Open channel flow meter for monitoring flow in trapezoidal or U-shaped channels and flow measurement method thereof

Abstract

The present invention discloses an open channel flow meter for monitoring flow in a trapezoidal or U-shaped channel and a flow measurement method thereof, comprising a channel water flow form monitoring device and a flow monitoring controller arranged in the trapezoidal or U-shaped channel; the flow measurement method comprises: S1, constructing a trapezoidal or U-shaped three-section flow measurement environment; S2, a control module issues a control instruction to control the pressure water level monitoring instruments on the upstream and downstream sides to monitor the flow in a set monitoring period Δ t According to the set acquisition frequency, the water level data of the upstream monitoring section Ls and the water level data of the downstream monitoring section Lx are synchronously collected; S3, the flow rate of the monitored section Le is calculated. The present invention breaks through the traditional flow measurement method, through the channel water flow form monitoring device installed at the monitored section position and the changes in the upstream and downstream water levels of the monitored channel section caused by the channel action, the average flow rate of the monitored section is monitored and calculated according to the energy conservation and channel continuity equation, and has the advantage of high measurement accuracy.

Description

Technical Field

[0001] The invention relates to the field of open channel flow monitoring, in particular to an open channel flow meter used for monitoring flow in a trapezoidal or U-shaped channel and a flow measurement method thereof. Background Art

[0002] Accurate monitoring of open channel flow is the basis of water conservation in irrigation areas. At present, the main means of monitoring and measuring open channel flow are the velocity area method, the core of which is to monitor the average velocity of the flow section. The methods of measuring flow velocity include electromagnetic method, ultrasonic (time difference method), Doppler method, and building flow measurement method. The electromagnetic method has the disadvantage of being difficult to break through the limitation of large-section flow measurement; the Doppler method is mainly used to measure strip flow velocity and has low accuracy; the multi-channel flow measurement equipment used by the ultrasonic time difference method has strict requirements for on-site installation and is very expensive. Summary of the invention

[0003] The present invention aims to provide an open channel flow meter which has high measurement accuracy and is easy to install and is used for monitoring the flow in a trapezoidal or U-shaped channel. Another object of the present invention is to provide a flow measurement method for the open channel flow meter.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] The open channel flowmeter for flow monitoring in a trapezoidal or U-shaped channel of the present invention comprises a channel water flow form monitoring device arranged in the trapezoidal or U-shaped channel and a flow monitoring controller arranged outside the trapezoidal or U-shaped channel; the channel water flow form monitoring device comprises a vertical tube with a diamond-shaped cross section, a base is arranged at the lower tube mouth of the vertical tube, and filter holes for eliminating water flow disturbance are respectively opened on four vertical plates constituting the vertical tube; a partition is arranged in the vertical tube to separate the inner cavity of the vertical tube into an upstream tube cavity and a downstream tube cavity with two isosceles triangle cross sections, an upstream side riser and a downstream side riser are respectively arranged in the upstream side tube cavity and the downstream side tube cavity, and filter holes for eliminating water flow disturbance are respectively opened on the circumferential surfaces of the upstream and downstream side risers; an upstream side pressure water level monitor and a downstream side pressure water level monitor are respectively arranged in the upstream and downstream side risers on the base, and the control interfaces of the upstream and downstream side pressure water level monitors are led out from the upper tube mouth of the vertical tube through cables, and the control interface cables are connected to the flow monitoring controller.

[0006] The flow monitoring controller comprises:

[0007] A basic parameter input control module, used to input the cross-sectional dimension data of the trapezoidal or U-shaped channel, the water blocking width data of the vertical tube and monitoring control parameters and store them in a memory;

[0008] A control module, used to issue control instructions to control the upstream and downstream pressure water level monitors to synchronously collect the water levels of the channel sections monitored by each of them according to the set collection frequency within the set monitoring period and calculate the average water level within the set monitoring period and the area of ​​the water-passing section of the average water level;

[0009] The instantaneous flow monitoring and calculation module is used to calculate the instantaneous average flow of the monitored section within the set monitoring period and calculate the average flow of the monitored section within the set monitoring time period.

[0010] The filter holes formed on the four vertical plate surfaces and the peripheral surfaces of the upstream and downstream vertical pipes are all rectangular vertical holes.

[0011] Notches are respectively opened on the bottom pipe walls of the upstream and downstream side risers, so that canal water can smoothly enter the upstream and downstream side risers.

