A flow field analysis method for optimizing the structure of a plug-jamming prevention regulating stop valve

Abstract

The application provides a flow field analysis method for optimizing the structure of a plug prevention and adjustment stop valve, and belongs to the technical field of stop valves, and comprises the following steps: step S1: based on an energy minimum multi-scale model, each phase medium is divided into a dense phase and a dilute phase through calculation of phase distribution in each region in the valve; step S2: the interphase momentum transfer resistance relationship of a liquid-solid two-phase pseudo-fluid model is corrected, a mass transfer and drag force action relationship is established between the dilute phase and the dense phase, and a first stage model is formed; step S3: the physical picture of the first stage model is continuously changed in medium, a single dilute phase and a dense phase are formed, a mass exchange and drag force action relationship between the two is established, the dense phase and the dilute phase are ensured to satisfy mass conservation, and a second stage model is constructed; in the application, the defects of the homogeneous phase assumption 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 actual working conditions, and the prediction error of an erosion risk area is greatly reduced.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of stop valves, in particular to a flow field analysis method for optimizing the structure of a jam-prevention regulating stop valve. BACKGROUND

[0002] In large petrochemical plants, jam-prevention 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 passage jamming and vibration noise.

[0003] Currently, the research on the flow mechanism of complex liquid-solid two-phase media mostly adopts the Euler-Euler (two-fluid method) or Euler-Lagrange method (multiphase particle grid method), and the treatment of liquid and solid phases is often based on the homogeneous continuity assumption, that is, it is assumed that the gas phase and solid phase distribution are uniform. Drag force is the most important interphase interaction in multiphase flow, and the drag force model is the key scientific problem that determines the success or failure of fluidization simulation. In recent years, a drag force model suitable for non-uniform systems has been developed, which adds a parameter representing the spatial structure to the drag force function. Among them, a structure multi-fluid model based on EMMS is developed under the constraint of stability conditions.

[0004] For liquid-solid two-phase flow, domestic and foreign researchers combine EMMS drag force with complete two-fluid model and discrete particle simulation to obtain good simulation results. The simplified two-fluid model using a simplified solid phase stress correlation and coupled with EMMS drag force is expected to improve the calculation speed and numerical calculation stability while ensuring high accuracy.

[0005] In the process of handling residual oil, heavy oil, wax oil and gasoline desulfurization in large petrochemical plants, the medium often contains viscous particles and other solid phase materials, and there is a spatiotemporal structure inhomogeneity and flow pattern polymorphism of liquid-solid two-phase conditions, and the interphase interaction is distributed on the macro scale. The existing two-phase flow model adopts the Eulerian / Eulerian two-fluid model to describe the relationship between the two phases, and the particle motion is studied in the Lagrangian coordinate system, only considering the interphase drag force and Magnus force of the particles on the two-fluid, without considering the virtual mass force, etc. It is difficult to accurately describe the mesoscale interphase forces and inertial and viscous mechanisms. This homogeneous continuous model is quite different from the actual working condition, and the actual flow field involves many difficulties such as high Reynolds number flow, liquid-solid interphase interaction, particle group breakage and coalescence, and complex boundary conditions. Therefore, there is a large error in the analysis results of cavitation and erosion, and it is difficult to accurately predict the erosion and jamming risk. The local solid phase scouring phenomenon is extremely serious, which leads to the serious failure of the valve internals in a short time. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings and deficiencies of the prior art, and to provide a flow field analysis method for optimizing the structure of an anti-blocking regulating stop valve.

[0007] The technical solutions adopted by the present application are as follows: The present application provides a flow field analysis method for optimizing the structure of an anti-blocking regulating stop valve, comprising the following steps:

[0008] Step S1: Based on the energy minimum multiscale model, the phase media are divided into dense phase and dilute phase through phase distribution calculation in each region in the valve;

[0009] Step S2: The interphase momentum transfer resistance relationship of the liquid-solid two-phase pseudo-fluid model is corrected, the mass transfer and drag force action relationship between the dilute phase and the dense phase is established, and a first stage model is formed;

[0010] Step S3: The physical picture of the first stage model is continuously medium, a single dilute phase and a dense phase are formed, the mass exchange and drag force action relationship between the two is established, the mass conservation of the dense phase and the dilute phase is ensured, and a second stage model is constructed.

