What are the applications of ultrasonic wind transducer sensor?

Ultrasound is different from audible sound waves in that it can be focused and has the characteristics of concentrated energy. Piezoelectric ceramics transducer or magnetostrictive materials can obtain high-power ultrasonic waves under the action of high-voltage narrow pulses, which can be focused and can be used for welding integrated circuits and plastics. After the ultrasonic wave is focused, it has good directionality. When is encountering the interface between two media, it can produce obvious reflection and refraction phenomena, which are similar to light waves.

When a weak sound wave signal acts on the liquid, ultrasonic transducer  sensor will generate a certain negative pressure on the liquid, that is, the volume of the liquid increases, the molecular gaps in the liquid increase, and many tiny bubbles are formed; when the strong sound wave signal acts on the liquid, then a certain positive pressure will be generated on the liquid, that is, the volume of the liquid is compressed and reduced, and the tiny air bubbles formed in the liquid are crushed. It has been proved by research that when the ultrasonic wave acts on the liquid, the rupture of each bubble in the liquid will generate a shock wave with great energy, which is equivalent to instantly generating a high temperature of several hundred degrees and a pressure of up to thousands of atmospheres. This phenomenon is called "Cavitation", ultrasonic transducer is to use the shock wave generated by the bubble rupture in the liquid to clean and wash the inner and outer surfaces of the workpiece. Ultrasonic Sensor is mostly used in industries such as semiconductors, machinery, glass, and medical instruments.

When the ultrasonic transmitter and receiver are placed on both sides of the measuring object, this type is called transmission type. Transmissive model can be used for remote control, anti-theft alarm, proximity switch, etc. Ultrasonic transmitters and receivers placed on the same side belong to the reflective type, and the reflective type can be used for proximity switches, distance measurement, liquid level or material level measurement, metal flaw detection, and thickness measurement. The principle of flow measurement by time difference method: install two pairs of ultrasonic transmitting and receiving probes (F1, T1) and (F2, T2) respectively at a certain distance upstream and downstream of the measured pipeline, where the ultrasonic waves of F1 and T1 propagate downstream. And F2, T2 ultrasound is countercurrent propagation. Due to the difference in the propagation speed of the two beams of ultrasonic waves in the liquid, the average velocity and flow rate of the fluid can be obtained by measuring the time difference Dt of ultrasonic wave propagation on the two receiving probes.

Principle of flow measurement transducer by frequency difference method: F1 and F2 are identical ultrasonic probes, which are installed outside the pipe wall and used as ultrasonic transmitters and receivers alternately through the control of electronic switches. First, the first ultrasonic pulse is emitted by F1, which is received by F2 through the pipe wall, fluid and the other side of the pipe wall. After the signal is amplified, it triggers the driving circuit of F1 again, so that F1 emits the second sound pulse. the ultrasonic pulse is transmitted by F2, and F1 is used as a receiver, and the pulse repetition frequency of F1 can be measured as f1. Similarly, the pulse repetition frequency of F2 can be measured as f2. The frequency difference D f between the downstream emission frequency f1 and the upstream emission frequency f 2 is proportional to the measured flow velocity v. Transmitting and receiving probes can also be installed on the same side of the pipe.

Applications of the Doppler Effect

Ultrasonic ranging:

The air ultrasonic probe emits ultrasonic pulses, and when it reaches the object under test, it is reflected back and received by another air ultrasonic probe. Measure the time t required from transmitting the ultrasonic pulse to receiving the ultrasonic pulse, and then multiply it by the sound speed of the air (340m/s), which is the distance traveled by the ultrasonic pulse at the measured distance, and divide it by 2 to get the distance.

Ultrasonic thickness measurement

The piezoelectric chip in the dual-crystal straight probe emits ultrasonic vibration pulses. When the ultrasonic pulse reaches the bottom of the specimen, it is reflected back and received by the other piezoelectric chip. As long as the time t required from transmitting the ultrasonic pulse to receiving the ultrasonic pulse is measured, and then multiplied by the sound velocity constant c of the measured object, it is the round-trip distance experienced by the ultrasonic pulse in the tested object, and then divided by 2 to obtain the thickness. d=ct/2. The x-axis of the display is 10ms/div (division), and the distance between the B wave and the T wave is 6 divisions, and the distance between the F wave and the T wave is 2 divisions. It is known that the sound velocity constant c=5900m/s of the longitudinal wave in the steel plate