1. Principles and Methods of Flow Measurement

ChannelMaster H-ADCP is a fixed acoustic Doppler flow automatic measuring instrument produced by Teledyne RD Instruments in the United States, used for real-time monitoring of flow velocity and flow in rivers and open channels. H-ADCP can be used as an independent real-time monitoring system for flow rate and flux by connecting to a computer through a cable. H-ADCP can also be integrated with other instruments and equipment to form a water quality and quantity telemetry station. The ChannelMaster type H-ADCP currently has three frequencies: 1200 kHz, 600 kHz and 300 kHz are suitable for cross-sections of different widths.

The ChannelMaster type H-ADCP measures flow rate through two horizontal ultrasonic probes and water level through an ultrasonic water level gauge, thereby completing flow measurement and calculation.

H-ADCP can use the indicator flow rate method for flow measurement. The indicator flow rate method is to establish the correlation between the measured flow rate (indicator flow rate) of H-ADCP and the average flow rate of the river or open channel section, that is, to calibrate the system using measured data to measure the flow rate. The specific comparison and calibration method is to use H-ADCP to measure the flow velocity (index flow velocity) while calculating the true flow rate of the river using other methods. Based on the water level and a pre known large cross-section, the flow area of the cross-section is calculated. The average flow velocity of the cross-section at this time is obtained by dividing the flow rate by the cross-section flow area; At this time, the flow velocity measured by H-ADCP (index flow velocity) corresponds to the average flow velocity of the cross-section. Multiple sets of indicator flow velocities and cross-sectional average flow velocities can be obtained under different flow rates and water depths. Through regression analysis (using least squares method), the correlation between cross-sectional average flow velocity and H-ADCP measured flow velocity (indicator flow velocity) can be established (regression equation).

The main advantages of ChannelMaster type H-ADCP are as follows:

-Adopting TRDI's broadband technology.

-High precision, high spatial and temporal resolution. Accurate flow velocity data can be obtained using smaller units and shorter sampling time steps.

-High quality test data can also be obtained for low flow rates and unsteady flows that are difficult to test.

-Standard configuration includes 1-128 optional units, 0.2-10m optional unit length, and 1-300m profile range (depending on system frequency). More flow velocity data can be obtained, allowing for the measurement of the horizontal distribution of water flow and providing great flexibility.

-Standard configuration includes ultrasonic water level gauge and pressure type water level gauge, making water level measurement more accurate and reliable.

-Standard configuration inclinometer. The inclinometer plays an important role in adjusting the H-ADCP mounting bracket and monitoring the tilt changes of the mounting bracket to ensure the quality of test data.

-The standard configuration of stainless steel mounting base makes the installation of H-ADCP very convenient.

-Adopting the latest acoustic Doppler technology. It has the advantages of easy installation, easy operation, not easily affected by biological attachment, moderate price, and convenient maintenance.

-There are multiple interfaces to choose from for data communication, which facilitates system integration.

2. Technical indicators

The technical specifications for flow velocity profile measurement (broadband technology) of ChannelMaster type H-ADCP are: