Optimal Design Method of Pressure Compensating Emitter

Abstract

The present invention relates to a pressure-compensating water emitter and an optimized design method thereof, wherein the pressure-compensating water emitter comprises: an upper cover, the upper cover being provided with a curved flow channel and a water outlet slow-flow pool, the center of the water outlet slow-flow pool being provided with a water outlet boss, the water outlet boss being provided with a water outlet; a base being a recessed structure, one side of the base being provided with a water inlet grille, the other side of the base being provided with a water inlet, the water inlet being connected to the water inlet grille; one end of the base being provided with a drainage groove extending along its width, the drainage groove being opposite to the head end of the curved flow channel on the upper cover, the drainage groove wall of the drainage groove being provided with an opening; the upper cover being accommodated in the base and tightly fitted with the base; and an elastic diaphragm being provided between the upper cover and the base. The present invention can improve its anti-clogging ability and hydraulic performance.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural water-saving irrigation, and in particular to an optimization design method for a pressure-compensating emitter. Background Art

[0002] Pressure-compensating emitters are available in both tube-mounted and internally inserted styles abroad. The pressure compensation range generally ranges from 0.05 MPa to 0.40 MPa, with a flow index less than 0.20. However, in China, only tube-mounted pressure-compensating emitters are available. This is primarily due to the unclear internal flow compensation mechanism, making it difficult to accurately design the product using numerical simulation. Consequently, the development of key technologies for pressure-compensating emitters is considered a bottleneck in the agricultural water conservation sector. Furthermore, the high investment required for pressure-compensating emitter production lines is a significant limitation to their industrialization, costing between 800,000 and 1,000,000 yuan. However, non-pressure-compensating emitter production lines are currently more widely used. Developing structural designs for pressure-compensating emitters that enable their production within non-pressure-compensating emitter production lines is crucial for their promotion. Therefore, developing pressure-compensating emitter products and structural optimization methods suitable for non-pressure-compensating emitter production lines is crucial for mitigating the current reliance on imports for pressure-compensating emitters.

[0003] In order to realize the localization of pressure-compensating sprinklers, many experts and scholars have conducted research on this issue. For example, Yang Peiling et al. proposed that the pressure-compensating sprinkler utilizes the efficient energy dissipation effect of the fractal flow channel and developed a tube-type pressure-compensating sprinkler, so that the pressure-compensating sprinkler can achieve effective pressure compensation under low-pressure conditions, ensuring the stable outflow of the sprinkler, and is more suitable for large-area and long-distance drip irrigation operations; Wang Yalin et al. proposed a streamlined plug-in pressure-compensating sprinkler, which addresses the problem of large local head loss caused by the sudden change in the capillary cross-section shape caused by the protrusion of the plug, minimizes the shape resistance of the plug part of the sprinkler, has a simple geometric shape, and has excellent fluid dynamic characteristics.

[0004] However, current emitter products mainly focus on the optimized design of certain components in tube-type pressure-compensated emitters to obtain better hydraulic performance, but there are few optimization design methods for the development of disc-type pressure-compensated emitters and their overall performance improvement, the synergistic interaction between components, and the optimal parameter control thresholds of different components. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to provide an optimization design method for pressure-compensating emitters. By controlling the shear force threshold of the emitter flow channel to improve its anti-clogging ability, the interaction between structural parameters is analyzed based on the fluid-structure coupling simulation method of the emitter under the full pressure field to improve its hydraulic performance, thereby developing a pressure-compensating emitter product with excellent hydraulic performance and anti-clogging performance.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] The pressure-compensating sprinkler described in the present invention includes: an upper cover, which is provided with a curved flow channel and a water outlet slow-flow pool, the center of the water outlet slow-flow pool is provided with a water outlet boss, and the water outlet boss is provided with a water outlet; a base, which is a recessed structure, one side of the base is provided with a water inlet grille, and the other side thereof is provided with a water inlet, and the water inlet is connected to the water inlet grille; one end of the base is provided with a drainage groove extending along its width direction, the drainage groove is opposite to the head end of the curved flow channel on the upper cover, and an opening is provided on the drainage groove wall of the drainage groove; the upper cover is accommodated in the base and tightly fits with the base; an elastic diaphragm is provided between the upper cover and the base.

[0008] In the pressure-compensating emitter, preferably, the elastic diaphragm does not block the water in the drainage groove from flowing into the curved flow channel.

[0009] The pressure-compensating water emitter preferably further includes a connecting boss and a connecting groove; a plurality of the connecting bosses are respectively arranged on the top and bottom of the upper cover, and a plurality of the connecting grooves are respectively arranged on the inner walls of the top and bottom of the base. When the upper cover is accommodated in the base, the connecting bosses cooperate with the connecting grooves to make the upper cover tightly fit with the base.

[0010] The pressure compensating emitter is preferably provided with an emitter screening slot extending along the length direction of the base on the grid side of the base.

