OK - One candle power source - necessarily mounted off-centre to the
turbine because the spindle occupies the centre position.
Therefore the force applied to the turbine disc by the rising column
of heated gas is off centre and will want to tilt the disc and
spindle away from the hot side of the circle. The little Xmas candle
turbines with which we are all familiar solve that problem by using
more than one candle to counteract that off-centre effect. Two,
three, or four candles are placed symmetrically under the disc to
keep the forces balanced.
Any decorative objects hung from the turbine disc will apply their
own off-centre weight and, as the disc turns, will apply their own
cyclic forces trying to wobble the disc. So those bits should be (as
nearly as possible) equal in weight to each other and symmetrically
placed around the circumference to minimize the tendency to wobble.
The driving force from the candle is small. The off-centre effort
from the one candle and the dynamic forces of the dangling
decorations may, at some rotational speed, coincide with the natural
harmonic frequency of the whole assembly and amplify a vibration,
albeit small, which my be difficult for the candle to overcome and
which may inhibit rotation. Alternatively and worse yet, it may pass
a tip-over point and evolve into a self-perpetuating exponential
feedback loop, producing a cyclonic vortex (think “firestorm”) or
mechanical vibrations strong enough to shatter nearby structures. .
My intuition is that you should work with minimum of two candles
opposite each other and a larger diameter disc to make things a bit
easier - maybe 4 inches.
Get things right and you may be on the verge of producing a
perpetual motion machine. A centuries-old dream realized.
and wear a hard hat
Marty - staying in dynamic balance here in Victoria