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PHYS-L Members,
I have received some help on my article, "The Nyth of
Superheated Steam",
for which I wish to thank you. However, there is one big scientific mystery
that I want to seek you help on.
This deals with the clockwise rotation of a fog nozzle used
on a confined
fire. The clockwise rotation produces a more active steam rotation that
moves away from the nozzle position and results in a faster knock-down
time. A counterclockwise rotation does just the opposite. The question is
why this difference?
The coriolis force is almost certainly too small to have
this effect. Also
the centrifugal fire pumps do not cause this since there is no standard for
these pumps. Manufacturers produce pumps that rotate clockwise as well as
counterclockwise.
This narrows the search down to electrical activity in the
fire itself. I
would like to quote from Bill Nelson's book, "Qualitative Fire Behavior" to
guide you toward any research or published material that might answer this
question.
"The distance that a body is deflected by the Coriolis
effect as it moves
across the earth is less than one foot per mile. This is too small an
amount ot have much effect on turbulent fire gases or the drain in the
bathrub.Another point which seems to confirm that the force causing fire
gases to move either clockwise or counterclockwise is much stronger than
the Coriolis force can be observed in the formation of whirlwinds around
structures well involved in fire. If we stand with backs to the wind and
watch a wind blow around a fire of this type, we will note that fire whirls
form on both sides of the building.
The whirls that form as the wind goes around the left side
of the building
will rotate counterclockwise while those that form as the fire goes around
the right side of the building will whirl clockwise. Both types of whirls
are formed with about equal frequency, but as we watch them we will observe
that those which circulate clockwise seem to draw themselves together
tighter, whirl more rapidly and last a longer time than those that whirl to
the left or counter-clockwise. This causes us to ask what characteristics
of fire gases might cause right or clockwise whirlwinds to tighten up and
be stronger than the left-hand whirls.
It is well known that a fire is a beehive of chemical
activity and that
electron exchange is a fundamental part of chemical activities. It can also
be demonstrated that a candle flame can be deflected by high-voltage
electric fields. It is most likely that there is a plentiful supply of
positive and negative ions in the fire gases.
It is also recognized that the rule of themb for the
direction of flow of
magnetic lines of force seems to fit well for fire whirls. This rule for
magntic lines of force states that if you have a current flowing in a wire
and you point your right thumb in the direction of the current flow your
fingers point to the direction of the flow of the magnetic lines of force.
For fire whirls, if you point your right thumb in the direction of the flow
of the gas your fingers will point in the direction of circulation for
clockwise whirls."
Of course Bill Nelson recognizes that all these ideas about clockwise
rotation of fire gases are purely speculative. I hope that some of you may
be able to guide me to some research or published materials that will
answer this question about clockwise rotation.
John D. Wiseman
jdwiseman@mindspring.com