Desilting performance simulation improving method and sheet type drip irrigation tape device

Abstract

The invention discloses a desilting performance simulation improving method and a sheet type drip irrigation belt device, and relates to the field of drip irrigation belts of drip irrigation systems. The desilting performance simulation improving method comprises the following steps: constructing a high-precision sediment transportation simulation model through a sediment motion equation; constructing a water flow simulation model; the structural configuration of the bidirectional flow channel sheet type drip irrigation tape is constructed, and structural parameters are set as flow channel width, flow channel depth and the number of positive and negative flow channel units; the hydraulic performance and the anti-blocking performance of the drip irrigation belt are cooperatively improved, and an optimal structure parameter threshold value is obtained; the sheet type drip irrigation belt device with high hydraulic performance and desilting performance is obtained; a high-precision sediment transportation simulation model of the flow channel of the drip irrigation belt is constructed, water flow simulation of the drip irrigation belt is carried out, and technical support is provided for hydraulic performance simulation and sediment discharge capacity numerical simulation; and meanwhile, the structure configuration of the bidirectional flow channel sheet type drip irrigation tape is constructed, the influence of different structure parameters on the performance of the drip irrigation tape is analyzed, and the high-performance structure control threshold value of the bidirectional flow channel sheet type drip irrigation tape is determined.

Description

Technical Field

[0001] The invention relates to the field of drip irrigation tapes of a drip irrigation system, and in particular to a sand discharge performance simulation improvement method and a sheet-type drip irrigation tape device. Background Art

[0002] Water shortage has become one of the key factors restricting sustainable agricultural production. Drip irrigation is considered to be one of the irrigation technologies with the greatest water-saving potential due to its precise and controllable water supply. Therefore, the development of drip irrigation for high-sand-content water is seen as an effective strategy to alleviate agricultural water shortage.

[0003] In the prior art, for example, ZL2009101807695 proposes an anti-clogging design method for emitters that eliminates the locations where suspended particles accumulate in the flow channel. The method first constructs a geometric structural model of the flow channel inside the drip irrigation emitter, and then numerically simulates the flow channel model using a computational fluid dynamics (CFD) solid-liquid two-phase flow model based on the boundary conditions. The cross-section with the percentage of suspended particle content at half of the flow channel is extracted, and the flow channel model is modified according to the minimum suspended particle concentration curve. Finally, the flow channel shape with the maximum suspended particle concentration closest to the inlet suspended particle concentration is selected. However, this method modifies the flow channel model boundary according to the minimum particle suspension concentration curve, fails to propose an index system and method for optimizing the emitter's sediment discharge capacity, and cannot achieve a coordinated improvement in hydraulic performance and sediment discharge performance.

[0004] ZL2006100184937 proposed an anti-clogging design method for drip irrigation emitters based on two-phase flow simulation. Through numerical simulation of the two-phase flow field within the emitter, the simulation results were used to analyze the areas in the flow channel where solids are most likely to deposit, and then the influence of the flow channel structure on the migration and deposition characteristics of the solids was analyzed. However, this method did not propose an emitter's sediment discharge capacity index or simulation method, nor did it mention an emitter optimization design method that synergistically improves hydraulic performance and sediment discharge performance.

[0005] Therefore, a method for simulating and improving sand discharge performance and a sheet-type drip irrigation belt device are provided to solve the above problems. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for simulating and improving sediment discharge performance and a sheet-type drip irrigation belt device, aiming to develop a high-precision sediment transport simulation model for the emitter flow channel, create an emitter sediment discharge capacity evaluation system based on the simulation method, and apply it to the emitter water flow and sediment simulation, propose a method for synergistically improving the hydraulic performance and anti-clogging performance of the emitter, and develop a sheet-type emitter product based on a bidirectional flow channel.

[0007] To achieve the above object, the present invention provides a method for simulating and improving sand discharge performance, comprising the following steps:

[0008] S1: Define the governing equations for sediment transport in a bidirectional channel;

[0009] S2: Construct a high-precision sediment transport simulation model using sediment motion equations;

[0010] S3: Build a water flow simulation model;

[0011] S4: Construct the structural configuration of the bidirectional flow channel sheet drip irrigation belt, and set the structural parameters as the flow channel width, flow channel depth and the number of forward and reverse flow channel units;

[0012] S5: Calculate the weights of hydraulic performance and anti-clogging performance based on the AHP-EWM method and construct an evaluation system;

[0013] S6: Comprehensively evaluate the hydraulic performance and anti-clogging performance of drip irrigation belts with different parameters to obtain the optimal structural parameter threshold;

[0014] S7: A sheet-type drip irrigation tape device that achieves high hydraulic performance and sand discharge performance.

