A structural optimization method for suppressing cavitation in cryogenic shut-off valves

Abstract

The application discloses a structure optimization method for inhibiting cavitation of a low-temperature stop valve, and comprises the following steps: S1, establishing a stop valve model and performing grid division; S2, performing a numerical calculation on the stop valve model after the grid division, obtaining a cavitation flow field cloud picture based on the calculation result, and determining a key position of cavitation occurrence; S3, optimizing the stop valve model, that is, setting a uniform grid-shaped flow guide plate at the key position of cavitation occurrence; S4, performing a second numerical calculation on the optimized stop valve model, obtaining an average gas phase volume and a flow coefficient based on the calculation result; S5, performing optimization judgment according to the average gas phase volume and the flow coefficient; and S6, repeating S4 and S5 until the average gas phase volume and the flow coefficient both meet the requirements, and outputting structure parameters of the optimized stop valve. The method can be widely applied to the design and optimization of stop valves in a low-temperature fluid conveying system, and has remarkable engineering application value.

Description

Technical Field

[0001] This invention relates to the field of valve technology, and in particular to a structural optimization method for suppressing cavitation in a cryogenic shut-off valve. Background Technology

[0002] In cryogenic fluid transport systems, gate valves, as critical control components, often face the challenge of cavitation. Cavitation typically occurs when the fluid pressure drops below its vapor pressure, causing bubbles to form in the fluid. These bubbles burst during subsequent flow, releasing significant energy and causing wear and damage to the valve and piping system. Cavitation is particularly prevalent at low temperatures, where the fluid's saturated vapor pressure is lower, severely impacting the valve's service life and safety.

[0003] Currently, research on cavitation problems in cryogenic shut-off valves mainly focuses on suppressing cavitation by changing the valve's geometry or material selection. For example, some studies have proposed mitigating the effects of cavitation by improving the valve's internal flow channel design, increasing fluid velocity, or modifying the valve seat material. However, these methods largely rely on empirical design and lack precise control and quantitative analysis of cavitation phenomena. Therefore, how to accurately suppress cryogenic cavitation by optimizing the valve structure and combining it with numerical calculation methods remains a technical challenge in valve design. Summary of the Invention

[0004] This invention provides a structural optimization method for suppressing cavitation in cryogenic shut-off valves. The aim is to effectively suppress cavitation in shut-off valves under cryogenic conditions through accurate numerical simulation and structural optimization design, thereby improving the valve's operational stability and reliability.

[0005] This application provides a structural optimization method for suppressing cavitation in a cryogenic shut-off valve, including:

[0006] S1: Establish the shut-off valve model and perform mesh generation;

[0007] S2: Perform a numerical calculation on the meshed shut-off valve model, then obtain the cavitation flow field cloud map based on the calculation results, and determine the key locations where cavitation occurs;

[0008] S3: Optimize the shut-off valve model by setting uniform grid-shaped guide plates at the key locations where cavitation occurs;

[0009] S4: Perform secondary numerical calculations on the optimized shut-off valve model, and obtain the average gas phase volume and flow coefficient based on the calculation results;

[0010] S5: Optimization judgment based on the average gas volume and flow coefficient:

[0011] When the average gas phase volume is greater than the first threshold, the aperture of the uniform mesh guide plate is increased; when the flow coefficient is less than the second threshold, the aperture of the uniform mesh guide plate is increased and its aperture arrangement is changed to a concentric ring distribution.

[0012] S6: Repeat S4 and S5 until the average gas volume and flow coefficient meet the requirements, and output the optimized shut-off valve structure parameters.

[0013] Optionally, both the first and second numerical calculation processes include:

[0014] Import the shut-off valve model into FLUENT software, and use the Scale option in the General tab to unify the units;

[0015] To establish a single-phase flow field, set the turbulence model and wall function in the Model option.

