The Flow Measurement Principle and Field Application of Flow meter in Hydrological Surveys

Flow meter is a hydrological velocity measuring instrument based on the direct proportionality between propeller speed and flow velocity. Its velocity measurement range is 0.06 to 8.00 meters per second, with a measurement error not exceeding 1.5%. It consists of a velocity sensor, a velocity calculator, and a measuring rod, and is suitable for measuring the flow velocity in various water bodies such as rivers, canals, and pipelines.

Flow meter is a general-purpose instrument for measuring flow velocity in hydrological surveys. It is used to measure the time-period average flow velocity at predetermined measuring points in cross-sections of rivers, lakes, reservoirs, and canals. The instrument uses the LS1206B propeller-type velocity sensor as its core, along with a velocity calculator and a 0.4-meter × 4Ф16 measuring rod. The entire set of equipment is housed in an aluminum alloy safe. Connecting the signal line allows for open channel flow velocity measurement and automatic display of the flow velocity value.

The working principle of Flow meter is based on the direct proportionality between propeller speed and flow velocity. Water flow impacts the propeller blades, causing them to rotate around their axis. An internal sensor detects the propeller's rotational speed and converts this mechanical rotation into electrical pulse signals. The pulse frequency is linearly correlated with the flow velocity. After measuring the propeller speed, the flow velocity value can be obtained by converting it using a calibration formula. The LS1206B current meter has a propeller rotation diameter of 70 mm, a hydraulic pitch of 120 mm, an initial rotational speed of 0.05 m/s, a speed measurement range of 0.06 to 8.00 m/s, and a relative standard deviation of no more than 1.5% across the entire range.

In terms of application, the Flow meter is widely applicable to hydrological surveys, water conservancy investigations, farmland irrigation, runoff experiments, and other fields. It is also suitable for flow velocity or flow monitoring in hydropower, environmental protection, mining, transportation, geology, research institutes, and municipal industries. The instrument is small in size, lightweight, compact, precise in structure, and easy to carry and use. It is suitable for small rivers, shallow areas during the dry season of large rivers, and irrigation and drainage channels. Thanks to its excellent dynamic sealing performance, the instrument can still function normally in waters with high sediment content—it can still be used normally even when the sediment content of the irrigation water in the irrigation area using Yellow River water reaches 20 kg per cubic meter. After structural modification, the instrument can also be used for ship speed measurement, and it has already completed ship speed measurement tasks in marine surveys in the South China Sea.