[0015] Preferably, step S1 specifically includes the following steps:

[0016] S11: Set the sediment density to 2800 kg / m 3 ;

[0017] S12: Obtain the kinematic equation of a single particle. The kinematic equation of a single particle is specifically set as:

[0018]

[0019] Among them, m p represents the particle mass, v p represents the particle velocity, t represents time, F g,b is the combined force of gravity and buoyancy, F D Indicates the drag force, F L represents the saffman lift, F turb represents the turbulent diffusion force.

[0020] Preferably, step S2 specifically includes the following steps:

[0021] S21: Calculate the resultant force F of gravity and buoyancy g,b , the resultant force of gravity and buoyancy is F g,b The specific settings are:

[0022]

[0023] Among them, F g Represents gravity, F b represents buoyancy, d p represents the particle size, ρ prepresents the particle density, g represents the acceleration due to gravity, ρ f represents the fluid density;

[0024] S22: Calculate the drag force F D , drag force F D The specific settings are:

[0025]

[0026] Where μ represents the fluid viscosity, C D Represents the resistance coefficient, Re p represents the Reynolds number, v f represents the fluid vector, v p represents the particle vector;

[0027] S23: Calculate the saffman lift F L , saffman lift F L The specific settings are:

[0028] F L =C L ρ f ν 0.5 |v f -v p |(ω×(v f -v p ))

[0029] Among them, C L represents the lift coefficient, ν represents the kinematic viscosity, and ω represents the fluid vortex vector;

[0030] S24: Calculation of turbulent diffusion force F turb , turbulent diffusion force F turb The specific settings are:

[0031]

[0032] Where ξ represents a random variable and k represents the turbulent kinetic energy.

[0033] Preferably, step S3 specifically includes the following steps:

[0034] S31: Construct the RNGk-ε turbulence model in the Euler framework, simulate the water flow through the time-averaged three-dimensional steady-state Navier-Stokes and continuity equations, and set the density of the continuous water phase to 998.2 kg / m 3 , the viscosity of the continuous aqueous phase was set to 0.001 kg / ms;

[0035] S32: The water inlet is set to a pressure inlet, and the pressures of the pressure inlet include 0 MPa, 0.02 MPa, 0.04 MPa, 0.06 MPa, 0.08 MPa, 0.10 MPa, 0.12 MPa and 0.14 MPa;

[0036] S33: Set the outlet as a pressure outlet, and set the pressure of the pressure outlet to 0 MPa;

[0037] S34: Use the Rebound boundary to simulate the collision of sediment particles on the wall, set the normal rebound coefficient to 0.10-0.50, and the tangential rebound coefficient to 0.30-0.90;

[0038] S35: Based on the original sediment particle data, the mixed particle size of the sediment was fitted with the Rosin-Rammler function, and the diffusion parameter was set to 1.30;

[0039] S36: Solve the pressure-velocity coupling using the SIMPLEC algorithm, set the difference format to the second-order upwind format, and set the convergence accuracy to 10 -4 .

[0040] Preferably, in step S35, the fitting formula is specifically set to:

[0041]

[0042] Among them, Y d represents the particle diffusion coefficient.

[0043] Preferably, step S5 specifically includes the following steps:

[0044] S51: Test the hydraulic performance of the drip irrigation tape, measure the outflow rate of the drip irrigation tape by weighing, and calculate the flow index and flow coefficient of the drip irrigation tape;

[0045] S52: Test the sediment discharge capacity of the drip irrigation tape, measure the dry weight of the outflow of the drip irrigation tape by weighing, and calculate the sediment discharge ratio Sediment deposition discharge ratio The specific settings are:

[0046]

[0047] Where m represents the dry weight of the drip irrigation tape during flow measurement, and the unit of the dry weight of the drip irrigation tape is g / m3; ρ represents the sediment concentration of the drip irrigation tape outflow, and the unit of the sediment concentration ρ of the drip irrigation tape outflow is g / L; v represents the cumulative irrigation volume, and the unit of the cumulative irrigation volume v is L.

[0048] S53: Flow index, discharge coefficient and sediment discharge ratio The evaluation index was set as the evaluation index, and the influence of different structural parameters on the hydraulic performance and sediment discharge capacity of the drip irrigation belt was tested by the AHP-EWM method.

