ultrasonic flow transmitter

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1. Brookfield DV3T

2. High score research paper proposal

Relevant information: Measurement principle of ultrasonic Doppler flowmeter 1. Basic working principle: The measurement of ultrasonic Doppler 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. The frequency change caused by relative motion is proportional to the relative velocity of two objects. In the ultrasonic Doppler flow measurement method, the ultrasonic transmitter is a fixed sound source, and the solid particles moving with the fluid act as the "observer" of relative motion with the sound source. Of course, it only reflects the ultrasonic waves incident on the solid particles back to the receiver. The frequency difference between the emitted sound waves and the received sound waves is the Doppler frequency shift of the sound waves produced less due to the motion of the solid particles in the fluid. Since this frequency difference is proportional to the fluid flow velocity, the measured frequency difference can obtain the flow velocity, and thus the fluid flow rate can be obtained. Therefore, A necessary condition for ultrasonic Doppler flow measurement is that the measured fluid medium should be a two-phase medium containing a certain number of solid particles or bubbles that can reflect sound waves. This working condition is actually one of its major advantages, that is, this flow measurement method is suitable for measuring two-phase flow, which is difficult for other flow meters to solve the problem of v

ertical alignment. Therefore, as a highly promising two-phase flow measurement method and flow meter, ultrasonic Doppler flow measurement method is increasingly being applied. 2. The flow fiber equation assumes that the angle between the ultrasonic beam and the fluid velocity is, the ultrasonic propagation velocity is c, and the velocity of suspended particles in the fluid is the same as the fluid velocity, both of which are u Taking the reflection of an ultrasonic beam on a solid particle as an example, the relationship between the Doppler frequency difference of sound waves and the flow velocity is derived. As shown in Figure 3-39, when the ultrasonic beam encounters a solid particle on the pipe axis, the particle moves along the axis at a velocity of u. For the ultrasonic transmitter, the particle leaves at a velocity of u cos a, so the ultrasonic frequency f2 received by the particle should be lower than the emitted ultrasonic frequency f1, and the reduced numerical value is f2-f1=- f1 (3-73), that is, the ultrasonic frequency received by the particle is f2=f1- f1 (3-74), where f1- the frequency of the emitted ultrasonic wave; A - Angle between ultrasonic beam and pipe axis; C - Sound velocity in fluid. The solid particles scatter the ultrasonic beam back to the receiver, and as it leaves the receiver at a speed of u cos a, the ultrasonic frequency f3 received by the receiver decreases again, similar to the calculation of f2, F3 can be expressed as f3=f2- f2 (3-75). Substituting the expression of f2 into the above equation, we can obtain: f3=f1 (1-) 2=f1 (1-2+) (3-76). Since the sound velocity c is much greater than the fluid velocity u, the square term in the above equation can be omitted. Therefore, we can obtain:

1. Brookfield DV3T

2. High score research paper proposal

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