[0012] The flow measurement method of the open channel flowmeter of the present invention comprises the following steps:

[0013] S1, constructing the trapezoidal or U-shaped three-section flow measurement environment:

[0014] The channel flow pattern monitoring device is installed on the channel centerline of the designated monitored section Le at the channel bottom, and the steps are as follows:

[0015] S1.1, fix the base of the vertical tube to the bottom of the channel, make the partition in the vertical tube overlap with the monitored section Le, and extend the upper tube mouth of the vertical tube above the channel;

[0016] S1.2, set the upstream side of the vertical tube as the upstream monitoring section Ls, set the downstream side of the vertical tube as the downstream monitoring section Lx; the upstream side pressure water level monitor is used to monitor the water level during the set monitoring period Δ t The water level of the upstream monitoring section Ls is collected according to the set collection frequency, and the downstream pressure water level monitor is used to collect the water level of the upstream monitoring section Ls in the set monitoring period Δ t Collecting the water level of the downstream monitoring section Lx according to the set collection frequency;

[0017] S2, the control module issues a control instruction to control the upstream and downstream pressure water level monitors to monitor the water level during the set monitoring period Δ t According to the set acquisition frequency, the water level data of the upstream monitoring section Ls and the downstream monitoring section Lx are collected synchronously, and the water level data of the set monitoring period Δ t The average water level hs data of the upstream monitoring section Ls, the average water level hx data of the downstream monitoring section Lx, and the average water flow area of ​​the monitored section Le Data, average water flow area of ​​upstream monitoring section Ls Data, average water flow area of ​​downstream monitoring section Lx Data; Among them, the average water area of ​​the monitored section Le Equal to the average water flow area of ​​the upstream monitoring section Ls Subtract the water blocking area of ​​the channel flow pattern monitoring device below the average water level hs of the upstream monitoring section Ls;

[0018] S3, flow calculation of monitored section Le:

[0019] The control module will obtain the average water level hs data, average water level hx data, and average water area Data, average water area Data and average water area The data is output to the instantaneous flow monitoring calculation module, which derives the Δ based on the above parameters according to the energy conservation principle of the three sections. t The calculation method of average flow rate during a period is as follows:

[0020] According to the three-section energy conservation principle, the instantaneous average total energy E of the upstream monitoring section Ls is LS Subtract the instantaneous average total energy E of the downstream monitoring section Lx Lx Equal to the average momentum change ΔE of the monitored section Le Lx ,in:

[0021] ;

[0022] ;

[0023] At the same time, according to the channel flow continuity equation Q s =Q x =Q e have:

[0024] ;

[0025] Thus we get ;

[0026] Q s : The upstream monitoring section Ls is in Δ t Average flow rate during the time period;

[0027] Q x : Downstream monitoring section Lx in Δ t Average flow rate during the time period;

[0028] Q e : The monitored section Le is in Δ t Average flow rate during the time period;

[0029] m : Δ t The average quality of water flowing through the three sections Ls, Le and Lx during a period of time;

[0030] V s : The upstream monitoring section Ls is in Δ t Average flow rate during the time period;

[0031] V x : Downstream monitoring section Lx in Δ t Average flow rate during the time period;

[0032] V e : The monitored section Le is in Δ t Average flow rate during the time period;

[0033] g - acceleration due to gravity.

[0034] In S2, the monitoring period ∆t is set between 5 seconds and 60 seconds, the acquisition frequency is 2-3 times per second, and the average water level hs data of the upstream monitoring section Ls and the average water level hx data of the downstream monitoring section Lx are calculated once in each monitoring period ∆t; when calculating the average water level hs data and the average water level hx data, the maximum value and the minimum value are removed respectively and the average value is taken.

[0035] The present invention breaks through the traditional flow measurement method. Through the channel flow form monitoring device installed at the monitored section and the changes in the upper and lower water levels of the monitored section caused by the channel action, the average flow of the monitored section is monitored and calculated based on the energy conservation and channel continuity equation. The error caused by the energy conversion of the transducer device in the traditional flow measurement method is eliminated, and parameter calibration is not required. It has the advantages of high measurement accuracy, simple installation and flow measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a structural schematic diagram of the channel water flow form monitoring device of the present invention.

[0037] Figure 2 yes Figure 1 AA section enlarged structural diagram.

[0038] Figure 3 It is a schematic diagram of the structure of the upstream riser (or downstream riser) of the present invention.

