Installation method and precautions of radar flowmeter and radar current meter in wide river measurement

The equipment installation method adopts the field integrated rack and stainless steel chassis. Install the chassis, communication antenna and other modules at the appropriate height of the waist of the vertical pole of the rack. On the solar panel, avoid the shading of tall buildings or trees. Each installation point can have certain adjustment ability in the horizontal and vertical directions to avoid mutual interference or blockage of the installation equipment.

1. Installation requirements
The equipment installation method adopts the field integrated rack and stainless steel chassis. Install the chassis, communication antenna and other modules at the appropriate height of the waist of the vertical pole of the rack. On the solar panel, avoid the shading of tall buildings or trees. Each installation point can have certain adjustment ability in the horizontal and vertical directions to avoid mutual interference or blockage of the installation equipment.
The RTU, communication module, data conversion module and other specifications are integrated into the integrated stainless steel chassis, and the installation is required to be firm. The cables in the box are arranged in wire grooves, and the cable heads are crimped with terminals.
(1) The chassis is made of stainless steel, and the integrated frame can be made of galvanized pipe or stainless steel.
(2) The appearance of the integrated rack and the chassis should be beautiful and generous, the proportions should be appropriate, and the surface should be smooth.
(3) The metal casing of the integrated rack, chassis, antenna, rain gauge and other components needs to form an equipotential body, and finally connect to the protective grounding network through the rack.
(4) The frame, chassis and other components are connected and fastened with stainless steel connectors and fasteners, and various exposed cables are protected by stainless steel plastic-coated bellows.
(5) On-site installation can be done by means of existing building foundations such as bridges and brackets, but the flowmeter must be installed horizontally, that is, the water level probe of the radar flowmeter emits radar waves perpendicular to the direction of the water flow, and the flow rate probe of the radar flowmeter The radar wave The angle between the launch direction and the water flow direction is about 35° (55° from the vertical direction). The installation of the flow meter should ensure that the angle between the radar wave emission direction of the speed probe and the water flow direction is about 35° (the angle with the vertical direction is 55°).

Installation method and precautions of radar flowmeter and radar current meter in wide river measurement
  

(6) The radar flowmeter and radar velocity meter should be installed behind the gate. If they are installed in front of the gate, the surface velocity will be very small, but the bottom velocity will be very large. When installing behind the gate, the installation position of the radar flowmeter and the current meter should be as far away as possible from the gate, and the location where the water flow is stable and the river section is relatively regular should be selected for installation.
2. Installation method
The non-contact flow monitoring of the river channel is to select different monitoring schemes according to the cross-section of the diversion channel and the width of the river channel under the condition that the flow measurement requirements are met: the river channel below 10m adopts the single-point (rod type) installation flow measurement method, and the 10- The 20m river channel adopts the double-point (rod type) installation flow measurement method, and the river channel above 20m adopts the array (cable channel) installation flow measurement method, and the appropriate flow measurement equipment is configured according to different installation methods.
Single point rod installation
The rod type current meter bracket is composed of three parts: the main steel pipe column, the horizontal steel pipe, and the reinforced concrete foundation. The height of the main steel pipe column is 5-6 meters, and the hot-dip galvanized octagonal variable-diameter steel pipe with a diameter of 300-200mm and a wall thickness of 8mm is selected. The solar panel is installed on the top of the column; the cantilever length of the horizontal steel pipe is 2-6 meters, and the diameter of 250- 150mm hot-dip galvanized octagonal variable diameter steel pipe with wall thickness of 6mm.Reinforced concrete foundation can use C30 independent foundation or pile foundation according to the geological conditions. When the construction site is located in the river, on a steep slope or the foundation soil is poor, the pile foundation is used.
The single-point rod installation method adopts the method of erecting a flowmeter on one side of the river to monitor the flow. Taking the installation position of the radar flowmeter 8 meters away from the river surface as an example, the diameter of the fan surface perpendicular to the direction of the water flow is about 4.25 meters. It can be seen that the coverage of the radar is limited, and it is difficult to use the flow velocity of the watershed covered by the flowmeter to represent the flow velocity of the entire section.
With this scheme, the construction amount on site is 100%, but the measured flow deviation of the river section is very large. Therefore, this solution is not recommended.

rod installation
The double-point rod installation method is basically the same as the single-point installation method, and the flow monitoring is carried out by setting up a flowmeter on both sides of the river. Each flowmeter represents half the flow of the entire river, and the flow algebraic sum of the two flowmeters is the flow of the entire river.
In the same way as the single-point rod installation, due to the limited coverage of the radar, it is difficult to use the flow velocity of the watershed covered by the flowmeter to represent the flow velocity of the entire section.
With this scheme, the on-site construction amount is small, but the measured flow deviation of the river section is still very large. Therefore, this solution is not recommended.

 

Array (cable channel) installation method
When the width of the river channel is greater than 20 meters, the array (cable channel) installation method is adopted. The installation method of the array (cable channel) consists of four parts: the cable channel steel column, the cable, the steel column foundation and the ground anchor foundation. The height of the steel pipe column of the cableway is 6 meters, and the hot-dip galvanized octagonal variable-diameter steel pipe with a diameter of 300-200 mm and a wall thickness of 12 mm is selected. The length should be determined according to the actual situation on site. The steel column foundation and the ground anchor foundation are all C30 independent foundations, and the natural foundation is used as the foundation bearing layer, and the characteristic value of the foundation bearing capacity is not less than 120kPa.
The array installation method, that is, a flowmeter with multiple flowmeters, can overcome the problem of large deviation of flow monitoring data caused by uneven flow velocity and irregular cross-section of the river. The array installation method is based on the characteristics of the river section, comprehensively considering the river bed elevation distribution and the full-section flow state distribution, and divides the entire flow monitoring section into several flow measurement divisions. Each flow measurement division is equipped with a velocity meter, and a radar flowmeter can be deployed. in any flow measurement zone. This installation method greatly reduces the deviation of the flow measurement caused by the irregular section of the natural river and the uneven distribution of the flow velocity. In terms of construction, existing bridges or cableways have mature engineering experience that can be used for reference. Therefore, it is recommended to use the array installation method to monitor the flow of the wide river.

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