[0042] Among them, m1 is the two-phase mass flow rate; A is the flow area where the blockage occurs; x is the gas phase mass flow rate Two-phase mass flow ratio; vg is the gas phase volume, vf is the liquid phase volume, both are physical parameters related to temperature and pressure; P is pressure.

[0043] In one embodiment, the above (S121) determines the pressure corresponding to the boundary condition of the simplified two-phase blocked flow outlet based on the two-phase content, temperature and two-phase mass flow of the upstream flow data by analyzing the correlation between the flow rate, two-phase content, temperature and pressure, including:

[0044] (1) Determine the flow area where the blockage occurs. The flow area is the cross-sectional area of ​​the pressure reducing flow restricting element for the passage of gas or liquid; for example, the cross-sectional area of ​​the orifice plate;

[0045] (2) Obtaining the temperature T and initial two-phase mass flow rate m0 of the upstream flow of the pressure reducing limiting element from the simulation;

[0046] (3) Calculate the weighted average temperature Ta and mass flow ratio x of the two phases;

[0047] (4) Determine the current assumed pressure P based on the upstream pressure or historical data.

[0048] Among them, the current assumed pressure P can be the upstream pressure or the pressure result of the previous calculation. Generally, in a simulation process, within a relatively small time interval or spatial distance, the pressure does not change significantly.

[0049] In one embodiment, the above method further includes:

[0050] (5) Calculate the first flow rate m1 using the two-phase flow rate calculation formula; m1 = f(Ta, x, P);

[0051] (6) Determine whether ABS(m1 - m0) < Residual holds; where Residual is a pre-determined value.

[0052] In one embodiment, the above method further includes:

[0053] (7) If ABS(m1 - m0) < Residual holds, return the current assumed pressure P to the simulation software as the boundary condition for the next iteration;

[0054] (8) If ABS(m1 - m0) < Residual does not hold, modify the current assumed pressure P and re-execute the above steps (5) to (8) until ABS(m1 - m0) < Residual holds.

[0055] The present invention proposes a simplified method for the gas-liquid two-phase choked flow outlet based on CFD simulation, which is used to replace the calculation of the two-phase choked flow outlet in CFD simulation. This method simplifies the flow-limiting and pressure-reducing device by using the empirical formulas commonly used in system simulation, simplifies the pressure-reducing and flow-limiting element where two-phase choked flow occurs into a pressure outlet, thereby reducing the complexity of the calculation domain and the demand for computing resources, significantly reducing the simulation calculation amount, and greatly improving the calculation efficiency of CFD simulation. The following combines Figure 2 and Figure 3 , and describes a specific example proposed by the present invention in detail.

[0056] For the complex two-phase flow process at the orifice of two-phase choked flow, the embodiment of the present invention adopts a two-phase choked flow rate model and simplifies it into a pressure boundary condition. By analyzing the correlation between flow rate, two-phase content, temperature and pressure, the outlet pressure is determined based on parameters such as the two-phase content, temperature and two-phase mass flow rate of the upstream incoming flow. See Figure 2As shown, part (a) is the original fluid domain with a flow-limiting orifice plate, and part (b) is the fluid domain simplified using a flow model; (1) and (4) both represent the upstream incoming flow, (2) represents the pressure-reducing orifice plate, (3) represents the downstream low-pressure environment, and (5) represents the pressure boundary condition applied by the flow model.

[0057] In this embodiment, the selectable two-phase flow calculation formula is as follows:

[0058]

[0059] Wherein, m1 is the two-phase mass flow rate; A is the flow area where choking occurs (for example: when using an orifice plate as the flow-limiting element, A is the orifice area of the orifice plate); x is the gas-phase mass flow rate and the two-phase mass flow rate ratio; v g is the gas-phase specific volume, v f is the liquid-phase specific volume, and both are physical property parameters related to temperature and pressure; P is the pressure.

[0060] Using the UDF function of Fluent, obtain the two-phase mass flow rate m0, two-phase mass flow rate ratio x, temperature T, etc. of the upstream incoming flow. Assume a pressure P0, and obtain the partial derivatives of the gas-phase v g and the liquid-phase specific volume v f with respect to the current pressure P and (The relevant physical property data can be obtained through the NIST database). Subsequently, use the flow formula (1) to calculate the two-phase mass flow rate m1; compare the difference between m0 and m1, modify the assumed pressure P, and recalculate the partial derivative of the specific volume with respect to the pressure and the two-phase mass flow rate until the error between the two calculation results is less than a certain value Residual. Then, assign the assumed pressure P to the pressure outlet of the simulation using UDF.

[0061] Combined with Figure 3 as shown, the calculation process of this method includes the following steps:

[0062] S31: Determine the orifice plate throttling area Ao; obtain the temperature T and two-phase mass flow rate m0 of the upstream incoming flow from the simulation;

[0063] S32: Calculate the weighted average temperature Ta and mass flow rate ratio x of the two phases;

[0064] S33: Assume a pressure P;

[0065] S34: Use the flow formula to calculate the flow rate m1, m1 = f(Ta, x, P);

[0066] S35: Determine whether ABS(m1 - m0) < Residual holds;

[0067] S36: If established, the pressure P is returned to the simulation software as a boundary condition for the next iteration;

[0068] S37: If not, modify the assumed pressure P, return and re-execute S34.