[0011] The optimization design method of the pressure-compensating emitter of the present invention comprises the following steps:

[0012] Model establishment: The configuration of pressure-compensated emitter is used as the basic model for model construction;

[0013] Numerical simulation: The pressure-compensated emitter uses Star-ccm+ and Abaqus combined with bidirectional fluid-solid coupling to simulate the deformation of the diaphragm and flow regulation during the entire pressure change process. The model is simplified into a fluid domain calculation model and a solid domain calculation model, which are simulated and calculated in Star-ccm+ and Abaqus respectively, and numerical transfer and coupling calculations are implemented in Star-ccm+.

[0014] Improved anti-clogging capability: Flow channel optimization uses a vortex wall-washing optimization design method to optimize the emitter flow channel structure based on the shear force control threshold near the flow channel wall. This involves connecting the boundaries with circular arcs. Considering the symmetry of vortex development, symmetrical optimization is adopted for the tooth tip water-facing area and the tooth root backwater area, and vice versa.

[0015] Optimization of hydraulic performance: The main structural parameters affecting the performance of the pressure-compensating water emitter are the flow channel structural parameters and the diaphragm mechanical performance parameters; the flow channel in the pressure-compensating water emitter adopts the flow channel form after the vortex wall washing flow channel structure optimization design, and the structural parameters that need to be further determined are the flow channel depth, diaphragm elastic modulus, and diaphragm thickness. The diaphragm thickness is determined by the sum of the flow channel depth. In the comparison, only the diaphragm parameters are set for comparison. The diaphragm elastic modulus is set to 0.3-2.0MPa, and the diaphragm thickness is set to 0.5-1.5mm respectively; the optimal parameters are determined by the numerical simulation method under the established full pressure field, and the pressure point flow simulation analysis is carried out between 0-0.40MPa to analyze its flow state index. Under the premise that the flow state index is less than 0.2, the structural parameter with the smallest flow state index is the optimal structural parameter of this product.

[0016] The optimization design method is preferably used to simulate the deformation and flow regulation of the diaphragm of the pressure-compensating emitter during the entire pressure change process using Star-ccm+ and abaqus combined bidirectional fluid-solid coupling. The model is simplified into a fluid domain calculation model and a solid domain calculation model, which are simulated and calculated in Star-ccm+ and abaqus respectively, and numerical transfer and coupling calculation are implemented in Star-ccm+. The method specifically includes the following steps:

[0017] Region division: divided into fluid domain and solid domain. The fluid domain consists of two parts: the fluid background domain and the fluid overlap grid domain. The fluid background domain includes the fluid part, while the fluid overlap grid domain is the elastic diaphragm part. The solid domain consists of two parts: the solid diaphragm calculation domain and the solid rigid bottom domain. The solid diaphragm calculation domain simplifies the elastic diaphragm. Since the diaphragm and the flow channel overlap, the overlapping part of the diaphragm is simplified into the form of the flow channel. The solid rigid bottom domain is used to avoid mesh distortion caused by excessive deformation of the elastic diaphragm solid domain when it contacts the fluid domain. It restricts and repairs the mesh deformation of the solid domain.

[0018] Boundary conditions: Boundary conditions include the inlet boundary, inlet wall boundary, wall boundary, tooth tip boundary, outlet wall boundary, and outlet boundary. The boundary conditions of the solid domain are all set as FSI surfaces, and all interfaces of the solid domain are set as fluid-solid coupling surfaces. At the same time, constraints are added around the fluid domain to reduce its degrees of freedom. A rigid bottom layer is set at the outlet and boss position of the solid domain. The rigid bottom layer properties are set as surfaces to impose constraints on all sides.

[0019] Meshing: Overlapping meshes are used, and the meshing is divided into fluid domain meshes and solid domain meshes. The fluid domain mesh is expanded to form a background domain, which is overlapped with the solid domain mesh. After mesh independence verification, the fluid domain mesh is finally selected to use a cut-body mesh with a mesh size of 0.04 mm and a mesh number of 5.5 million. The solid domain mesh is selected to use a hexahedral mesh with a mesh size of 0.04 mm and a mesh number of 980,000.

[0020] Material properties: The materials used in the pressure-compensated emitter simulation are water and a flexible diaphragm. Since the actual diaphragm cannot be simulated accurately, the boundary conditions of the diaphragm are simplified and its material parameters are equivalent accordingly. The density of water is 1000 kg / m 3 , dynamic viscosity 0.001Pa.s; diaphragm density 1000kg / m 3 , elastic modulus 1.51MPa, Poisson's ratio 0.45, at the same time, the parameters of the rigid bottom layer are set, and its density is 7850kg / m 3 , elastic modulus 326GPa, Poisson's ratio 0.28;

[0021] Fluid-solid coupling method: The simulation of the pressure-compensated emitter uses star-ccm+ and abaqus coupling to realize diaphragm deformation and cut off or connect the flow channel. The flow field is calculated by star-ccm+, that is, the flow field information in the compensator under different pressures is calculated, and the pressure and shear force are mapped to the abaqus structure for deformation calculations such as displacement. Abaqus then transmits the displacement information to star-ccm+ to realize bidirectional fluid-solid coupling. The flow field calculation is based on the unsteady-state solution of the NS equation, and the turbulence model is the SST k-turbulence model; the solid diaphragm solution adopts an implicit unsteady-state solution.

