A turbine is placed in the center of the pipeline, and both ends are supported by bearings. When the fluid passes through the pipeline, it impacts the blades of the turbine flowmeter, generating a driving torque for the turbine flowmeter, and making the turbine flowmeter rotate against the friction torque and fluid resistance torque. In a certain flow range, the rotational angular velocity of the turbine flowmeter is directly proportional to the fluid velocity. Therefore, the fluid velocity can be obtained by the rotational angular velocity of the turbine flowmeter, so as to calculate the fluid flow through the pipeline.

The rotational speed of the turbine flowmeter is detected by a sensor coil installed outside the housing. When the blade of the turbine flowmeter cuts the magnetic field lines generated by the permanent magnet steel in the casing, the magnetic flux in the sensor coil will change. The sensor coil sends the detected magnetic flux periodic change signal to the preamplifier, and after amplification and shaping, it generates a pulse signal proportional to the flow, which is sent to the unit conversion and flow integration circuit to obtain and display the accumulated flow value. At the same time, the pulse signal is sent to the frequency-current conversion circuit, which converts the pulse signal into analog current and then indicates the instantaneous flow value.