CN105466527A - Thin sheet flow roll wave measurement system and method based on electromagnetic sensors - Google Patents

Abstract

The invention relates to a thin-layer water flow roll measurement system and method based on an electromagnetic sensor, comprising: a plurality of electromagnetic roll sensors arranged on a flat slope, the plurality of electromagnetic roll sensors are divided into multiple groups, and each group Two electromagnetic rolling wave sensors, each group of electromagnetic rolling wave sensors are arranged in a line along the water flow direction, the distance between each group of electromagnetic rolling wave sensors is smaller than the distance between the measured rolling waves, and greater than the width of the measured rolling waves; each electromagnetic rolling wave sensor The wave sensor is sequentially connected with the data acquisition controller and the control computer. The present invention installs the electromagnetic rolling wave sensor on the position where the thin-layer water flow rolling wave is generated, such as the water channel, the dam spillway or the water tank in the laboratory, and uses the sensitive electromagnetic rolling wave sensor to detect the thickness change of the water flow to realize the observation of the rolling wave , and accurate data collection completely eliminates the factors of human detection, and completes the collection of various data fully automatically, which is accurate and fast, saves manpower and material resources, and improves observation efficiency.

Description

A thin-layer water flow rolling wave measurement system and method based on electromagnetic sensors

technical field

The invention relates to a thin-layer water flow rolling wave measurement system and method based on an electromagnetic sensor, which is an experimental system and method, a system and method for hydraulic measurement, and a method for measuring thin-layer water flow. Automatic measurement system and method for parameters such as water depth, rolling wave height, period, frequency, and wave velocity, as well as rolling wave momentum and kinetic energy during the process.

Background technique

Under certain critical conditions, the surface of slope water flow and open channel water flow often loses stability and develops a series of fluctuation processes. These fluctuations may be periodic, and the wave speed and wave shape remain unchanged, and the wave speed is always greater than the movement speed of water flow particles; Fragmentation eventually occurs. These phenomena are collectively referred to as roll. Rolling waves are often found on natural slopes, urban roads, steep discharge channels of hydropower stations, spillways of dams, floodways of rivers, and aqueducts. The emergence of rolling waves will bring a series of adverse consequences, such as the change of water flow from constant flow to unsteady flow; the enhanced ability of water flow to erode soil on slopes and the ability of soil particles to peel off and transport sediment; the water depth at the wave crest Exceeding the design water depth of the river (canal) will cause overflow; strong water aeration will cause atomization; at the same time, it will cause overload pressure or stress on the hydraulic structures on the river (canal) and so on. Therefore, the study of the critical conditions for the formation of rolling waves and its evolution law is of great significance to the soil erosion process and the configuration of soil and water conservation measures, as well as how to eliminate rolling waves in engineering practice and the theoretical research of related disciplines, such as moving bed resistance and water flow sediment transport. Significance.

The existing observation is to use the hydrological probe to observe directly. This method mainly determines the relative position of the probe and the rolling wave manually. Because it is a manual visual measurement, and the rolling wave changes very fast, the human visual inspection often cannot meet the requirements. Some effects, the measurement is difficult to guarantee the accuracy, due to artificial measurement, its stability is poor, each measurement result is not the same, can only increase the number of measurements, using statistical methods to approximate the measurement. This method makes rolling wave measurement a complicated physical labor that needs to be repeated many times, and its accuracy becomes worse and worse as the physical strength of the person declines. Therefore, there is a need for an accurate system to replace this onerous physical strength measurement.

Contents of the invention

In order to overcome the problems of the prior art, the present invention proposes a thin-layer water flow rolling wave measurement system and method based on an electromagnetic sensor. The system and method utilize the electromagnetic rolling wave sensor to realize the real-time dynamic measurement of the water level of the thin layer of water flow and the rolling wave through system integration and automation methods, thereby effectively improving the accuracy and stability of the measurement and improving the observation efficiency.