[0022] The present invention has the following advantages due to the adoption of the above technical solution:

[0023] (1) The present invention proposes a pressure-compensating emitter that can be applied to a production line of a non-pressure-compensating emitter. The emitter is composed of three parts: an upper cover, an elastic diaphragm, and a base. The overall height is controlled between 2.1-2.8 mm, the width is 5.0-7.0 mm, and the length is controlled within the range of 10-30 mm. This allows the pressure-compensating emitter to be shared with the non-pressure-compensating emitter production line, thereby reducing the production cost of the product.

[0024] (2) The present invention establishes a pressure-compensating emitter optimization design method that synergistically improves hydraulic performance and anti-clogging performance. The method proposes a pressure-compensating emitter configuration, improves its anti-clogging ability by controlling the shear force threshold of the emitter flow channel, and analyzes the interaction between structural parameters based on the emitter fluid-solid coupling simulation method under the full pressure field to improve its hydraulic performance.

[0025] (3) Based on the traditional fluid-solid coupling method of pressure-compensating sprinklers, the present invention simplifies the water flow-elastic diaphragm bidirectional fluid-solid coupling analysis model, and innovatively adds a rigid contact layer at the bottom grid of the fluid domain, and establishes a fluid-solid coupling simulation method for sheet-type pressure-compensating sprinklers under full pressure field based on star-ccm and Abqus coupling analysis.

[0026] (4) Based on the long-term, in-situ CT continuous observation of the spatial distribution characteristics of the formation and growth process of clogging materials in pressure-compensating sprinklers, the present invention inverts the clogging material space inside the pressure-compensating sprinklers at different periods. Combined with the numerical simulation method, the local micro-domain hydrodynamic coupling relationship under the condition of clogging material attachment is established, and the flow channel shear force control threshold for improving the anti-clogging ability of the pressure-compensating sprinkler is proposed.

[0027] (5) Based on the near-wall shear force threshold suitable for the growth of clogging materials in the internal flow channel of the pressure-compensating sprinkler, the present invention establishes a flow channel form of a pressure-compensating sprinkler with high anti-clogging ability, explores the influence of different elastic modulus, tensile strength and other performance parameters of the elastic diaphragm on the flow index and flow field, and clarifies the appropriate threshold of the key parameters of the elastic diaphragm. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present invention. Throughout the drawings, the same reference numerals are used to denote the same components. In the drawings:

[0029] Figure 1 It is a schematic diagram of the overall structure of the pressure-compensating emitter of the present invention;

[0030] Figure 2 yes Figure 1 A front view of the upper cover;

[0031] Figure 3 yes Figure 1 a rear view of the upper cover;

[0032] Figure 4 yes Figure 1 Schematic diagram of the structure of the elastic diaphragm;

[0033] Figure 5 yes Figure 1 A front view of the base;

[0034] Figure 6 yes Figure 1 Rear view of the base;

[0035] Figure 7 is a flow chart of the method for optimizing the design of a pressure-compensating emitter according to the present invention;

[0036] Figure 8 is the relationship between the average thickness of the attached biofilm and the shear force near the wall;

[0037] Figure 9 Figure 9 is a simplified calculation model diagram of the fluid domain, where 9(a) is the fluid background domain and 9(b) is the overlapping grid domain;

[0038] Figure 10 It is a simplified calculation model diagram of the solid domain, where 10(a) is the solid diaphragm calculation domain and 10(b) is the solid rigid formation domain;

[0039] Figure 11 is a schematic diagram of the fluid domain boundary, where 11(a) is the inlet boundary, 11(b) is the inlet wall boundary, 11(c) is the wall boundary, 11(d) is the tooth tip boundary, 11(e) is the outlet wall boundary, and 11(f) is the outlet boundary;

[0040] Figure 12 This is a schematic diagram of the flow channel characteristics after near-wall shear force optimization;

[0041] Figure 13 This is the effect of the elastic modulus of the diaphragm on the hydraulic performance of the pressure-compensated emitter;

[0042] Figure 14 This is a diagram showing the influence of diaphragm thickness on the hydraulic performance indicators of pressure-compensating emitters.

