Ultrasonic cavitation

A, ultrasonic cavitation formation
Ultrasonic cavitation refers to exist in the liquid gas nuclear cavitation in ultrasonic vibration under the action of the pressure, and when to a certain value of growth
And the collapse of the dynamic process.

Ultrasonic cavitation in liquid form the collapse of high temperature and high pressure and discharge, shine and shock wave functions. One hole forming factors may be strong
Ultrasonic irradiation, when the explosion, high-speed fluid shock or severe piecewise friction chemistry etc.

Second, ultrasonic cavitation mechanism

Ultrasonic cavitation generally includes 3: neither cavitation bubble formed, grew up and severe crash. Specifically when filled with liquid container the ultrasonic,
Due to the vibration liquid in the process of tens of thousands of tiny bubbles, also is the cavitation bubble. These bubbles formed in ultrasonic transmission of longitudinal negative growth, but in the area
Pressure area, thus rapidly closing in alternate negative pressure effect by compression and stretching. Compressed air bubbles collapse in the moment, until can produce great instantaneous pressure, a
As can be as high as dozens of mpa to hundreds of megabytes. According to the related experimental measurement: the cavitation can be reached the opposite contentious 5200K temperature, reaction temperature of liquid effectively
Around 1900, K, degree in 5 O5 partial pressure, the temperature variation kPa 10 $10, and K/s with strong shock wave and speed up to 400 km of the jet.
In this great instantaneous pressure, can make the solid surface suspension in liquid by sharply. Usually HuaFen empty for ultrasonic cavitation and instant steady cavitating two
Type:

Steady cavitating refers to the low intensity in less than 10 w/cm) when the cavitation bubble, its size in its balance size, near the oscillation of a number of cycles. Periodic
When the expanded to make its own resonant frequency and acoustic frequency equal, the biggest energy field coupling with bubbles, the cavitation.

Transient cavitation is refers to the larger than the sound intensity (generally not w/cm) under the action of survival period shorter cavitation bubble (mostly occurs in a sound cycle).

Third, the application of ultrasonic cavitation effect

Using the empty into ultrasonic cavitation that goes to and the mechanical effect, heating, chemistry, biology effect, widely used in various industries, mechanical efficiency
The application should be mainly displays in the opposite of the interface should increase, And the application of chemistry is mainly due to the cavitation process of high temperature and high pressure, make polymer decomposition
Learn key fracture and generate free radicals, etc. Using the mechanical effect of process including adsorption, crystallization, electrochemical, the chemical reaction, filtration and ultrasonic cleaning, use
The process of learning effects include organic matter degradation, polymer chemistry and other radicals reaction. Ultrasonic cavitation can be used to promote chemical reaction, grinding fluid in suspension
FuWu, manufacturing and kill bacteria or washing machine and many other industries. Which has been widely used as ultrasonic cleaning.

Four, the influence factors of ultrasonic cavitation effect

Ultrasonic cavitation intensity and acoustical parameters and the physical and chemical properties of liquid. Specific include the following aspects:

1, the intensity of ultrasonic. Ultrasonic strength refers to the per unit area of ultrasonic cavitation power, size and intensity of ultrasound. For general liquid ultrasonic
Strength increases, the cavitation intensity increases, but also to a certain value, cavitation will be saturated, add ultrasonic strength of will not delivering
Bubble, thus increasing the scattering attenuation, reduces the cavitation intensity.

2, ultrasonic frequency. Ultrasonic frequency in the lower in liquid, the easier it will be cavitation. That will cause cavitation, high frequency sound intensity, need more
Big. As to produce in water cavitation, ultrasonic frequency in 400 kHz needed power than in October 10 times greater kHz, namely when the cavitation is as frequency
High and reduce. Generally USES frequency range of 20-40 kHz.

3, liquid surface tension and adhesion coefficient. Liquid surface tension, the greater the cavitation intensity is higher, the less prone to cavitational effect. Large liquid viscous coefficient
To produce the cavitation, and propagation loss is great, so as to produce cavitation.

4, liquid temperature. The higher the temperature, fluid of cavitation of more favorable, but not absolutely, because when the temperature is high, the bubbles in the increase of vapour pressure
Bubble closed enhanced cushioning and make the cavitation.