The object of the present invention is achieved like this: a kind of thin layer water flow rolling wave measuring system based on electromagnetic sensor, comprises: a plurality of electromagnetic rolling wave sensors that are arranged on the flat slope surface, and described electromagnetic rolling wave sensor is arranged like this Divide a plurality of electromagnetic rolling wave sensors into multiple groups, each group has two electromagnetic rolling wave sensors, each group of electromagnetic rolling wave sensors is arranged in a line along the direction of water flow, and the distance between each group of electromagnetic rolling wave sensors is less than The distance between the measured rolling waves is greater than the width of the measured rolling waves; the two electromagnetic rolling wave sensors in each group are arranged in a line along the water flow direction, and the distance between the two electromagnetic rolling wave sensors is greater than the peak and trough of the measured rolling waves Each of the electromagnetic rolling wave sensors is connected with the data acquisition controller and the control computer in sequence.

Further, the electromagnetic rolling wave sensor includes: a U-shaped communication tube, one end of the U-shaped communication tube is arranged at the bottom of the slope, the other end of the U-shaped communication tube is open to the atmosphere, and the U-shaped communication tube A guide rod is provided on the side open to the atmosphere, an electromagnetic induction element is arranged in the guide rod, and an annular float is sleeved on the guide rod.

Further, the electromagnetic induction element is a float of ferromagnetic material and a Hall element or an induction coil.

Further, the slope is the bottom of the test tank, and the test tank includes: sides on both sides and a bottom connected to the sides, and the sides and bottom are set on the steel structure On the rack, one end of the water tank is provided with a water inlet, and the other end is provided with a water outlet. The water outlet is connected to the pipeline of the circulating pool, the water inlet is connected to the pipeline of the circulating pool through a water pump, and the steel structure A hinge is arranged on one side of the water outlet of the frame, and a lifting mechanism is arranged on the other side.

A method for measuring rolling waves of thin-layer water flow based on electromagnetic sensors using the above-mentioned system, the steps of the method are as follows:

Steps for setting the acquisition frequency: used to set the sampling frequency of the electromagnetic roll sensor through the computer;

Acquisition steps: When the water flow with rolling waves comes, all sensors collect water level data synchronously, and import the collected data into the computer, analyze and process the data and directly calculate the rolling wave period, frequency, wave height, and wave speed along the way and mean water depth;

Steps for calculating roll wave energy: used to estimate roll wave energy using roll wave water depth, time interval and along-way wave velocity data.

Further, the calculation method of the average water depth, wave height, wave velocity, cycle and frequency of the rolling wave is as follows:

Calculation of the average water depth: when there is water flow on the slope surface, the electromagnetic rolling wave sensor measures the height h ₁ of the water surface, after n times of collection, average the n water depths to obtain the average water depth of the section ;

Judgment of rolling wave and calculation of wave height: compare each collected water level value with the average water level value, and if the water level value monitored for 3 consecutive times is greater than the average water level value, it is rolling wave, and record the maximum water level value and maximum water level value during this period h _max and mean water level The difference is the wave height;

Calculation of rolling wave velocity: the distance l between each group of electromagnetic rolling wave sensors divided by the time difference t of the maximum water level value of each group of electromagnetic rolling wave sensors is the rolling wave velocity v;

Rolling wave cycle and frequency: The time difference between two rolling waves of a single sensor is the rolling wave cycle T, and the reciprocal of the cycle is the rolling wave frequency f.

Further, the calculation steps of the rolling wave energy are as follows:

Take the product of the rolling wave velocity and the duration between two consecutive records of the electromagnetic rolling wave sensor as the abscissa, and take the difference between the water level value that is continuously recorded and greater than the average water level and the average water level value as the vertical axis to plot the rolling wave. cross section;

Calculate the area of the cross-section of the roll;

The single-width mass of the rolling wave is obtained by multiplying the area of the rolling wave cross-section by the water density;

Multiply the single-width mass by the wave velocity to get the momentum of the rolling wave;

Multiplying the single-width mass by the wave velocity to the power of 1/2 gives the kinetic energy of the rolling wave.

