At 06:02 PM 12/30/2012, David Roberson wrote:
I just came to the realization that most of the demonstrations that
Russ has performed do not show much real work output. The piston is
driven upward by the spark activated mixture, but then returns to
the starting point. Any work done on the mass of the piston is
returned back to the gas when it retracts for a net of zero. On
occasions I have seen him toss items into the air which intercept
his fan or ceiling, but the mass is small and little damage appears
to be caused by the projectile.
It is going to be difficult to get accurate measurements for a valid
determination of energy released unless that energy remains stored
somewhere and compared to the electrical input.
David, I think you have missed the point. Yes, gravity will continue
to act on the driven piston, so it will return to the start.
However, there would not be a "return to zero," as such. Work would
be done on the weight. What happens to the energy released?
It would end up where it almost always ends up, as heat.
But that is not the issue. When the piston is lifted, there is a
force operating over a distance, against the inertia of the piston
and against gravity. Force times distance is work, or energy. The
energy that has been dumped into the piston should be measureable.
The energy expressed as work, through the lifting of the piston,
would be equal to that, if there is no XP, or less than that, because
of friction. Friction will cause diversion of the energy into heat.
The gas in the cylinder expanded. What happens to the expanded gas?
If the piston is sealed, it stays expanded, does it? What happens to the gas?
The gas must collapse if this cycle can be repeated with a sealed
cylinder. The motion of that cylinder, from a single pop, could be
quite interesting!
The force exerted on the weight, over a time which can be found by
observation of the piston lift, can be used to predict how an engine
would behave, to a degree, though more is involved, i.e., how the gas
then collapses.
I suspect that the spark creates a transient high pressure, but only
slightly elevates the temperature, and whatever temperature increase
exists is rapidly dissipated. The motion of the piston, observed,
could show the pressure behavior.