[0043] The symbols in the accompanying drawings represent the following:

[0044] 1-upper cover; 11-water outlet boss; 12-water outlet; 13-water outlet slow flow pool; 14-curved flow channel; 15-connecting boss; 2-elastic diaphragm; 3-base; 31-irrigator screening slot; 32-water inlet grille; 33-water inlet; 34-drainage slot; 35-drainage slot wall; 36-connecting groove. DETAILED DESCRIPTION

[0045] Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0046] The present invention provides an optimization design method for a pressure-compensating emitter. First, a pressure-compensating emitter configuration that can be applied to a non-pressure-compensating emitter production line is proposed. The anti-clogging ability of the emitter is improved by controlling the shear force threshold of the emitter flow channel. The interaction between structural parameters is analyzed based on the emitter fluid-solid coupling simulation method under the full pressure field to improve the hydraulic performance, thereby developing a pressure-compensating emitter product with both excellent hydraulic performance and anti-clogging performance.

[0047] like Figures 1 to 6 As shown, the pressure-compensating sprinkler provided by the present invention includes: an upper cover 1, which is provided with a curved flow channel 14 and a water outlet slow-flow pool 13, and the center of the water outlet slow-flow pool 13 is provided with a water outlet boss 11, and the water outlet boss 11 is provided with a water outlet 12; a base 3, which is a recessed structure, and a water inlet grille 32 is provided on one side of the base 3, and a water inlet 33 is provided on the other side thereof, and the water inlet 33 is connected to the water inlet grille 32; one end of the base 3 is provided with a drainage groove 34 extending along its width direction, and the drainage groove 34 is opposite to the head end of the curved flow channel 14 on the upper cover 1, and an opening is provided on the drainage groove wall 35 of the drainage groove 34 (not shown in the figure); the upper cover 1 is accommodated in the base 3 and is tightly fitted with the base 3; the elastic diaphragm 2 is provided between the upper cover 1 and the base 3.

[0048] In the above embodiment, preferably, the elastic diaphragm 2 does not block the water in the drainage groove 34 from flowing into the curved flow channel 14 .

[0049] In the above embodiment, preferably, the present invention further includes connecting protrusions 15 and connecting grooves 36; a plurality of connecting protrusions 15 are respectively arranged on the top and bottom of the upper cover 1, and a plurality of connecting grooves 36 are respectively arranged on the inner walls of the top and bottom of the base 3. When the upper cover 1 is accommodated in the base 3, the connecting protrusions 15 cooperate with the connecting grooves 36 to make the upper cover 1 tightly fit with the base 3.

[0050] In the above embodiment, preferably, the grid side of the base 3 is provided with an emitter screening groove 31 extending along the length direction of the base. The screening groove is used to unify the conveying direction in the production line during the emitter production process, and facilitate operations such as punching after bonding with the drip irrigation tape wall.

[0051] It should be noted that the height of the upper cover is 0.8-1.6mm, the width is 4.0mm-5.0mm, and the length is 9-20mm; the overall height of the base is 2.1-2.8mm, the width is 6.0mm, and the length is 10-20mm; the overall height is controlled between 2.1-2.8mm, the width is 5.0-7.0mm, and the length is controlled within the range of 10-30mm;

[0052] The water flow process is as follows: the water flows through the water inlet grille 32 at the base 3 for preliminary filtration and then enters the water inlet 33, thereby contacting the elastic diaphragm 2. Under the action of the water pressure difference, the elastic diaphragm 2 is deformed and contacts the curved flow channel 14 and the connecting boss 15 at the upper cover 1, changing the cross-sectional area of ​​the water outlet between the elastic diaphragm 2 and the water outlet 12. At the same time, the water flows through the drainage groove 34 to the other side of the elastic diaphragm 2, and then enters the curved flow channel 14, and then enters the water outlet boss 11, and flows out from the water outlet 12. Among them, the change of the elastic diaphragm 2 is mainly affected by the pressure difference between the upper and lower parts of the elastic diaphragm. Due to the energy dissipation effect of the curved flow channel 14, the greater the water inlet pressure, the greater the pressure difference between the upper and lower parts of the diaphragm, and thus the smaller the cross-sectional area of ​​the outflow between the diaphragm, the curved flow channel, and the water outlet, thereby achieving the purpose of constant flow.

[0053] like Figure 7 As shown, the optimization design method of the pressure compensating emitter provided by the present invention includes the following steps:

[0054] Model establishment: The configuration of pressure-compensated emitter is used as the basic model for model construction;

[0055] (1) Numerical simulation: The pressure-compensated emitter is simulated in the entire pressure change process using Star-ccm+ and abaqus combined bidirectional fluid-solid coupling to achieve diaphragm deformation and flow regulation. The model is simplified into a fluid domain calculation model and a solid domain calculation model, which are simulated and calculated in Star-ccm+ and abaqus respectively, and numerical transfer and coupling calculations are implemented in Star-ccm+;