[0049] Preferably, step S6 specifically includes the following steps:

[0050] S61: Convective Flow Index, Discharge Coefficient, and Sediment Deposition Discharge Ratio Normalization was performed, and the flow index ratio was set to 0.4, the discharge coefficient ratio was set to 0.1, and the sediment discharge ratio was set to The ratio is set to 0.5;

[0051] S62: Calculate the subjective weights through the analytic hierarchy process (AHP) and construct a judgment matrix for each evaluation indicator. The specific method for constructing the judgment matrix is as follows:

[0052] A ij =(a ij ) n×n

[0053] Among them, a ij Indicates a in the evaluation system i to a j The importance level is expressed as 1, 2, 3, and 4, indicating equal, slightly, stronger, and extremely important, respectively;

[0054] The judgment matrix is checked for consistency. The specific consistency check method is set as:

[0055]

[0056] Among them, λ max represents the maximum eigenvalue of the judgment matrix, CI represents the consistency index of the judgment matrix, RI represents the average consistency index, CR represents the random consistency ratio, and when the random consistency ratio CR is less than 0.1, the judgment matrix passes the consistency test;

[0057] After the consistency test is passed, the subjective weight of each evaluation index in the judgment matrix is analyzed using yaahp software AHP ;

[0058] S63: Standardize the evaluation indicators through evaluation indicator standardization, and distinguish between positive and negative indicators based on the correlation between the evaluation indicators and the comprehensive benefit score;

[0059] S64: After the normalization process, the objective weight is calculated using the entropy weight method (EWM), and the elements in the normalization matrix are converted into probability values to obtain a probability matrix P. The specific conversion method is set as follows:

[0060]

[0061] Among them, P ij It represents the proportion of the i-th data in the j-th indicator in the evaluation system;

[0062] Calculate the difference coefficient G and objective weight ω of each indicator EWM , the specific calculation method of the difference coefficient G is set as:

[0063]

[0064] Among them, G j represents the coefficient of variation of the jth indicator;

[0065] Objective weight ω EWM The specific calculation method is set as:

[0066]

[0067] Among them, ω EWMj represents the objective weight of the jth indicator;

[0068] S65: Calculate the combined weight ω of the AHP-EWM method evaluation. The specific calculation method of the combined weight ω is set as:

[0069]

[0070] Preferably, in step S63, the standardization processing method is specifically set as follows:

[0071]

[0072] Among them, y represents the standardized value of each evaluation index, x represents the measured value of each evaluation index, and x max Indicates the maximum value of each evaluation index, x min Indicates the minimum measurement value of each evaluation index.

[0073] A sheet-type drip irrigation tape device with a simulated sand discharge performance improvement method includes a bidirectional flow channel and a water inlet arranged under the bidirectional flow channel. The flow channel depth of the bidirectional flow channel is set to 0-0.8 mm, the flow channel width of the bidirectional flow channel is set to 0-0.8 mm, the bidirectional flow channel includes a forward flow channel and a reverse flow channel, and the number of units of the forward flow channel and the reverse flow channel is set to 0-18.

[0074] Therefore, the present invention adopts the above-mentioned sand discharge performance simulation and improvement method and the sheet-type drip irrigation belt device, which has the following beneficial effects:

[0075] (1) This proposal proposes a high-precision sediment transport simulation model for the drip irrigation belt flow channel, constructs the sediment particle motion equation under the influence of gravity, buoyancy, drag force, Saffman lift, and turbulent diffusion force, clarifies the rebound coefficient of the sediment wall of the drip irrigation belt, and proposes the sediment discharge capacity with the sediment deposition and discharge ratio as an indicator. The accuracy is compared between simulation and actual measurement, and the simulation error is within 10%, which solves the problem of unclear sediment transport process and poor simulation accuracy in the sheet drip irrigation belt;

[0076] (2) This scheme proposes a bidirectional flow channel sheet drip irrigation belt structure configuration. The sheet drip irrigation belt flow channel consists of two parts: a forward flow channel and a reverse flow channel. The combination of the forward and reverse flow channels cleverly achieves the counter-energy dissipation between the mainstream area and the non-mainstream area, improves the hydraulic performance, and improves the sediment entrainment capacity of the mainstream area. It can also significantly improve the self-sand discharge capacity and anti-negative suction capacity of the flow channel, effectively improving the sediment discharge capacity of the drip irrigation belt while reducing the blockage problem caused by the negative pressure mud suction effect;

[0077] (3) This proposal proposes a method for synergistically improving the hydraulic performance and sediment discharge capacity of drip irrigation belts, systematically analyzes the influence of flow channel width, depth and the number of forward and reverse flow channel units on the hydraulic performance and sediment discharge capacity, and constructs a drip irrigation belt hydraulic performance and sediment discharge capacity evaluation system based on the AHP-EWM method. It proposes a synergistic improvement method that can synergistically improve the hydraulic performance and sediment discharge capacity, clarifies the high-performance structure control threshold of the bidirectional flow channel sheet drip irrigation belt, and obtains a sheet drip irrigation belt device with high hydraulic performance and sediment discharge capacity.

