Demonstration device and method for sand tank formed by drip irrigation lower section wetting body

Abstract

The invention discloses a sand tank demonstration device and method for drip irrigation lower section wet body formation. The sand tank demonstration device comprises a rectangular sand tank, a water supply mechanism and a drip irrigation simulation assembly. The rectangular sand tank comprises a sand storage device made of a transparent material; the water supply mechanism is provided with a fixing device, a water storage device, a lifting device and a water conveying device. The water storage device is used for storing liquid for demonstration; the lifting device is used for adjusting the height of the water supply mechanism relative to the rectangular sand tank; the water supply mechanism is fixedly connected with the rectangular sand tank through a fixing device; the drip irrigation simulation assembly is installed on the rectangular sand tank, the water supply mechanism conveys liquid in the water storage device to the drip irrigation simulation assembly through the water conveying device, and the drip irrigation simulation assembly presses the non-woven fabric into the sand storage device of the rectangular sand tank till the sand surface is flush and tightened; liquid infiltrates into the rectangular sand tank through the drip irrigation simulation assembly, and demonstration of formation of a drip irrigation lower section wetting body is completed; the system has intuitiveness, timeliness, repeatability and portability, and can meet the requirements of modern irrigation and water conservancy teaching.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of farmland water conservancy experiment teaching equipment, in particular to a sand tank demonstration device for profile wetting body formation under drip irrigation, and a sand tank demonstration method for profile wetting body formation under drip irrigation. BACKGROUND

[0002] Traditional farmland water conservancy experiment teaching has significant limitations in classroom application. For example, the study of the formation process of drip irrigation wetting body has low visualization of the evolution process of the wetting body profile due to the opacity of the soil medium. Existing teaching methods rely on static models or two-dimensional chart displays, which cannot intuitively present the dynamic expansion process of the drip irrigation wetting body, and students have difficulty understanding the water migration law. At the same time, due to the permeability of undisturbed soil, the experimental period is often long, which does not match the classroom teaching time, and the physical and chemical properties of the soil are prone to significant variation during the experiment. The same soil sample cannot be directly used for the next experiment after the experiment, resulting in poor experimental repeatability, which not only increases the cost of soil sample procurement and pretreatment, but also wastes a lot of time on repeated sampling. Secondly, the traditional experimental device has the problems of large volume and complex structure. The connection mode of the components is fixed, and the device is difficult to transfer and transport, which makes it difficult to deploy flexibly between the classroom and the laboratory, seriously restricting the development of instant demonstration and interactive teaching in the classroom. In view of the above problems, the existing experimental methods are difficult to meet the modern farmland water conservancy teaching needs in terms of intuitiveness, timeliness, repeatability and portability, and a new experimental device and method that can solve the above problems are urgently needed. SUMMARY

[0003] The present application aims to utilize the axial symmetry of the semi-ellipsoidal wetting body formed by drip irrigation, and provide a sand tank demonstration device and method for profile wetting body formation under drip irrigation, which has intuitiveness, timeliness, repeatability and portability, and realizes instant demonstration in the classroom.

[0004] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application will be further described below in conjunction with the drawings and embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0005] For the person skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the scope of protection of the present application. It is worth noting that the "front", "back", "left", "right" and other orientation words involved herein are relative to the view angle of the drawings.

[0006] To achieve the above functions, the present application designs a sand groove demonstration device for forming a profile wetting body under drip irrigation, comprising a rectangular sand groove 1, a water supply mechanism 2, a drip irrigation simulation assembly 3;

[0007] The rectangular sand groove 1 includes a sand storage device made of transparent material; the sand storage device stores a porous medium simulating soil; the water supply mechanism 2 has a fixing device, a water storage device, a lifting device and a water delivery device; the water storage device is used to store liquid for demonstration; the lifting device is used to adjust the height of the water supply mechanism 2 relative to the rectangular sand groove 1; the water supply mechanism 2 is fixedly connected with the rectangular sand groove 1 through the fixing device; the drip irrigation simulation assembly 3 is installed on the rectangular sand groove 1; the water supply mechanism 2 delivers the liquid in the water storage device to the drip irrigation simulation assembly 3 through the water delivery device; the non-woven fabric is pressed into the sand storage device of the rectangular sand groove 1 by the drip irrigation simulation assembly 3 until the sand surface is flush and taut; the liquid infiltrates into the sand storage device of the rectangular sand groove 1 through the drip irrigation simulation assembly 3, completing the demonstration of the formation of a profile wetting body under drip irrigation.

[0008] As a preferred technical solution of the present application: the porous medium filled in the sand storage device of the rectangular sand groove 1 is white quartz sand with a particle size of 0.3mm-0.4mm.

[0009] As a preferred technical solution of the present application: the liquid contained in the water storage device of the water supply mechanism 2 includes two types: one is potassium permanganate dyeing solution, and the other is vitamin C solution used for fading before the next round of potassium permanganate color development.

[0010] As a preferred technical solution of the present application: the rectangular sand groove 1 includes a sand groove main body 11, a screw support frame 12, a support boss 13, a spring buckle 14 and a quick-release drainage base 15.