[0016] In the Material tab, define the cryogenic medium as gaseous and liquid oxygen;

[0017] Define boundary conditions in the Boundary Condition tab;

[0018] Set the calculation method in the Solution Methods tab;

[0019] Set the convergence residual in the Monitors tab;

[0020] In the Solution Initialization tab, click the "Compute from" dropdown menu and select "Import Now". Then click the "Initialize" option to complete the initialization.

[0021] In the Calculation Activities module, set the number of iterations and the save location in the Run Calculation tab, then click the Calculate option to start the calculation;

[0022] After the calculation is complete, open the Mixture model in the Model tab, set the main phase, secondary phase and cavitation models in the Phases tab in turn, set the saturated vapor pressure as a function of temperature, and correct the evaporation coefficient and condensation coefficient to adapt to the low temperature conditions. Then, set the number of iteration steps in the Run Calculation tab and click the Calculation option to start the calculation.

[0023] After the calculation is complete, change the TIME option to Transient in the General tab, and then set the time step and number of iterations in the RunCalculation tab. Click the Calculation option to start the calculation. After the calculation is complete, you will get the simulation data in the CASE file and DATA file.

[0024] Optionally, the key location where cavitation occurs is the location where the cavitation volume fraction shown in the cavitation flow field cloud map is greater than 0.2.

[0025] Optionally, the formula for calculating the flow coefficient is:

[0026] ;

[0027] in K v denoted as the flow coefficient, Q as the inlet volumetric flow rate, ΔP as the pressure difference across the valve, and p as the working fluid density.

[0028] Optionally, the uniform mesh guide plate is made of stainless steel, nickel-based alloy or engineering ceramic, and can be detachably installed on the valve body of the shut-off valve by means of threaded connection, snap-fit ​​or pin connection.

[0029] This application visualizes and analyzes the flow characteristics of the flow channels in the original and optimized gate valve models, specifically using cavitation flow field cloud maps. In particular, it employs the average gas volume to characterize the cavitation intensity of the gate valve and combines this with the flow coefficient as the basis for evaluating the cavitation suppression effect of the optimized structure. This significantly simplifies the cavitation suppression criterion and improves the efficiency and accuracy of structural optimization. Through numerical calculation and iterative optimization design, not only is the cavitation suppression effect of the valve improved, but the valve structure can also be precisely adjusted according to different operating conditions, ensuring efficient operation under cryogenic conditions. This method can be widely applied to the design and optimization of gate valves in cryogenic fluid transport systems, demonstrating significant engineering application value. Attached Figure Description

[0030] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0031] Figure 1 This is a flowchart illustrating a structural optimization method for suppressing cavitation in a cryogenic shut-off valve according to an exemplary embodiment.

[0032] Figure 2 This is a schematic diagram of the overall structure of a cavitation suppression type shut-off valve according to an exemplary embodiment.

[0033] Figure 3This is a diagram of the original shut-off valve flow channel mesh model according to an exemplary embodiment.

[0034] Figure 4 This is a cross-sectional view of a valve body with a deflector plate shown according to an exemplary embodiment.

[0035] Figure 5 This is a schematic diagram of a cavitation suppression guide plate according to an exemplary embodiment.

[0036] Figure 6 This is a cavitation cloud diagram illustrating the cavitation suppression effect at 100% opening, according to an exemplary embodiment.

[0037] Figure 7 This is a comparison graph of average gas phase volume and flow coefficient illustrating the cavitation suppression effect according to an exemplary embodiment.