The beneficial effect that the present invention produces is: the present invention adopts the position that produces thin-layer water flow rolling wave, as installing electromagnetic rolling wave sensor on the water channel in water channel, dam spillway or laboratory, utilizes sensitive electromagnetic rolling wave sensor to detect the thickness of water flow Changes, to achieve the observation of rolling waves, and accurate data collection, completely eliminating the factors of human detection, and complete the collection of various data fully automatically, which is accurate and fast, saves manpower and material resources, and improves observation efficiency.

Description of drawings

The present invention will be further described below in conjunction with drawings and embodiments.

Fig. 1 is a schematic diagram of the principle of the system described in Embodiment 1 of the present invention;

Figure 2 is a schematic diagram of the width of rolling waves and the distance between two rolling waves, which is an enlarged view of point E in Figure 1;

Fig. 3 is a structural schematic diagram of the electromagnetic rolling wave sensor and the water tank described in Embodiments 2 and 4 of the present invention, which is a cross-sectional view of A-A in Fig. 4;

Fig. 4 is a schematic structural view of the water tank according to Embodiment 4 of the present invention.

detailed description

Embodiment one:

This embodiment is a thin-layer water flow rolling wave measurement system based on an electromagnetic sensor, as shown in FIG. 1 . This embodiment includes: a plurality of electromagnetic roll sensors 2 arranged on a flat slope 1, the electromagnetic roll sensors are arranged in this way: a plurality of electromagnetic roll sensors are divided into multiple groups, each group has two electromagnetic rolling wave sensors, each group of electromagnetic rolling wave sensors is arranged in a line along the water flow direction, the distance between each group of electromagnetic rolling wave sensors is smaller than the distance between the measured rolling waves, and greater than the width of the measured rolling waves; Two electromagnetic rolling wave sensors are arranged in a line along the direction of water flow, the distance between the two electromagnetic rolling wave sensors is greater than the distance between the peak and the trough of the measured rolling wave, and each electromagnetic rolling wave sensor is sequentially connected with the data acquisition control Device 3, control computer 4 connection.

The thin-layer water flow described in this embodiment refers to the water flow whose thickness is below 30 centimeters. This "thin-layer water flow" is a customary title in the industry, and is not relative to the "thick-layer water flow", because, There is no such term as "thick layer flow" in the industry.

The flat slope described in this embodiment can be the simulated channel bottom surface with a certain slope in the laboratory, or the real channel bottom surface with a certain slope, or the bottom surface of an inclined dam spillway, or in the field Select a flat slope.

The flatness of the slope is relative, requiring two key points, one is that there are no obvious protrusions on the slope, and the other is that the slope should be basically flat, without obvious arches and depressions, that is, along the direction of water flow and vertical water flow The slope line of the profile in the direction should be a straight line or close to a straight line. The slope can be a very flat surface, such as the bottom of a channel simulated in a laboratory using plates such as glass or plastic, or the bottom of a real channel or dam spillway. The bottom surface of the real channel or dam spillway is artificially constructed, basically flat, with no obvious protrusions. A slope selected in the field requires no obvious protrusions, and avoids the overall curved surface of the slope from being arched and depressed. Of course, it is a different matter if you specialize in rolling waves with integrally arched or sunken slopes.

The electromagnetic rolling wave sensor described in this embodiment can use a guide rod type magnetic float liquid level gauge, or a specially designed electromagnetic rolling wave sensor. The basic principle of the electromagnetic rolling wave sensor is to place a float made of magnetic material on the water surface. When the float floats up and down with the water level, the magnetic field will undergo displacement and other changes, and an electromagnetic induction element, such as a Hall element or an electromagnetic induction coil, will be used to detect the magnetic field. Displacement change, the change of the magnetic field is converted into an electrical signal, which is finally collected by the collector as water level change data.

The structure of the guide rod magnetic float liquid level gauge is that the float is made into a ring and sleeved on a guide rod, and the float moves up and down along the guide rod with the change of the liquid level. A permanent magnetic object is set in the float, and a magnetic sensitive element is set inside the guide rod. The position of the float is detected by the magnetic sensitive element and converted into a corresponding electrical signal representing the liquid level for output. This type of liquid level gauge performs better when there is violent movement of the medium in the container, and it has the characteristics of simple structure when only remote signals are required and no on-site liquid level gauge indication is required.

