Sediment starting flow velocity measuring device based on trapezoidal groove distribution characteristics

Abstract

The invention discloses a sediment starting flow velocity measuring device based on trapezoidal groove distribution characteristics, and belongs to the field of sediment starting flow velocity measurement. The device comprises a trapezoidal groove, a guide rail, a laser section plotter, a point type current meter and an annular water tank, the trapezoid-shaped groove is erected in an annular water tank test area, a guide rail is erected on the side wall of the water tank, and the laser section plotter and the point type current meter are erected above the trapezoid-shaped groove through the guide rail and can move through the guide rail; water flow enters from the wide end of the trapezoid-shaped groove and flows towards the narrow end, and the flow speed is gradually increased along with gradual decreasing of the groove width. A test sand sample is laid in the trapezoid-shaped groove, the elevation change of the sand sample is monitored through a laser section plotter, an elevation mutation feature point is a feature mutation point for converting static sediment into starting sediment, and the starting flow velocity of the sand sample can be obtained by obtaining the typical flow velocity of the feature point through a point type flow velocity meter.

Description

Technical Field

[0001] The invention relates to the field of sediment starting flow velocity measurement, in particular to a sediment starting flow velocity measurement device based on the distribution characteristics of trapezoidal grooves. Background Art

[0002] The mechanical mechanism of sediment movement includes the initiation, transport and sedimentation of sediment particles. These processes are crucial to understanding the formation of important geomorphic units such as underwater beaches and troughs. However, it is not easy to truly understand the initiation mechanism of sediment particles. Even the very basic problem of judging the initiation of sediment has many difficulties: (1) First, the water flow that drives sediment movement is turbulent. Even if the flow rate is the same, the velocity and direction of the water flow in the area of ​​interest fluctuate randomly, which causes the force acting on the sediment particles to also vary.

[0003] (2) Sediment mobilization itself is highly random, that is, under the same water flow conditions, not all sediment particles will be mobilized at the same time. This objectively poses a considerable challenge to the determination of the critical water flow conditions for sediment mobilization.

[0004] (3) There is currently no unified method to determine whether sediment has started to move. In most cases, it is judged directly by the naked eye. When sediment is observed to begin to move on the bed surface, it is considered that the water flow condition is the critical starting condition for sediment. However, the judgment standards of different people are unlikely to be exactly the same, which leads to a strong subjectivity in the measurement results.

[0005] (4) For the same sand sample, when the water depth is shallow, the contact between the water flow and the riverbed is more direct, and the kinetic energy of the water flow is more easily transferred to the sediment particles, so the sediment particles are easier to start, and the required starting flow rate is relatively small; on the contrary, when the water depth is greater, the kinetic energy of the water flow needs to be transferred to the riverbed through a deeper water body, and the energy transfer efficiency is lower, so the sediment particles need a larger flow rate to start. At present, the water depth condition of some sediment starting flow rate test devices is to gradually adjust from zero water depth to the target water depth, which easily leads to the situation that the sediment starts before reaching the test water depth. Summary of the invention

[0006] The purpose of the present invention is to address the shortcomings of the prior art and provide a sediment starting flow velocity measuring device based on the distribution characteristics of a trapezoidal trough. By utilizing the non-uniformity of the water flow velocity distribution in the trapezoidal trough, the characteristic points of the sediment scouring mutation are found, thereby more accurately determining the sediment starting flow velocity.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a sediment starting flow velocity measuring device based on the distribution characteristics of a trapezoidal trough, comprising a water trough, one section of which is a trapezoidal trough, a test sand sample is placed at the bottom of the trapezoidal trough, a guide rail is provided above, and a laser profiler and a point flow meter are provided on the guide rail.

[0008] In the present invention, the test sand sample is laid on the bottom side of the trapezoidal trough. After the water flows through the trapezoidal trough and the scouring is stable, the characteristic bed scouring morphology of the test area can be obtained by the laser profiler, and the characteristic elevation mutation point of the bed surface can be obtained. Then, the characteristic flow velocity of the point can be obtained by the point velocity meter, which is the starting flow velocity of the sediment. The flow velocity distribution of the water flow in the trapezoidal trough is non-uniform. The flow velocity of the water flow in the trapezoidal trough is related to its size. The smaller the flow cross section, the greater the flow velocity. By observing the scouring behavior of sediment in different areas of the trapezoidal trough, the flow velocity corresponding to the water flow mutation point can be efficiently found and used as the starting flow velocity of the sediment, which can effectively avoid the subjective errors existing in the traditional judgment method.