[0011] In some embodiments, the following steps are further included:

[0012] Based on the energy minimum multiscale model, a three-phase pseudo-fluid model is established on the basis of the assumption that mass transfer does not occur between the dense phase and the dilute phase and only the drag force action between the two is considered.

[0013] In some embodiments, in step S2:

[0014] According to the multiscale structure characteristics of the gas-liquid-solid flow in the valve, and in combination with the differences between the dilute phase discrete bubble flow form and the fluid-solid pseudo-fluid phase, the influence of the microscale action between the particles in the liquid of the mesoscale is corrected to the effective volume fraction, and the influence of the microscale solid particles on the mesoscale action with the liquid is attributed to the properties of the fluid-solid pseudo-fluid, such as viscosity and density.

[0015] In some embodiments, in step S2:

[0016] The complex flow field is multiscale decomposed into microscale between the liquid and the solid particles and macroscale between the two-phase medium and the boundary of the stop valve, the conservation relationship of each scale and the correlation of different scales are established;

[0017] The energy minimum multiscale model is combined with the two-phase pseudo-fluid model, based on the unsteady turbulent flow model, a numerical simulation platform is established by using the TVD spatial discretization method and the Runge-Kutta time advancing format, the complex three-phase non-uniform flow multiscale coupling characteristics and the flow mechanism of the gas-liquid-solid flow are analyzed, and a three-phase flow field calculation method is obtained.

[0018] In some embodiments, further comprising three-dimensional flow field mathematical model establishment, comprising the following steps:

[0019] Based on the theory of computational fluid dynamics, a three-dimensional flow field mathematical model including mass conservation, momentum conservation and energy conservation is established by using Realizable-K-Epsilon turbulence model and Enhanced Wall Treatment processing method.

[0020] In some embodiments, further comprising the following steps:

[0021] Determine the fluid calculation domain, based on the three-dimensional model of the valve, establish the fluid calculation domain in the working state, extend the pipeline model in front of and behind the inlet and outlet of the valve by 5-8 times the diameter of the pipeline, so as to reduce the influence of the flow state of the inlet and outlet on the calculation of the flow field in the valve.

[0022] In some embodiments, further comprising the following steps:

[0023] Grid division step, a mixed grid division method combining hexahedral O structured grid and unstructured grid is adopted, unstructured grid is used for complex structure areas such as valve clapper and adjusting sleeve, and structured grid is used for the rest of the flow passage to improve the calculation efficiency.

[0024] The beneficial effects of the present application are as follows: Compared with the existing model based on the homogeneous assumption, the present application does not consider the spatial arrangement of particles, which leads to large simulation error of erosion, and the defects of the homogeneous assumption are corrected by the multi-stage model, which can reflect the influence of particle aggregation on flow, make the liquid-solid two-phase flow simulation closer to the actual working condition, and reduce the prediction error of the erosion risk area. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings obtained according to these drawings without creative labor are still within the scope of the present application.

[0026] Figure 1 The flow chart of the flow field analysis method for optimizing the structure of the anti-clogging regulating stop valve in the present application;

[0027] Figure 2 The schematic diagram of grid division of the stop valve in the present application;

[0028] Figure 3 The cross-sectional velocity distribution cloud chart in the present application;

[0029] Figure 4A local velocity distribution cloud chart in the present application;

[0030] Figure 5 A cross-sectional schematic view in the present application;

[0031] Figure 6 A cross-sectional velocity cloud chart in the present application;

[0032] Figure 7 A cross-sectional pressure distribution cloud chart in the present application;

[0033] Figure 8 A local pressure distribution cloud chart in the present application;

[0034] Figure 9 A local dynamic pressure distribution cloud chart in the present application;

[0035] Figure 10 A cross-sectional streamline distribution chart in the present application. DETAILED DESCRIPTION

[0036] The following description provides specific applications and requirements of the present specification, and aims to enable those skilled in the art to manufacture and use the contents of the present specification. Various local modifications of the disclosed embodiments are obvious to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of the present specification. Therefore, the present specification is not limited to the shown embodiments, but to the widest scope consistent with the claims.

[0037] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "radial", "length", "width", "thickness", "up", "down", "left", "right", "front", "back", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and these terms are mainly used to better describe the present application and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific orientation, or to be constructed and operated in a specific orientation.

[0038] It should be noted that the terms "first", "second" and similar words do not represent any order, quantity or importance, but are only used to distinguish different components, and should not be understood as a limitation on the embodiments of the present application.

