What is the working principle of ultrasonic flowmeter?

According to the principle of signal detection, ultrasonic flowmeter can be divided into propagation velocity difference method (direct time difference method, time difference method, phase difference method and frequency difference method), beam migration method, Doppler method, cross correlation method, spatial filtering method and noise method. Ultrasonic flowmeter and ultrasonic flowmeter, because there are no obstacles in the flow channel of the instrument, belong to smooth flowmeter, which is suitable for solving the flow measurement problem of a flowmeter, especially in large flow measurement, and is a kind of flowmeter that develops rapidly. Ultrasonic flowmeter adopts the principle of time difference measurement: the signal of one probe passes through the pipe wall, medium and the other side of the pipe wall and is received by another probe. At the same time, due to the influence of medium speed, the signal transmitted by the second probe is also the lag of Δ t received by the first probe. According to the calculation, the flow rate Q can be obtained from the conversion relationship between the flow rate V and the time difference Δ TV = (C2)/2lxΔ T.

When ultrasonic waves propagate in a moving fluid, they will carry information about the velocity of the fluid. Therefore, the received ultrasonic wave can detect the flow rate of the fluid and convert it into the flow rate. According to the different detection methods, it can be divided into different types of ultrasonic flowmeters, such as propagation velocity difference method, Doppler method, electron beam migration method, noise method and correlation method. Ultrasonic flowmeter is a non-contact instrument which has been applied with the rapid development of integrated circuit technology in recent ten years. It is suitable for measuring the flow of fluids and large pipelines that are difficult to contact and observe. It can be used with water level gauge to measure the flow of open water. Using ultrasonic flow ratio does not need to install measuring elements in the fluid, so it will not change the flow state of the fluid and produce additional resistance. The installation and maintenance of the instrument will not affect the production pipeline, and it is an ideal energy-saving flowmeter.

Industrial flow measurement generally exists in large-diameter pipelines, and it is difficult to measure large flow. This is because the common flowmeter will bring difficulties to manufacturing and transportation when measuring the diameter of pipeline, resulting in increased cost and energy consumption. Installation not only has these disadvantages, but also can avoid using ultrasonic flowmeter. Because all kinds of ultrasonic flowmeters can be installed outside the pipeline for non-contact flow measurement, the cost of the instrument is basically independent of the diameter of the pipeline to be measured, while the cost of other types of flowmeters increases greatly with the increase of cost. The diameter of. Therefore, compared with other flowmeters with the same function, the larger the diameter of ultrasonic flowmeter, the better its function price. Ultrasonic flowmeter is considered to be a good instrument for measuring the runoff of large pipelines, which can measure the flow of two-phase media, so it can be used to measure dirty flow such as sewage. In power plants, it is more convenient to use portable ultrasonic flowmeter to measure large-scale pipeline runoff (such as turbine inlet water and turbine circulating water) than the past stripped pipe flowmeter. Ultrasonic waves generated by fluid flow can also be used for gas measurement. The pipe diameter varies from 2 cm to 5 m, from a few meters wide open culvert to a 500 m wide river channel. In addition, the ultrasonic flow measurement accuracy of the measuring instrument is almost not affected by human body temperature measurement, but by parameters such as pressure, viscosity and density. It can be made into a non-contact portable measuring instrument, which can solve the measurement problems that other types of instruments are difficult to measure, and has strong corrosion resistance, conductivity, radioactivity and fluidity of flammable and explosive media. In addition, due to its non-contact measurement characteristics and reasonable electronic circuit, a single instrument can be used to measure various pipe diameters and flow ranges. The adaptability of ultrasonic flowmeter is incomparable with other instruments. Ultrasonic flowmeter has the above advantages, so it is paid more and more attention. With the development of serialization and generalization of products, it is made into instruments with different channel standards, high temperature resistance, explosion protection and moisture resistance to adapt to different media and different environments. And flow measurement under different pipeline conditions.

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