[0011] The sand groove main body 11 is a sand storage device made of transparent material; the screw support frame 12 is fixedly connected on the left upper end of the sand groove main body 11 by screws, and a first limiting hole 121 is formed on the surface; the support boss 13 is fixedly connected on the left lower end of the sand groove main body 11, and a second limiting hole 131 is formed on the surface; the quick-release drainage base 15 is slidingly connected to the bottom of the sand groove main body 11 through a slide rail, and a buckle joint 151 is arranged on the left side wall of the quick-release drainage base 15; the quick-release drainage base 15 is clamped with the spring buckle 14 on the bottom of the sand groove main body 11 through the buckle joint 151.

[0012] A perforated partition plate 152 is fixedly arranged on the top of the quick-release drainage base 15; a plurality of through holes arranged in an array are formed on the perforated partition plate 152; a through hole is formed on the right side wall of the quick-release drainage base 15, and a multifunctional valve 153 made of metal is fixedly connected to the through hole through a flange.

[0013] As a preferred technical solution of the present application: the diameter of each through hole of the perforated partition plate 152 of the quick-release drainage base 15 is Φ1±0.05mm.

[0014] As a preferred technical solution of the present application: the water supply mechanism 2 comprises a lifting assembly 21, a water storage assembly 22, a stable support 23 and a water conveying pipeline 24.

[0015] The lifting assembly 21 comprises a supporting tray 211, a support screw 212, a helical gear set 213, a limiting screw 214, a spur gear set 215, a staggered gear set 216, a manual handle 217 and a screw fixing mechanism 218; the supporting tray 211 is fixed on the top of the support screw 212; the limiting screw 214 is sleeved and fixed on the bottom of the support screw 212; the screw fixing mechanism 218 is arranged on the support boss 13 in the rectangular sand groove 1; the support screw 212 serves as a connecting carrier and penetrates through the first limiting hole 121 of the screw support frame 12, the second limiting hole 131 of the support boss 13 and the screw fixing mechanism 218 in the rectangular sand groove 1; the gears in the spur gear set 215 are sleeved and fixed on a plurality of rod-shaped structures respectively; the gears in the spur gear set 215 are in parallel meshing transmission; one gear in the spur gear set 215 is in orthogonal meshing transmission with the staggered shaft gear set 216; the manual handle 217 is fixedly connected with the staggered shaft gear set 216; another gear in the spur gear set 215 is sleeved and fixed on the same rod-shaped structure with the helical gear set 213; the helical gear set 213 is in meshing transmission with the support screw 212; each rod-shaped structure and the manual handle 217 are supported by the screw fixing mechanism 218;

[0016] The water storage assembly 22 comprises a mar bottle 221 and a screw type water outlet valve 222; the mar bottle 221 is placed above the supporting tray 211; the bottom of the mar bottle 221 is connected with the screw type water outlet valve 222; the stable support 23 is arranged below the supporting boss 13 and is fixed by screws; the water conveying pipeline 24 comprises a water outlet pipe 241 and a water flow smoother 242; one end of the water outlet pipe 241 is connected with the screw type water outlet valve 222 of the mar bottle 221, and the other end is communicated with the water flow smoother 242.

[0017] As a preferred technical scheme of the present application: the drip irrigation simulation assembly 3 is composed of a non-woven fabric pulling device 31, a downward pressing telescopic plate 32, an outflow support plate 33 and an outflow device fixing seat 34.

[0018] The non-woven fabric pulling device 31 is fixedly connected at the top of the sand tank main body 11, and left and right drive assemblies 311 and 313 with synchronous rotation function are arranged at the left and right sides respectively; the left and right drive assemblies 311 and 313 are fixedly connected above the rectangular sand tank 1 through left and right fixed supports 312 and 314 respectively, and the two groups of drive assemblies perform bidirectional torque transmission through non-woven fabric as a link; the downward pressing telescopic plate 32 is formed into a telescopic structure by a slide rail organic glass groove combination, and a positioning screw 321 is arranged on the downward pressing telescopic plate 32; a wedge-shaped pressing edge is arranged at the bottom of the downward pressing telescopic plate 32; the outflow support plate 33 comprises a slidingly connected telescopic water guide box 331; the bottom of the telescopic water guide box 331 is provided with uniformly distributed water permeable holes; the outflow device fixing seat 34 serves as a connecting carrier, is fixedly connected with the downward pressing telescopic plate 32 through an upper positioning shaft 341, is fixedly connected with the outflow support plate 33 through a lower positioning shaft 342, and is fixedly connected with the right fixed support 314 through screws.

