"Gilligan" wrote in message ...
|
| "Paladin" noneofyourbusiness.www wrote in message
| ...
|
| "Gilligan" wrote in message
| . ..
| |
| | "Paladin" noneofyourbusiness.www wrote in message
| | ...
| |
| | "Gilligan" wrote in message
| | . ..
| | |
| | | http://encarta.msn.com/media_4615415...for_Water.html
| | |
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| | The diagram proves my point. Since there is no significant temperature
| | change involved with a propeller but there is a significant pressure
| | change
| | then the water does not vaporize because it boils. Rather it vaporizes
| | because
| | of the pressure change.
| |
| | I'm just so brilliant. You can't even manage to misdirect me.
| |
| |
| | I can't misdirect you, but I can set you straight.
|
| You've done an inadequate job of it so far...
|
| | When water boils, as in your kettle, those "bubbles" are water vapor
| | suspended in the liquid water.
|
| Agreed. But, suspended is a poor word choice. I prefer to call it
| water vapor displacing the liquid water.
|
| | Cavitation is caused by the propeller slipping on water vapor suspended
| in
| | the liquid water.
|
| Quaintly envisioned. Highly inadequate. Cavitation is a descriptive term
| used
| to describe the vaporization of the water near the low pressure side of
| the
| propeller blades resulting in over-revving of the engine. The over-revving
| of
| the engine is caused by the prop losing contact with the water.
|
|
| | Would it then be reasonable to say that cavitation is caused by water
| | boiling?
|
| Not in the case of a boat unless it was in a giant pot of boiling water
| on the stove.
|
| | OR
| |
| | Cavitation can only happen in your tea kettle?
|
| Cavitation could very well be caused by operating a prop in boiling
| water but the prop doesn't cause the water to boil. The fire under
| the tea kettle is doing that job.
|
| Now, who's straightening out whom?
|
| Suppose I have water in a beaker and place it in a bell jar. The air in the
| bell jar is pumped out, lowering the pressure. Eventually the water begins
| to boil.
|
| Where is the heat source causing it to boil?

There is no heat source in that case but the water
is not boiling.

Go to a dictionary and look up the definition of boil.
You will note that it mentions application of heat.

Lowering pressure does not add heat. Therefore, to
use the word boil is incorrect to describe the bubbling
action lowering the pressure causes.

Water plus heat = boil
Water minus pressure = vaporization

Your thinking is sound; it's your use of the verb 'boil'
that's faulty and it muddles the issue. People like
Old Tom quickly get lost. (or should I say "more lost?")

Get it?


Paladin

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