Flow field analysis method capable of optimizing anti-blocking adjusting stop valve structure

Abstract

The invention provides a flow field analysis method capable of optimizing an anti-blocking adjusting stop valve structure, and belongs to the technical field of stop valves, and the method comprises the following steps: S1, based on an energy minimum multi-scale model, dividing each phase medium into a dense phase and a dilute phase through calculation of each phase distribution in each region in a valve; s2, correcting an inter-phase momentum transfer resistance relationship of the liquid-solid two-phase quasi-fluid model, and establishing a mass transfer and drag action relationship between a dilute phase and a dense phase to form a first-stage model; s3, performing medium serialization on the physical image of the first-stage model to form a single dilute phase and a single concentrated phase, establishing a mass exchange and drag action relationship between the dilute phase and the concentrated phase, ensuring that the concentrated phase and the dilute phase meet mass conservation, and constructing a second-stage model; according to the method, the defects of homogeneous hypothesis are corrected through the multi-stage model, the influence of particle aggregation on flow can be reflected, liquid-solid two-phase flow simulation is closer to the actual working condition, and the prediction error of the erosion risk area is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of stop valves, and in particular to a flow field analysis method capable of optimizing the structure of an anti-clogging regulating stop valve. Background Art

[0002] In large-scale petrochemical plants, anti-clogging regulating stop valves need to handle solid-containing viscous media such as residual oil and heavy oil. Such media exhibit complex liquid-solid two-phase flow characteristics, which can easily lead to problems such as valve sealing surface erosion, flow channel blockage, and vibration noise.

[0003] Currently, most studies on the flow mechanisms of complex liquid-solid two-phase flows employ the Euler-Euler (two-fluid method) or Euler-Lagrangian method (multiphase particle-mesh method). The treatment of the liquid and solid phases is often based on the homogeneous continuity assumption, which assumes that the gas and solid phases are uniformly distributed. Drag is the most important interphase interaction in multiphase flow, and the drag model is a key scientific issue that determines the success of fluidization simulations. Considering the influence of particle spatial arrangement, a drag model suitable for inhomogeneous systems has been developed in recent years. This model incorporates parameters that represent spatial structure into its drag function. Among these is a structural multifluid model based on EMMS, constrained by stability conditions.

[0004] For liquid-solid two-phase flow, researchers at home and abroad have combined EMMS drag with a complete two-fluid model and discrete particle simulation, achieving excellent simulation results. Using a simplified two-fluid model that simplifies the solid-phase stress correlation and couples it with EMMS drag is expected to improve the calculation speed and numerical stability while ensuring high accuracy.

[0005] In large-scale petrochemical plants, processes such as desulfurization of residual oil, heavy oil, wax oil, and gasoline often involve solid phases such as viscous particles. This results in spatiotemporal structural heterogeneity and polymorphic flow patterns within the liquid-solid two-phase flow regime, with interphase interactions occurring at the macroscale. Existing two-phase flow models employ the Eulerian / Eulerian two-fluid model to describe the interphase relationship. These models examine particle motion in the Lagrangian coordinate system, considering only the interphase drag and Magnus forces exerted by particles on the two fluids without factoring in virtual mass forces. This makes it difficult to accurately describe the interphase forces, inertia, and viscosity mechanisms at the mesoscopic scale. This homogeneous, continuous model differs significantly from actual operating conditions, which involve numerous challenges such as high Reynolds number flow, liquid-solid interactions, particle group breakup and coalescence, and complex boundaries. Consequently, their analysis results for cavitation, erosion, and other issues are subject to significant errors, making it difficult to accurately predict erosion and blockage risks. Localized solid-phase erosion is extremely severe, leading to rapid failure of valve trim. Summary of the Invention

[0006] The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a flow field analysis method that can optimize the structure of an anti-clogging regulating stop valve.

[0007] The technical solution adopted by the present invention is as follows: This application provides a flow field analysis method for optimizing the anti-clogging regulating stop valve structure, comprising the following steps: Step S1: Based on the energy minimum multi-scale model, the distribution of each phase in each area in the valve is calculated to divide the medium into a concentrated phase and a dilute phase; Step S2: Modify the interphase momentum transfer resistance relationship of the liquid-solid two-phase pseudo-fluid model, establish the mass transfer and drag force relationship between the dilute phase and the concentrated phase, and form the first-stage model; Step S3: The physical picture of the first-stage model is made medium-continuous to form a single dilute phase and a concentrated phase, and the mass exchange and drag force relationship between the two is established to ensure that the concentrated phase and the dilute phase satisfy the mass conservation, and then the second-stage model is constructed.

[0008] In some embodiments, the following steps are further included: On the basis of assuming that there is no mass transfer between the dense phase and the dilute phase and only considering the drag force between the two, a three-phase pseudo-fluid model is established based on the energy minimum multi-scale model.

[0009] In some embodiments, in step S2: According to the multi-scale structural characteristics of the gas-liquid-solid flow in the valve, combined with the differences between the dilute phase discrete bubble flow form and the fluid-solid pseudo-fluid phase, the influence of the microscale interaction between the mesoscale particles and the liquid is corrected to the effective volume rate, and the influence of the microscale solid particles on the mesoscale interaction with the liquid is attributed to the physical properties of the fluid-solid pseudo-fluid, such as viscosity and density.

[0010] In some embodiments, in step S2: Perform multi-scale decomposition of complex flow fields, dividing them into the microscale between liquid and solid particles and the macroscale between the two-phase medium and the stop valve boundary, and establish conservation relationships at each scale and correlations between different scales; The energy minimum multiscale model is combined with the two-phase pseudo-fluid model. Based on the unsteady turbulence model, the TVD spatial discretization method and the Runge-Kutta time-marching format are used to establish a numerical simulation platform. The multi-field coupling characteristics and flow mechanism of the complex gas-liquid-solid three-phase non-uniform flow are analyzed, and the three-phase flow field calculation method is obtained.

[0011] In some embodiments, the method further includes establishing a three-dimensional flow field mathematical model, which includes the following steps: Based on the theory of computational fluid dynamics, the Realizable-K-Epsilon turbulence model and the Enhanced Wall Treatment method are used to establish a three-dimensional flow field mathematical model that includes the relationships of mass conservation, momentum conservation, and energy conservation.

[0012] In some embodiments, the following steps are further included: Determine the fluid calculation domain and establish the fluid calculation domain under the working state based on the three-dimensional valve model. Extend the pipeline model before and after the valve inlet and outlet by 5-8 times the pipeline diameter to reduce the impact of the inlet and outlet flow state on the flow field calculation inside the valve.

[0013] In some embodiments, the following steps are further included: The meshing step adopts a hybrid meshing method combining hexahedral O-type structured mesh and unstructured mesh. Unstructured mesh is used for complex structural areas such as valve disc and regulating sleeve, and structured mesh is used for other flow channel parts to improve calculation efficiency.

[0014] The beneficial effects of the present invention are as follows: Compared with the existing model based on the homogeneous assumption, the present invention does not consider the spatial arrangement of particles, resulting in large erosion simulation errors. The defects of the homogeneous assumption are corrected through a multi-stage model, which can reflect the influence of particle aggregation on the flow, making the liquid-solid two-phase flow simulation closer to the actual working conditions, and reducing the prediction error of the erosion risk area. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, other drawings obtained based on these drawings still fall within the scope of the present invention.

[0016] Figure 1 This is a flow chart of a flow field analysis method for optimizing the structure of an anti-clogging regulating stop valve in the present invention; Figure 2 Schematic diagram of grid division of the stop valve in the present invention; Figure 3 It is the velocity distribution cloud diagram of the middle section in the present invention; Figure 4 It is the local velocity distribution cloud map in the present invention; Figure 5 It is a cross-sectional schematic diagram of the present invention; Figure 6 It is the velocity cloud diagram of each cross section in the present invention; Figure 7It is the pressure distribution cloud diagram of the middle section in the present invention; Figure 8 It is the local pressure distribution cloud map in the present invention; Figure 9 It is the local dynamic pressure distribution cloud map in the present invention; Figure 10 This is the streamline distribution diagram of the mid-section in the present invention. DETAILED DESCRIPTION

[0017] The following description provides specific application scenarios and requirements for this specification, with the goal of enabling those skilled in the art to make and use the contents of this specification. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of this specification. Therefore, this specification is not limited to the embodiments shown, but is intended to be accorded the broadest scope consistent with the claims.

[0018] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "longitudinal", "transverse", "radial", "length", "width", "thickness", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. These terms are mainly intended to better describe this application and its embodiments, and are not intended to limit the indicated devices, elements or components to a specific orientation, or to be constructed and operated in a specific orientation.