[0019] The present application also designs a sand tank demonstration method for forming a drip irrigation lower cross-section wetting body, based on the sand tank demonstration device for forming a drip irrigation lower cross-section wetting body, the following steps S1-S7 are performed to complete the demonstration of the drip irrigation lower cross-section wetting body formation:

[0020] Step S1: according to experimental or teaching requirements, determine the soil type to be simulated and the corresponding soil parameters, the soil parameters include saturated hydraulic conductivity K s , field moisture capacity θ fc , soil moisture content before irrigation θ i ;

[0021] Step S2: select the drip head flow rate and the target irrigation amount, based on the soil parameters obtained in step S1, calculate the maximum horizontal wetting distance R x and the maximum vertical wetting distance R y of the drip irrigation wetting body, and establish a theoretical model of the wetting body shape under drip irrigation conditions;

[0022] Step S3: the water supply mechanism 2 and the drip irrigation simulation assembly 3 are combined and installed; according to the experimental or teaching requirements, the specification of the water storage device in the water supply mechanism 2 is selected, and the white quartz sand is filled into the rectangular sand tank 1 as the porous medium simulating the soil;

[0023] Step S4: based on the maximum wetting distance R x and the maximum wetting distance R y in the vertical direction calculated in step S2, the position of the drip irrigation simulation assembly 3 is adjusted, the non-woven fabric is pressed into the rectangular sand tank 1 until the sand surface is flush, and the driving assembly at the upper end of the rectangular sand tank 1 is rotated to make the non-woven fabric in a tight state;

[0024] Step S5: the lifting device of the water supply mechanism 2 is adjusted to control the relative height of the water storage device and the sand surface of the rectangular sand tank 1, so that the outflow state of the screwed water outlet valve 222 is consistent with the flow rate of the experimental or teaching requirement, and then the connection of the water delivery device is completed, the potassium permanganate solution consistent with the designed irrigation amount is added into the marshall bottle 221;

[0025] Step S6: the water delivery device of the water supply mechanism 2 is opened, the high-manganese acid tracer solution is input into the white quartz sand in the rectangular sand tank 1, and the dynamic data of the wetting body in the horizontal and vertical directions formed by the high-manganese acid tracer solution in the white quartz sand is recorded in real time;

[0026] Step S7: after the experiment is completed, the water storage device in the water supply mechanism 2 is replaced by the marshall bottle 221 containing the vitamin C solution, and the water delivery device is reconnected, so that the vitamin C solution flows into the rectangular sand tank 1, and the vitamin C solution reacts with the residual potassium permanganate solution in the quartz sand to restore the white color, preparing for the next round of experiment.

[0027] As a preferred technical solution of the present application: in step S2, the maximum wetting distance R x and the maximum wetting distance R y in the vertical direction of the drip irrigation wetting body are calculated as follows:

[0028] Δθ=θ fc -θ i

[0029]

[0030] The theoretical model of the wetting body shape under the established drip irrigation conditions is as follows:

[0031]

[0032] In the formula, θ fc is the field moisture capacity, with the unit of cm 3 ·cm-3 ; θ i is the soil water content before irrigation, unit: cm 3 · cm -3 ; Δθ is the effective water-holding capacity of the soil, unit: cm 3 · cm -3 ; q is the flow rate of the dripper, unit: L·h -1 ; v is the drip irrigation water, unit: L·dripper -1 s K is the saturated hydraulic conductivity, unit: cm·d -1 .

[0033] Advantages: Compared with the prior art, the advantages of the present application include:

[0034] (1) The experimental device directly shows the formation process of the wetting body through the transparent structure and the potassium permanganate tracer solution, combines the quartz sand to replace the original soil to shorten the experimental period and support the repetition, can reproduce the formation process of the soil profile semi-elliptical wetting body under drip irrigation in a short period and repeatedly, at the same time, lightweight materials such as organic glass and modular design are used to improve the classroom integration degree and facilitate multi-scene use;

[0035] (2) The water supply mechanism, rectangular sand tank and drip irrigation simulation assembly are independent components, which significantly improve the assembly and maintenance efficiency, and are convenient for storage;

[0036] (3) Through the chemical action of potassium permanganate solution and vitamin C solution, the device and materials are highly repeatable, and the teaching cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 It is the overall structure schematic diagram of the sand tank demonstration device for the formation of profile wetting body under drip irrigation provided by the embodiment of the present application;

[0038] Figure 2 It is the structure schematic diagram of the rectangular sand tank provided by the embodiment of the present application;

[0039] Figure 3 It is the structure schematic diagram of the quick-release drainage base provided by the embodiment of the present application;

[0040] Figure 4 It is the structure schematic diagram of the water supply mechanism provided by the embodiment of the present application;

[0041] Figure 5 It is the structure schematic diagram of the lifting assembly provided by the embodiment of the present application;

[0042] Figure 6 It is the structure schematic diagram of the water storage assembly provided by the embodiment of the present application;

[0043] Figure 7 ​is a structural schematic view of a water delivery pipeline according to an embodiment of the present application;

[0044] Figure 8 is a structural schematic view of a drip irrigation simulation assembly according to an embodiment of the present application;

[0045] Figure 9 is a structural schematic view of a lower pressing flexible plate and an outflow support plate according to an embodiment of the present application;

