Target types using the principle of fluid momentum; Turbine formulas using angular momentum theorem: vortex type and vortex street type using fluid oscillation principle; Pitot tube type, volumetric type, weir type, trough type, etc. use the total static pressure difference.
2. Electrical principle: The instruments used in this principle include electromagnetic, differential capacitance, inductance and strain resistance.
3. Acoustic principle: Ultrasonic waves and sound waves (shock waves) are used to measure the flow.
4. Thermal principle: there are calorimeters, direct calorimeters and indirect calorimeters. Measure the flow by thermal principle.
5. Optical principle: both laser and photoelectric instruments belong to this principle.
6. Primitive physical principle: both nuclear magnetic vibration and nuclear radiation belong to this principle.
7. Other principles: labeling principle (tracer principle, nuclear magnetic resonance principle), correlation principle, etc.
Extended data
Flowmeter is one of the important instruments in industrial measurement. With the development of industrial production, the accuracy and range of flow measurement are increasingly demanding, and the flow measurement technology is changing with each passing day. In order to adapt to various uses, various types of flowmeters have come out. At present, more than 100 flowmeters have been put into use.
Each product has its specific applicability and limitations. According to the measurement principle, there are mechanical principle, thermal principle, acoustic principle, electrical principle, optical principle, atomic physics principle and so on.
According to the structural principle of flowmeter, it is classified. Fluid oscillation flowmeter includes volumetric flowmeter, differential pressure flowmeter, float flowmeter, turbine flowmeter, electromagnetic flowmeter, vortex flowmeter, mass flowmeter and plug-in flowmeter.
According to the measurement object, there are two types: closed pipeline and open channel; According to the purpose of metering, it can be divided into total metering and flow metering, and their instruments are called total meter and flowmeter respectively.
The total meter measures the flow through the pipeline in a period of time, which is expressed by dividing the total flow in a short period of time by the time. In fact, a flowmeter is usually equipped with a totalizer, and the totalizer is also equipped with a flow signal device. Therefore, strictly speaking, it is of no practical significance to distinguish between flowmeter and master meter.
Baidu encyclopedia-flowmeter