[0038] Reference numerals: 1. Valve stem; 2. Valve body; 3. Valve core; 4. Cavitation suppression guide plate; 5. Outlet channel; 6. Inlet channel. Detailed Implementation

[0039] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0040] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0041] Figure 1 This is a flowchart illustrating a structural optimization method for suppressing cavitation in a cryogenic shut-off valve according to an exemplary embodiment. (Reference) Figure 1 The method may include the following steps:

[0042] S1: Establish the shut-off valve model and perform mesh generation;

[0043] S2: Perform a numerical calculation on the meshed shut-off valve model, then obtain the cavitation flow field cloud map based on the calculation results, and determine the key locations where cavitation occurs;

[0044] S3: Optimize the shut-off valve model by setting uniform grid-shaped guide plates at the key locations where cavitation occurs;

[0045] S4: Perform secondary numerical calculations on the optimized shut-off valve model, and obtain the average gas phase volume and flow coefficient based on the calculation results;

[0046] S5: Optimization judgment based on the average gas volume and flow coefficient:

[0047] When the average gas phase volume is greater than the first threshold, the aperture of the uniform mesh guide plate is increased; when the flow coefficient is less than the second threshold, the aperture of the uniform mesh guide plate is increased and its aperture arrangement is changed to a concentric ring distribution.

[0048] S6: Repeat steps S4 and S5 until the average gas volume and flow coefficient meet the requirements, and output the optimized shut-off valve structure parameters.

[0049] As can be seen from the above embodiments, this application visualizes and analyzes the flow characteristics of the flow channels in the original and optimized gate valve models, i.e., the cavitation flow field cloud diagrams. Specifically, it uses the average gas phase volume to characterize the cavitation intensity of the gate valve and combines it with the flow coefficient as the basis for evaluating the cavitation suppression effect of the optimized structure. This greatly simplifies the cavitation suppression criterion and improves the efficiency and accuracy of structural optimization. Through numerical calculation and iterative optimization design, not only is the cavitation suppression effect of the valve improved, but the valve structure can also be precisely adjusted according to different operating conditions to ensure efficient operation under low-temperature conditions. This method can be widely applied to the design and optimization of gate valves in cryogenic fluid transport systems and has significant engineering application value.

[0050] In the specific implementation of S1: a shut-off valve model is established and mesh generation is performed;

[0051] Specifically, refer to Figure 2 Based on the actual structure of the cryogenic shut-off valve, Solidworks software was used to model the cryogenic shut-off valve, resulting in a shut-off valve model.

[0052] In the specific implementation of S2: a numerical calculation is performed on the meshed shut-off valve model, and then the cavitation flow field cloud map is obtained based on the calculation results to determine the key locations where cavitation occurs. This step may include the following sub-steps:

[0053] 1) Import the meshed shut-off valve model into FLUENT software, and use the Scale option in the General tab to unify the units;

[0054] Specifically, the original valve model was adjusted to 100% opening for the extraction of a three-dimensional flow channel, resulting in a three-dimensional flow channel model. To ensure sufficient flow development, the inlet of the three-dimensional flow channel model was extended by 8 times the valve diameter length, and the outlet by 12 times the valve diameter length, thus obtaining a three-dimensional fluid computational domain. This three-dimensional fluid computational domain model was imported into ICEM mesh generation software for unstructured mesh generation. To improve the computational accuracy of critical regions, the valve body region was locally refined, resulting in a mesh model. The original shut-off valve mesh model is shown below. Figure 3 As shown. Import the mesh model into Fluent software, and define the unit as mm in Scale Mesh under General.

[0055] 2) Establish a single-phase flow field by setting the turbulence model and wall function in the Model option;

[0056] Specifically, a Realizable k-ε turbulence model is used to capture complex flow field characteristics, and Enhanced Wall Treatment is selected as the wall function to improve the calculation accuracy in the near-wall region.

[0057] 3) In the Material tab, define the cryogenic medium as gaseous and liquid oxygen;

[0058] Specifically, in the Material tab, select gaseous and liquid oxygen, and set fluid in Cell Zone Conditions to liquid oxygen.

[0059] 4) Define boundary conditions in the Boundary Condition tab;

[0060] Specifically, the boundary conditions are set as follows: inlet total pressure 0.6 MPa, outlet total pressure 0.3 MPa, static pressure 0, gas volume fraction at both inlet and outlet is set to 0, and system operating temperature is 98 K.