[0046] In the figure: 1, rectangular sand tank; 11, sand tank column; 12, screw support frame; 121, first limiting hole; 13, support boss; 131, second limiting hole; 14, spring buckle; 15, quick-release drainage base; 151, buckle joint; 152, perforated partition; 153, multifunctional valve; 2, water supply mechanism; 21, lifting assembly; 211, supporting tray; 212, support screw; 213, helical gear set; 214, limiting screw; 215, spur gear set; 216, staggered shaft gear set; 217, manual handle; 218, screw fixing mechanism; 22, water storage assembly; 221, marshall bottle; 222, screw type water outlet valve; 23, stable support; 24, water delivery pipeline; 241, water outlet pipe; 242, water flow smoother; 3, drip irrigation simulation assembly; 31, non-woven fabric stretching device; 311, left drive assembly; 312, left side fixed support; 313, right drive assembly; 314, right side fixed support; 32, lower pressing flexible plate; 321, fixing screw; 33, outflow support plate; 331, flexible water guide box; 34, outflow device fixing seat; 341, upper positioning shaft; 342, lower positioning shaft. DETAILED DESCRIPTION

[0047] The present application will be further described below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and cannot be used to limit the protection scope of the present application.

[0048] The sand tank demonstration device provided by the embodiment of the present application is formed by a drip irrigation lower profile wetting body, and refers to Figure 1 , which comprises a rectangular sand tank 1, a water supply mechanism 2, and a drip irrigation simulation assembly 3.

[0049] The rectangular sand tank 1 includes a sand storage device made of transparent material; the sand storage device is a groove structure made of transparent organic glass material, and porous medium simulating soil is stored in the sand storage device; the porous medium filled in the sand storage device is white quartz sand with a particle size of 0.3mm-0.4mm; the water supply mechanism 2 has a fixing device, a water storage device, a lifting device and a water delivery device; the water storage device is used for storing liquid for demonstration, including two types: one is potassium permanganate dyeing solution, and the other is vitamin C solution for fading before the next potassium permanganate color development; the lifting device is used for adjusting the height of the water supply mechanism 2 relative to the rectangular sand tank 1; the water supply mechanism 2 is fixedly connected with the rectangular sand tank 1 through the fixing device; the drip irrigation simulation assembly 3 is installed on the rectangular sand tank 1; the water supply mechanism 2 delivers the liquid in the water storage device to the drip irrigation simulation assembly 3 through the water delivery device; the drip irrigation simulation assembly 3 presses the non-woven fabric into the sand storage device of the rectangular sand tank 1 until the sand surface is flush and taut; the liquid infiltrates into the sand storage device of the rectangular sand tank 1 through the drip irrigation simulation assembly 3, and the demonstration of the formation of the drip irrigation profile wetting body is completed.

[0050] With reference to Figure 2 , the rectangular sand tank 1 includes a sand tank body 11, a screw support frame 12, a support boss 13, a spring buckle 14 and a quick-release drainage base 15;

[0051] The sand tank body 11 is a sand storage device made of transparent material; the screw support frame 12 is fixedly connected on the left upper end of the sand tank body 11 by screws, and a first limiting hole 121 is formed on the surface thereof; the support boss 13 is fixedly connected on the left lower end of the sand tank body 11, and a second limiting hole 131 is formed on the surface thereof; Figure 3 With reference to

[0052] The quick-release drainage base 15 is slidingly connected to the bottom of the sand tank body 11 through a slide rail, and a buckle joint 151 is arranged on the left side wall of the quick-release drainage base 15; the quick-release drainage base 15 is integrally formed by an organic glass; the quick-release drainage base 15 is clamped with the spring buckle 14 on the bottom of the sand tank body 11 through the buckle joint 151, which not only ensures the sealing property of the connection but also supports quick disassembly; Figure 3 A porous partition plate 152 is fixedly arranged on the top of the quick-release drainage base 15 and integrally formed by an injection molding process; a plurality of through holes arranged in an array are formed on the porous partition plate 152 for preventing the porous medium from leaking out; in an embodiment, the diameter of each through hole is Φ1±0.05mm; a through hole is formed on the right side wall of the quick-release drainage base 15, and a multifunctional valve 153 made of metal is fixedly connected to the through hole through a flange; the multifunctional valve 153 can switch the water inlet / outlet function to meet the fluid control requirements of different test scenarios.

[0053] With reference to Figure 4, the water supply mechanism 2 includes four core components of lifting assembly 21, water storage assembly 22, stable support 23 and water pipeline 24; each component realizes the coordinated operation of water storage, water supply and water head height adjustment through modular design;