[0078] The method scheme of the present invention is further described in detail below through the drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 This is a flow chart of a method for simulating and improving sand discharge performance according to the present invention;

[0080] Figure 2 Schematic diagram of the model verification results of an embodiment of the present invention, wherein (a) flow verification results; (b) sediment deposition discharge ratio verification results;

[0081] Figure 3 Schematic diagram of flow characteristics of the reverse flow channel and the forward flow channel according to an embodiment of the present invention;

[0082] Figure 4 Schematic diagram of hydraulic performance and sediment discharge capacity of different structural parameters in some experiments of the embodiment of the present invention, including (a) flow index; (b) discharge coefficient; (c) sediment deposition and discharge ratio;

[0083] Figure 5 This is a structural diagram of a sheet-type drip irrigation tape device of the present invention.

[0084] Among them: 1. Water inlet; 2. Bidirectional flow channel; 3. Forward flow channel; 4. Reverse flow channel; W, flow channel width; D, flow channel depth. DETAILED DESCRIPTION

[0085] The method scheme of the present invention is further described below through the drawings and examples.

[0086] Unless otherwise defined, technical terms or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0087] The words “include” or “comprising” and similar words used in the present invention mean that the elements before the word include the elements listed after the word, and do not exclude the possibility of also including other elements. The orientation or position relationship indicated by the terms “inside”, “outside”, “upper”, “lower”, etc. is based on the orientation or position relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation of the present invention. When the absolute position of the described object changes, the relative position relationship may also change accordingly. In the present invention, unless otherwise clearly stipulated and limited, the terms such as “attachment” should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral whole; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0088] Example

[0089] like Figure 1 As shown, the present invention provides a method for simulating and improving sand discharge performance, comprising the following steps:

[0090] S1: Define the governing equations for sediment transport in a bidirectional channel;

[0091] Step S1 specifically includes the following steps:

[0092] S11: Set the sediment density to 2800 kg / m 3 ;

[0093] S12: Obtain the kinematic equation of a single particle, and track its motion trajectory through the kinematic equation of the single particle. The kinematic equation of the single particle is specifically set as:

[0094]

[0095] Among them, m p represents the particle mass, v prepresents the particle velocity, t represents time, F g,b is the combined force of gravity and buoyancy, F D Indicates the drag force, F L represents the saffman lift, F turb represents the turbulent diffusion force.

[0096] S2: Construct a high-precision sediment transport simulation model using sediment motion equations;

[0097] Step S2 specifically includes the following steps:

[0098] S21: Since the density of sediment is much greater than that of water, its gravity F is considered. g and buoyancy F b The sedimentation effect caused by the combined force of gravity and buoyancy F g,b The specific settings are:

[0099]

[0100] Among them, F g Represents gravity, F b represents buoyancy, d p represents the particle size, ρ p represents the particle density, g represents the acceleration due to gravity, ρ f represents the fluid density;

[0101] S22: The water flow speed inside the drip irrigation belt is usually fast, and the sediment particles will be affected by a significant drag force, so the drag force F is considered. D The influence of drag force F D The specific settings are:

[0102]

[0103] Where μ represents the fluid viscosity, C D Represents the resistance coefficient, Re p represents the Reynolds number, v f represents the fluid vector, v p represents the particle vector;

[0104] S23: The flow inside the drip irrigation belt may have shear flow fields, such as contraction-expansion zone, secondary flow and vortex, etc. L It will affect the movement trajectory of sediment, saffman lift F L The specific settings are:

[0105] F L =C L ρ f ν 0.5 |v f -v p|(ω×(v f -v p ))

[0106] Among them, C L represents the lift coefficient, ν represents the kinematic viscosity, and ω represents the fluid vortex vector;

[0107] S24: The flow field inside the drip irrigation belt is usually turbulent. Random turbulence will affect the diffusion of small particles, making them randomly distributed in space. Therefore, the turbulent diffusion force F is considered. turb The influence of turbulent diffusion force F turb The specific settings are:

[0108]

[0109] Where ξ represents a random variable and k represents the turbulent kinetic energy.