[0039] Figure 4 It is a plan view of the channel water flow pattern monitoring device of the present invention arranged in a ladder-shaped channel.

[0040] Figure 5 It is a schematic elevation view of the channel water flow pattern monitoring device of the present invention arranged in a ladder-shaped channel.

[0041] Figure 6 It is a block diagram of the circuit control system of the present invention.

[0042] Figure 7 It is a flowchart of the method described in the present invention. DETAILED DESCRIPTION

[0043] The following is a detailed description of an embodiment of the present invention in conjunction with the accompanying drawings. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0044] like Figure 1-6 As shown, the present invention is now described by taking a trapezoidal channel as an example:

[0045] The open channel flow meter for monitoring flow in a trapezoidal channel comprises a channel water flow form monitoring device arranged in the trapezoidal channel 1 and a flow monitoring controller arranged outside the trapezoidal channel.

[0046] The channel water flow form monitoring device comprises a vertical tube 2 with a diamond-shaped cross section, a base 3 is arranged at the lower tube mouth of the vertical tube 2, and filtering holes 5.1 for eliminating water flow disturbance are respectively opened on the four vertical plates 4.1, 4.2, 4.3, and 4.4 that compose the vertical tube 2. The filtering hole 5.1 selects a rectangular vertical hole structure, which makes it easier to eliminate water flow disturbance.

[0047] A partition 6 is arranged in the vertical tube 2 to divide the inner cavity of the vertical tube into two upstream cylinder cavities 7 and downstream cylinder cavities 8 with isosceles triangle cross sections. An upstream side vertical pipe 9 and a downstream side vertical pipe 10 are arranged in the upstream side cylinder cavity 7 and the downstream side cylinder cavity 8, respectively. Filter holes 5.2 for eliminating water flow disturbance are respectively opened on the circumference of the upstream and downstream side vertical pipes 9 and 10. The filter holes 5.2 are rectangular vertical hole structures, which are easier to eliminate water flow disturbance. Notches 11 are respectively opened on the bottom pipe walls of the upstream and downstream side vertical pipes 9 and 10, so that the canal water can smoothly enter the upstream and downstream side vertical pipes 9 and 10. An upstream side pressure water level monitor 12 and a downstream side pressure water level monitor 13 are respectively arranged in the upstream and downstream side vertical pipes 9 and 10 on the base 3. The control interfaces of the upstream and downstream side pressure water level monitors 12 and 13 are led out from the upper tube port of the vertical tube 2 through cables, and the control interface cables are connected to the flow monitoring controller.

[0048] like Figure 6 As shown, the flow monitoring controller includes:

[0049] A basic parameter input control module is used to input the cross-sectional dimension data of the trapezoidal channel, the water blocking width data of the vertical tube 2 and the monitoring control parameters and store them in the memory;

[0050] The control module is used to issue control instructions to control the upstream and downstream pressure water level monitors 12 and 13 to synchronously collect the water levels of the channel sections monitored by each of them according to the set collection frequency within the set monitoring period and calculate the average water level within the set monitoring period and the area of ​​the water-passing section of the average water level;

[0051] The instantaneous flow monitoring and calculation module is used to calculate the instantaneous average flow of the monitored section within the set monitoring period, and calculate the average flow of the monitored section within the set monitoring time period.

[0052] like Figure 1-7 As shown, the flow measurement method of the open channel flowmeter of the present invention comprises the following steps:

[0053] S1, construct a trapezoidal three-section flow measurement environment:

[0054] Install the channel flow pattern monitoring device at the designated monitored section Le on the channel centerline 14 at the bottom of the channel, the steps are as follows:

[0055] S1.1, fix the base 3 of the vertical tube 2 to the bottom of the channel, make the partition 6 in the vertical tube 2 coincide with the monitored section Le, and extend the upper tube mouth of the vertical tube 2 out of the channel;

[0056] S1.2, set the section where the upstream side vertical edge 15 of the vertical tube 2 is located as the upstream monitoring section Ls, set the section where the downstream side vertical edge 16 of the vertical tube 2 is located as the downstream monitoring section Lx; the upstream side pressure water level monitor 12 is used to monitor the water level during the set monitoring period Δ t The water level of the upstream monitoring section Ls is collected according to the set collection frequency, and the downstream pressure water level monitor 13 is used to collect the water level of the upstream monitoring section Ls in the set monitoring period Δ t The water level of the downstream monitoring section Lx is collected according to the set collection frequency;