[0054] Referring to Figure 5 , the lifting assembly 21 includes a supporting tray 211, a supporting screw 212, a helical gear set 213, a limiting screw 214, a spur gear set 215, a staggered gear set 216, a manual handle 217, and a screw fixing mechanism 218. The supporting tray 211 is fixed to the top of the supporting screw 212. The limiting screw 214 is fixed to the bottom of the supporting screw 212. The screw fixing mechanism 218 is arranged on the supporting boss 13 in the rectangular sand tank 1. The supporting screw 212 serves as a connecting carrier, penetrating the first limiting hole 121 of the screw support frame 12 in the rectangular sand tank 1, the second limiting hole 131 of the supporting boss 13, and the screw fixing mechanism 218, forming axial positioning constraints. The gears in the spur gear set 215 are respectively fixedly sleeved on a plurality of rod-shaped structures. The gears in the spur gear set 215 are driven in parallel engagement. One gear in the spur gear set 215 is driven in orthogonal engagement with the staggered shaft gear set 216. The manual handle 217 is fixedly connected with the staggered shaft gear set 216. Another gear in the spur gear set 215 is fixedly sleeved with the helical gear set 213 on the same rod-shaped structure. The helical gear set 213 is engaged with the supporting screw 212. Each rod-shaped structure and the manual handle 217 are supported by the screw fixing mechanism 218. The staggered shaft gear set 216 and the spur gear set 215 are driven in orthogonal engagement and parallel engagement, cooperating with the manual handle 217 to achieve two-stage speed reduction. Finally, the helical gear set 213 and the supporting screw 212 are driven by the helical pair engagement to drive the supporting tray 211 to linearly ascend and descend.

[0055] Referring to Figure 6 , the water storage assembly 22 includes a marshall bottle 221 and a screw type water outlet valve 222. The marshall bottle 221 is placed above the supporting tray 211. The marshall bottle 221 is a laboratory commonly used water supply device that maintains constant water head by using atmospheric pressure principle. The experimenter can select a marshall bottle 221 with appropriate capacity according to needs. The bottom of the marshall bottle 221 is connected with the screw type water outlet valve 222. This design not only ensures the sealed connection of the water tank and the water outlet pipeline, but also supports quick disassembly and separation during maintenance. The water storage assembly 22 is used in cooperation with the lifting assembly 21 to realize the pressure water head regulation function of the water supply device. The stable support 23 is arranged below the supporting boss 13 and fixed by screws. Figure 7The water delivery pipeline 24 comprises a water outlet pipe 241 and a water flow smoother 242; one end of the water outlet pipe 241 is connected with the rotating water outlet valve 222 of the Mahle bottle 221, and the other end is communicated with the water flow smoother 242, forming a continuous water delivery channel; the water flow smoother 242 can effectively smooth water flow fluctuation, ensuring stability and uniformity of the water outlet process.

[0056] With reference to Figure 8 The drip irrigation simulation assembly 3 is composed of a non-woven fabric pulling device 31, a downward pressing telescopic plate 32, an outflow support plate 33 and an outflow device fixing seat 34.

[0057] The non-woven fabric pulling device 31 is fixedly connected at the top of the sand tank main body 11, and left and right drive assemblies 311 and 313 with synchronous rotation function are arranged at the left and right sides, respectively; in an embodiment, the left and right drive assemblies 311 and 313 are knobs; the left and right drive assemblies 311 and 313 are fixedly connected above the rectangular sand tank 1 through left and right fixed supports 312 and 314, respectively; the two groups of drive assemblies perform bidirectional torque transmission through non-woven fabric as a link, realizing symmetric tension control of the non-woven fabric.

[0058] With reference to Figure 9 The downward pressing telescopic plate 32 is formed into a telescopic structure by a slide rail combined with an organic glass groove, and a positioning screw 321 is arranged on the downward pressing telescopic plate 32; the positioning screw 321 adjusts the length of the downward pressing telescopic plate 32, realizes multi-stage positioning and can adapt to different positioning requirements; a wedge-shaped pressing edge is arranged at the bottom of the downward pressing telescopic plate 32, which can accurately position and place the non-woven fabric, ensuring positioning accuracy of the drip irrigation area; the outflow support plate 33 comprises a telescopic water guide box 331 connected in a sliding mode; the bottom of the telescopic water guide box 331 is provided with uniformly distributed water permeable holes, realizing uniform water flow dispersion and being able to be attached to the surface of the sand body in the tank; the outflow device fixing seat 34 is connected with the downward pressing telescopic plate 32 through an upper positioning shaft 341 and connected with the outflow support plate 33 through a lower positioning shaft 342, forming a three-dimensional support structure, ensuring cooperative operation of the downward pressing telescopic plate 32 and the outflow support plate 33, dynamically adapting to the filling height of the sand body and vertically pressing the non-woven fabric into the sand tank, realizing horizontal attachment of the non-woven fabric to the surface of the sand body; the outflow device fixing seat 34 is fixedly connected with the right fixed support 314 through a screw.

[0059] In summary, the general idea of the present application is as follows:

[0060] The sand tank demonstration device adopts transparent organic glass material to construct the tank structure, and adds white quartz sand with a particle size of 0.3mm-0.4mm as a porous medium simulating soil in the device, through the water supply mechanism which can adjust the irrigation water pressure head, the potassium permanganate dyeing solution is formed into infiltration on the upper part of the sand tank through the water supply pipeline, and the diffusion and distribution of the infiltrated water in the sand tank profile under the drip irrigation state are simulated through the specific shape of the outflow device, and then the rapid demonstration of the change of the wetting body shape after irrigation is realized, and then through the oxidation-reduction reaction of the potassium permanganate solution and the vitamin C solution, the quartz sand dyeing is quickly removed, and the efficient recycling of the quartz sand is realized.