[0061] 5) Set the calculation method in the Solution Methods tab;

[0062] Specifically, the SIMPLE algorithm was chosen as the calculation method. The gradient discretization method in the SIMPLE algorithm adopts the least squares method based on the unit volume. The pressure, momentum, turbulent kinetic energy, and dissipation in the SIMPLE algorithm all adopt the second-order upwind scheme.

[0063] 6) Set the convergence residuals in the Monitors tab;

[0064] Specifically, the convergence criterion for all residuals is uniformly set to 1.0 × 10⁻⁶. -6 This is to ensure the stability and accuracy of the numerical solution during the iterative calculation process.

[0065] 7) In the Solution Initialization tab, click the drop-down menu under Compute from, select the entry point, and then click the Initialize option to complete the initialization;

[0066] Specifically, in numerical simulation, to ensure computational convergence and accuracy, flow field initialization is necessary. In the Solution Initialization tab, select the inlet from the Compute from dropdown menu, and then click the Initialize button to initialize the flow field within the computational domain. This ensures that the velocity, pressure, and turbulent flow parameters in each region are consistent with the inlet conditions, providing a reasonable initial solution for subsequent iterative calculations.

[0067] 8) In the Calculation Activities module, in the Run Calculation tab, set the number of iterations and the save location, then click the Calculate option to start the calculation;

[0068] Specifically, the iteration step number is set to 10,000 steps to ensure that the flow field calculation can converge fully; then the Calculate command is started to iteratively solve the entire computational domain and automatically save the calculation results in the set path.

[0069] 9) After the calculation is completed, open the Mixture model in the Model tab, and set the main phase, secondary phase and cavitation models in the Phases tab in turn. Set the saturated vapor pressure as a function of temperature, and correct the evaporation coefficient and condensation coefficient to adapt to low temperature conditions.

[0070] Specifically, after the calculation is complete, open the Mixture model in the Model tab, and in the Phases tab, set liquid oxygen as the main phase and oxygen as the secondary phase, and select Zwart-Gerber-Belamri as the cavitation model. To adapt to low-temperature conditions, the cavitation model parameters are modified, and the evaporation coefficient F... vap The condensation coefficient F is revised to 3. cond Corrected to 0.0005. Simultaneously, the saturated vapor pressure is set as a function of temperature; the relationship between the saturated vapor pressure of a pure substance and temperature is as follows: In the formula, P sat Let T be the saturated vapor pressure of the liquid phase, A be the temperature, and B be the Antonie constant. The data is imported into the FLUENT software using a user-defined function (UDF) to achieve dynamic correction of the temperature-dependent saturated vapor pressure, thereby improving the accuracy of low-temperature cavitation simulation.

[0071] 10) In the General tab, change the TIME option to Transient. Then, in the Run Calculation tab, set the time step and number of iterations, and click the Calculation option to start the calculation. After the calculation is completed, you will get the simulation data in the CASE file and DATA file.

[0072] Specifically, in the General tab, change the TIME option to Transient to capture the evolution of the flow field over time. Then, in the Run Calculation tab, set the transient calculation parameters, with the time step set to 5 × 10⁻⁶. -5 The iteration step count is set to 6000 steps. After completing the parameter settings, the Calculate command is started to perform transient solution. After the calculation is completed, the CASE file and DATA file are obtained.

[0073] 11) Import the calculated data into Tecplot software to obtain cavitation cloud map, and determine the installation position of the guide vane based on the cloud map;

[0074] Specifically, regions with a cavitation volume fraction greater than 0.2 in the cavitation flow field cloud map are identified as key locations for cavitation occurrence, and these regions serve as the basis for optimizing and arranging the guide vane structure. In the specific implementation of S3: the shut-off valve model is optimized by setting uniformly grid-shaped guide vanes at the key locations for cavitation occurrence;

[0075] refer to Figure 4 In the diagram, 1 represents the valve stem; 2 represents the valve body; 3 represents the valve core; 4 represents the cavitation suppression guide plate; 5 represents the outlet channel; and 6 represents the inlet channel. Guide plates with different structures were drawn using Solidworks software and named small-aperture uniform mesh guide plate, medium-aperture uniform mesh guide plate, and large-aperture concentric annular guide plate, and set as follows: Figure 4 At the same location, each scheme is numbered, and the schemes without guide vanes, small-diameter uniform mesh guide vanes, medium-diameter uniform mesh guide vanes, and large-diameter concentric annular guide vanes are respectively numbered a, b, c, and d, see Figure 5 .