In order to obtain the change of the water level, under normal circumstances, it is necessary to use pipelines to guide the water level out of the flow channel, and then use the electromagnetic induction element to obtain the signal of the water level change. The general method is to open a hole in the bottom plate of the water tank, and connect the electromagnetic rolling wave sensor with the water tank to form a connected pipe type device. Arrays are arranged in the direction of water flow, such as 5-10 groups of electromagnetic rolling wave sensors, or more, and two electromagnetic rolling wave sensors are arranged in each group. For example, 20 electromagnetic rolling wave sensors are set in a 15-meter-long water tank, and are connected to the acquisition controller through connecting wires. A group of sensors are arranged at intervals of 1m, and the distance between sensors in a group is set to 5cm.

The electromagnetic rolling wave sensor must be installed vertically to ensure that the float assembly can move freely up and down in the main tube. Moreover, no magnetic conductor is allowed to approach the main body of the electromagnetic roll wave sensor, otherwise it will directly affect the correct operation of the electromagnetic roll wave sensor. After the electromagnetic rolling wave sensor is installed, it needs to be calibrated with a magnetic steel to guide the turning column once so that it will display red below the zero position and white above the zero position.

This is a very accurate measurement method, which can measure the thin layer of water flow with a thickness of a few millimeters, and the water level change of a few tenths of a millimeter. Due to the need for pipeline installation, it is more suitable for high-precision measurement in the laboratory.

Since this embodiment measures the rolling waves of the thin-layer water flow, the water level change is relatively small, especially when the experiment is carried out in a water tank erected in the laboratory, very accurate measurement results can be obtained. There are many ways to measure the water level by using the electromagnetic rolling wave sensor, one of which is to use the U-shaped tube electromagnetic rolling wave sensor.

The arrangement of electromagnetic roll wave sensors is also very particular, which must be adapted to the needs of the experiment and the environment for on-site detection of roll waves. The idea of the arrangement proposed in this embodiment is: since multiple rolling waves may appear on the slope, multiple sets of electromagnetic rolling wave sensors are used to measure these rolling waves on the slope respectively. Two electromagnetic roll sensors in each group are used to judge and detect a single roll. The distance between the individual sensors in each group should be larger than the width d of a single roll, but smaller than the distance L between two rolls. The width of the rolling waves described in this embodiment refers to the length of the part where the water depth of a single rolling wave is greater than the average water depth in the direction of water flow, as shown in FIG. 2 , where the dotted line in the figure indicates the average water depth.

On a longer slope, 8-10 sets of electromagnetic roll sensors can be installed, while on a shorter slope, a few sets of electromagnetic roll sensors can be used. Only 5 sets of electromagnetic roll sensors are shown in Figure 1. , you can actually add more groups.

In this embodiment, the change of the current signal of the electromagnetic roll wave sensor is collected by the controller of the data collector to deduce the change of the depth of the water flow, so as to study the hydrodynamic parameters of the thin-layer water flow and the characteristic parameters of the roll wave. The data collected by a single electromagnetic roll sensor can obtain the average water depth of the water flow and the period, frequency and wave height of the roll wave. And each group of liquid level gauges calculates the wave velocity of the rolling wave through the time difference of the collected wave height and the distance between the electromagnetic rolling wave sensors.

The data acquisition controller is an instrument that controls the acquisition frequency, converts the collected current signal into a digital signal, and collects the data of the sensor in real time. Since multiple sets of common electromagnetic roll sensors are required, the acquisition controller needs to be equipped with at least the same number of acquisition channels as the electromagnetic roll sensors, and the acquisition between each channel does not interfere with each other.

The control computer has a program for controlling the parameters of the collector, a program for importing and collecting data, and a software for processing and analyzing the collected data. Its main function is to control the acquisition frequency of the collector and import the data in the acquisition card into the computer in real time for analysis and processing to obtain the average water depth, the wave height, period, frequency and wave velocity of the rolling wave, and the kinetic energy of the rolling wave.