[0039] It should be noted that the terms "mounting", "arrangement", "provided with", "connected", "linked" should be interpreted broadly. For example, it can be fixed connection, detachable connection, or integral structure; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium, or internal communication between two devices, elements or components.

[0040] It should be noted that the terms "in some embodiments", "exemplarily", "for example" and the like are used to indicate an example, illustration or description. Any embodiment or design scheme described as "in some embodiments", "exemplarily", "for example" in this application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. On the contrary, the use of "in some embodiments", "exemplarily", "for example" and the like is intended to present the relevant concept in a specific way, meaning that the specific features, structures or properties described in conjunction with the embodiments can be included in at least one embodiment of the application. The occurrence of the above terms at different positions in the specification does not necessarily mean the same embodiment, nor is it an independent or alternative embodiment that is not 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.

[0041] For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0042] With regard to the drawings of the present application, it should be clearly understood that the drawings are for illustrative and descriptive purposes only, and are not intended to limit the scope of the specification. It should also be understood that the drawings are not necessarily drawn to scale.

[0043] As Figures 1 to 2 shown, the present specification provides a flow field analysis method for optimizing the structure of a plug prevention adjustment stop valve, comprising the following steps:

[0044] Step S1: Based on the energy minimum multiscale model (EMMS model) for the non-uniformity of the liquid-solid two-phase spatiotemporal structure and the polymorphism of the flow pattern, the spatial distribution of the liquid-solid two-phase medium in the valve is calculated. According to the difference in particle concentration, the medium is divided into dense phase and dilute phase, i.e. the region with high particle concentration and the region with low particle concentration; wherein the EMMS model describes the multiphase flow structure through the "energy minimum" criterion, which is a classical method for existing multiphase flow simulation. The particle volume fraction threshold is determined by numerical calculation, such as dense phase ≥ 15% and dilute phase ≤ 5%. The division result is used for subsequent interphase action analysis.

[0045] Because the medium of large petrochemical devices contains solid particles, and the difference in particle concentration will lead to different erosion and blockage risks, dense phase particles are easy to aggregate and block the flow channel, and the erosion of dilute phase particles is weak. After division, the key areas for subsequent analysis can be clearly defined, avoiding excessive calculation of low-risk dilute phase areas and improving analysis efficiency.

[0046] Step S2: According to the multi-scale structure characteristics of gas-liquid-solid flow in the valve, combined with the differences between dilute phase discrete bubble flow and fluid-solid pseudo-fluid phase, the resistance formula of interphase momentum transfer in the two-phase pseudo-fluid model is corrected. The influence of microscale interaction between particles and liquid on mesoscale is corrected to the effective volume fraction, and the influence of microscale solid particles on mesoscale interaction with liquid is attributed to the properties of fluid-solid pseudo-fluid, such as viscosity and density. The relationship between mass transfer and drag force is established between dilute phase and dense phase, and the first stage model is formed.

[0047] Compared with the existing model based on homogeneous assumption, the spatial arrangement of particles is not considered, which leads to large simulation error of erosion. By correction, the influence of particle aggregation on flow can be reflected, the simulation of liquid-solid two-phase flow is closer to the actual working condition, and the prediction error of erosion risk area is reduced.

[0048] Step S3: The physical picture of the first stage model is continuously processed, forming a single dilute phase and a dense phase, and establishing the mass exchange and drag force relationship between them to ensure that the dense phase and the dilute phase satisfy the mass conservation, and the second stage model is constructed. The non-uniformity of complex two-phase flow increases the calculation complexity, and the continuous processing can simplify the model while retaining the key action relationship, which is convenient for engineering calculation.

[0049] On the basis of assuming that the dense phase and the dilute phase do not mass transfer and only considering the drag force between them, 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 as a liquid-solid two-phase model, covering the gas-containing condition, so that the model is applicable to more complex petrochemical processes.

[0050] In step S2, according to the multi-scale structure characteristics of gas-liquid-solid flow in the valve, the complex flow field is decomposed into microscale between liquid and solid particles and macroscale between two-phase medium and the boundary of the stop valve (such as wall and inlet and outlet), the conservation relationship of each scale and the correlation between different scales are established, such as the mass conservation, momentum conservation relationship of each scale and the correlation between scales, and the turbulent kinetic energy converted from the work of buoyancy is given as the main control factor, and the stability condition of liquid-solid two-phase mutual coordination is given. From the mesoscale, the interphase action mechanism is accurately described, and the overall dynamics parameters are predicted.