[0056] (2) Improvement of anti-clogging ability: The coupling relationship between hydrodynamics and blocking materials was quantitatively analyzed by scanning-reconstruction-simulation method, and characteristic points were sampled and analyzed. Overall, the average thickness of the blockage under different blockage degrees showed a significant quadratic linear positive correlation with the near-wall shear force (R 2 >0.50, p<0.05, Figure 8); The accumulation of clogging materials showed a characteristic of first increasing and then decreasing with the increase of near-wall shear force. At the six operating times of 80h, 160h, 240h, 320h, 400h, and 480h, the near-wall shear forces corresponding to the peak accumulation of clogging materials were 0.363Pa, 0.335Pa, 0.349, 0.331, 0.352, and 0.353Pa, respectively; the interval where the absolute value of the slope of the fitting curve was less than 1 was defined as the shear force that was conducive to the growth of attached biofilms. The range of 0.18-0.50Pa can be obtained. This range should be avoided in the design of the emitter flow channel to improve the anti-clogging ability of the emitter. The flow channel optimization is based on the shear force control threshold near the flow channel wall. The vortex wall washing optimization design method is used to optimize the structure of the emitter flow channel, that is, the boundaries are connected by arcs. Considering the symmetry of vortex development, symmetrical optimization is adopted for the tooth tip water-facing area and the tooth root backwater area, and the tooth tip backwater area and the tooth root water-facing area of ​​the flow channel unit.

[0057] (3) Optimization of hydraulic performance: The main structural parameters affecting the performance of the pressure-compensating water emitter are the flow channel structural parameters and the diaphragm mechanical performance parameters; the flow channel in the pressure-compensating water emitter adopts the flow channel form after the vortex wall washing flow channel structure optimization design, and the structural parameters that need to be further determined are the flow channel depth, diaphragm elastic modulus, and diaphragm thickness. The diaphragm thickness and the flow channel depth are determined by the sum of the two parameters. In the comparison, only the diaphragm parameters are set for comparison. The diaphragm elastic modulus is set to 0.3-2.0MPa, and the diaphragm thickness is set to 0.5-1.5mm respectively; the numerical simulation method under the established full pressure field is used to determine the optimal parameters, and the pressure point flow simulation analysis is carried out between 0-0.40MPa to analyze its flow index. Under the premise that the flow index is less than 0.2, the structural parameter with the smallest flow index is the optimal structural parameter of this product.

[0058] In the above embodiment, preferably, the pressure-compensating emitter is simulated in the entire pressure change process using Star-ccm+ and abaqus combined bidirectional fluid-solid coupling to achieve diaphragm deformation and flow regulation. The model is simplified into a fluid domain calculation model and a solid domain calculation model, which are simulated and calculated in Star-ccm+ and abaqus respectively, and numerical transfer and coupling calculation are implemented in Star-ccm+, specifically including the following steps:

[0059] Region division: mainly divided into fluid domain and solid domain. The fluid domain consists of two parts: the fluid background domain and the fluid overlapping grid domain. The fluid background domain includes the fluid part, while the fluid overlapping grid domain is the elastic diaphragm part. The solid domain consists of two parts: the solid diaphragm calculation domain and the solid rigid bottom domain. The solid diaphragm calculation domain simplifies the elastic diaphragm. Since the diaphragm and the flow channel overlap, the overlapping part of the diaphragm is simplified into the form of the flow channel. The solid rigid bottom domain is used to avoid mesh distortion caused by excessive deformation of the elastic diaphragm solid domain in contact with the fluid domain. It restricts and repairs the mesh deformation of the solid domain.

[0060] Boundary conditions: Boundary conditions mainly include inlet boundary, inlet wall boundary, wall boundary, tooth tip boundary, outlet wall boundary, and outlet boundary. The boundary conditions of the solid domain are all set as FSI surfaces, and all interfaces of the solid domain are set as fluid-solid coupling surfaces. At the same time, constraints are added around the fluid domain to reduce its degrees of freedom. A rigid bottom layer is set at the outlet and boss position of the solid domain. The rigid bottom layer characteristics are set as surfaces to perform constraints on all sides.

[0061] Meshing: Overlapping meshes are used, and the meshing is divided into fluid domain meshes and solid domain meshes. The fluid domain mesh is expanded to form a background domain, which is overlapped with the solid domain mesh. After mesh independence verification, the fluid domain mesh is finally selected to use a cut-body mesh with a mesh size of 0.04 mm and a mesh number of 5.5 million. The solid domain mesh is selected to use a hexahedral mesh with a mesh size of 0.04 mm and a mesh number of 980,000.

[0062] Material properties: The materials used in the pressure-compensated emitter simulation are water and a flexible diaphragm. Since the actual diaphragm cannot be simulated accurately, the boundary conditions of the diaphragm are simplified and its material parameters are equivalent accordingly. The density of water is 1000 kg / m 3 , dynamic viscosity 0.001Pa.s; diaphragm density 1000kg / m 3 , elastic modulus 1.51MPa, Poisson's ratio 0.45, at the same time, the parameters of the rigid bottom layer are set, and its density is 7850kg / m 3 , elastic modulus 326GPa, Poisson's ratio 0.28;

[0063] Fluid-solid coupling method: The simulation of the pressure-compensated emitter uses star-ccm+ and abaqus coupling to realize diaphragm deformation and cut off or connect the flow channel. The flow field is calculated by star-ccm+, that is, the flow field information in the compensator under different pressures is calculated, and the pressure and shear force are mapped to the abaqus structure for deformation calculations such as displacement. Abaqus then transmits the displacement information to star-ccm+ to realize bidirectional fluid-solid coupling. The flow field calculation is based on the unsteady-state solution of the NS equation, and the turbulence model is the SST k-turbulence model; the solid diaphragm solution adopts an implicit unsteady-state solution.

