Working principle of turbine flowmeter

Turbine flowmeter is a kind of velocity flowmeter with temperature and pressure compensation function. It belongs to one kind of velocity flowmeter. Its working principle is as follows: the power of flowing fluid drives the turbine blade to rotate, and its rotation speed is approximately proportional to the volume flow rate. Turbine flowmeter is widely used in petroleum, chemical industry, electric power, gas pipe network, urban gas and other fields, and is widely used in trade settlement because of its high measuring accuracy, good repeatability and stability, wide range, rapid response to flow changes, strong anti-interference ability, easy signal transmission and other characteristics.

Flowmeter using turbine for measurement. It converts the flow rate into the turbine's speed, which is then converted into an electrical signal proportional to the flow rate. This flowmeter is used to detect instantaneous flow rate and total accumulated flow rate, and its output signal is frequency, which is easy to digitize. The induction coil is attached to the housing along with the permanent magnet. When a ferromagnetic turbine blade passes over a magnet, the magnetoreluctance of the magnetic circuit changes, resulting in an induced signal. The signal is amplified and shaped by an amplifier and sent to a counter or frequency meter to display the total accumulated flow rate. At the same time, pulse frequency is transferred through frequency-voltage conversion to indicate instantaneous flow rate. The speed of the impeller is proportional to the flow rate, and the number of revolutions of the impeller is proportional to the total amount of flow. The output of turbine flowmeter is frequency modulation signal, which not only improves the anti-interference of detection circuit, but also simplifies the flow detection system. Its range ratio can be up to 10:1, and the accuracy is within ±0.2%. Turbine flowmeters with small inertia and size have time constants up to 0.01 second.Elliptical gear flowmeter is a type of volumetric flowmeter used for precise continuous or intermittent measurement of liquid flow or instantaneous flow in pipelines. It is particularly suitable for flow measurement of high viscosity media such as heavy oil and resin.

Working principle of elliptical gear flow meter
The flow meter is a sealed initial lunar cavity (not sealed due to the rotation of the gears) formed by a measuring box and a pair of elliptical gears installed in the measuring box, along with the upper and lower cover plates, as the calculation unit of primary displacement. When the measured liquid enters the flow meter through the pipeline, the pressure difference generated at the inlet and outlet drives a pair of gears to continuously rotate, continuously conveying the liquid measured by the initial lunar cavity to the outlet. The product of the revolution of the elliptical gear and four times the displacement each time is the total flow of the measured liquid (see principle diagram). The flowmeter mainly consists of a casing, a counter, an elliptical gear, and a coupling (divided into magnetic coupling and axial coupling).