[0051] Exemplarily, the liquid-solid two-phase coordination stability condition is determined with the constraint condition of "minimizing the suspension conveying energy consumed by conveying unit mass of particles and liquid", the interphase interaction mechanism is described from the mesoscale, and the overall dynamics parameters are predicted.

[0052] The influence mechanisms of particle impact and valve body wall constraint on flow characteristics are different, and separate analysis can determine the contribution of each factor and accurately locate the root cause of the flow problem, such as micro-particle impact leading to sealing surface wear and macro-valve curvature leading to vortex.

[0053] Finally, the energy minimum multiscale model is combined with the two-phase pseudo-fluid model, based on the unsteady turbulent flow model, a numerical simulation platform is established by using high-precision TVD spatial discretization method and Runge-Kutta time advancing format, compared with traditional discrete methods which are prone to error accumulation, this method can reduce shock calculation error and improve time domain accuracy, analyze the coupling characteristics of complex three-phase non-uniform flow multi-fields (such as velocity field, pressure field, concentration field) and its flow mechanism, and provide a high-precision three-phase flow field calculation method for valve strength design, structure optimization, material damage analysis, sealing leakage quantitative calculation and vibration noise analysis.

[0054] In this way, the multi-stage model corrects the defects of the homogeneous assumption, greatly reduces the simulation error of liquid-solid two-phase flow, and can accurately identify the erosion risk area of particle aggregation in dense phase.

[0055] The continuity equation, momentum equation and particle motion equation used in numerical calculation are as follows:

[0056] Continuity equation:

[0057]

[0058] Momentum equation:

[0059]

[0060] Particle motion equation:

[0061]

[0062] In the formula:

[0063]

[0064]

[0065] Further, in order to better optimize the structure of the stop valve, a three-dimensional flow field mathematical model is also included, which comprises the following steps:

[0066] According to the harsh working conditions of high temperature, high pressure, solid-containing and viscous, based on the theory of computational fluid dynamics, Realizable-K-Epsilon turbulence model and Enhanced Wall Treatment processing method are adopted to study the main reasons of energy loss and vibration in the flow process by adjusting the pressure distribution, velocity distribution and flow state of the three-dimensional flow field of the anti-blocking regulating stop valve. The research results provide important technical support for the structural design and optimization of the stop valve.

[0067] The Realizable-K-Epsilon turbulence model and Enhanced Wall Treatment processing method are prior art. The Realizable-K-Epsilon turbulence model includes a turbulent kinetic energy equation and a turbulent dissipation rate equation, wherein the turbulent kinetic energy equation considers the average velocity gradient, the turbulent kinetic energy generation caused by buoyancy and the turbulent dissipation, and the turbulent dissipation rate equation introduces an empirical constant and a user-defined source term.

[0068] Due to the existence of strong turbulence in the valve flow field, such as high-speed area and vortex, the Realizable-K-Epsilon model has higher precision in simulating turbulence; the flow velocity gradient near the wall is large, and the enhanced wall treatment can reduce the near-wall error, so as to accurately capture the turbulent characteristics in the valve, such as turbulent kinetic energy distribution, and provide reliable data for analyzing the causes of vibration.

[0069] Specifically, a three-dimensional flow field mathematical model including mass conservation, momentum conservation and energy conservation relationships is established.

[0070] In the three-dimensional flow field mathematical model:

[0071] The mass conservation relationship is used to describe the correlation between the density and velocity of the medium in time and space;

[0072] The mass conservation equation is:

[0073]

[0074] In the formula: ;

[0075] ;

[0076] , s;

[0077] The momentum conservation relationship is used to describe the influence of pressure, dynamic viscosity and source term in the medium motion;

[0078] The momentum conservation equation is:

[0079]

[0080] In the formula: ;

[0081] .

[0082] The energy conservation relationship is used to describe the correlation between the medium temperature change and heat transfer, viscous dissipation.

[0083] In the formula:

[0084]

[0085] In the formula: ; ;

[0086] ; The fluid mechanical energy dissipation caused by the medium viscous force and the heat source in the fluid, that is, the viscous dissipation term in computational fluid dynamics.