[0076] In the specific implementation of S4: a second numerical calculation is performed on the optimized shut-off valve model, and the average gas phase volume and flow coefficient are obtained based on the calculation results;

[0077] Specifically, the numerical calculation process described in S2 was used to simulate the three optimization schemes, obtaining the cavitation cloud map, average gas phase volume (time average of instantaneous gas phase volume calculated within a 0.3s time range), and flow coefficient (calculated using the formula) under the optimized structure. ,in K vWhere Q is the flow coefficient, Q is the inlet volumetric flow rate, ΔP is the pressure difference across the valve, and p is the working fluid density. Figure 6 The cavitation cloud diagram shows the cavitation suppression effect of the shut-off valve at 100% opening. It can be seen that compared with a, c is the most effective in weakening high-intensity cavitation; b is the second most effective; and d is the weakest in cavitation suppression. Figure 7 The figure shows a comparison of the average gas phase volume and flow coefficient for cavitation suppression. As can be seen from the figure, compared with the original structure, the average gas phase volume of all optimized schemes is reduced. Among them, the medium-diameter uniform grid baffle has the smallest average gas phase volume, indicating that it has the best cavitation suppression effect, but its flow coefficient decreases the most. The small-diameter uniform grid baffle is at a medium level in terms of cavitation suppression and flow performance. The large-diameter concentric ring baffle has the smallest decrease in flow coefficient, but the highest average gas phase volume, and its cavitation suppression effect is relatively weak.

[0078] In the specific implementation of S5: optimization judgment is made based on the average gas phase volume and flow coefficient.

[0079] When the average gas phase volume is greater than the first threshold, the aperture of the uniform mesh guide plate is increased; when the flow coefficient is less than the second threshold, the aperture of the uniform mesh guide plate is increased and its aperture arrangement is changed to a concentric ring distribution.

[0080] Specifically, the baffle structure is optimized based on the average gas volume and flow coefficient: when the average gas volume is greater than a first threshold, the aperture of the uniform mesh baffle is increased to reduce the volume of the cavitation region; when the flow coefficient is less than a second threshold, the aperture of the uniform mesh baffle is increased, and its aperture arrangement is adjusted from the original mesh structure to a concentric ring distribution, thereby improving the guiding characteristics of the fluid channel and enhancing the overall flow performance. The calculation results of S4 show that c performs best in reducing the average gas volume, indicating the strongest cavitation suppression effect, but its flow coefficient decreases the most; b maintains a moderate level between cavitation suppression and flow performance; d has the smallest decrease in flow coefficient, but the weakest cavitation suppression effect.

[0081] During the optimization process, if scheme b meets the cavitation suppression requirements but the flow coefficient is insufficient, the orifice diameter should be appropriately increased and its orifice arrangement changed to a concentric ring distribution to reduce flow resistance; if scheme b does not suppress cavitation sufficiently, the orifice diameter of the uniform grid guide plate should be increased.

[0082] In the specific implementation of S6: repeat steps S4 and S5 until the average gas volume and flow coefficient meet the requirements, and output the optimized shut-off valve structure parameters.

[0083] Specifically, the baffle structure adjusted in step S5 is recalculated according to the process in step S4 and compared with the first threshold and the second threshold. If the conditions are not met, the adjustment and calculation continue until the average gas phase volume is not greater than the first threshold and the flow coefficient is not less than the second threshold. The final baffle aperture and aperture arrangement are then output to complete the optimization. Through iterative calculation and judgment, the automatic convergence and optimal matching of the baffle structure under different operating conditions can be achieved.