[0009] Specifically, the trapezoidal groove is open at both ends, and the water in the water tank flows in from the wide side of the trapezoidal groove and flows out from the narrow side. The trapezoidal groove is set in the water tank, so that the water flows in from the wide end of the trapezoidal groove and flows out from the narrow end. As the water flows, the flow velocity in the trapezoidal groove gradually increases, forming a natural flow velocity gradient. By setting the flow velocity gradient, the number of tests can be reduced and the test efficiency can be improved. Compared with the test method of gradually increasing the flow velocity, the experimental data is more accurate and reliable.

[0010] Specifically, the guide rail is a parallel double rail, and both rails are provided with a first sliding connection block and a second sliding connection block, and a through hole is provided in the middle of the first sliding connection block and the second sliding connection block. The first sliding connection block is provided with a limit hole, and the laser profiler cooperates with its limit hole through the first instrument connection plate; the second sliding connection block is provided with a limit hole, and the point velocity meter cooperates with its limit hole through the second instrument connection plate. The laser profiler and the point velocity meter can move on the guide rail to obtain characteristic velocities at different positions. The setting of the first sliding connection block and the second sliding connection block makes the operation convenient, and the positions of the laser profiler and the point velocity meter on the guide rail can be adjusted according to the starting position of the sediment in the test.

[0011] Specifically, the water tank is connected to a water pump through a pipeline, the water pump is placed in the water body, and the pipeline is provided with an electromagnetic flowmeter. The water pump can draw water from the water body and flow it into the water tank through the water inlet. An electromagnetic flowmeter is provided between the water pump and the water tank, and the electromagnetic flowmeter can be used to monitor the flow rate flowing into the water tank to prevent the water in the water tank from being too little or too much and affecting the measurement effect.

[0012] Specifically, the water tank is an annular water tank, provided with a water inlet, an energy dissipation shoal on one side of the water inlet, and a water baffle on the other side, wherein the height of the water baffle is less than the minimum side wall height of the water tank. The energy dissipation shoal is used to offset the turbulence of water flow entering the water tank, so as to stabilize the flow rate of the water flow. The present invention can control the water surface elevation inside the water tank by adjusting the elevation of the water baffle inside the water tank, thereby controlling the test water depth. The overall device is simple, has low energy consumption, and is easy to operate.

[0013] Specifically, a first water drain is provided between the energy dissipation beach and the water retaining plate, and a second water drain is provided on the other side of the water retaining plate, and water flowing out of the first water drain and the second water drain both flows toward the water body.

[0014] The water tank is provided with a first drain port and a second drain port for draining clockwise and counterclockwise water flow, and the drainage flows to a water body, which can be an underground water pool. During the test, the first drain port is closed. Due to the setting of the water baffle, the water flows through the energy dissipation beach and then flows to the trapezoidal trough in the test area, and then flows out from the second drain port. If the water level near the water baffle is level with the height of the water baffle, part of the incoming water will flow out from the second drain port over the water baffle, and part will flow to the energy dissipation beach and the trapezoidal trough and then flow out from the second drain port. Changing the height of the water baffle can change the test water depth of the trapezoidal trough. After the test, the first drain port can be opened for drainage. The drainage water flow entering the water body can flow to the water inlet of the water tank again through the water pump, and be discharged through the first drain port or the second drain port, thereby realizing the recycling of test water.

[0015] The beneficial effects of the present invention are as follows: the present invention utilizes the non-uniformity of the water flow velocity distribution in the trapezoidal trough to find the characteristic points of sediment scouring mutation, thereby more accurately determining the starting velocity of sediment. Water flows through the trapezoidal trough along the wide end and out of the narrow end to form a natural gradient. The design of the trapezoidal trough solves the efficiency problem of measuring the starting velocity of sediment and needs to constantly change the flow velocity in the water trough; a laser profiler and a point flow meter are arranged above the trapezoidal trough. The laser profiler is used to measure the bed scouring morphology, and the point flow meter is used to measure the velocity value of the characteristic points inside the trapezoidal trough. Through the cross-sectional mutation point, the position of the sediment flow velocity mutation is effectively found, and then the starting velocity of sediment is accurately determined; the annular water trough is arranged above the water body, and the test water circulation is realized through the water inlet, the first drain port, the second drain port and the water pump. The device is simple to operate and has low production cost. It can efficiently measure the starting velocity of sediment samples, improve the test efficiency, and has high reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0017] Figure 1 It is a structural schematic diagram of the trapezoidal trough sediment starting flow velocity measuring device of the present invention.

[0018] Figure 2 It is a schematic diagram of the guide rail connection of the present invention.

[0019] Figure 3 This is the layout diagram of the annular water tank of the present invention.