[0057] S2, the control module issues a control instruction to control the upstream and downstream pressure water level monitors 12 and 13 to monitor the water level during the set monitoring period Δ t According to the set acquisition frequency, the water level data of the upstream monitoring section Ls and the downstream monitoring section Lx are collected synchronously, and the water level data of the set monitoring period Δ t The average water level hs data of the upstream monitoring section Ls, the average water level hx data of the downstream monitoring section Lx, and the average water flow area of ​​the monitored section Le Data, average water flow area of ​​upstream monitoring section Ls Data, average water flow area of ​​downstream monitoring section Lx Data; Among them, the average water area of ​​the monitored section Le Equal to the average water flow area of ​​the upstream monitoring section Ls Subtract the water blocking area of ​​the channel flow pattern monitoring device below the average water level hs of the upstream monitoring section Ls, that is, the projection area of ​​the vertical tube 2 in the direction perpendicular to the channel axis;

[0058] S3, flow calculation of monitored section Le:

[0059] The control module will obtain the average water level hs data, average water level hx data, and average water area Data, average water area Data and average water area The data is output to the instantaneous flow monitoring calculation module, which derives the Δ based on the above parameters according to the energy conservation principle of the three sections. t The calculation method of average flow rate during a period is as follows:

[0060] According to the three-section energy conservation principle, the instantaneous average total energy E of the upstream monitoring section Ls is LS Subtract the instantaneous average total energy E of the downstream monitoring section Lx Lx Equal to the average momentum change ΔE of the monitored section Le Lx ,in:

[0061] ;

[0062] ;

[0063] At the same time, according to the channel flow continuity equation Q s =Q x =Q e have:

[0064] ;

[0065] Thus we get ;

[0066] Q s : The upstream monitoring section Ls is in Δ t Average flow rate during the time period;

[0067] Q x : Downstream monitoring section Lx in Δ t Average flow rate during the time period;

[0068] Q e : The monitored section Le is in Δ t Average flow rate during the time period;

[0069] m : Δ t The average quality of water flowing through the three sections Ls, Le and Lx during a period of time;

[0070] V s: The upstream monitoring section Ls is in Δ t Average flow rate during the time period;

[0071] V x : Downstream monitoring section Lx in Δ t Average flow rate during the time period;

[0072] V e : The monitored section Le is in Δ t Average flow rate during the time period;

[0073] g - acceleration due to gravity.

[0074] In S2, the monitoring period ∆t is set between 5 seconds and 60 seconds, and the collection frequency is 2-3 times per second. The average water level hs data of the upstream monitoring section Ls and the average water level hx data of the downstream monitoring section Lx are calculated once in each monitoring period ∆t. When calculating the average water level hs data and the average water level hx data, the maximum value and the minimum value are removed respectively and the average value is taken.

Claims

1. An open channel flow meter for monitoring flow in a trapezoidal or U-shaped channel, characterized in that: It comprises a channel water flow form monitoring device arranged in a trapezoidal or U-shaped channel and a flow monitoring controller arranged outside the trapezoidal or U-shaped channel; the channel water flow form monitoring device comprises a vertical tube with a diamond-shaped cross section, a base is arranged at the lower tube mouth of the vertical tube, and filter holes for eliminating water flow disturbance are respectively opened on four vertical plates forming the vertical tube; a partition is arranged in the vertical tube to divide the inner cavity of the vertical tube into an upstream tube cavity and a downstream tube cavity with two isosceles triangle cross sections, an upstream side riser and a downstream side riser are respectively arranged in the upstream side tube cavity and the downstream side tube cavity, and filter holes for eliminating water flow disturbance are respectively opened on the circumference of the upstream and downstream side risers; an upstream side pressure water level monitor and a downstream side pressure water level monitor are respectively arranged in the upstream and downstream side risers on the base, and the control interfaces of the upstream and downstream side pressure water level monitors are led out from the upper tube mouth of the vertical tube through cables, and the control interface cables are connected to the flow monitoring controller.

2. The open channel flowmeter for monitoring flow in a trapezoidal or U-shaped channel according to claim 1, characterized in that: The flow monitoring controller comprises: A basic parameter input control module, used to input the cross-sectional dimension data of the trapezoidal or U-shaped channel, the water blocking width data of the vertical tube and monitoring control parameters and store them in a memory; A control module, used to issue control instructions to control the upstream and downstream pressure water level monitors to synchronously collect the water levels of the channel sections monitored by each of them according to the set collection frequency within the set monitoring period and calculate the average water level within the set monitoring period and the area of ​​the water-passing section of the average water level; The instantaneous flow monitoring and calculation module is used to calculate the instantaneous average flow of the monitored section within the set monitoring period and calculate the average flow of the monitored section within the set monitoring time period.

