Application of Ultrasonic sensor

The core of the underwater acoustic transducer is a piezoelectric wafer in its outer casing, and there are many kinds of materials constituting the wafer. The size of the wafer, such as diameter and thickness, varies, so the performance of each probe is different and its performance must be known before use.

The main performance indicators of ultrasonic sensors are as follows:

(1) Working frequency. The operating frequency is the resonant frequency of the piezoelectric wafer. When the frequency of the alternating voltage applied to it is equal to the resonant frequency of the wafer, the energy output is the largest and the sensitivity is also the highest.

(2) Working temperature. Since the Curie point of the piezoelectric material is generally high, especially the depth sounder transducer for detecting uses a small power of the ultrasonic sensor, the operating temperature is relatively low, and the work can be performed for a long time without failure.

(3) Sensitivity. It mainly depends on the manufacturing of the wafer itself, and the electromechanical coupling coefficient is large and the sensitivity is high.

Ultrasonic sensor application

The ultrasonic piezoelectric transducer adopts the ultrasonic echo positioning principle, uses the time difference measurement technology to detect the distance between the sensor and the target, and adopts the small angle and small blind area ultrasonic sensor, which has accurate measurement, no contact, waterproof, anti-corrosion, low cost, etc. Advantages,which mainly applied to liquid level, level, level detection, etc. The basic principle of the ultrasonic sensor is the system sends an ultrasonic pulse from the transmitting sensor, and the object is reflected and returned to the receiving sensor, and the ultrasonic pulse is detected from the emission. By the time required for reception, and based on the speed of sound in the medium, the distance from the sensor to the object being measured can be obtained to determine the position. Taking into account the influence of the ambient temperature on the ultrasonic propagation speed, the propagation speed is corrected by the temperature compensation method to improve the measurement accuracy.

transducer for flowmeter is measured in a variety of ways, such as propagation velocity variation, wave velocity shifting, Doppler effect, and flow listening. However, the current widely used method is mainly the ultrasonic propagation time difference method.
When the ultrasonic wave propagates in the fluid, the propagation velocity in the stationary fluid and the flowing fluid is different. With this feature, the velocity of the fluid can be determined, and then the flow rate of the fluid can be known according to the cross-sectional area of the fluid of the pipeline.

Ultrasonic flow meter transducers have the characteristics of not obstructing fluid flow. There are many types of fluids that can be measured. Whether it is a non-conductive fluid, a high-viscosity fluid, or a slurry fluid, it can be measured as long as it can transmit ultrasonic waves. Ultrasonic flow meters can be used to measure tap water, industrial water, agricultural water, and the like. It is also suitable for the measurement of flow rates such as sewers, agricultural irrigation channels, and rivers.

The doppler method uses the acoustic doppler principle to determine the fluid flow rate by measuring the ultrasonic doppler of the scatterer scattering in a non-uniform fluid, and is suitable for fluid flow measurement including suspended particles and bubbles. The correlation method uses the relevant technology to measure the flow rate. In principle, the measurement accuracy of this method is independent of the sound velocity in the fluid, and thus has nothing to do with the fluid temperature and concentration, so the measurement accuracy is high and the application range is wide. However, the price of the correlator is expensive and the line is complicated. This shortcoming can be overcome after the microprocessor is popularized. The noise method (listening method) is a principle that uses noise generated when a fluid flows in a pipe is related to a flow velocity of a fluid, and detects a flow rate or a flow rate value by detecting noise. The method is simple, the equipment is cheap, but the accuracy is low.

Ultrasonic sensor inspection
For high-frequency ultrasonic waves, because of its short wavelength, it is not easy to produce diffraction, and it will have obvious reflection when it encounters impurities or interfaces. It has good directionality and can be directional and propagated as rays; it has small attenuation in liquid and solid, and wears. Through the power of the big.These characteristics make ultrasonic waves an important tool for non-destructive testing.

(1) Penetration method. Penetration method is a method for judging the internal quality of a workpiece based on the change of energy after the ultrasonic wave penetrates the workpiece. The penetrating method uses two ultrasonic sensor probes to lie on the opposite side of the workpiece, one for transmitting ultrasonic waves and one for receiving ultrasonic waves. The transmitted wave can be a continuous wave or a pulse wave. In the detection, when there is no defect in the workpiece, the receiving energy is large, and the meter indication value is large; when there is a defect in the workpiece, part of the energy is reflected, the receiving energy is small, and the meter indicating value is small. According to this change, the internal defects of the workpiece can be detected.

(2) Reflective flaw detection. Reflective flaw detection is a method of detecting defects by the difference in the reflection of ultrasonic waves in the workpiece. The following is an example of the longitudinal wave primary pulse reflection to illustrate the detection principle.