Update: 2019-08-12 14:30 Source: LUFTMY
The first thing we need to know is what is the doppler effect? The "doppler effect" can be similarly understood as when a motor vehicle is approaching, the sound is higher and higher and the pitch is higher and higher. When the car leaves, the sound is lower and the pitch is weaker and lower.From a scientific point of view, that is, when the sound wave is gradually transmitted to people, the receiving frequency will be higher, and when it is far away from the source, the receiving frequency will be lower. This phenomenon is known as the doppler effect.
The vehicle radar tachometer USES the doppler effect. The velocimeter sends out the laser line and returns to the velocimeter through the reflection of the motor vehicle. During the process, the micro-information processing in the velocimeter detects the difference between the two wavelengths coming and going, and the measurement result is obtained. The denser the wavelength is, the faster the speed is proved.
The doppler test system is a series of scattered light waves whose intensity varies with time when the particles in the fluid pass through the fringe area after the focusing lens converges two beams of incident light at an Angle. It is called doppler signal.
The frequency at which the intensity of the wave changes is called the doppler shift.The higher the velocity, the higher the doppler shift.If the velocity of the particle perpendicular to the stripe direction is divided by the stripe interval, and the refractive index of the fluid is taken into account, the linear relationship between the doppler frequency shift and the velocity of the fluid can be obtained.Doppler velocity measurement system USES the linear relationship between velocity and doppler frequency shift to determine the velocity.
The main part of the doppler testing system is the laser doppler velocimeter, which measures the doppler signal of the tracer particles through the laser probe. Because of the laser measurement, there is no interference to the flow field and the wide range of velocity measurement, it is the instrument with the highest accuracy of velocity measurement on the market at present.