Cavitation in Hydraulic Systems
Hello, I’m Nurefşan. I’m a final-year student of Aerospace Engineering. In my last post, I wrote about how 5000 psi systems reduce the weight of aircraft. Now, I’d like to explain one of the biggest problems with the pumps that generate this high pressure, namely cavitation, as far as I understand it.
What is Cavitation?
Cavitation is the sudden formation of vapor bubbles in a hydraulic fluid and the violent bursting of these bubbles.
According to my research, this usually occurs at the pump inlet, where the pressure drops significantly. Small voids and bubbles form in the fluid. When these bubbles reach the high-pressure areas of the pump, they collapse suddenly under the effect of pressure, creating extremely powerful shock waves at the micro level on metal surfaces.
Why is this an undesirable situation?
When bubbles burst, extremely high pressures are generated at the micro level on metal surfaces. These bursts cause fractures on the surface. Over time, these fractures merge, creating holes and roughness on the metal.
How Do We Prevent Cavitation in Aviation?
Cavitation in aircraft is prevented by pressurizing hydraulic reservoirs. Compressed air is pumped into the reservoir to ensure that the fluid always reaches the pump inlet at a high pressure. This prevents the pressure from falling below the fluid’s vaporization point, thereby preventing bubble formation.
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Cavitation was a really good example that showed me how meticulous one must be in hydraulic system design. For a hydraulic pump to operate smoothly for many years, these explosions must be calculated and prevented during the design stage. From what I’ve researched, the risk of cavitation increases significantly in high-pressure systems, especially those operating at 5000 psi, due to the extremely high flow velocity. This situation helped me better understand why such careful attention is paid to the material selection of sealing elements and pump internal components.
I will continue to share my technical notes as I continue my research.
Nurefşan Adsız