[0110] S3: Build a water flow simulation model;

[0111] Step S3 specifically includes the following steps:

[0112] S31: Water flow is treated as a continuous phase in the Euler framework. The RNGk-ε turbulence model is constructed in the Euler framework. The water flow motion is simulated by the time-averaged three-dimensional steady-state Navier-Stokes and continuity equations. The density of the continuous water phase is set to 998.2 kg / m 3 , the viscosity of the continuous aqueous phase was set to 0.001 kg / ms;

[0113] S32: The water inlet is set to a pressure inlet, and the pressures of the pressure inlet include 0 MPa, 0.02 MPa, 0.04 MPa, 0.06 MPa, 0.08 MPa, 0.10 MPa, 0.12 MPa and 0.14 MPa;

[0114] S33: Set the outlet as a pressure outlet, and set the pressure of the pressure outlet to 0 MPa;

[0115] S34: Use the Rebound boundary to simulate the collision of sediment particles on the wall, set the normal rebound coefficient to 0.10-0.50, and the tangential rebound coefficient to 0.30-0.90;

[0116] S35: Based on the original sediment particle data, the mixed particle size of the sediment was fitted with the Rosin-Rammler function, and the diffusion parameter was set to 1.30;

[0117] In step S35, the fitting formula is specifically set to:

[0118]

[0119] Among them, Yd represents the particle diffusion coefficient.

[0120] S36: Solve the pressure-velocity coupling using the SIMPLEC algorithm, set the difference format to the second-order upwind format, and set the convergence accuracy to 10 -4 .

[0121] S4: As Figure 3 As shown in the figure, the structural configuration of the bidirectional flow channel sheet drip irrigation belt is constructed, which consists of a reverse flow channel and a forward flow channel. The flow channel has a strong counteraction effect, and the difference between the forward and reverse flows is large. The structural parameters are set as the flow channel width, flow channel depth and the number of forward and reverse flow channel units;

[0122] S5: Synergistically improve the hydraulic performance and anti-clogging performance of the drip irrigation belt to obtain the optimal structural parameter threshold;

[0123] Step S5 specifically includes the following steps:

[0124] S51: Test the hydraulic performance of the drip irrigation tape. Since outdoor tests are easily affected by the environment, which may cause test and measurement deviations, the outflow rate of the drip irrigation tape is measured by weighing method, and the flow index and flow coefficient of the drip irrigation tape are calculated.

[0125] S52: Test the sediment discharge capacity of the drip irrigation tape by measuring the dry weight of the outflow of the drip irrigation tape by weighing. Use a 300mL sampling bottle to collect samples at the water source and the outflow of the drip irrigation tape, and calculate the sediment discharge ratio. Sediment deposition discharge ratio The specific settings are:

[0126]

[0127] Where m represents the dry weight of the drip irrigation tape during flow measurement, and the unit of the dry weight of the drip irrigation tape is g / m3; ρ represents the sediment concentration of the drip irrigation tape outflow, and the unit of the sediment concentration ρ of the drip irrigation tape outflow is g / L; v represents the cumulative irrigation volume, and the unit of the cumulative irrigation volume v is L.

[0128] like Figure 2 As shown, in this embodiment, the flow rate and sediment deposition discharge ratio test of four drip irrigation belts E1, E2, E3, and E4 are carried out. The simulated flow rate is smaller than the measured flow rate, but the deviation is between 3.68% and 6.86%. The results of the simulated sediment deposition discharge ratio are smaller than the measured results, and the deviation is between 4.69% and 10.59%. Therefore, this simulation method is relatively reliable.

[0129] S53: Flow index, discharge coefficient and sediment discharge ratio The evaluation index was set as the evaluation index, and the influence of different structural parameters on the hydraulic performance and sediment discharge capacity of the drip irrigation belt was tested by the AHP-EWM method.

