Is cavitation worse at depth? (Fluid pressure and Vapor pressure boiling)

[Timtam]

I am wondering about the impact of the hydro static pressure of a fluid on its boiling point.
The simplest real world example scenario I can think of is the rate/onset of cavitation at a large depth vs a shallow depth.

As we increase the submarine propellor speed to a speed where the adjacent fluid is brought below its vapour pressure would cavitation occur at lower propeller speeds at shallower depths or deeper.

If this is complicating the issue too much then in the standard vacuum boiling example (where we know boiling onset is decreased if the gas phase pressure is continually maintained at a lower pressure than the vapour pressure of the fluid) , conversely if we could iso-thermally maintain the liquid pressure slightly higher than the gas phase above it would boiling onset be earlier for a given temperature?

Many thanks

 

[Chestermiller]

It would occur at lower propeller speeds at shallower depths. The absolute pressure must be decreased below the equilibrium vapor pressure of water for boiling or cavitation to occur.

 

[Timtam]

It would occur at lower propeller speeds at shallower depths. The absolute pressure must be decreased below the equilibrium vapor pressure of water for boiling or cavitation to occur.

Thanks ChesterMiller that makes sense , what are your thoughts on the second example- raising the liquid pressure, is that analogous to raising the temperature of the liquid ? I can't think of a real world example of where a liquid could be a higher pressure at the surface than the gas phase above but if that was the case would boiling be onset earlier ?

 

[Chestermiller]

Thanks ChesterMiller that makes sense , what are your thoughts on the second example- raising the liquid pressure, is that analogous to raising the temperature of the liquid ? I can't think of a real world example of where a liquid could be a higher pressure at the surface than the gas phase above but if that was the case would boiling be onset earlier ?

I don't understand this question.

 

[Baluncore]

A cavity is formed when the fluid cannot accelerate sufficiently to fill the volume left by the rotating propeller. Cavitation is reduced at greater hydrostatic pressures because the force available to keep the cavity closed is greater.

The boiling point at high pressure is not important. The cavity formed will contain vapour at the vapour pressure expected at that temperature. That vapour will be violently compressed as the cavity closes, which causes the corrosion problems.