[0019] It should be noted that the terms "first", "second" and similar words do not indicate any order, quantity or importance, but are only used to distinguish different components and should not be understood as limitations on the embodiments of the present application.

[0020] It should be noted that the terms "installed," "set," "provided with," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, removable connections, or integral structures; mechanical connections or electrical connections; direct connections or indirect connections through an intermediary; or internal communication between two devices, elements, or components.

[0021] It should be noted that the terms "in some embodiments", "exemplarily", "for example", etc. are used to indicate examples, illustrations or descriptions. Any embodiment or design described in this application as "in some embodiments", "exemplarily", "for example" should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "in some embodiments", "exemplarily", "for example" is intended to present related concepts in a concrete way, meaning that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of the above words in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] For those skilled in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0023] Regarding the drawings of this application, it should be clearly understood that the drawings are for illustration and description purposes only and are not intended to limit the scope of this specification. It should also be understood that the drawings are not necessarily drawn to scale.

[0024] like Figures 1 to 2 As shown, this specification provides a flow field analysis method for optimizing the anti-clogging regulating stop valve structure, comprising the following steps: Step S1: In view of the heterogeneity of the spatiotemporal structure of the liquid-solid two-phase in the valve and the polymorphism of the flow pattern, the spatial distribution of the liquid-solid two-phase medium in the valve is calculated based on the energy minimum multiscale model, namely the EMMS model. The medium is divided into a dense phase and a dilute phase according to the difference in particle concentration, that is, an area with a higher particle concentration and an area with a lower particle concentration. Among them, the EMMS model describes the multiphase flow structure through the "energy minimum" criterion and is a classic method for existing multiphase flow simulation. The particle volume fraction threshold is determined by numerical calculation, such as the dense phase ≥15% and the dilute phase ≤5%. The division result is used for subsequent phase interaction analysis.

[0025] Since the media of large-scale petrochemical plants contain solid particles, and differences in particle concentration will lead to different risks of erosion and blockage, dense phase particles are prone to aggregation and block the flow channel, while dilute phase particles have weaker erosion. After division, the key areas for subsequent analysis can be clarified, avoiding overcalculation of low-risk dilute phase areas and improving analysis efficiency.

[0026] Step S2: Based on the multi-scale structural characteristics of the gas-liquid-solid flow in the valve, combined with the difference between the dilute phase discrete bubble flow form and the fluid-solid pseudo-fluid phase, the resistance formula for interphase momentum transfer in the two-phase pseudo-fluid model is modified, the influence of the microscale interaction between the mesoscale particles and the liquid is corrected to the effective volume rate, and the influence of the microscale solid particles on the mesoscale interaction with the liquid is attributed to the physical properties of the fluid-solid pseudo-fluid, such as viscosity and density. The mass transfer and drag action relationship is established between the dilute phase and the concentrated phase to form the first stage model.

[0027] Compared with the existing model which is based on the homogeneous assumption and does not consider the spatial distribution of particles, resulting in large erosion simulation errors, the correction can reflect the influence of particle aggregation on the flow, making the liquid-solid two-phase flow simulation closer to the actual working conditions and reducing the prediction error of the erosion risk area.

[0028] Step S3: The physical picture of the first-stage model is continuousized to form a single dilute phase and a concentrated phase. The mass exchange and drag relationship between the two is established to ensure that the concentrated phase and the dilute phase satisfy the mass conservation law, and the second-stage model is constructed. Among them, the heterogeneity of complex two-phase flow will increase the computational complexity. The continuous processing can simplify the model while retaining the key interaction relationship, facilitating engineering calculations.

[0029] On the basis of assuming that there is no mass transfer between the dense phase and the dilute phase and only considering the drag force between the two, a gas-liquid-solid three-phase pseudo-fluid model is established based on the energy minimum multi-scale model; if the gas phase can be ignored, it is simplified to a liquid-solid two-phase model to cover gas-containing conditions, making the model suitable for more complex petrochemical processes.

