Kavitationsprocesser

Kavitationsprocesser, or cavitation, refers to the formation, growth, and subsequent collapse of vapor or gas-filled bubbles within a liquid. This phenomenon typically occurs when the local pressure in a liquid drops below its vapor pressure. Under such conditions, the liquid essentially boils at a temperature below its normal boiling point, leading to the formation of these cavities or bubbles.

The process of cavitation involves several stages. Initially, as a region of low pressure develops, vapor or dissolved gas comes out of solution, forming bubbles. These bubbles then grow as they are transported to regions of slightly higher pressure, but still below the vapor pressure. The critical and most energetic stage is the violent collapse of these bubbles when they reach a region of sufficiently high pressure, such as near a solid surface or where the pressure gradient reverses. This collapse can generate localized high temperatures and pressures, shock waves, and microjets of liquid, which can have significant effects on surrounding materials and systems.

Cavitation is observed in a wide range of applications and natural phenomena. In engineering, it can be a detrimental force, causing damage to pumps, turbines, propellers, and even medical equipment like ultrasonic cleaners. The erosive effects of cavitation are due to the repeated impact of collapsing bubbles and the associated shock waves. Conversely, cavitation can also be harnessed for beneficial purposes. For instance, ultrasonic cavitation is used in cleaning, sonochemistry for chemical reactions, and in some medical treatments like lithotripsy (breaking kidney stones) and targeted drug delivery. Understanding the physics of cavitation is crucial for both mitigating its negative impacts and exploiting its potential.