[0069] The embodiment of the present invention couples the flow model to the CFD simulation, simplifies the orifice plate or pipeline where two-phase choked flow occurs in actual engineering into a pressure outlet boundary condition, significantly reduces the consumption of computing resources, and thus realizes the overall CFD simulation of the experimental system containing the two-phase choked flow phenomenon.

[0070] This method can simulate the flow and pressure relationship of choked flow under different pressure, temperature, orifice size, gas-liquid ratio and pressure difference in a computer environment, so as to evaluate the impact of choked flow on system safety. It not only reduces the dependence on actual experiments, saves time and cost, but also effectively avoids potential experimental risks.

[0071] In addition, an embodiment of the present invention further provides a simplified system for gas-liquid two-phase blocked flow outlet based on CFD simulation, the system comprising:

[0072] A fluid domain construction module is used to construct an upstream fluid domain for CFD simulation and determine a new pressure outlet of the upstream fluid domain;

[0073] A data acquisition module is used to obtain upstream flow data of the pressure reducing flow limiting element during CFD simulation from the new pressure outlet of the upstream fluid domain using a custom module of the simulation software; the upstream flow data includes: temperature, flow rate and two-phase mass flow rate;

[0074] The calculation module is used to iteratively calculate the target pressure according to the upstream flow data through the two-phase flow calculation formula; the target pressure is the corresponding pressure of the new pressure outlet boundary condition of the upstream fluid domain; the target pressure is returned to the CFD simulation process as the simulation boundary condition.

[0075] In one embodiment, the above-mentioned calculation module is also used to: determine the pressure corresponding to the boundary condition of the simplified two-phase congestion flow outlet based on the two-phase content, temperature and two-phase mass flow of the upstream flow data by analyzing the correlation between flow rate, two-phase content, temperature and pressure.

[0076] The simplified system for a gas-liquid two-phase blocked flow outlet based on CFD simulation provided in the embodiment of the present application can be specific hardware on the device or software or firmware installed on the device, etc. The implementation principle and technical effects of the system provided in the embodiment of the present application are the same as those of the aforementioned method embodiment. For the sake of brief description, the parts not mentioned in the system embodiment can refer to the corresponding contents in the aforementioned method embodiment. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working processes of the systems, devices and units described above can all refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. The simplified system for a gas-liquid two-phase blocked flow outlet based on CFD simulation provided in the embodiment of the present application has the same technical features as the simplified method for a gas-liquid two-phase blocked flow outlet based on CFD simulation provided in the aforementioned embodiment, so it can also solve the same technical problems and achieve the same technical effects.

[0077] An embodiment of the present application further provides an electronic device. Specifically, the electronic device includes a processor and a storage device. The storage device stores a computer program, and when the computer program is executed by the processor, it executes the method described in any one of the above-mentioned embodiments.

[0078] Figure 4 A structural schematic diagram of an electronic device provided in an embodiment of the present application, the electronic device 400 includes: a processor 40, a memory 41, a bus 42 and a communication interface 43, wherein the processor 40, the communication interface 43 and the memory 41 are connected via the bus 42; the processor 40 is used to execute an executable module stored in the memory 41, such as a computer program.

[0079] The memory 41 may include a high-speed random access memory (RAM), and may also include a non-volatile memory, such as at least one disk memory. The communication connection between the system network element and at least one other network element is realized through at least one communication interface 43 (which may be wired or wireless), and the Internet, wide area network, local area network, metropolitan area network, etc. may be used.

[0080] The bus 42 may be an ISA bus, a PCI bus, or an EISA bus, etc. The bus may be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 4 Only one bidirectional arrow is used in the diagram, but this does not mean that there is only one bus or only one type of bus.

[0081] Among them, the memory 41 is used to store programs, and the processor 40 executes the program after receiving the execution instruction. The method executed by the process definition device disclosed in any embodiment of the above-mentioned embodiment of the present invention can be applied to the processor 40 or implemented by the processor 40.

[0082] The processor 40 may be an integrated circuit chip with signal processing capabilities. In the implementation process, each step of the above method can be completed by the hardware integrated logic circuit or software instructions in the processor 40. The above processor 40 can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components. The methods, steps and logic block diagrams disclosed in the embodiments of the present invention can be implemented or executed. The general-purpose processor can be a microprocessor or the processor can also be any conventional processor. The steps of the method disclosed in the embodiments of the present invention can be directly embodied as a hardware decoding processor to execute, or can be executed by a combination of hardware and software modules in the decoding processor. The software module can be located in a mature storage medium in the field such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. The storage medium is located in the memory 41, and the processor 40 reads the information in the memory 41 and completes the steps of the above method in combination with its hardware.

[0083] Corresponding to the above method, an embodiment of the present application also provides a computer-readable storage medium, which stores machine-executable instructions. When the computer-executable instructions are called and executed by a processor, the computer-executable instructions prompt the processor to execute the steps of the above method.