[0064] Example 1:

[0065] Take the design of a pressure-compensating emitter with a flow rate of 1.6 L / h as an example to illustrate.

[0066] (1) Model establishment

[0067] use Figure 1-6 The pressure-compensating sprinkler product configuration shown is used to construct a simulation method for the basic model. It consists of three parts: an upper cover, a diaphragm, and a base. Its specific structural parameters are an overall height of 2.8 mm, a width of 6.0 mm, and a length of 15.7 mm. Among them, the upper cover has a height of 1.2 mm, a width of 4.8 mm, and a length of 14.9 mm; the lower cover has a height of 2.8 mm, a width of 6.0 mm, and a length of 15.7 mm.

[0068] (2) Numerical simulation method

[0069] The pressure-compensated emitter simulation uses Star-CCM+ and Abaqus for bidirectional fluid-structure coupling to achieve diaphragm deformation and flow regulation throughout the entire pressure change process. The model is simplified into a fluid domain model and a solid domain model, which are simulated and calculated in Star-CCM+ and Abaqus, respectively. Numerical transfer and coupling calculations are also implemented in Star-CCM+.

[0070] ①Regional division

[0071] Among them, the main areas of the fluid domain are divided into Figure 9 As shown in the figure, it mainly consists of two parts: the fluid background domain and the fluid overlapping grid domain. The fluid background domain includes the fluid part and the elastic diaphragm part, and the fluid overlapping grid domain consists of two entities, mainly the diaphragm part and the expansion part, and the elastic diaphragm area of ​​the two parts overlaps.

[0072] The main areas of the solid domain are divided into Figure 10As shown in the figure, it mainly consists of two parts: the solid diaphragm calculation domain and the solid rigid bottom domain. The solid diaphragm calculation domain mainly simplifies the elastic diaphragm. Since the diaphragm and the flow channel partially overlap, the overlapping part of the diaphragm is simplified to the form of the flow channel. The solid rigid bottom domain mainly avoids mesh distortion caused by excessive deformation of the elastic diaphragm solid domain and the fluid domain. It restricts and repairs the mesh deformation of the solid domain.

[0073] ②Boundary conditions

[0074] In order to realize the simulation of pressure compensation, the wall boundary conditions of the fluid domain and the solid domain are set respectively. The specific boundary conditions of the fluid domain are set as follows: Figure 11 As shown, the boundary conditions mainly include the inlet boundary, inlet wall boundary, wall boundary, tooth tip boundary, outlet wall boundary, and outlet boundary, and their positions are as follows: Figure 11 As shown in (a)-(f), the boundary conditions of the solid domain are all set as FSI surfaces, and all interfaces of the solid domain are set as fluid-solid coupling surfaces.

[0075] At the same time, constraints are added around the fluid domain to reduce its degrees of freedom. A rigid bottom layer is set at the outlet and boss position of the solid domain. The characteristics of the rigid bottom layer are set to surface, and constraints are applied on all sides to ensure smoother contact between the fluid domain and the solid domain and reduce the possibility of data divergence.

[0076] ③ Grid division

[0077] Aiming at the problem that negative volume grids are easily generated after the fluid domain and solid domain of the pressure-compensating water emitter come into contact, this structure adopts overlapping grids (overset grids) for grid division. In this paper, the grid division is divided into fluid domain grids and solid domain grids. The fluid domain grid is expanded to form a background domain, which is overlapped with the solid domain grid. After grid independence verification, the fluid grid is finally selected to use a cut-body grid with a grid size of 0.04 mm and a grid number of 5.5 million; the solid domain grid uses a hexahedral grid with a grid size of 0.04 mm and a grid number of 980,000.

[0078] ④Material properties

[0079] The materials used in the simulation of the pressure-compensated emitter are water and a flexible diaphragm. Since the actual diaphragm cannot be simulated realistically, the boundary conditions of the diaphragm are simplified and its material parameters are equivalent accordingly. The density of water is 1000kg / m 3 , dynamic viscosity 0.001Pa.s; diaphragm density 1000kg / m 3 , elastic modulus 1.51MPa, Poisson's ratio 0.45, at the same time, the parameters of the rigid bottom layer are set, and its density is 7850kg / m 3 , elastic modulus 326GPa, Poisson's ratio 0.28.