[0087] Further, the method further comprises the following steps:

[0088] The fluid calculation domain is determined, the fluid calculation domain in the working state is established based on the three-dimensional model of the valve, and pipeline models with a length corresponding to 5-8 times the pipeline diameter are respectively extended before and after the inlet and outlet of the valve, so as to reduce the influence of the inlet and outlet flow states on the calculation of the flow field in the valve.

[0089] Exemplarily, according to the three-dimensional model of the anti-blocking regulating stop valve for a large petrochemical device, the fluid calculation domain model of the valve in the working state is established, and in order to facilitate the full development of flow and reduce the influence of the inlet and outlet flow states on the fluid calculation domain inside the stop valve, pipeline models are respectively established before and after the valve for appropriate extension, and the pipeline length is 5 times the pipeline diameter.

[0090] Further, the method further comprises the following steps:

[0091] The grid division step adopts a mixed grid division mode combining hexahedral O-shaped structured grid and unstructured grid, unstructured grid is adopted for complex structure regions such as the valve disc and the adjusting sleeve, and structured grid is adopted for the remaining flow passage part to improve the calculation efficiency.

[0092] Exemplarily, as Figure 2As shown, the grid data structure 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 is also the same on each layer. Structured grid can save computing resources and reduce computing time, but it is very difficult to generate structured grid when encountering complex structure of the calculation domain. The connection between the grid cells of the unstructured grid is irregular, there is no concept of layer, and the distribution of grid nodes is random, so it has flexibility. Since the structure of the check valve disc and the pilot valve is complex, but the structure of the remaining flow passage is relatively simple, in order to improve the calculation efficiency, a hybrid grid division method combining hexahedral O-shaped structured grid and unstructured grid is adopted, and the grid division is as shown in Figure 2 For the complex structure of the flow passage turning and its internal structure, the Realizable-K-Epsilon turbulence model is adopted, and the Enhanced Wall Treatment processing method is adopted to fully consider the influence of the change of turbulent motion in the near-wall region on the flow.

[0093] Since the flow state of the inlet and outlet will affect the flow field in the valve, the extension pipe can ensure that the flow is fully developed; the complex structure is more suitable for unstructured grid, and the straight pipe section uses structured grid to save computing resources. Finally, the disturbance of the boundary condition to the flow field in the valve is minimized, the grid division efficiency is improved, and the calculation accuracy of the complex region is ensured.

[0094] In summary, the application proposes a complex liquid-solid two-phase flow non-uniform flow multi-field coupling characteristic analysis method and flow field precise control technology for the anti-clogging regulating check valve, which effectively solves the important scientific problems of anti-erosion and anti-clogging of the check valve for viscous medium containing solid.

[0095] Secondly, the flow characteristic analysis technology of the anti-clogging regulating check valve based on three-dimensional flow field is developed, which provides important technical support for the structure design and optimization of the check valve.

[0096] Exemplarily, as shown in Figures 3 to 10 The above method is applied to the actual research of the check valve, and the application example is as follows:

[0097] ①Velocity distribution research

[0098] Overall velocity distribution: Figure 5 is a velocity distribution cloud chart of the cross section in the check valve when the flow is in a steady state. The velocity distribution at the pipeline inlet is uniform, and the flow is stable. Due to the influence of the upwardly inclined flow passage, the flow velocity at the valve inlet begins to change, and a low-speed region is formed at the corner of the pre-valve flow passage.

[0099] Figure 4The local velocity distribution cloud chart shows that the medium flow rate is relatively large at position A due to the sudden reduction of the flow passage cross section. As the medium enters the valve body, the flow passage cross section area gradually increases, and the flow rate begins to fall. However, due to the blocking effect of the valve body wall, a small range of high-speed zone is formed at positions B to C, and a low-speed zone exists at the right lower side of the valve body due to the inertial effect, indicating that the flow passage at this position is not fully utilized. As the flow proceeds, the medium enters the outlet flow passage area of the valve body, and Figure 4 it can be seen that the flow at this position is not fully developed, and the main flow at the outlet flow passage of the valve body is concentrated on the lower wall of the pipe, resulting in uneven velocity distribution and large flow rate gradient, leading to flow loss. Moreover, due to the influence of the outlet flow passage shape, a large area of high-speed zone is formed at position D, and the above high-speed zones may cause erosion to the inner wall of the valve body.