[0084] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely schematic. For example, the division of the units is only a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some communication interfaces, and the indirect coupling or communication connection of the devices or units can be electrical, mechanical or other forms.

[0085] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0086] In addition, each functional unit in the embodiments provided in the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0087] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, electronic device, or network device, etc.) to perform all or part of the steps of the methods described in each embodiment of the present invention. The aforementioned storage medium includes: various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk.

[0088] It should be noted that similar numbers and letters represent similar items in the accompanying drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A simplified method for gas-liquid two-phase blocked flow outlet based on CFD simulation, characterized in that: Comprising: Construct an upstream fluid domain for CFD simulation and determine a new pressure outlet of the upstream fluid domain; Use a custom module of the simulation software to obtain upstream flow data of the pressure-reducing and flow-limiting element during the CFD simulation from the new pressure outlet of the upstream fluid domain; The upstream flow data includes: temperature, flow rate, and two-phase mass flow ratio; According to the upstream flow data, iteratively calculate a target pressure through a two-phase flow rate calculation formula; the target pressure is the corresponding pressure of the boundary condition of the new pressure outlet of the upstream fluid domain; the target pressure is used as a boundary condition of the simulation and returned to the CFD simulation process again.

2. The simplified method for gas-liquid two-phase blocked flow outlet based on CFD simulation according to claim 1, characterized in that: Construct an upstream fluid domain for CFD simulation and determine a new pressure outlet of the upstream fluid domain, including: When constructing the fluid domain, truncate the pressure-reducing and flow-limiting element where two-phase choking flow occurs from a preset distance upstream of the choking flow, and use the generated cross-section as the new pressure outlet of the upstream.

3. The simplified method for gas-liquid two-phase blocked flow outlet based on CFD simulation according to claim 1, characterized in that: According to the upstream flow data, iteratively calculate a target pressure through a two-phase flow rate calculation formula, including: By analyzing the correlation between flow rate, two-phase content, temperature, and pressure, determine the pressure corresponding to the boundary condition of the simplified two-phase choking flow outlet based on the two-phase content, temperature, and two-phase mass flow rate of the upstream flow data.

4. The simplified method for gas-liquid two-phase blocked flow outlet based on CFD simulation according to claim 3, characterized in that: The two-phase flow rate calculation formula includes: Among them, m1 is the two-phase mass flow rate; A is the flow area where the blockage occurs; x is the gas phase mass flow rate Two-phase mass flow The ratio of g is the gas volume, v f is the liquid specific volume, both are physical parameters related to temperature and pressure; P is the pressure.

5. The simplified method for gas-liquid two-phase blocked flow outlet based on CFD simulation according to claim 4, characterized in that: By analyzing the correlation between flow rate, two-phase content, temperature, and pressure, determine the pressure corresponding to the boundary condition of the simplified two-phase choking flow outlet based on the two-phase content, temperature, and two-phase mass flow rate of the upstream flow data, including: Determine the flow area where the choking phenomenon occurs, and the flow area is the area of the cross-section of the pressure-reducing and flow-limiting element for passing gas or liquid; Obtain the temperature and initial two-phase mass flow rate m0 of the upstream flow of the pressure-reducing and flow-limiting element from the simulation; Calculate the weighted average temperature and mass flow ratio of the two phases; Determine the current assumed pressure P based on the upstream pressure or historical data.

6. The simplified method for gas-liquid two-phase blocked flow outlet based on CFD simulation according to claim 5, characterized in that: The method further includes: Use the two-phase flow rate calculation formula to calculate a first flow rate m1; Judge whether ABS(m1 - m0) < Residual holds; where Residual is a pre-determined value.

7. The simplified method for gas-liquid two-phase blocked flow outlet based on CFD simulation according to claim 6, characterized in that: The method further includes: If ABS(m1 - m0) < Residual holds, return the current assumed pressure P to the simulation software as the boundary condition for the next iteration; If ABS(m1 - m0) < Residual does not hold, modify the current assumed pressure P and re-execute the steps of the method described in claim 6 above until ABS(m1 - m0) < Residual holds.

8. A simplified system for gas-liquid two-phase blocked flow outlet based on CFD simulation, characterized in that: Comprising: A fluid domain construction module for constructing an upstream fluid domain for CFD simulation and determining a new pressure outlet of the upstream fluid domain; A data acquisition module for using a custom module of the simulation software to obtain upstream flow data of the pressure-reducing and flow-limiting element during the CFD simulation from the new pressure outlet of the upstream fluid domain; The upstream flow data includes: temperature, flow rate, and two-phase mass flow ratio; A calculation module is used to iteratively calculate the target pressure according to the upstream flow data through a two-phase flow calculation formula; the target pressure is the corresponding pressure of the new pressure outlet boundary condition of the upstream fluid domain; the target pressure is returned to the CFD simulation process as a simulation boundary condition.

9. An electronic device comprising a memory and a processor, wherein the memory stores a computer program that can be run on the processor, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores machine-executable instructions. When the computer-executable instructions are called and executed by a processor, the computer-executable instructions cause the processor to execute the method according to any one of claims 1 to 7.

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