Embodiment two:

This embodiment is an improvement of the first embodiment, and is a refinement of the embodiment regarding the electromagnetic roll sensor. The electromagnetic rolling wave sensor described in this embodiment includes: a U-shaped communication tube 204, one end of the U-shaped communication tube is arranged at the bottom of the slope, the other end of the U-shaped communication tube is open to the atmosphere, and the U-shaped communication tube is connected to the atmosphere. A guide rod 201 is provided on the side of the tube open to the atmosphere, the guide rod is provided with an electromagnetic induction element 202, and an annular float 203 is sleeved on the guide rod, as shown in FIG. 3 .

The water inlet of the U-shaped pipe is arranged at the bottom of the slope, and the other end of the U-shaped pipe is opened to the atmosphere, and the U-shaped pipe is filled with water. When there is no water flowing across the slope, the water in the U-shaped tube remains at the same height as the bottom of the slope. When there is water flow, the water level of the U-shaped tube rises to the height of the water flow. When the rolling waves pass by, the water in the U-shaped tube The water level of the water increases with the water roll, and the ring float in the U-shaped tube floats upward with the water surface, changing the magnetic field and finally generating the electrical signal of the roll.

Embodiment three:

This embodiment is an improvement of the second embodiment, and is a refinement of the second embodiment regarding the electromagnetic induction element. The electromagnetic induction element described in this embodiment is a float of ferromagnetic material and a Hall element or an induction coil.

Floats can be mixed with non-metallic materials and magnetic powder, and processed into rings, hollow balls or hollow cylinders.

If the float is ring-shaped, it is set on the guide rod, and the induction coil or Hall element is placed in the guide rod, which can produce a sensitive electromagnetic induction effect.

Embodiment four:

This embodiment is an improvement of the above embodiment, and is a refinement of the above embodiment regarding the slope. The slope described in this embodiment is the bottom of the experimental tank, and the test tank includes: sides 101 and bottom 103 connected with the sides, the sides and the bottom are arranged on On the steel structure frame 102, one end of the water tank is provided with a water inlet 106, and the other end is provided with a water outlet 109, and the water outlet is connected to the circulating pool 108 pipeline, and the described water inlet is connected to the circulating pool pipeline through a water pump 107. To connect, a hinge 104 is set on one side of the water outlet of the steel structure frame, and a lifting mechanism 105 is set on the other side, as shown in Figures 3 and 4.

This embodiment is a water tank that can be installed in a laboratory. The steel frame supports the water tank, and the steel frame can change the angle of the water tank through hinges and lifting mechanisms to carry out experiments on various slope angles. Sinks can be made of materials such as glass or plexiglass.

The two ends of the water tank are respectively provided with a water inlet and a water outlet, and the water flow in the water tank is circulated through the water pump and the circulating pool. The water pump can use a frequency conversion pump to carry out water flow experiments with various flows.

For precise flow control, an electromagnetic flowmeter can be installed between the flow control valve and the water tank. Precise thin-layer water flow is generated through flow control valves and electromagnetic flow meters.

In order to ensure the stability of the water flow in the tank and reduce the interference to the rolling waves, multiple water inlets can be arranged in a line on the top of the tank (the line is perpendicular to the direction of the water flow), so that the water flow can be formed in a uniform tank. Thin layer of water flow.

In most cases, the water flow output by the water pump has a certain pulsation. If the outlet of the water pump (the water inlet of the tank) is directly set on the top of the tank, the formed water flow will be disturbed by the pulsation, making the water flow process uneven and disturbing the thin-layer water flow. The formation of the middle rolling wave does not reach the experimental effect. Therefore, a water flow rectifying device can be arranged at the top water tank water inlet of the water tank to stabilize the water flow.

The water flow rectification device is actually a system to eliminate the instability of the water supply flow, which can ensure the stability and uniformity of the water flow process, thereby eliminating the impact of water supply on the generation and development of rolling waves.

The water flow rectification device can be a water tank, that is, a water tank is set on the top of the tank slope to store a certain amount of water. The water outlet of the water tank (the water outlet flowing to the tank) is an overflow weir, which absorbs the water generated by the water pump by using the volume of the water in the tank. Shock, using the overflow to create a steady, thin layer of water flow.