[0061] The embodiment of the present application also provides a sand tank demonstration method for forming a profile wetting body under drip irrigation, which is based on the sand tank demonstration device for forming a profile wetting body under drip irrigation and performs the following steps S1-S7 to complete the demonstration of the profile wetting body under drip irrigation:

[0062] Step S1: according to the experimental or teaching requirements, the soil type to be simulated and the corresponding soil parameters are determined, the soil parameters include saturated hydraulic conductivity K s , field moisture capacity θ fc , soil moisture content before irrigation θ i ;

[0063] Step S2: select the flow rate of the drip head and the target irrigation amount, based on the soil parameters obtained in step S1, calculate the maximum horizontal wetting distance R x and the maximum vertical wetting distance R y of the drip irrigation wetting body, and establish a theoretical model of the wetting body shape under drip irrigation conditions;

[0064] The maximum horizontal wetting distance R x and the maximum vertical wetting distance R y of the drip irrigation wetting body are calculated as follows:

[0065] Δθ=θ fc -θ i

[0066]

[0067] The theoretical model of the wetting body shape under drip irrigation conditions is as follows:

[0068]

[0069] y<0

[0070] In the formula, θ fc is the field moisture capacity (cm 3 ·cm -3 ), θ i is the soil moisture content before irrigation (cm 3· cm -3 ), Δθ is the effective water-holding capacity of the soil (cm 3 · cm -3 ), q is the emitter flow rate (L·h -1 ), v is the drip irrigation water volume (L·emitter -1 ), K s is the saturated hydraulic conductivity (cm·d -1 ).

[0071] Step S3: Assemble the rectangular sand tank 1, the water supply mechanism 2, and the drip irrigation simulation assembly 3; ensure that each component is stably connected and functions normally; select the size of the Mariotte bottle 221 according to the experimental requirements, fill the white quartz sand into the rectangular sand tank 1 as the porous medium simulating the soil, and fill the quartz sand to a distance of 5 cm from the top end of the rectangular sand tank 1;

[0072] Step S4: Based on the maximum wetting distance R x and the maximum wetting distance R y calculated in step S2, adjust the extension length of the lower pressing plate 32 and the extension amount of the outflow support plate 33 in the drip irrigation simulation assembly 3 to complete the spatial positioning calibration of the simulation device;

[0073] Wrap the non-woven fabric at both ends around the driving assembly on the top of the rectangular sand tank 1, and press the non-woven fabric into the rectangular sand tank 1 to the level of the sand surface by using the wedge-shaped pressing edge structure of the lower pressing plate 32 and the extension water guide box 331 of the outflow support plate 33 to achieve the close fit of the non-woven fabric with the inner wall and sand surface of the rectangular sand tank 1;

[0074] Unidirectional stretching can significantly reduce the water permeability of the non-woven fabric. The fundamental mechanism is that the non-woven fabric is composed of disordered short fibers, unidirectional stretching forces the fibers to arrange in the direction of force, the interlayer gap is compressed, the equivalent pore size is reduced, and the water permeability is reduced. According to the infiltration requirements, apply a symmetric torque by rotating the left driving assembly 311 and the right driving assembly 313 on the top of the rectangular sand tank 1 to make the non-woven fabric in a tense state and weaken its water permeability, thereby accelerating the lateral migration of water;

[0075] Step S5: Rotate the manual crank 217 of the lifting assembly 21 to lift the Mariotte bottle 221 to the desired infiltration water head height according to the experimental or teaching requirements, so that the outflow state of the screwed water valve 222 is consistent with the emitter flow rate required by the experiment or teaching; then align and place the water flow smoother 242 above the outflow support plate 33 to complete the connection of the water delivery path, and add the designed irrigation amount of potassium permanganate solution into the Mariotte bottle 221;

[0076] Step S6: open the screw type water outlet valve 222 of the water storage assembly, the tracer solution is input into the telescopic water guide box 331 through the water outlet pipe 241 and the water flow smoother 242, the water outlet is opened, and the formation of the wet body is triggered; the dynamic data of the wet body formed by the potassium permanganate tracer solution in the white quartz sand in the horizontal and vertical directions is recorded in real time;

[0077] Step S7: after the experiment is completed, the mason bottle 221 containing the potassium permanganate solution is replaced by a mason bottle 221 containing a vitamin C solution; the vitamin C solution can make the potassium permanganate solution fade; the basic mechanism is that the strong reducing property of vitamin C reduces the +7 valence manganese in the permanganate ion (MnO4 - ) to colorless +2 valence manganese ion (Mn 2+ ), resulting in the fading of purple; the screw type water outlet valve 222 is opened again, the vitamin C solution flows into the rectangular sand groove 1, reacts with the residual potassium permanganate tracer solution in the quartz sand, and makes it restore white, so as to prepare for the next round of experiment.

[0078] The embodiments of the application are described in detail above in combination with the drawings, but the application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the application.