[0030] In step S2, multi-scale decomposition is performed based on the multi-scale structural characteristics of the gas-liquid-solid flow in the valve, and the complex flow field is decomposed into the microscale between the liquid and solid particles and the macroscale between the two-phase medium and the boundary of the stop valve (such as the wall and the inlet and outlet, etc.). The conservation relationship of each scale and the association between different scales are established, for example, the conservation relationship of mass and momentum at each scale and the association between scales are established, and the turbulent kinetic energy converted from buoyancy work is proposed as the main control factor. The stability conditions for the mutual coordination of the liquid-solid two phases are given, the interphase interaction mechanism is accurately described from the mesoscopic scale, and its overall dynamic parameters are predicted.

[0031] For example, with the constraint of "minimum suspension transport energy consumed to transport unit mass of particles and liquid", the liquid-solid two-phase coordination stability condition is determined, the interphase interaction mechanism is described at the mesoscopic scale, and the overall kinetic parameters are predicted.

[0032] Particle impact and valve wall constraint have different mechanisms for influencing flow characteristics. Analyzing them separately can clarify the contribution of each factor and accurately locate the root cause of flow problems, such as microscopic particle impact causing sealing surface wear and macroscopic valve body curvature causing vortexes.

[0033] Finally, the energy minimum multiscale model is combined with the two-phase pseudo-fluid model. Based on the unsteady turbulence model, a numerical simulation platform is established using the high-precision TVD spatial discretization method and the Runge-Kutta time-marching format. Compared with traditional discrete methods that are prone to error accumulation, this method can reduce shock wave calculation errors, improve time domain accuracy, and analyze the coupling characteristics of multiple fields (such as velocity field, pressure field, and concentration field) of complex gas-liquid-solid three-phase non-uniform flow and its flow mechanism. It can provide a high-precision three-phase flow field calculation method for valve strength design, structural optimization, material damage analysis, quantitative calculation of seal leakage, and vibration and noise analysis.

[0034] In this way, the multi-stage model corrects the defects of the homogeneous assumption, greatly reducing the simulation error of liquid-solid two-phase flow and accurately identifying the erosion risk areas where dense phase particles accumulate.

[0035] The continuity equation, momentum equation, and particle motion equation used in the numerical calculation are as follows: Continuity equation: Momentum equation: Particle motion equation: Where: Furthermore, in order to better optimize the structure of the stop valve, a three-dimensional flow field mathematical model is established, which includes the following steps: In response to demanding operating conditions such as high temperature, high pressure, solid content, and viscosity, this study employed the Realizable-K-Epsilon turbulence model and Enhanced Wall Treatment method based on computational fluid dynamics theory. By adjusting the flow field characteristics of the globe valve's three-dimensional flow field, including pressure distribution, velocity distribution, and flow state, the authors investigated the main causes of energy loss and vibration during the flow process. These findings provide important technical support for the structural design and optimization of globe valves.

[0036] The Realizable-K-Epsilon turbulence model and Enhanced Wall Treatment method are existing technologies. The Realizable-K-Epsilon turbulence model includes a turbulent kinetic energy equation and a turbulent dissipation rate equation. The turbulent kinetic energy equation considers the average velocity gradient, turbulent kinetic energy generation caused by buoyancy, and turbulent dissipation, while the turbulent dissipation rate equation introduces empirical constants and custom source terms.

[0037] Due to the presence of strong turbulence in the flow field within the valve, such as high-speed regions and eddies, the Realizable-K-Epsilon model provides higher accuracy in turbulence simulation. The velocity gradient near the wall is large, and enhanced wall processing can reduce near-wall errors. This accurately captures the turbulent flow characteristics within the valve, such as the distribution of turbulent kinetic energy, providing reliable data for analyzing the causes of vibration.

[0038] Specifically, a three-dimensional flow field mathematical model including the conservation of mass, momentum and energy is established.

[0039] In the three-dimensional flow field mathematical model: The mass conservation relationship is used to describe the relationship between the changes in medium density and velocity in time and space; Among them, the mass conservation equation is: Where: ; ; , s; Momentum conservation relations are used to describe the effects of pressure, dynamic viscosity, and source terms on medium motion; Among them, the momentum conservation equation is: Where: ; .

[0040] The energy conservation relationship is used to describe the relationship between medium temperature change and heat transfer and viscous dissipation.

[0041] Among them, the energy conservation equation is: Where: ; ; ; is the dissipation of fluid mechanical energy caused by the viscous force of the medium and the heat source in the fluid, which is the viscous dissipation term in computational fluid dynamics.