[0130] S6: Comprehensively evaluate the hydraulic performance and anti-clogging performance of drip irrigation belts with different parameters to obtain the optimal structural parameter threshold;

[0131] Step S6 specifically includes the following steps:

[0132] S61: Convective Flow Index, Discharge Coefficient, and Sediment Deposition Discharge Ratio Normalization was performed, and the flow index ratio was set to 0.4, the discharge coefficient ratio was set to 0.1, and the sediment discharge ratio was set to The ratio is set to 0.5;

[0133] S62: Calculate the subjective weights through the analytic hierarchy process (AHP). According to the broad bean measurement indicators, a hierarchical structure system for the corresponding crops is constructed, and a judgment matrix for each evaluation indicator is constructed. The specific method for constructing the judgment matrix is set as follows:

[0134] A ij =(a ij ) n×n

[0135] Among them, a ij Indicates a in the evaluation system i to a j The importance level is expressed as 1, 2, 3, and 4, indicating equal, slightly, stronger, and extremely important, respectively;

[0136] The judgment matrix is checked for consistency. The specific consistency check method is set as:

[0137]

[0138] Among them, λ max represents the maximum eigenvalue of the judgment matrix, CI represents the consistency index of the judgment matrix, RI represents the average consistency index, and the average consistency index RI can be obtained by looking up the table, CR represents the random consistency ratio, and when the random consistency ratio CR is less than 0.1, the judgment matrix passes the consistency test;

[0139] After the consistency test is passed, the subjective weight of each evaluation index in the judgment matrix is analyzed using yaahp software AHP ;

[0140] S63: Standardize the evaluation indicators through evaluation indicator standardization, and distinguish between positive and negative indicators based on the correlation between the evaluation indicators and the comprehensive benefit scores, where the higher the indicator, the better, that is, the positive indicator;

[0141] In step S63, the standardization processing method is specifically set as follows:

[0142]

[0143] Among them, y represents the standardized value of each evaluation index, x represents the measured value of each evaluation index, and x max Indicates the maximum value of each evaluation index, x min Indicates the minimum measurement value of each evaluation index.

[0144] S64: After the normalization process, the objective weight is calculated using the entropy weight method (EWM), and the elements in the normalization matrix are converted into probability values to obtain a probability matrix P. The specific conversion method is set as follows:

[0145]

[0146] Among them, P ij It represents the proportion of the i-th data in the j-th indicator in the evaluation system;

[0147] Calculate the difference coefficient G and objective weight ω of each indicator EWM , the specific calculation method of the difference coefficient G is set as:

[0148]

[0149] Among them, G j represents the coefficient of variation of the jth indicator;

[0150] Objective weight ω EWM The specific calculation method is set as:

[0151]

[0152] Among them, ω EWMj represents the objective weight of the jth indicator;

[0153] S65: Calculate the combined weight ω of the AHP-EWM method evaluation. The specific calculation method of the combined weight ω is set as:

[0154]

[0155] S7: A sheet-type drip irrigation tape device that achieves high hydraulic performance and sand discharge performance.

[0156] Therefore, the control thresholds of the emitter with high hydraulic performance and sediment discharge capacity were finally determined as follows: the number of forward flow channel units is 0-18, the number of reverse flow channel units is 0-18, the width of the flow channel unit is 0-0.8mm, and the depth of the flow channel unit is 0-0.8mm;

[0157] like Figure 4As shown in the figure, if a 1.0L / h sheet-type drip irrigation belt with high hydraulic performance and sand drainage capacity is required to be developed, the control threshold of the emitter with high hydraulic performance and sand drainage capacity is used to make preliminary parameter determination. The number of forward and reverse flow channel units has a great influence on its performance. According to preliminary tests, when the total number of flow channel units is less than 9, the emitter will spray water instead of dripping.

[0158] In order to achieve a lower cost investment, the present invention intends to use a total of 9 flow channel units, of which the number of forward flow channel units is 0-9, and the corresponding number of reverse flow channel units is 9-0. At the same time, the flow channel unit widths are set to 0.25mm, 0.40mm, 0.55mm, and 0.70mm; the depths are 0.25mm, 0.40mm, 0.55mm, and 0.70mm, for a total of 160 groups of treatments;

[0159] The results were weighted using the AHP-EWM method and comprehensively evaluated. The optimal result was obtained when the flow channel depth was 0.5 mm, the width was 0.4 mm, the number of forward flow channel units was 6, and the number of reverse flow channel units was 3. These results were then used as the final parameters for the 1.0 L / h sheet-type sprinkler product.

[0160] like Figure 5 As shown, a sheet-type drip irrigation tape device with a simulated sand discharge performance improvement method includes a bidirectional flow channel 2 and a water inlet 1 arranged under the bidirectional flow channel 2. The flow channel depth D and the flow channel width W of the bidirectional flow channel 2 are both set to 0-0.8 mm. The bidirectional flow channel 2 includes a forward flow channel 3 and a reverse flow channel 4. The number of units of the forward flow channel 3 and the reverse flow channel 4 are both set to 0-18.