3. The open channel flowmeter for monitoring flow in a trapezoidal or U-shaped channel according to claim 1 or 2, characterized in that: The filter holes formed on the four vertical plate surfaces and the peripheral surfaces of the upstream and downstream vertical pipes are all rectangular vertical holes.

4. The open channel flowmeter for monitoring flow in a trapezoidal or U-shaped channel according to claim 1 or 2, characterized in that: Notches are respectively opened on the bottom pipe walls of the upstream and downstream side risers, so that canal water can smoothly enter the upstream and downstream side risers.

5. The flow measurement method of the open channel flowmeter according to claim 1, characterized in that: The steps include: S1, constructing the trapezoidal or U-shaped three-section flow measurement environment: The channel flow pattern monitoring device is installed on the channel centerline of the designated monitored section Le at the channel bottom, and the steps are as follows: S1.1, fix the base of the vertical tube to the bottom of the channel, make the partition in the vertical tube overlap with the monitored section Le, and extend the upper tube mouth of the vertical tube above the channel; S1.2, set the upstream side of the vertical tube as the upstream monitoring section Ls, set the downstream side of the vertical tube as the downstream monitoring section Lx; the upstream side pressure water level monitor is used to monitor the water level during the set monitoring period Δ t The water level of the upstream monitoring section Ls is collected according to the set collection frequency, and the downstream pressure water level monitor is used to collect the water level of the upstream monitoring section Ls in the set monitoring period Δ t The water level of the downstream monitoring section Lx is collected according to the set collection frequency; S2, the control module issues a control command to control the upstream and downstream pressure water level monitors to monitor the water level during the set monitoring period Δ t According to the set acquisition frequency, the water level data of the upstream monitoring section Ls and the downstream monitoring section Lx are collected synchronously, and the water level data of the set monitoring period Δ t The average water level hs data of the upstream monitoring section Ls, the average water level hx data of the downstream monitoring section Lx, and the average water flow area of ​​the monitored section Le Data, average water flow area of ​​upstream monitoring section Ls Data, average water flow area of ​​downstream monitoring section Lx Data; Among them, the average water area of ​​the monitored section Le Equal to the average water flow area of ​​the upstream monitoring section Ls Subtract the water blocking area of ​​the channel flow pattern monitoring device below the average water level hs of the upstream monitoring section Ls; S3, flow calculation of monitored section Le: The control module will obtain the average water level hs data, average water level hx data, and average water area Data, average water area Data and average water area The data is output to the instantaneous flow monitoring calculation module, which derives the Δ based on the above parameters according to the energy conservation principle of the three sections. t The calculation method of average flow rate during a period is as follows: According to the three-section energy conservation principle, the instantaneous average total energy E of the upstream monitoring section Ls is LS Subtract the instantaneous average total energy E of the downstream monitoring section Lx Lx Equal to the average momentum change ΔE of the monitored section Le Lx ,in: ； ； ； ； At the same time, according to the channel flow continuity equation Q s =Q x =Q e have: ； Thus we get ； Q s : The upstream monitoring section Ls is in Δ t Average flow rate during the time period; Q x : Downstream monitoring section Lx in Δ t Average flow rate during the time period; Q e : The monitored section Le is in Δ t Average flow rate during the time period; m : Δ t The average quality of water flowing through the three sections Ls, Le and Lx during a period of time; V s : The upstream monitoring section Ls is in Δ t Average flow rate during the time period; V x : Downstream monitoring section Lx in Δ t Average flow rate during the time period; V e : The monitored section Le is in Δ t Average flow rate during the time period; g - acceleration due to gravity.

6. The monitoring method of the open channel flowmeter according to claim 5, characterized in that: In S2, the monitoring period Δt is set between 5 seconds and 60 seconds, the acquisition frequency is 2-3 times per second, and the average water level hs data of the upstream monitoring section Ls and the average water level hx data of the downstream monitoring section Lx are calculated once in each monitoring period Δt; when calculating the average water level hs data and the average water level hx data, the maximum value and the minimum value are removed respectively and the average value is taken.

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