Claims

1. A sand trough demonstration device for the formation of a wetted body under a drip irrigation section, characterized in that: It comprises a rectangular sand trough (1), a water supply mechanism (2), and a drip irrigation simulation component (3); The rectangular sand trough (1) comprises a sand storage device made of a transparent material; a porous medium for simulating soil is stored in the sand storage device; the water supply mechanism (2) comprises a fixing device, a water storage device, a lifting device and a water delivery device; the water storage device is used to store liquid for demonstration; the lifting device is used to adjust the height of the water supply mechanism (2) relative to the rectangular sand trough (1); the water supply mechanism (2) is fixedly connected to the rectangular sand trough (1) via the fixing device; the drip irrigation simulation component (3) is installed on the rectangular sand trough (1); the water supply mechanism (2) delivers liquid in the water storage device to the drip irrigation simulation component (3) via the water delivery device; the drip irrigation simulation component (3) presses a non-woven fabric into the sand storage device of the rectangular sand trough (1) until the sand surface is flush and tightened; the liquid infiltrates into the sand storage device of the rectangular sand trough (1) through the drip irrigation simulation component (3), completing the demonstration of the formation of a wet body in the lower cross section of the drip irrigation.

2. The sand trough demonstration device for forming a wetted body under a drip irrigation lower section according to claim 1, characterized in that: The porous medium filled in the sand storage device of the rectangular sand trough (1) is white quartz sand with a particle size of 0.3 mm to 0.4 mm.

3. The sand trough demonstration device for forming a wetted body under a drip irrigation lower section according to claim 1, characterized in that: The liquid contained in the water storage device of the water supply mechanism (2) includes two types: one is a potassium permanganate dyeing solution, and the other is a vitamin C solution used for fading before the next round of potassium permanganate color development.

4. The sand trough demonstration device for forming a wetted body under a drip irrigation lower section according to claim 1, characterized in that: The rectangular sand trough (1) comprises a sand trough body (11), a screw support frame (12), a support boss (13), a spring buckle (14), and a quick-release drainage base (15); The sand trough body (11) is a sand storage device made of a transparent material; the screw support frame (12) is fixedly connected to the upper left end of the sand trough body (11) by screws, and a first limiting hole (121) is provided on the surface; the supporting boss (13) is fixedly connected to the lower left end of the sand trough body (11), and a second limiting hole (131) is provided on the surface; the quick-detachable drainage base (15) is slidably connected to the bottom of the sand trough body (11) by a slide rail, and a snap joint (151) is provided on the left side wall of the quick-detachable drainage base (15), and the quick-detachable drainage base (15) is snap-connected to the spring snap joint (14) at the bottom of the sand trough body (11) through the snap joint (151); A porous partition (152) is fixedly arranged on the top of the quick-detachable drainage base (15); a plurality of through holes arranged in an array are provided on the porous partition (152); a through hole is provided on the right side wall of the quick-detachable drainage base (15), and a multifunctional valve (153) made of metal is fixed to the through hole via a flange connection.

5. The sand trough demonstration device for drip irrigation lower cross-section wetted body formation according to claim 4, characterized in that: The aperture of each through hole of the porous partition (152) of the quick-disassembly drainage base (15) is Φ1±0.05mm.

6. The sand trough device for demonstrating the formation of a wetted body in a lower cross section of drip irrigation according to claim 4, characterized in that: A water supply mechanism (2) includes a lifting assembly (21), a water storage assembly (22), a stabilizing support (23) and a water delivery pipeline (24); The lifting assembly (21) comprises a support tray (211), a support screw (212), a helical gear set (213), a limit screw (214), a spur gear set (215), a staggered gear set (216), a manual crank (217), and a screw fixing mechanism (218); the support tray (211) is fixed to the top of the support screw (212); the limit screw (214) is sleeved and fixed to the bottom of the support screw (212); the screw fixing mechanism (218) is arranged on the support boss (13) in the rectangular sand trough (1); the support screw (212) serves as a connecting carrier, passing through the first limit hole (121) of the screw support frame (12) in the rectangular sand trough (1) and the support boss (13). a second limiting hole (131), and a screw fixing mechanism (218); the gears in the spur gear set (215) are respectively sleeved and fixed on a plurality of rod-shaped structures, the gears in the spur gear set (215) are driven by parallel meshing, and one gear in the spur gear set (215) is driven by orthogonal meshing with the staggered axis gear set (216); the manual crank (217) is fixedly connected to the staggered axis gear set (216); another gear in the spur gear set (215) is sleeved and fixed with the helical gear set (213) on the same rod-shaped structure; the helical gear set (213) is meshed with the support screw (212); each rod-shaped structure and the manual crank (217) are supported by the screw fixing mechanism (218); The water storage assembly (22) comprises a Malvern flask (221) and a rotary water outlet valve 222; the Malvern flask (221) is placed above the support tray (211); the bottom of the Malvern flask (221) is connected to the rotary water outlet valve (222); the stabilizing support (23) is arranged below the supporting boss (13) and fixed by screws; the water delivery pipeline (24) comprises a water outlet pipe (241) and a water flow smoother (242); one end of the water outlet pipe (241) is connected to the rotary water outlet valve (222) of the Malvern flask (221), and the other end is connected to the water flow smoother (242).