[0080] ⑤ Fluid-structure coupling method

[0081] The simulation of a pressure-compensated emitter uses Star-CCM+ and Abaqus coupled to implement diaphragm deformation and flow channel interruption or connection. Star-CCM+ calculates the flow field within the compensator at different pressures, mapping pressure and shear forces to the Abaqus structure for deformation calculations such as displacement. Abaqus then transmits this displacement information to Star-CCM+, enabling bidirectional fluid-structure interaction.

[0082] The flow field calculation is based on the unsteady-state solution of the NS equations, and the turbulence model is the SST k-turbulence model; the solid diaphragm solution adopts the implicit unsteady-state solution.

[0083] (3) Improved anti-clogging ability

[0084] The flow channel optimization approach uses a vortex-washing optimization design method to optimize the emitter flow channel structure, based on the shear force control threshold near the channel wall. This involves connecting the emitter's boundaries with circular arcs. Considering the symmetry of vortex development, symmetrical optimization is employed for the channel unit's front-end and back-end areas, and vice versa.

[0085] Based on the tooth-shaped flow channel, sawtooth-shaped flow channel and sawtooth arc-shaped flow channel commonly seen in current emitters, arcs of different radii are used to optimize the flow channel boundaries in the tooth tip backwater area and the tooth root frontwater area. The specific results are as follows: Figure 12 As shown. Figure 8 It can be seen that the flow channel forms are the same after optimization of different flow channel forms. At this time, the vortex is most fully developed, and its vortex rotation significantly increases the flow velocity near the wall. The water flow has the strongest ability to flush the near wall and transport particles. The self-cleaning ability of the emitter is the highest. Figure 8 The flow channel structure is the optimal structure after the emitter is optimized. Blocking substances are least likely to adhere and deposit, so its anti-blocking performance is the best.

[0086] (4) Optimizing hydraulic performance

[0087] The main structural parameters affecting the performance of pressure-compensating emitters are the flow channel structural parameters (width, length, and depth) and the diaphragm mechanical performance parameters (elastic modulus and thickness). The flow channel in this emitter adopts the optimized design of the vortex wall-washing flow channel structure. Therefore, the structural parameters that need to be further determined are the flow channel depth, diaphragm elastic modulus, and diaphragm thickness. The diaphragm thickness is determined by the sum of the flow channel depth. Therefore, only the diaphragm parameters are set for comparison in this comparison. The diaphragm elastic modulus is set to 1.1MPa, 1.2MPa, 1.3MPa, 1.4MPa, 1.5MPa, and 1.6MPa, and the diaphragm thickness is set to 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm, and 1.0mm, respectively.

[0088] ① Elastic modulus

[0089] The flow coefficient and discharge coefficient of the pressure compensation emitter under different elastic modulus of the elastic diaphragm are as follows: Figure 13 As shown in the figure, with the increase of elastic modulus, the flow index and flow coefficient both show an upward trend. Under the condition of elastic modulus of 1.1MPa, its flow index is 0.05 and the flow coefficient is 1.02. When the elastic modulus increases to 1.2MPa, 1.3MPa, 1.4MPa, 1.5MPa, and 1.6MPa, its flow index increases by 75.16%, 93.15%, 167.67%, 204.50%, and 285.44%, respectively, and its flow coefficient increases by 17.74%, 35.47%, 67.15%, 106.02%, and 201.07%, respectively. Therefore, under the same thickness conditions, a smaller elastic modulus will result in a smaller flow index, so an elastic modulus of 1.1MPa is selected.

[0090] ②Diaphragm thickness

[0091] The effects of different elastic diaphragm thicknesses on the flow coefficient and discharge coefficient of the pressure compensation emitter are analyzed under the elastic diaphragm of 1.1 MPa. Figure 14 As shown in the figure, the flow index and discharge coefficient both show a trend of first decreasing and then increasing with increasing diaphragm thickness. When the elastic diaphragm thickness is 0.5 mm, the flow index is 0.35 and the discharge coefficient is 18.02. When the elastic modulus increases to 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, and 1.0 mm, the flow index decreases by 28.90%, 86.60%, 72.45%, 56.56%, and 57.42%, respectively, and the discharge coefficient decreases by 61.29%, 94.33%, 93.10%, 82.15%, and 72.21%, respectively. Since the flow index is lowest at 0.7 mm, and the discharge coefficient is 1.6 at this time, it is recommended that the emitter diaphragm thickness be within the range of 0.7 mm.

[0092] Therefore, the structural parameters of this emitter product are as follows: overall height 2.8mm, width 6.0mm, length 15.7mm, of which the upper cover height 1.2mm, width 4.8mm, length 14.9mm, lower cover height 2.8mm, width 6.0mm, length 15.7mm, diaphragm hardness 1.3MPa, diaphragm thickness 0.7mm. Its flow index is 0.04, and flow index is 1.58.

