Propellers

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Divingdon

Contributor
Scuba Instructor
Messages
80
Reaction score
1
Location
Sharm el Sheikh, Red Sea
# of dives
500 - 999
For a time now I have been wondering about propellers. When they rotate through water they create pockets of gas. My question is where does this gas come from? Is it (presumably O2) coming out of saturation, or do propellers have enough force to break the bonds of an H2O molecule and release O2 from the water??? Puzzling....:confused:
 
Divingdon:
For a time now I have been wondering about propellers. When they rotate through water they create pockets of gas. My question is where does this gas come from? Is it (presumably O2) coming out of saturation, or do propellers have enough force to break the bonds of an H2O molecule and release O2 from the water??? Puzzling....:confused:

There'd be some water vapor in the cavitation due
to the vapor pressure of water at that temperature.
But that's irrelevant. The propeller is basically
just pulling a vacuum as far as the mechanics goes.

No more H2O molecule bonds are broken in this
process as are in spilling milk.

Regards,

--Mike
 
PanamaMike:
There'd be some water vapor in the cavitation due
to the vapor pressure of water at that temperature.
But that's irrelevant. The propeller is basically
just pulling a vacuum as far as the mechanics goes.

No more H2O molecule bonds are broken in this
process as are in spilling milk.

Regards,

--Mike
How do you know this? :crafty:
 
Yep, its basically a vacuum with some water vapor and other dissolved gasses. The damage to the prop comes from the shockwave of this hole in the water collapsing.

How do you know this? :crafty:
Uncommon knowledge is common to some :)
 
Hehe, you know you spent too much time in engineering when cavitation and mixed-phase flows seem like normal, everyday conversation. :D
 
The term your seeking is cavitation. Read about it. There is some controvery concerning the topic and exactly what is happening. At extremes it can damage propellers. N
 
that is similar to a diver farting underwater...Molecule bonds being broken..:wink:
inert gas spewing from areas less ummm...vented. No need for drysuit inflation...
 
scarefaceDM:
that is similar to a diver farting underwater...Molecule bonds being broken..:wink:
inert gas spewing from areas less ummm...vented. No need for drysuit inflation...

If you ignite the fart, you'd certainly break molecule
bonds but make some new ones, too.

Regards,

--Mike
 
https://www.shearwater.com/products/peregrine/

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