7. The sand trough demonstration device for forming a wetted body in a drip irrigation lower section according to claim 4, characterized in that: The drip irrigation simulation component (3) is composed of a non-woven fabric stretching device (31), a downward-pressing telescopic plate (32), an outflow support plate (33), and an outflow device fixing seat (34); The non-woven fabric stretching device (31) is fixedly connected to the top of the sand trough body (11), and a left drive assembly (311) and a right drive assembly (313) with a synchronous rotation function are respectively provided on both sides; the left drive assembly (311) and the right drive assembly (313) are respectively fixedly connected to the top of the rectangular sand trough (1) through a left fixed bracket (312) and a right fixed bracket (314), and the two sets of drive assemblies are used as a link to perform bidirectional torque transmission; the downward pressing telescopic plate (32) is formed by a combination of organic glass grooves with slide rails to form a telescopic structure, and the downward pressing telescopic plate (32) is provided with a positioning screw (321); a wedge-shaped pressing edge is provided at the bottom of the downward-pressing telescopic plate (32); the outflow branch plate (33) includes a telescopic water guide box (331) connected in a sliding manner; the bottom of the telescopic water guide box (331) is provided with evenly distributed water-permeable holes; the outflow device fixing seat (34) serves as a connection carrier, is fixedly connected to the downward-pressing telescopic plate (32) through an upper positioning shaft (341), and is fixedly connected to the outflow branch plate (33) through a lower positioning shaft (342); the outflow device fixing seat (34) is fixedly connected to the right fixing bracket (314) through a screw.

8. A sand trough demonstration method for forming a wetted body under a drip irrigation section, characterized in that: Based on the sand trough demonstration device for the formation of a wetted body in a drip irrigation lower cross section according to any one of claims 1 to 7, the following steps S1 to S7 are performed to complete the demonstration of the formation of a wetted body in a drip irrigation lower cross section: Step S1: Determine the soil type to be simulated and the corresponding soil parameters according to the experimental or teaching requirements. The soil parameters include saturated hydraulic conductivity K s 、Field water holding capacity θ fc , soil moisture content before irrigation θ i ; Step S2: Select the dripper flow rate and target irrigation volume, and calculate the maximum horizontal wetting distance R of the drip irrigation wetted body based on the soil parameters obtained in step S1. x Maximum wet distance R in vertical direction y , establish a theoretical model of wetted body morphology under drip irrigation conditions; Step S3: Assemble and install the water supply mechanism (2) and the drip irrigation simulation component (3); select the specifications of the water storage device in the water supply mechanism (2) according to the experimental or teaching requirements, and fill the rectangular sand trough (1) with white quartz sand as a porous medium for simulating soil; Step S4: Based on the maximum horizontal wetting distance R of the drip irrigation wetting body calculated in step S2 x Maximum wet distance R in vertical direction y , adjust the position of the drip irrigation simulation component (3), press the non-woven fabric into the rectangular sand trough (1) until the sand surface is flush, and rotate the driving component at the upper end of the rectangular sand trough (1) to keep the non-woven fabric in a taut state; Step S5: adjusting the lifting device of the water supply mechanism (2) and regulating the relative height between the water storage device and the sand surface of the rectangular sand trough (1) so that the outflow state of the rotary water outlet valve (222) is consistent with the dripper flow rate required for the experiment or teaching, and then completing the connection of the water delivery device, adding potassium permanganate solution consistent with the designed water filling volume into the Martens flask (221); Step S6: turning on the water supply device of the water supply mechanism (2), inputting the potassium permanganate tracer solution into the white quartz sand in the rectangular sand trough (1), and recording in real time the dynamic data of the horizontal and vertical directions of the wetted body formed by the potassium permanganate tracer solution in the white quartz sand; Step S7: After the experiment is completed, the water storage device in the water supply mechanism (2) is replaced with a Malvern flask (221) filled with vitamin C solution, and the water supply device is reconnected to allow the vitamin C solution to flow into the rectangular sand trough (1). The vitamin C solution reacts with the potassium permanganate solution remaining in the quartz sand, causing it to return to white color, preparing for the next round of experiments.

9. The sand trough demonstration method for forming a wetted body in a drip irrigation lower section according to claim 8, characterized in that: In step S2, the maximum horizontal wetting distance R of the drip irrigation wetting body is calculated. x Maximum wet distance R in vertical direction y Here’s how: Δθ=θ fc -θ i The theoretical model of wetted body morphology under drip irrigation conditions is as follows: y<0 Where θ fc is the field water holding capacity, in cm 3 cm -3 θ i is the soil moisture content before irrigation, in cm 3 cm -3 ; Δθ is the effective water holding capacity of the soil, in cm 3 cm -3 ; q is the dripper flow rate, unit is L·h -1 ; v is the drip irrigation water volume, unit is L·drip head -1 ;K s is the saturated hydraulic conductivity, in cm·d -1 .

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