[0084] Other embodiments of this application will readily occur to those skilled in the art upon consideration of the specification and practice of the disclosure herein. This application is intended to cover any variations, uses, or adaptations of this application that follow the general principles of this application and include common knowledge or customary techniques in the art not disclosed herein. The specification and embodiments are to be considered exemplary only, and the true scope and spirit of this application are indicated by the claims.

[0085] It should be understood that this application is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is limited only by the appended claims.

Claims

1. A method of structural optimization to inhibit cavitation in cryogenic stop valves, characterized in that, The method comprises the following steps: S1: establishing a stop valve model and performing mesh division; S2: performing a numerical calculation on the mesh-divided stop valve model, obtaining a cavitation flow field cloud map based on the calculation result, and determining a key position of cavitation occurrence; S3: optimizing the stop valve model, that is, setting a uniform grid-shaped guide plate at the key position of cavitation occurrence; S4: performing a second numerical calculation on the optimized stop valve model, and obtaining an average gas volume and a flow coefficient based on the calculation result; S5: performing optimization judgment according to the average gas volume and the flow coefficient: when the average gas volume is greater than a first threshold value, the aperture of the uniform grid-shaped guide plate is increased, and when the flow coefficient is less than a second threshold value, the aperture of the uniform grid-shaped guide plate is increased and the hole type arrangement is changed to a concentric ring-shaped distribution; S6: repeating S4 and S5 until the average gas volume and the flow coefficient meet the requirements, and outputting the optimized stop valve structure parameters.

2. A method of structural optimization to suppress cavitation in cryogenic stop valves according to claim 1, characterized in that, The first and second numerical calculation processes both comprise the following steps: importing the stop valve model into FLUENT software, and uniformly setting units by using a Scale option in a General tab; establishing a single-phase flow field, and sequentially setting a turbulence model and a wall function in a Model option; defining low-temperature medium as gaseous and liquid oxygen in a Material tab; defining boundary conditions in a Boundary Condition tab; setting a calculation method in a Solution Methods tab; setting a convergence residual in a Monitors tab; clicking Now Inlet in a drop-down option of a Compute from option in a Solution Initialization tab, and completing initialization by clicking an Initialize option; setting an iteration step number and a saving position in a Run Calculation option in a Calculation Activities module, and starting calculation by clicking a Calculate option; after calculation is completed, opening a Mixture model in the Model tab, sequentially setting a primary phase, a secondary phase and a cavitation model in a Phases tab, setting a saturated vapor pressure as a function of temperature, and correcting evaporation and condensation coefficients to adapt to low-temperature working conditions, setting an iteration step number in the Run Calculation tab again, and starting calculation by clicking the Calculate option; after calculation is completed, changing a TIME option in the General tab to Transient, setting a time step and an iteration step number in the Run Calculation tab again, and starting calculation by clicking the Calculate option, and obtaining simulation data of a CASE file and a DATA file after calculation is completed.

3. The method of structural optimization to suppress cavitation in cryogenic stop valve according to claim 1, characterized in that, The key position of cavitation occurrence is a position at which a cavitation volume fraction displayed in the cavitation flow field cloud map is greater than 0.

2.

4. The method of structural optimization to suppress cavitation in cryogenic stop valve according to claim 1, characterized in that, The calculation formula of the flow coefficient is: ； wherein K v is the flow coefficient, Q is the inlet volume flow, ΔP is the pressure difference across the valve, and p is the working fluid density.

5. The method of structural optimization to suppress cavitation in cryogenic stop valve according to claim 1, characterized in that, The material of the uniform grid-shaped guide plate is stainless steel, nickel-based alloy or engineering ceramics, and the uniform grid-shaped guide plate is detachably installed on the valve body of the stop valve through a threaded connection, a buckle fitting or a pin connection.

Images