[0042] Furthermore, the method further comprises the following steps: Determine the fluid calculation domain and establish the fluid calculation domain under the working state based on the three-dimensional valve model. Extend the pipeline model before and after the valve inlet and outlet by 5-8 times the pipeline diameter to reduce the impact of the inlet and outlet flow state on the flow field calculation inside the valve.

[0043] For example, based on the three-dimensional model of an anti-clogging regulating stop valve used in a large petrochemical plant, a fluid calculation domain model of the valve in the working state is established. At the same time, in order to facilitate the full development of the flow and reduce the impact of the inlet and outlet flow states on the internal fluid calculation domain of the stop valve, pipeline models are established before and after the valve and appropriately extended. The pipeline length is 5 times the pipeline diameter.

[0044] Furthermore, the method further comprises the following steps: The meshing step adopts a hybrid meshing method combining hexahedral O-type structured mesh and unstructured mesh. Unstructured mesh is used for complex structural areas such as valve disc and regulating sleeve, and structured mesh is used for other flow channel parts to improve calculation efficiency.

[0045] For example, Figure 2 As shown, according to the grid data structure, it can be divided into structured grid and unstructured grid. The structured grid is an orderly arrangement of grid cells and nodes, and the total number of nodes on each layer is the same. Structured grids can save computing resources and reduce computing time, but when encountering a computational domain with a complex structure, it is very difficult to generate a structured grid. The connection between the grid cells of the unstructured grid is irregular, and there is no concept of layers. The distribution of the grid nodes is random, so it is flexible. Since the structure of the stop valve disc and the pilot valve is complex, but the structure of the rest of the flow channel is relatively simple, in order to improve the computing efficiency, a hybrid grid division method combining hexahedral O-type structured grid and unstructured grid is adopted. The grid division is as follows: Figure 2 To account for the complexities of the channel bends and its internal structure, the Realizable-K-Epsilon turbulence model was used. Furthermore, to fully consider the impact of turbulent changes near the wall on the flow, the Enhanced Wall Treatment method was employed.

[0046] Because the inlet and outlet flow conditions affect the flow field within the valve, extending the pipe ensures full flow development. Unstructured meshes are more suitable for complex structures, while structured meshes for straight pipe sections save computing resources. Ultimately, this minimizes the interference of boundary conditions on the flow field within the valve, improves meshing efficiency, and maintains computational accuracy in complex areas.

[0047] In summary, this application proposes a multi-field coupling characteristic analysis method for complex liquid-solid two-phase flow non-uniform flow and flow field precision control technology for anti-clogging regulating stop valves, which effectively solves the important scientific problems of anti-erosion and anti-clogging of stop valves containing solid viscous media.

[0048] Secondly, a flow characteristic analysis technology for anti-clogging regulating stop valves based on three-dimensional flow fields was developed, providing important technical support for the structural design and optimization of stop valves.

[0049] For example, Figures 3 to 10 The following is an example of a practical application of the above method to a globe valve: ① Velocity distribution research Overall velocity distribution: Figure 5 is a distribution cloud diagram of the cross-sectional velocity in the stop valve when the flow is in a steady state. The velocity distribution at the pipeline inlet is uniform and the flow is relatively stable. Due to the influence of the upward inclined flow channel, the flow velocity at the valve body inlet begins to change, and a low-speed area is formed at the corner of the flow channel in front of the valve.

[0050] Figure 4 The figure is a local velocity distribution cloud diagram. Since the flow channel cross section at A suddenly decreases, the medium flow velocity here is relatively high. As the medium enters the valve body, the flow channel cross section area gradually increases and the flow velocity begins to decrease. However, due to the obstruction of the valve body wall, the fluid forms a small high-speed area at B to C. At the same time, under the action of inertia, there is a low-speed area on the lower right side of the valve body, indicating that the flow channel there is not fully utilized. As the flow continues, the medium enters the valve body outlet flow channel area, Figure 4 As can be seen, the flow at this location is not fully developed. The main flow at the valve body outlet flow channel is concentrated on the lower wall of the tube, resulting in uneven velocity distribution, large velocity gradients, and flow losses. Furthermore, due to the shape of the outlet flow channel, a large high-velocity zone is formed at point D. These high-velocity zones may cause erosion of the valve body inner wall.