[0093] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A method for optimizing the design of a pressure-compensating emitter, characterized in that: The steps include: Model establishment: The configuration of pressure-compensated emitter is used as the basic model for model construction; Numerical simulation: The pressure-compensated emitter uses Star-ccm+ and Abaqus combined with bidirectional fluid-solid coupling to simulate the deformation of the diaphragm and flow regulation during the entire pressure change process. The model is simplified into a fluid domain calculation model and a solid domain calculation model, which are simulated and calculated in Star-ccm+ and Abaqus respectively, and numerical transfer and coupling calculations are implemented in Star-ccm+. Improved anti-clogging capability: Flow channel optimization uses a vortex wall-washing optimization design method to optimize the emitter flow channel structure based on the shear force control threshold near the flow channel wall. This involves connecting the boundaries with circular arcs. Considering the symmetry of vortex development, symmetrical optimization is adopted for the tooth tip water-facing area and the tooth root backwater area, and vice versa. Optimizing hydraulic performance: The main structural parameters affecting the performance of pressure-compensating emitters are the flow channel structural parameters and the diaphragm mechanical performance parameters. The flow channel in the pressure-compensating emitter adopts the flow channel form after the optimized design of the vortex wall-washing flow channel structure. The structural parameters that need to be further determined are the flow channel depth, diaphragm elastic modulus, and diaphragm thickness. The numerical simulation specifically includes the following steps: Region division: divided into fluid domain and solid domain. The fluid domain consists of two parts: the fluid background domain and the fluid overlap grid domain. The fluid background domain includes the fluid part, while the fluid overlap grid domain is the elastic diaphragm part. The solid domain consists of two parts: the solid diaphragm calculation domain and the solid rigid bottom domain. The solid diaphragm calculation domain simplifies the elastic diaphragm. Since the diaphragm and the flow channel overlap, the overlapping part of the diaphragm is simplified into the form of the flow channel. The solid rigid bottom domain is used to avoid mesh distortion caused by excessive deformation of the elastic diaphragm solid domain when it contacts the fluid domain. It restricts and repairs the mesh deformation of the solid domain. Boundary conditions: Boundary conditions include the inlet boundary, inlet wall boundary, wall boundary, tooth tip boundary, outlet wall boundary, and outlet boundary. The boundary conditions of the solid domain are all set as FSI surfaces, and all interfaces of the solid domain are set as fluid-solid coupling surfaces. At the same time, constraints are added around the fluid domain to reduce its degrees of freedom. A rigid bottom layer is set at the outlet and boss position of the solid domain. The rigid bottom layer properties are set as surfaces to impose constraints on all sides. Meshing: Using overlapping meshes, the meshing is divided into fluid domain meshes and solid domain meshes. The fluid domain mesh is expanded to form a background domain, which is overlapped with the solid domain mesh. After mesh independence verification, the fluid domain mesh is finally selected as the cutting body mesh. Material properties: The materials used in the pressure-compensating emitter simulation are water and a flexible diaphragm. Since the actual diaphragm cannot be realistically simulated in the simulation, the boundary conditions of the diaphragm are simplified and its material parameters are equivalent accordingly. Fluid-solid coupling method: The simulation of the pressure-compensated emitter uses star-ccm+ and abaqus coupling to realize diaphragm deformation and cut off or connect the flow channel. The flow field is calculated by star-ccm+, that is, the flow field information in the compensator under different pressures is calculated, and the pressure and shear force are mapped to the abaqus structure for displacement deformation calculation. Abaqus then transmits the displacement information to star-ccm+ to realize bidirectional fluid-solid coupling. The flow field calculation is based on the unsteady-state solution of the NS equation, and the turbulence model is the SST k-turbulence model; the solid diaphragm solution adopts an implicit unsteady-state solution.

2. The optimization design method of the pressure-compensating emitter according to claim 1, characterized in that: The pressure compensating emitter comprises: An upper cover is provided with a curved flow channel and a water outlet slow flow pool, a water outlet boss is provided at the center of the water outlet slow flow pool, and a water outlet is provided on the water outlet boss; The base is a recessed structure, with a water inlet grille provided on one side of the base and a water inlet provided on the other side, the water inlet being connected to the water inlet grille; a drainage groove extending along its width is provided at one end of the base, the drainage groove being opposite to the head end of the curved flow channel on the upper cover, and an opening being provided on the drainage groove wall of the drainage groove; the upper cover is accommodated in the base and tightly fits with the base; The elastic diaphragm is arranged between the upper cover and the base.

3. The optimization design method of the pressure-compensating emitter according to claim 2, characterized in that: The elastic diaphragm does not block the water in the drainage groove from flowing into the curved flow channel; Among them, it also includes a connecting convex seat and a connecting groove; Several connecting protrusions are respectively arranged on the top and bottom of the upper cover, and several connecting grooves are respectively arranged on the inner walls of the top and bottom of the base. When the upper cover is accommodated in the base, the connecting protrusions cooperate with the connecting grooves to make the upper cover tightly fit with the base.

4. The optimization design method of the pressure-compensating emitter according to claim 2, characterized in that: The grille side of the base is provided with an emitter screening slot extending along the length direction of the base.

Images