The overflow water supply of the water tank also has problems such as instability and vibration of the water tank, which cause instability in the overflow process of the water tank. Therefore, the overflow weir can be further changed into a multi-layer rectification orifice plate or a rectification tube plate, and the output water flow can be further stabilized by using the orifice plate or the tube plate. The rectifying orifice plate is a stainless steel plate with a thickness of about 2mm that is densely marked with water holes with a diameter of about 1mm. Through multi-layer superimposition, it is placed between the water inlet and the overflow edge of the tank, so as to eliminate the leakage caused by the outflow process of the water supply pipe of the water tank. of water fluctuations. The rectification hole tube is to eliminate the uneven eddy current formed during the overflow process of the water tank. The upper rectification tube plate of the tank placed after the overflow is made of closely arranged PVC pipes with a diameter of 1cm and a length of 2~3cm.

Embodiment five:

This embodiment is a method for measuring thin-layer water flow rolling using the system described in the above embodiments.

Principle of the method described:

1. Depth measurement

Calculation of the average water depth: The magnetic float level gauge and the water tank form a connected device. When the water is discharged, the change of the water depth of the water flow causes the position of the float of the liquid level gauge to change, thereby causing the change of the current. The collector collects the real-time current. Then, the change of the water depth is calculated through the corresponding formula of the calibrated current and the water depth, and the collected data are averaged to obtain the average water depth of the water flow.

2. Rolling wave height measurement

Judgment of rolling wave and calculation of wave height: compare each collected water level value with the average water level value, and if the water level value monitored for 3 consecutive times is greater than the average water level value, it is rolling wave, and automatically record the maximum water level value during this period, the maximum water level Value h _max and mean water level value The difference is the wave height.

3. Rolling wave velocity, wave frequency measurement and along the way wave velocity, wave frequency measurement

Calculation of rolling wave velocity: the distance between each group of liquid level gauges divided by the time difference of the maximum water level value of each liquid level gauge is the rolling wave velocity, that is Where v is the rolling wave velocity, l is the spacing of a group of liquid level gauges, and t is the time difference of the maximum water level value of each liquid level gauge in each group.

The time difference between two rolling waves of a single magnetic float level gauge is the period T of the rolling wave, and the reciprocal of the period is the frequency f. which is , where: f is the frequency and T is the period.

4. Rolling momentum and kinetic energy measurement

Calculation of rolling wave energy: take the product of the rolling wave velocity and the time between two consecutive records of the liquid level gauge as the abscissa, and plot the difference between the water level value that is continuously recorded and greater than the average water level and the average water level value as the ordinate, that is The cross-section of the rolling wave can be drawn, and the area of the cross-section can be estimated by CAD software, and the mass of the single-width rolling wave can be obtained by multiplying the area by the density of water. The mass multiplied by the wave velocity is the rolling momentum, and the mass multiplied by the wave velocity to the power of 1/2 is the kinetic energy of the rolling wave.

The calculation formula is:

Rolling momentum: p=ρAv, where is the density of water, A is the area of rolling wave cross section, obtained by CAD software, is the wave velocity of the rolling wave.

Rolling energy: Among them, ρ is the density of water, A is the area of rolling wave cross section, obtained by CAD software, and v is the wave velocity of rolling wave.

The concrete steps of described method are as follows:

Steps for setting the acquisition frequency: it is used to set the sampling frequency of the electromagnetic roll sensor through the computer. The sampling frequency is the frequency at which the data collector collects the sensor measurement signal into the computer. The sampling frequency can be adjusted according to the visual roll frequency, and generally should be more than 10 times the visual roll frequency.

Acquisition steps: When the water flow with rolling waves comes, all electromagnetic rolling wave sensors collect water level data synchronously, and import the collected data into the computer, analyze and process the data and directly calculate the rolling wave period, frequency, wave height, edge Wave velocity and mean water depth. What the electromagnetic roll sensor collects is the height change of the water surface. Therefore, it is necessary to judge the appearance of the roll wave and various parameters of the roll wave according to the height of the water surface. Due to the use of two sets of electromagnetic rolling wave sensors, the rolling wave can be collected at two positions at the same time. According to the collection time, the distance between the two sensors, and the collected water level, the cycle is obtained. , frequency, wave height, wave speed along the way and average water depth and other parameters.