[0051] Cross-sectional velocity distribution: Since the change of flow channel cross-sectional area has a great influence on the flow velocity, the velocity distribution at the place with smaller flow channel area should be analyzed. The cross-sectional position is as follows: Figure 5 shown. Figure 6 is the velocity cloud diagram of each section, among which section 1 has the smallest area, followed by section 4. The maximum velocity in each section is at the wall of section 2, as shown in Figure 6 As shown at E in (b), this position corresponds to Figure 4 On both sides of point C, the fluid medium collides and convects here, resulting in a large change in velocity gradient, which can easily cause wear on the inner wall of the valve body at point E. By comparing the maximum velocities at the four sections, it can be seen that although the velocity distribution is greatly affected by the cross-sectional area of ​​the flow channel, it is also related to the state of the medium during flow.

[0052] ②Pressure distribution study Figure 7 This is the pressure distribution cloud diagram of the valve cross section. The inlet and outlet pressure distribution is relatively uniform, the pressure gradient in the valve body changes more dramatically, and the inlet and outlet pressure difference is large. The pressure drop of the flow channel is mainly used to overcome the resistance before and after the stop valve.

[0053] Figure 8 The pressure gradient in the upper part of the middle cavity of the middle valve body is larger, and the pressure on the left and right sides of the upper part is greater than that in the middle area. This is because the fluid forms convection after flowing into the middle cavity, which in turn forms this pressure distribution characteristic.

[0054] Figure 9 This is a cloud diagram of the dynamic pressure distribution within the valve. The concept of dynamic pressure originates from the Bernoulli equation, where its value is half the product of density and velocity squared. Given the incompressible flow studied, the dynamic pressure increases where the velocity of the medium is greater. The figure shows that the flow characteristics of the medium vary significantly in areas with sudden changes in the flow area and within the valve body, resulting in uneven and fluctuating dynamic pressure distribution.

[0055] ③ Flow characteristics research Figure 10 This is a streamline diagram of the mid-section. Because streamlines and fluid vectors are tangent at every point, and arrows indicate the direction of fluid motion, streamline diagrams can reveal the fluid's motion trends. The figure shows that the flow at both the pipe inlet and the valve inlet is relatively stable, with minimal obstruction. Upon entering the valve body, due to the design constraints, the wall obstruction forms small vortices at points a, b, and c, respectively.

[0056] After the medium enters the valve body, due to the obstruction of the wall, a backflow from left to right is formed on the left side of the valve body. This then forms a countercurrent with the inflowing medium, forming a distinct convection zone at the centerline of the valve body. This convection zone extends all the way to the valve body outlet. Combined with the previous velocity and pressure analysis, the impact of the convection zone can be divided into three stages: initial, intermediate, and final.

[0057] In the early stage of convection, the convection effect is relatively strong, and the fluids in both directions stagnate in the middle of the convection zone. Due to the stagnation phenomenon, a low-speed zone is formed. At the same time, according to Bernoulli's principle, this is also Figure 8 The reason for the increase in pressure at point F.

[0058] In the middle stage of convection, due to the large radius of curvature of the lower half of the valve body, the flow here cannot be fully developed, forming a low flow velocity area. The medium in this area produces a shear effect with the convection area above, forming a large vortex in the lower right part of the valve body. The speed in the large vortex area is significantly lower. The vortex here forms violent turbulence, causing an increase in turbulent kinetic energy, which is one of the main reasons for head loss (the main component of flow loss) and vibration during the flow process.

[0059] In the later stages of convection, the flow gradually dissipates and flows downstream. However, due to the shear effect of the mid-stage convection, two vortices with the same rotational direction form in the upper portion of the valve body outlet flow channel. The flow velocity is relatively low there, and the presence of these vortices hinders the main flow. Because vortices in the valve body and valve channel outlet are a major cause of head loss and vibration, future valve flow channel designs may consider reducing the arc curvature of the lower half of the valve body to minimize vortex formation and flow losses, thereby reducing flow resistance.

[0060] In summary, after reading this detailed disclosure, those skilled in the art will appreciate that the foregoing detailed disclosure may be presented by way of example only and may not be limiting. Although not expressly stated herein, those skilled in the art will understand that the present application requires various reasonable changes, improvements, and modifications to the embodiments. Such changes, improvements, and modifications are intended to be proposed by the present application and are within the spirit and scope of the exemplary embodiments of the present application.