[0161] Therefore, the present invention adopts the above-mentioned sand discharge performance simulation and improvement method and sheet-type drip irrigation belt device, constructs a high-precision sediment transport simulation model of the drip irrigation belt flow channel, performs drip irrigation belt water flow simulation, and provides technical support for hydraulic performance simulation and sand discharge capacity numerical simulation; at the same time, it constructs a bidirectional flow channel sheet-type drip irrigation belt structural configuration, analyzes the influence of different structural parameters on the performance of the drip irrigation belt, clarifies the high-performance structure control threshold of the bidirectional flow channel sheet-type drip irrigation belt, and develops a sheet-type drip irrigation belt device with high hydraulic performance and sand discharge capacity.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the method scheme of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary method personnel in this field should understand that they can still modify or replace the method scheme of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified method scheme to deviate from the spirit and scope of the method scheme of the present invention.

Claims

1. A method for simulating and improving sand discharge performance, characterized in that: The following steps are involved: S1: Define the governing equations for sediment transport in a bidirectional channel; S2: Construct a high-precision sediment transport simulation model using sediment motion equations; S3: Build a water flow simulation model; S4: Construct the structural configuration of the bidirectional flow channel sheet drip irrigation belt, and set the structural parameters as the flow channel width, flow channel depth and the number of forward and reverse flow channel units; S5: Calculate the weights of hydraulic performance and anti-clogging performance based on the AHP-EWM method and construct an evaluation system; S6: Comprehensively evaluate the hydraulic performance and anti-clogging performance of drip irrigation belts with different parameters to obtain the optimal structural parameter threshold; S7: A sheet-type drip irrigation tape device that achieves high hydraulic performance and sand discharge performance.

2. A sand removal performance simulation improvement method according to claim 1, characterized in that: Step S1 specifically includes the following steps: S11: Set the sediment density to 2800 kg / m 3 ; S12: Obtain the kinematic equation of a single particle. The kinematic equation of a single particle is specifically set as: Among them, m p represents the particle mass, v p represents the particle velocity, t represents time, F g,b is the combined force of gravity and buoyancy, F D Indicates the drag force, F L represents the saffman lift, F turb represents the turbulent diffusion force.

3. The method for simulating and improving sand discharge performance according to claim 1, characterized in that: Step S2 specifically includes the following steps: S21: Calculate the resultant force F of gravity and buoyancy g,b , the resultant force of gravity and buoyancy is F g,b The specific settings are: Among them, F g Represents gravity, F b represents buoyancy, d p represents the particle size, ρ p represents the particle density, g represents the acceleration due to gravity, ρ f represents the fluid density; S22: Calculate the drag force F D , drag force F D The specific settings are: Where μ represents the fluid viscosity, C D Represents the resistance coefficient, Re p represents the Reynolds number, v f represents the fluid vector, v p represents the particle vector; S23: Calculate the saffman lift F L , saffman lift F L The specific settings are: F L =C L ρ f ν 0.5 |v f -v p |(ω×(v f -v p )) Among them, C L represents the lift coefficient, ν represents the kinematic viscosity, and ω represents the fluid vortex vector; S24: Calculation of turbulent diffusion force F turb , turbulent diffusion force F turb The specific settings are: Where ξ represents a random variable and k represents the turbulent kinetic energy.

4. The method for simulating and improving sand discharge performance according to claim 1, characterized in that: Step S3 specifically includes the following steps: S31: Construct the RNGk-ε turbulence model in the Euler framework, simulate the water flow through the time-averaged three-dimensional steady-state Navier-Stokes and continuity equations, and set the density of the continuous water phase to 998.2 kg / m 3 , the viscosity of the continuous aqueous phase was set to 0.001 kg / ms; S32: The water inlet is set to a pressure inlet, and the pressures of the pressure inlet include 0 MPa, 0.02 MPa, 0.04 MPa, 0.06 MPa, 0.08 MPa, 0.10 MPa, 0.12 MPa and 0.14 MPa; S33: Set the outlet as a pressure outlet, and set the pressure of the pressure outlet to 0 MPa; S34: Use the Rebound boundary to simulate the collision of sediment particles on the wall, set the normal rebound coefficient to 0.10-0.50, and the tangential rebound coefficient to 0.30-0.90; S35: Based on the original sediment particle data, the mixed particle size of the sediment was fitted with the Rosin-Rammler function, and the diffusion parameter was set to 1.30; S36: Solve the pressure-velocity coupling using the SIMPLEC algorithm, set the difference format to the second-order upwind format, and set the convergence accuracy to 10 -4 .