[0100] Cross-sectional velocity distribution: Since the change of the flow passage cross-sectional area has a great influence on the flow rate, the velocity distribution at the position with small flow passage area should be analyzed. The cross-sectional positions are shown in Figure 5 . Figure 6 The velocity cloud chart of each cross section is shown in the figure. The cross section 1 has the smallest area, and the cross section 4 has the second smallest area. The maximum velocity in each cross section is at the wall of the cross section 2, as shown in Figure 6 (b). This position corresponds to the positions C on both sides in Figure 4 , because the fluid medium collides and convects at this position, resulting in a large change in velocity gradient, which is easy to cause wear to the inner wall of the valve body at position E. By comparing the maximum velocities at the four cross sections, it can be seen that although the velocity distribution is greatly influenced by the flow passage cross-sectional area, it is also related to the state of the medium flow process.

[0101] ②Pressure distribution research

[0102] Figure 7 The cross-sectional pressure distribution cloud chart of the valve is shown in the figure. The pressure distribution at the inlet and outlet is relatively uniform, and the pressure gradient in the valve body part changes sharply. Moreover, the pressure difference between the inlet and outlet is large, and the pressure drop of the flow passage is mainly used to overcome the resistance before and after the stop valve.

[0103] Figure 8 The pressure gradient in the upper part of the valve body cavity is large, and the pressure on the left and right sides of the upper part is greater than that in the middle region, which is due to the convection of the fluid after flowing into the cavity, and then forming this pressure distribution characteristic.

[0104] Figure 9 The dynamic pressure distribution cloud chart of the valve is shown in the figure. The concept of dynamic pressure is derived from Bernoulli's equation, and its value is half of the product of density and velocity square. Since the research content is incompressible flow, the position where the medium velocity is greater, the dynamic pressure is greater. As can be seen from the figure, the flow characteristics of the medium change greatly at the sudden change of the flow area and in the valve body, resulting in uneven dynamic pressure distribution and large fluctuations.

[0105] ③Flow characteristic research

[0106] Figure 10 The middle section streamline diagram, because the streamline and fluid vector are tangent everywhere, and the arrow is the direction of fluid movement, so the streamline diagram can show the movement trend of the fluid. As can be seen from the diagram, the flow in the pipe inlet section and the valve body inlet section is stable, and the fluid is less hindered. After entering the valve body, due to the shape restriction, small angle vortices are formed at a, b, and c under the wall blocking effect.

[0107] After the medium enters the valve body, due to the wall blocking effect, a backflow with a flow direction from left to right is formed on the left side of the valve body, which further forms a convection with the incoming medium, and an obvious convection zone is formed at the valve body centerline position, which extends to the valve body outlet. Combined with the previous speed and pressure analysis, the influence of the convection zone can be divided into three stages: early, middle, and late.

[0110] In the early convection stage, the convection effect is relatively strong, and the two-direction fluid appears to be stagnant in the middle of the convection zone. Due to the stagnation phenomenon, a low-speed zone is formed, and according to Bernoulli's principle, this is also the reason for the increase in pressure at F.

[0108] Figure 8 In the middle convection stage, due to the large curvature radius of the lower half of the valve body, the flow at this position cannot develop fully, forming a low flow rate zone. The medium in this area produces a shear effect with the upper convection zone, forming a large vortex in the lower right part of the valve body. The speed in the large vortex zone is significantly lower, and the vortex forms a severe turbulent flow, which increases the turbulent energy and is one of the main reasons for the water head loss (main component of flow loss) and vibration in the flow process.

[0109] In the late convection stage, the convection gradually dissipates and develops downstream, but due to the influence of the shear effect in the middle convection stage, two vortices with the same rotation direction are formed in the upper part of the valve outlet flow passage. The flow velocity at this position is low, and the existence of the vortex forms an obstruction to the main flow fluid. Since the vortex at the valve body and the valve outlet is one of the main reasons for water head loss and vibration, in future valve flow passage design, the curvature of the lower half of the valve body can be appropriately reduced to reduce vortex formation and flow loss, thereby achieving the purpose of reducing flow resistance.

[0110] In summary, after reading the detailed disclosure, those skilled in the art can understand that the foregoing detailed disclosure can be presented only in an exemplary manner and can not be limiting. Although not explicitly stated here, those skilled in the art can understand that the present application requires to encompass various reasonable changes, improvements and modifications to the embodiments. These 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.

[0111] In summary, after reading the detailed disclosure, those skilled in the art can understand that the foregoing detailed disclosure can be presented only in an exemplary manner and can not be limiting. Although not explicitly stated here, those skilled in the art can understand that the present application requires to encompass various reasonable changes, improvements and modifications to the embodiments. These 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.