[0061] Furthermore, it should be understood that in the foregoing descriptions of the embodiments of this application, in order to facilitate understanding of a feature and to simplify this application, this application combines various features into a single embodiment, figure, or description thereof. However, this does not mean that the combination of these features is required. When reading this application, it is entirely possible for a person skilled in the art to label some of the devices as separate embodiments. In other words, the embodiments of this application can also be understood as the integration of multiple sub-embodiments. This also applies when the content of each sub-embodiment is less than all the features of a single aforementioned disclosed embodiment.

[0062] Finally, it should be understood that the embodiments of the application disclosed herein are illustrations of the principles of the embodiments of the present application. Other modified embodiments are also within the scope of the present application. Therefore, the embodiments disclosed in the present application are merely examples and not limitations. Those skilled in the art can adopt alternative configurations based on the embodiments in the present application to implement the applications in the present application. Therefore, the embodiments of the present application are not limited to the embodiments precisely described in the application.

Claims

1. A flow field analysis method for optimizing the structure of an anti-clogging regulating stop valve, characterized in that: The following steps are involved: Step S1: Based on the energy minimum multi-scale model, the distribution of each phase in each area of ​​the valve is calculated to divide the medium into a concentrated phase and a dilute phase; Step S2: Modify the interphase momentum transfer resistance relationship of the liquid-solid two-phase pseudo-fluid model, establish the mass transfer and drag force relationship between the dilute phase and the concentrated phase, and form the first-stage model; Step S3: The physical picture of the first-stage model is made medium-continuous to form a single dilute phase and a concentrated phase, and the mass exchange and drag force relationship between the two is established to ensure that the concentrated phase and the dilute phase satisfy the mass conservation, and then the second-stage model is constructed.

2. A flow field analysis method for optimizing the anti-clogging regulating stop valve structure according to claim 1, characterized in that: The following steps are also included: On the basis of assuming that there is no mass transfer between the dense phase and the dilute phase and only considering the drag force between the two, a three-phase pseudo-fluid model is established based on the energy minimum multi-scale model.

3. A flow field analysis method for optimizing the structure of an anti-clogging regulating stop valve according to claim 1, characterized in that: In step S2: According to the multi-scale structural characteristics of the gas-liquid-solid flow in the valve, combined with the differences between the dilute phase discrete bubble flow form and the fluid-solid pseudo-fluid phase, the influence of the microscale interaction between the mesoscale particles and the liquid is corrected to the effective volume rate, and the influence of the microscale solid particles on the mesoscale interaction with the liquid is attributed to the physical properties of the fluid-solid pseudo-fluid, such as viscosity and density.

4. A flow field analysis method for optimizing the anti-clogging regulating stop valve structure according to claim 3, characterized in that: In step S2: Perform multi-scale decomposition of complex flow fields, dividing them into the microscale between liquid and solid particles and the macroscale between the two-phase medium and the stop valve boundary, and establish conservation relationships at each scale and correlations between different scales; The energy minimum multiscale model is combined with the two-phase pseudo-fluid model. Based on the unsteady turbulence model, a numerical simulation platform is established using the TVD spatial discretization method and the Runge-Kutta time-marching format. The multi-field coupling characteristics and flow mechanism of the complex gas-liquid-solid three-phase non-uniform flow are analyzed, and a three-phase flow field calculation method is obtained.

5. The flow field analysis method for optimizing the anti-clogging regulating stop valve structure according to claim 1 is characterized in that: The method also includes establishing a three-dimensional flow field mathematical model, which includes the following steps: Based on computational fluid dynamics theory, the Realizable-K-Epsilon turbulence model and Enhanced Wall Treatment method are used to establish a three-dimensional flow field mathematical model that includes the relationships of mass conservation, momentum conservation, and energy conservation.

6. A flow field analysis method for optimizing the anti-clogging regulating stop valve structure according to claim 5, characterized in that: The following steps are also included: Determine the fluid calculation domain and establish the fluid calculation domain under the working state based on the three-dimensional valve model. Extend the pipeline model before and after the valve inlet and outlet by 5-8 times the pipeline diameter to reduce the impact of the inlet and outlet flow state on the flow field calculation inside the valve.

7. A flow field analysis method for optimizing the structure of an anti-clogging regulating stop valve according to claim 6, characterized in that: The following steps are also included: The meshing step adopts a hybrid meshing method combining hexahedral O-type structured mesh and unstructured mesh. Unstructured mesh is used for complex structural areas such as valve disc and regulating sleeve, and structured mesh is used for other flow channel parts to improve calculation efficiency.

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