Steps for calculating roll wave energy: used to estimate roll wave energy using roll wave water depth, time interval and along-way wave velocity data. Calculate the kinetic energy of the rolling wave through the various rolling wave parameters obtained in the previous step. Rolling wave energy is an important index to measure the strength of water flow on the underlying surface and the ability of water flow to carry sand.

Embodiment six:

This embodiment is an improvement of the fifth embodiment, and is a refinement of the calculation of the average water depth, wave height, wave velocity, cycle and frequency of rolling waves in the fifth embodiment. The calculation methods of rolling wave average water depth, wave height, wave velocity, cycle and frequency described in this embodiment are as follows:

Calculation of the average water depth: when there is water flow on the slope surface, the electromagnetic rolling wave sensor measures the height h ₁ of the water surface, after n times of collection, average the n water depths to obtain the average water depth of the section . In the water flow experiment, when there is no water flow passing through the electromagnetic rolling wave sensor, the water volume in the U-shaped tube is kept at the same position at the bottom of the slope, that is, the position h ₀ at the bottom of the tank, where h ₀ =0. The collected data is converted to obtain the height h ₁ between the electromagnetic sensor and the water surface. Then the water depth is h=h ₀ -h ₁ , after n times of collection, the n water depths are averaged to obtain the average water depth of the section . In order to find an accurate average water depth, the number n of detections usually reaches thousands, or tens of thousands of times.

Judgment of rolling wave and calculation of wave height: compare each collected water level value with the average water level value, and if the water level value monitored for 3 consecutive times is greater than the average water level value, it is rolling wave, and record the maximum water level value and maximum water level value during this period h _max and mean water level The difference is the wave height.

Calculation of rolling wave velocity: the distance l between each group of electromagnetic rolling wave sensors divided by the time difference t of the maximum water level value of each group of electromagnetic rolling wave sensors is the rolling wave velocity v. which is Where v is the rolling wave velocity, l is the distance between a group of sensors, and t is the time difference of the maximum water level value of each group of sensors.

Rolling wave cycle and frequency: The time difference between two rolling waves of a single sensor is the rolling wave cycle T, and the reciprocal of the cycle is the rolling wave frequency f. which is , where: f is the frequency and T is the period.

Embodiment seven:

This embodiment is an improvement of the sixth embodiment, and it is a refinement of the sixth embodiment regarding the roll wave energy. The calculation steps of the rolling wave energy described in this embodiment are as follows:

Take the product of the rolling wave velocity and the duration between two consecutive records of the electromagnetic rolling wave sensor as the abscissa, and take the difference between the water level value that is continuously recorded and greater than the average water level and the average water level value as the vertical axis to plot the rolling wave. cross section;

Calculate the area of the cross-section of the roll. You can use drawing software such as CAD to calculate the area of the cross-section of the rolling wave, or you can directly use hand-drawn calculations.

The single-width mass of the roll is obtained by multiplying the area of the roll cross-section by the density of the water.

Multiply the single-width mass by the wave velocity to get the momentum of the rolling wave, namely: p=ρAv, where is the density of water, A is the area of rolling wave cross-section, is the wave velocity of the rolling wave.

Multiply the single-width mass by the 1/2 power of the wave velocity to get the kinetic energy of the rolling wave, namely: .

Finally, it should be noted that the above is only used to illustrate the technical solution of the present invention and not to limit it. Although the present invention has been described in detail with reference to the preferred arrangement, those skilled in the art should understand that the technical solutions of the present invention (such as The fixing method of the electromagnetic rolling wave sensor, the rolling wave acquisition method, the sequence of steps, etc.) are modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention.

