Cavitation: definition and development

Cavitation is a phenomenon that occurs in liquids and is caused by the formation and dissolution of vapor-filled cavities or vapor bubbles. The word comes from the Latin and means "to hollow out". Cavitation occurs when the pressure in a liquid falls below the vapor pressure of the liquid and vapor bubbles form. These vapor bubbles can contract and dissolve again due to pressure fluctuations in the liquid.

Causes of cavitation

Cavitation can be triggered by various causes, such as

• A rapid flow of the liquid, which leads to a decrease in pressure
• A narrowing of the flow cross-section, which leads to an acceleration of the fluid and thus to a drop in pressure
• The presence of air or other gaseous substances in the liquid, which leads to a higher sensitivity to cavitation
• The use of pumps or other flow machines that generate strong turbulence in the liquid and can thus contribute to the formation of cavitation.

Effects of cavitation

Cavitation can have an impact in many areas, such as hydraulics, pneumatics, chemistry or biology. Cavitation can cause material damage to the walls of pipes, valves or pumps and thus contribute to their failure. Cavitation can also lead to a loss of energy, as the drop in pressure in the fluid leads to an increase in energy requirements in flow machines.

Measures to prevent cavitation

Various measures can be taken to prevent cavitation. One possibility is to reduce the flow velocity of the liquid, for example by increasing the diameter of pipes. Another possibility is to improve the surface quality of pipes or valves in order to reduce sensitivity to cavitation. Another measure is to remove the air or gas bubbles from the liquid before it is used in turbomachinery.

Applications of cavitation

Cavitation can also be beneficial in some applications, such as surface cleaning. Cavitation can also help to improve the effectiveness of cleaning agents by leading to the formation of microbubbles that remove the dirt particles from the surface. In medicine, cavitation can be used to destroy tumor cells or to release drugs from microbubbles. In agriculture, cavitation can be used to improve soil quality and irrigation by preventing the formation of air pockets and thus improving soil permeability.

Summary

To summarize, cavitation is an important phenomenon that can have an impact in many areas. Cavitation can lead to material damage and a loss of energy, but can also be beneficial in some applications, such as cleaning or medicine. Suitable measures to avoid cavitation can prevent damage to turbomachinery and improve the efficiency of processes.