[0020] Figure 4 This is a cross-sectional view of the test area of ​​the present invention.

[0021] Figure 5 It is a structural schematic diagram of the sand sample recovery and material replacement mechanism in the second embodiment.

[0022] Figure 6 This is the internal layout diagram of the sand sample recovery and material replacement mechanism in Example 2.

[0023] Explanation of the reference numerals: 10-trapezoidal groove; 11-guide rail; 20-laser profiler; 21-first instrument connecting plate; 22-first sliding connecting block; 221-through hole; 222-limiting hole; 30-point flowmeter; 31-second instrument connecting plate; 32-second sliding connecting block; 40-water tank; 41-water pump; 42-electromagnetic flowmeter; 43-water body; 44-energy dissipation beach; 45-water retaining plate; 46-water inlet; 47-first water discharge port; 48-second water discharge port; 50-test sand sample; 60-upper frame; 61-rod; 62-bottom plate; 63-limiting block; 70-housing; 71-sandblasting mechanism; 72-pump; 73-heater; 74-sand storage chamber; 75-first sand discharge port; 76-second sand discharge port. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The following first describes the concepts involved in the present application in conjunction with the accompanying drawings. It should be noted that the following description of each concept is only to make the content of the present application easier to understand, and does not limit the scope of protection of the present application; at the same time, the embodiments and features in the embodiments of the present application can be combined with each other in the absence of conflict. The present application will be described in detail with reference to the accompanying drawings and in conjunction with the embodiments.

[0026] Embodiment 1 like Figures 1 to 4As shown, a sediment starting flow velocity measuring device based on the distribution characteristics of trapezoidal troughs includes a water trough 40, a section of which is a trapezoidal trough 10, a test sand sample 50 is placed at the bottom of the trapezoidal trough 10, a guide rail 11 is provided above, and a laser profiler 20 and a point flow meter 30 are provided on the guide rail 11.

[0027] In the present invention, the test sand sample 50 is laid on the bottom side of the trapezoidal trough 10. After the water flows through the trapezoidal trough 10 and the scouring is stable, the characteristic bed scouring morphology of the test area can be obtained by the laser profiler 20, and the characteristic elevation mutation point of the bed can be obtained. Then, the characteristic flow velocity of the point can be obtained by the point velocity meter 30, which is the starting flow velocity of the sediment. The flow velocity distribution of the water flow in the trapezoidal trough 10 is non-uniform. The flow velocity of the water flow in the trapezoidal trough 10 is related to its size. The smaller the flow cross section, the greater the flow velocity. By observing the scouring behavior of sediment in different areas of the trapezoidal trough 10, the flow velocity corresponding to the water flow mutation point can be efficiently found and used as the starting flow velocity of the sediment, which can effectively avoid the subjective errors existing in the traditional judgment method.

[0028] Specifically, both ends of the trapezoidal groove 10 are open, and the water of the water tank 40 flows in from the wide side of the trapezoidal groove 10 and flows out from the narrow side. The trapezoidal groove 10 is arranged in the water tank 40, so that the water flows in from the wide end of the trapezoidal groove 10 and flows out from the narrow end. As the water flows, the flow velocity in the trapezoidal groove 10 gradually increases, forming a natural flow velocity gradient.

[0029] Specifically, the guide rail 11 is a parallel double rail, and both rails are provided with a first sliding connection block 22 and a second sliding connection block 32, and a through hole is provided in the middle of the first sliding connection block 22 and the second sliding connection block 32. The first sliding connection block 22 is provided with a limit hole, and the laser profiler 20 cooperates with its limit hole through the first instrument connection plate 21; the second sliding connection block 32 is provided with a limit hole, and the point velocity meter 30 cooperates with its limit hole through the second instrument connection plate 31. The laser profiler 20 and the point velocity meter 30 can move on the guide rail 11 to obtain characteristic velocities at different positions. The provision of the first sliding connection block 22 and the second sliding connection block 32 facilitates operation and improves measurement efficiency.

[0030] Specifically, the water tank 40 is connected to the water pump 41 through a pipeline, and the water pump 41 is placed in the water body 43. The pipeline is provided with an electromagnetic flowmeter 42. The water pump 41 can pump water from the water body 43 and flow into the water tank 40 through the water inlet 46. The electromagnetic flowmeter 42 is provided between the water pump 41 and the water tank 40. Before the test, the water flows slowly into the water tank 40 to reach the test water depth, and then the second drain port 48 is opened, and the water flow rate is adjusted to conduct the test. The electromagnetic flowmeter 42 can be used to monitor the flow rate flowing into the water tank 40 to maintain the test water depth, so as to prevent the water in the water tank 40 from being too little or too much and affecting the measurement effect.

