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technical article
Noise resistant Doppler ultrasonic flowmeter
2012-2-17 9:35:15

的测量原理是以物理学中的多普勒效应为基础的。 The measurement principle of the Doppler ultrasonic flowmeter is based on the Doppler effect in physics. According to the acoustic Doppler effect, when there is relative motion between the sound source and the observer, the frequency of the sound perceived by the observer will be different from the frequency emitted by the sound source. This frequency change due to relative motion is proportional to the relative speed of the two objects. In the flow measurement method of the Doppler ultrasonic flowmeter, the ultrasonic transmitter is a fixed sound source. The solid particles moving with the fluid play the role of an "observer" that moves relative to the sound source. The ultrasonic waves reflected on the solid particles are reflected back to the receiving data. The frequency difference between the transmitted sound wave and the received sound wave is the Doppler frequency shift of the sound wave due to the movement of solid particles in the fluid. Since this frequency difference is proportional to the fluid flow rate, the flow rate can be determined by measuring the frequency difference. Further, the flow rate of the fluid can be obtained.


是以物理学中的多普勒效应为基础,根据声学多普勒效应,当声源和观察者之间有相对运动时,观察者所感受到的声频率将不同于声源所发出的频率。 The Doppler ultrasonic flowmeter is based on the Doppler effect in physics. According to the acoustic Doppler effect, when there is relative motion between the sound source and the observer, the sound frequency experienced by the observer will be different from the sound. The frequency emitted by the source. This frequency change due to relative motion is proportional to the relative speed of the two objects. Dongxiang instrument Doppler ultrasonic flowmeter can simultaneously record various parameters such as instantaneous flow, total flow, flow rate, pH value and downhole temperature in the pipeline. There are three main reasons for the Doppler ultrasonic flowmeter's error in use:
(1) The error of the flow meter itself. (2) Flowmeter area / rate sensor installation error. (3) Reasons for current hydraulic conditions.
The measurement error of Doppler ultrasonic flowmeter is mainly caused by objective reasons such as sensor installation and hydraulic conditions. In order to reduce the error, the position must be accurate when installing the rate / area sensor. At the same time, the liquid level of the pipe section to be detected should be above 6cm. The relative accuracy of the flow meter itself can basically meet the requirements. Dongxiang Instrument proposes to use the measurement principle of Doppler ultrasonic flowmeter and corresponding rate / area sensor, which can be applied to the current flow monitoring in the drainage pipeline. It can be more realistic and coordinated with the graphs of various data. Fully reflect the current flow change law in the drainage pipeline, and be able to measure relatively real flow data. The Doppler ultrasonic flowmeter is equipped with corresponding data transmission and acquisition equipment, which can monitor the dynamics of the current drainage facility flow rate, and grasp the change of the water volume in the drainage pipe network in real time, combined with the drainage operation monitoring information management system, using GIS technology It can realize more flexible, accurate and real-time comprehensive analysis, optimized operation and scheduling modes, and create conditions for the realization of urban "digital drainage".

是利用多普勒效应测量的一种测流装置。 The Doppler ultrasonic flowmeter is a kind of flow measuring device that uses the Doppler effect to measure. Nowadays, it is an important instrument for measuring industrial water and sewage flow. The practical application is portable and fixed. Ultrasonic transducers are available in contact and non-contact. The measuring pipe diameter is 12 ~ 5000mm, and the accuracy is within ± 1% ~ ± 5%. Although it is not comparable to the time difference method, its instrument price is relatively low. The principle of Doppler ultrasonic flowmeter The principle of Doppler ultrasonic flowmeter. Transmitting T emits a certain frequency of ultrasonic waves to the bubbles and solid particles in the flowing liquid to generate scattered waves. The scattered waves are received by the receiving transducer R, and the frequency change is proportional to the moving speed of the particles (or bubbles) The device has a certain directivity, so the scattered signal received is basically transmitted from the vicinity of the center of the pipe). Doppler ultrasonic flowmeter, which consists of an ultrasonic flow transducer and a controller. The Doppler flowmeter is a newly emerged product whose controller enables the transducer to intermittently generate two continuous wave acoustic signals of different frequencies for a short period of time. The generated Doppler signal has a fixed frequency difference from the original frequency, and the noise is not. The two Doppler signals are overlapped and boosted. After the information processing, the Doppler frequency shift? D is obtained, and the flow velocity or flow rate is calculated. This new Doppler flowmeter is resistant to noise and significantly improves measurement accuracy.