[0112] Furthermore, it should be understood that, throughout this application, various features of the present embodiments are described as being combined in a single embodiment, figure, or description of an embodiment. This is for purposes of expedience and ease of description, and is not necessarily intended to exclude separate embodiments from being claimed. Additionally, it should be understood that the description of features in a single embodiment does not mean that the features must necessarily be combined in that embodiment. Rather, the description of features in a single embodiment is merely to describe one possible embodiment among many, and is not intended to exclude separate embodiments from being claimed. Thus, the various embodiments described herein can be combined in a single embodiment, or in multiple embodiments, without departing from the scope of the present application.

[0113] Finally, it should be understood that the application embodiments disclosed herein are illustrative of the principles of the present application. Other modifications that are obvious to those skilled in the art are intended to be within the scope of the application. Accordingly, the application embodiments disclosed herein are intended to be illustrative only and not in a limiting sense. Numerous variations and modifications will be apparent to those skilled in the art in light of the application embodiments described. Therefore, the application embodiments described herein are intended to cover any and all modifications of the application within the scope of the claims.

Claims

1. A flow field analysis method for optimizing the structure of a choke valve with anti-clogging adjustment, characterized in that, The method comprises the following steps: Step S1: Based on the energy minimum multiscale model, the phase medium is divided into dense phase and dilute phase through the calculation of the distribution of each phase in each region in the valve; Step S2: The interphase momentum transfer resistance relationship of the liquid-solid two-phase pseudo-fluid model is corrected, the mass transfer and drag force action relationship between the dilute phase and the dense phase is established, and a first stage model is formed; Step S3: The physical picture of the first stage model is continuously medium, a single dilute phase and a dense phase are formed, the mass exchange and drag force action relationship between the two is established, the dense phase and the dilute phase are ensured to satisfy the mass conservation, and a second stage model is constructed; In step S2: According to the multi-scale structure 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 action between the particles in the medium scale liquid is corrected to the effective volume fraction, and the influence of the microscale solid particles on the medium scale action with the liquid is attributed to the physical properties of the fluid-solid pseudo-fluid; In step S2: The complex flow field is decomposed into microscale between the liquid and the solid particles and macroscale between the two-phase medium and the boundary of the stop valve, the conservation relationship of each scale and the correlation of different scales are established; The energy minimum multiscale model and the two-phase pseudo-fluid model are combined, based on the unsteady turbulent flow model, the TVD spatial discretization method and the Runge-Kutta time advancing format are adopted to establish a numerical simulation platform, the multi-field coupling characteristics and the flow mechanism of the complex three-phase non-uniform flow are analyzed, and a three-phase flow field calculation method is obtained.

2. A method of analyzing a flow field of a structure of an optimal anti-blocking regulating stop valve according to claim 1, characterized in that, Further comprising the following steps: Based on the energy minimum multiscale model, a three-phase pseudo-fluid model is established on the premise that mass transfer does not occur between the dense phase and the dilute phase and only the drag force action between the two is considered.

3. A method of analyzing flow field of a choke valve structure with optimized anti-blocking adjustment according to claim 1, characterized in that, Further comprising the establishment of a three-dimensional flow field mathematical model, comprising the following steps: Based on the computational fluid dynamics theory, the Realizable-K-Epsilon turbulent flow model and the Enhanced Wall Treatment processing method are adopted to establish a three-dimensional flow field mathematical model comprising mass conservation, momentum conservation and energy conservation relationship.

4. A method of analyzing a flow field of a structure of an optimal anti-blocking regulating stop valve according to claim 3, wherein Further comprising the following steps: The fluid calculation domain is determined, the fluid calculation domain in the working state is established based on the three-dimensional model of the valve, and the pipeline model with a length of 5-8 times the pipeline diameter is extended before and after the inlet and outlet of the valve to reduce the influence of the flow state of the inlet and outlet on the calculation of the flow field in the valve.

5. A method of flow field analysis for optimizing the structure of a choke valve to prevent blockage, according to claim 4, characterized in that, Further comprising the following steps: The mesh division step adopts a mixed mesh division method combining hexahedral O structured mesh and unstructured mesh, unstructured mesh is adopted for the complex region of the valve disc and the adjusting sleeve structure, and structured mesh is adopted for the remaining flow passage part to improve the calculation efficiency.

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