[0031] Specifically, the water tank 40 is an annular water tank, provided with a water inlet 46, an energy dissipation shoal 44 is provided on one side of the water inlet 46, and a water baffle 45 is provided on the other side, and the height of the water baffle 45 is less than the minimum side wall height of the water tank 40. A first water discharge port 47 is provided between the energy dissipation shoal 44 and the water baffle 45, and a second water discharge port 48 is provided on the other side of the water baffle 45, and the water flowing out of the first water discharge port 47 and the second water discharge port 48 both flows to the water body 43. The energy dissipation shoal 44 is used to offset the turbulence of the water flow entering the water tank 40, so that the flow rate of the water flow is stable. The present invention can control the water surface elevation inside the water tank 40 by adjusting the elevation of the water baffle 45 inside the water tank 40, and then control the test water depth. The annular water tank 40 is provided with a first water discharge port 47 and a second water discharge port 48, which can be directly adjusted to the target water depth, avoiding the situation where the sediment has been started before the test water depth is reached when adjusting from zero water depth to target water depth, thereby increasing the reliability of the test.

[0032] The first drain port 47 and the second drain port 48 are used for draining clockwise and counterclockwise water flow, and the water flows to the water body 43, which can be an underground water pool. During the test, the first drain port 47 is closed. Due to the setting of the water baffle 45, the water flows through the energy dissipation beach 44 and then flows to the trapezoidal trough 10 in the test area, and then flows out from the second drain port 48. If the water level between the energy dissipation beach 44 and the water baffle 45 is level with the height of the water baffle 45, part of the water entering will submerge the water baffle 45 and flow out from the second drain port 48, and part of the water will flow to the energy dissipation beach 44 and the trapezoidal trough 10 and then flow out from the second drain port 48. Changing the height of the water baffle 45 can change the test water depth of the trapezoidal trough 10. After the test, the first drain port 47 can be opened to drain water. The drainage water flow enters the water body 43 and can flow to the water inlet 46 of the water tank 40 again through the water pump 41, and is discharged through the first drain port 47 or the second drain port 48, thereby realizing the recycling of the test water. The overall device is simple, low in energy consumption and easy to operate.

[0033] Embodiment 2 like Figure 5 and Figure 6 , based on further optimization of the first embodiment: The height of the trapezoidal trough 10 is smaller than the water tank 40. A sand sample recovery and material replacement mechanism is provided at the bottom of the trapezoidal trough 10. The sand sample recovery and material replacement mechanism is provided with a fixed module and a movable module. The movable module is a frame body composed of an upper frame 60, a bottom plate 62 and a rod 61. The upper part of the upper frame 60 and the lower part of the bottom plate 62 are both provided with a limit block 63. The main body of the fixed module is a shell 70 with an upper opening, and the open end is connected to the movable module. The shell 70 can accommodate the entire movable module. A sand storage chamber 74 is provided at the bottom of the shell 70. A second sand discharge port 76 is provided above the sand storage chamber 74. A pump 72 is connected to the side through a conduit. The pump 72 is connected to the sand blasting mechanism 71 at the upper end of the shell 70 through a conduit. A heater 73 is provided on the side of the shell 70. The sand storage chamber 74 is located at the lower wind outlet of the heater 73. A first sand discharge port 75 is provided on the side of the shell 70.

[0034] The movable module can move up and down, and can be driven manually or electrically. The upper frame 60 or the bottom plate 62 is fixed to be flush with the bottom of the trapezoidal groove 10 by the limit block 63. When the bottom plate 62 is flush with the bottom of the trapezoidal groove 10, the sand sample recovery and material replacement mechanism has good airtightness.

[0035] After a set of tests is completed, it is necessary to change the test water level before conducting the test again. The morphology of the test sand sample 50 changes. This embodiment designs a sand sample recovery and material replacement mechanism to recover the test sand sample 50 and replace it with a new sand sample, thereby controlling the test sand sample height and flatness variables to be consistent, thereby making the experimental results more reliable, as follows: During the test, the test sand sample 50 is placed on the bottom plate 60, the bottom plate 60 is flush with the bottom surface of the trapezoidal groove 10, and water is introduced into the water inlet 46; after the test, the water in the trapezoidal groove 10 is drained, the movable module is moved to make the upper frame 60 flush with the bottom surface of the trapezoidal groove 10, the movable module is placed in the fixed module, and the heater 73 is turned on to blow the test sand sample 50 above the sand storage chamber 74; the pump 72 sends the sand sample in the sand storage chamber 74 to the sand blasting mechanism 71, the sand blasting mechanism 71 sprays sand evenly on the bottom plate 60, and the movable module moves up to make the bottom plate 60 flush with the bottom surface of the trapezoidal groove 10. The test is repeated in this way. After the sand sample above the sand storage chamber 74 is dried, the second sand discharge port 76 is opened and the sand sample is poured into the sand storage chamber 74 for recycling. The sand sample recovery and material replacement mechanism can be removed from the bottom of the trapezoidal groove 10, and the first sand discharge port 75 is used to discharge the remaining sand sample inside the sand sample recovery and material replacement mechanism.