5. A sand removal performance simulation and improvement method according to claim 4, characterized in that: In step S35, the fitting formula is specifically set to: Among them, Y d represents the particle diffusion coefficient.

6. The method for simulating and improving sand removal performance according to claim 1, characterized in that: Step S5 specifically includes the following steps: S51: Test the hydraulic performance of the drip irrigation tape, measure the outflow rate of the drip irrigation tape by weighing, and calculate the flow index and flow coefficient of the drip irrigation tape; S52: Test the sediment discharge capacity of the drip irrigation tape, measure the dry weight of the outflow of the drip irrigation tape by weighing, and calculate the sediment discharge ratio Sediment deposition discharge ratio The specific settings are: Where m represents the dry weight of the drip irrigation tape during flow measurement, and the unit of the dry weight of the drip irrigation tape is g / m3; ρ represents the sediment concentration of the drip irrigation tape outflow, and the unit of the sediment concentration ρ of the drip irrigation tape outflow is g / L; v represents the cumulative irrigation volume, and the unit of the cumulative irrigation volume v is L. S53: Flow index, discharge coefficient and sediment discharge ratio The evaluation index was set as the evaluation index, and the influence of different structural parameters on the hydraulic performance and sediment discharge capacity of the drip irrigation belt was tested by the AHP-EWM method.

7. The method for simulating and improving sand removal performance according to claim 1, characterized in that: Step S6 specifically includes the following steps: S61: Convective Flow Index, Discharge Coefficient, and Sediment Deposition Discharge Ratio Normalization was performed, and the flow index ratio was set to 0.4, the discharge coefficient ratio was set to 0.1, and the sediment discharge ratio was set to The ratio is set to 0.5; S62: Calculate the subjective weights through the analytic hierarchy process (AHP) and construct a judgment matrix for each evaluation indicator. The specific method for constructing the judgment matrix is as follows: A ij =(a ij ) n×n Among them, a ij Indicates a in the evaluation system i to a j The importance level is expressed as 1, 2, 3, and 4, indicating equal, slightly, stronger, and extremely important, respectively; The consistency test is performed on the judgment matrix. The specific consistency test method is set as: Among them, λ max represents the maximum eigenvalue of the judgment matrix, CI represents the consistency index of the judgment matrix, RI represents the average consistency index, CR represents the random consistency ratio, and when the random consistency ratio CR is less than 0.1, the judgment matrix passes the consistency test; After the consistency test is passed, the subjective weight of each evaluation index in the judgment matrix is analyzed using yaahp software AHP ; S63: Standardize the evaluation indicators through evaluation indicator standardization, and distinguish between positive and negative indicators based on the correlation between the evaluation indicators and the comprehensive benefit score; S64: After the normalization process, the objective weight is calculated using the entropy weight method (EWM), and the elements in the normalization matrix are converted into probability values to obtain a probability matrix P. The specific conversion method is set as follows: Among them, P ij It represents the proportion of the i-th data in the j-th indicator in the evaluation system; Calculate the difference coefficient G and objective weight ω of each indicator EWM , the specific calculation method of the difference coefficient G is set as: Among them, G j represents the coefficient of variation of the jth indicator; Objective weight ω EWM The specific calculation method is set as: Among them, ω EWMj represents the objective weight of the jth indicator; S65: Calculate the combined weight ω of the AHP-EWM method evaluation. The specific calculation method of the combined weight ω is set as:

8. A sand removal performance simulation and improvement method according to claim 7, characterized in that: In step S63, the standardization processing method is specifically set as follows: Among them, y represents the standardized value of each evaluation index, x represents the measured value of each evaluation index, and x max Indicates the maximum value of each evaluation index, x min Indicates the minimum measurement value of each evaluation index.

9. A sheet-type drip irrigation tape device according to the method for simulating and improving sand discharge performance according to any one of claims 1 to 8, characterized in that: It includes a bidirectional flow channel and a water inlet arranged under the bidirectional flow channel. The flow channel depth of the bidirectional flow channel is set to 0-0.8mm, the flow channel width of the bidirectional flow channel is set to 0-0.8mm, the bidirectional flow channel includes a forward flow channel and a reverse flow channel, and the number of units of the forward flow channel and the reverse flow channel are both set to 0-18.

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