Claims (7)

1. the sheet flow roll wave measuring system based on electromagnetic sensor, it is characterized in that, comprise: be arranged on smooth domatic on multiple electromagnetism roll wave sensors, described electromagnetism roll wave sensor is arrangement like this: multiple electromagnetism roll wave sensor is divided into multiple groups, often organize two electromagnetism roll wave sensors, each group of electromagnetism roll wave sensor is along the arrangement of water (flow) direction yi word pattern, and the distance between each group electromagnetism roll wave sensor is less than the spacing of tested roll wave, is greater than the width of tested roll wave; Two electromagnetism roll wave sensors in each group are along water (flow) direction word order, distance between two electromagnetism roll wave sensors is greater than the distance between the crest of tested roll wave and trough, each described electromagnetism roll wave sensor successively with data acquisition controller, control computer and be connected.

2. system according to claim 1, it is characterized in that, described electromagnetism roll wave sensor comprises: U-shaped cross over pipe, one end of described U-shaped cross over pipe is arranged on domatic bottom, the other end of described U-shaped cross over pipe opens wide to air, U-shaped cross over pipe opens wide side to air and arranges guide rod, is provided with electromagnetism sensing unit in described guide rod, and on described guide rod, cover has annular float.

3. system according to claim 2, is characterized in that, described electromagnetism sensing unit is the float of ferromagnetic material and Hall element or inductive coil.

4. system according to claim 2, it is characterized in that, described domatic be the bottom land of experimental trough, described experimental tank comprises: both sides ledge and the bottom land be connected with described ledge, described ledge and bottom land are arranged on steel frame, described tank one end arranges water inlet, the other end sets out the mouth of a river, described water delivering orifice is connected with circulating water pool pipeline, described water inlet is connected with described circulating water pool pipeline by water pump, described steel frame water delivering orifice side arranges hinge, and opposite side arranges elevating mechanism.

5. use the sheet flow roll wave measuring method that system described in claim 1 is carried out based on electromagnetic sensor, its feature exists, and the step of described method is as follows:

The step of setting frequency acquisition: for the sample frequency by computer setting electromagnetism roll wave sensor;

The step gathered: for coming interim at the current with roll wave, all the sensors synchronous acquisition waterlevel data, and by the data importing computer that gathers, to data carry out analyzing and processing directly calculate the roll wave cycle, frequency, wave height, along journey velocity of wave and mean depth;

Calculate the step of roll wave kinetic energy: for utilizing the roll wave depth of water, time interval and along journey velocity of wave data estimation roll wave kinetic energy.

6. method according to claim 5, is characterized in that, the computing method of described roll wave mean depth, wave height, velocity of wave, cycle and frequency are as follows:

The calculating of mean depth: when domatic have current to flow through time, the height h of the electromagnetism roll wave sensor measurement water surface ₁, gather through n time, n the depth of water be averaged, obtain the mean depth ` of section ;

The judgement of roll wave and the calculating of wave height: each water level value collected and average water place value are made comparisons, continuous 3 monitoring water level values are greater than average water place value and are roll wave, record maximum stage value during this period, maximum stage value h _maxwith average water place value ` difference be wave height;

Roll wave velocity of wave calculates: divided by often organizing electromagnetism roll wave sensor, the spacing l often organized between electromagnetism roll wave sensor occurs that the mistiming t of maximum stage value is roll wave velocity of wave v;

Roll wave cycle and frequency: single-sensor occurs that the mistiming of twice roll wave is exactly the cycle T of roll wave, and the inverse in cycle is then the frequency f of roll wave.

7. method according to claim 5, is characterized in that, the calculation procedure of described roll wave kinetic energy is as follows:

Amass as horizontal ordinate with the duration between roll wave velocity of wave and the double record of electromagnetism roll wave sensor, map to record continuously and to be greater than the water level value of mean water and the difference of average water place value for ordinate, depict the transversal section of roll wave;

Calculate the area of the transversal section of roll wave;

The wide quality of list of roll wave is obtained by the density that the area of the transversal section of roll wave is multiplied by water;

Single wide quality is multiplied by the momentum that velocity of wave obtains roll wave;

1/2 power that single wide quality is multiplied by velocity of wave is obtained the kinetic energy of roll wave.