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RE: Air Flow and Pressure



Gary--

To find specific numbers, you'd probably need a physics book of some sort.
Look for the Bernouli Principle.  Comments interspersed below.

> Original Poster: gweaver <gweaver-at-earthlink-dot-net>
>
> I am doing some TC experements and could use some HELP.
>
> I know I have read this some place in one of my books but I can
> not find it
> now when I really need it. I have looked in my Physics, Science and
> Engineering books and can not find the answer.  These are just
> basic laws of
> physics that can not be changed.
>
> If I blow air threw a short smooth pipe with a constant diameter the air
> velocity and air pressure will say the same though out the inside
> of the pipe.

Yes.

> If I take a second short smooth pipe whose area is exactly half
> that of the
> first pipe and blow air threw it as I did before in the first
> experement the
> air velocity will double.  What will happen to the air pressure inside of
> the pipe???

If you put the same volume of air as in the first case, velocity will
increase, and pressure will decrease, by exactly how much I don't know.

> What I really need to know is if a pipe is large, then tapers
> down smaller,
> the air velocity will increase in the smaller pipe, will the air pressure
> inside the smaller pipe increase, decrease or stay the same???

As the pipe tapers, the velocity of the air will increase, and its pressure
will decrease.  Think of the pressure as the 'static' energy and the
velocity as the kinteic energy.  The total energy stays the same, so as one
changes, the other must change in the opposite direction.  (This is how
airplane wings and propellers work, and how carburetors do as well.)

> If a smooth pipe makes a 90 degree turn and air is blown threw it
> as before
> in the other 2 experements will the air on the outside of the curve be
> higher density air because of centrifical force???

That one I'm not really going to take a stab at.  The airflow patterns will
probably be very dependant on the velocity of the air as well as how sharply
the pipe bends- there is a lot to fluid dynamics.....

Hope this helped a little.

Best

Pat