[0036] It should be noted that the terms used in this application are only for describing specific embodiments, rather than limiting the scope of this application. As shown in the specification of this application, unless the context clearly indicates an exception, the words "one", "a", "a kind of" and / or "the" do not specifically refer to the singular, but may also include the plural. The terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method or device. In the absence of further restrictions, the elements defined by the statement "include one..." do not exclude the presence of other identical elements in the process, method or device including the elements.

[0037] It should also be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", etc. should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0038] The embodiments and / or implementation methods described above are only used to illustrate the preferred embodiments and / or implementation methods for realizing the technology of the present invention, and are not intended to limit the implementation methods of the technology of the present invention in any form. Any technical personnel in this field may make slight changes or modifications to other equivalent embodiments without departing from the scope of the technical means disclosed in the content of the present invention, but they should still be regarded as technologies or embodiments that are essentially the same as the present invention. This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and its core ideas of this application. The above is only the preferred implementation method of this application. It should be pointed out that due to the limitations of textual expression and the objective existence of infinite specific structures, ordinary technicians in this technical field can make several improvements, modifications or changes without departing from the principles of this application, and can also combine the above technical features in an appropriate manner; these improvements, modifications, changes or combinations, or the direct application of the concept and technical solution of the invention to other occasions without improvement, should be regarded as the scope of protection of this application.

Claims

1. A device for measuring sediment starting flow velocity based on the distribution characteristics of trapezoidal grooves, comprising a water groove (40), characterized in that: One section of the water tank (40) is a trapezoidal trough (10), a test sand sample (50) is placed at the bottom of the trapezoidal trough (10), a guide rail (11) is provided above, and a laser profiler (20) and a point velocity meter (30) are provided on the guide rail (11).

2. The device for measuring the sediment starting velocity based on the distribution characteristics of the trapezoidal grooves according to claim 1 is characterized in that: The trapezoidal groove (10) is open at both ends, and water in the water tank (40) flows in from the wide side of the trapezoidal groove (10) and flows out from the narrow side.

3. The device for measuring the sediment starting velocity based on the distribution characteristics of the trapezoidal grooves according to claim 1 is characterized in that: The guide rails (11) are parallel double rails, each of which is provided with a first sliding connection block (22) and a second sliding connection block (32), and a through hole is provided in the middle of the first sliding connection block (22) and the second sliding connection block (32).

4. The device for measuring the sediment starting flow velocity based on the distribution characteristics of the trapezoidal grooves according to claim 3 is characterized in that: The first sliding connection block (22) is provided with a limiting hole, and the laser profiler (20) cooperates with the limiting hole via a first instrument connection plate (21).

5. The device for measuring the sediment starting flow velocity based on the distribution characteristics of the trapezoidal grooves according to claim 3 is characterized in that: The second sliding connection block (32) is provided with a limiting hole, and the point velocity meter (30) cooperates with the limiting hole via a second instrument connection plate (31).

6. The device for measuring the sediment starting flow velocity based on the distribution characteristics of trapezoidal grooves according to claim 1, characterized in that: The water tank (40) is connected to a water pump (41) via a pipeline; the water pump (41) is placed in a water body (43); and the pipeline is provided with an electromagnetic flowmeter (42).

7. The device for measuring sediment starting flow velocity based on the distribution characteristics of trapezoidal grooves according to claim 1, characterized in that: The water tank (40) is an annular water tank and is provided with a water inlet (46). An energy dissipation beach (44) is provided on one side of the water inlet (46), and a water retaining plate (45) is provided on the other side. The height of the water retaining plate (45) is less than the minimum side wall height of the water tank (40).

8. The device for measuring sediment starting flow velocity based on the distribution characteristics of trapezoidal grooves according to claim 7, characterized in that: A first water discharge port (47) is provided between the energy dissipation beach (44) and the water retaining plate (45), and a second water discharge port (48) is provided on the other side of the water retaining plate (45); water flowing out of the first water discharge port (47) and the second water discharge port (48) both flows toward the water body (43).

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