There are three main types of flow monitoring methods: hydraulic construction method, water level flow curve fitting method, and flow velocity method. Most of the river hydrological monitoring stations in China use the principle of flow velocity area method to carry out flow testing. The basic principle is to measure the flow rate of water at some points in the water body, and then calculate the flow rate by combining the flow velocity distribution model and the water flow area.
Because the actual situation of river flow is very complex, and the situation of each hydrological station to test the river channel is very different, the selection of the implementation of the flow measurement method is different, the more traditional method of measuring the water flow velocity is to use the rotor flow meter, buoy, etc., at present, the more widely used is the radar flow meter using electromagnetic wave testing, the acoustic Doppler (ADCP) current meter using ultrasonic velocity, etc.
Different current measurement instruments correspond to the corresponding flow test calibration method.
The following is a comparison of the current measurement methods in 4:
The technical scheme of non-contact radar flow measurement system realizes mathematical modeling through the collection of river surface flow velocity and river water level, combined with the calibration algorithm of flow velocity, water level and flow, and then completes the functions of real-time monitoring, data collection, data calculation, and data reporting of river flow.
The algorithm for flow calculation in the non-contact radar current measurement system still uses the traditional flow velocity area method. Flow calculation is to calculate the real-time cross-section flow rate and flow rate by collecting real-time perpendicular flow velocity distribution data and water level data.
In the non-contact radar current measurement system, the front-end sensing device reports the collected and calculated data to the central platform through the wireless network. The communication network supports GPRS, CDMA, 3G, 4G, NB-IoT and other wireless networks. By measuring the water depth and flow velocity, as well as the cross-section shape set inside the equipment, the flow velocity of the cross-section can be calculated using the velocity area method. Microwave radar is not affected by temperature gradients, pressure, air density, wind, or other meteorological environmental conditions, making it easy to maintain and easy to use.