As regular readers know, I’m interested in small devices for generating trickle charging solutions for batteries out in the cloudy mountains where the sun rarely shines. We’ve looked at potentially useful stirling engine designs before, but I just found this interesting video on Youtube which differs fundamentally from the stirling design, while retaining some of its thermodynamic features.
This type of very simple engine is known by various names such as laminar flow, thermo-acoustic, thermal lag etc, but no-on seems to have a fully developed thermodynamic theory of exactly how it works. Unlike classic stirling engines, there is no ‘displacer’ to shunt the working gas from the hot to the cold end in order to drive a cycle of expansion/contraction which then sucks and pushes a power piston which drives a flywheel (or a linear electric motor). It’s more reminiscent in a way of a pulse-jet engine, but with a closed cycle, rather than an open system generating thrust directly from the explosive expansion of combustible gases.
But besides thinking about the way this engine operates as a collection of glass and aluminium parts heated at one end, it put me in mind of the way the Sun ‘pulses’ every eleven years or so. So this is today’s brainstormer. If objects can be set into oscillation by the application of heat (and let’s not forget thermodynamic theory here, whereby atoms and molecules ‘vibrate’ more vigorously as heat is applied to them), then what if the heavy dense metallic hydrogen core of the Sun is set into oscillation by the heat generated in the fusion process? It wouldn’t oscillate so easily in the X-Y plane, because the Sun is rotating, but it is freer to move in the Z axis.
What evidence exists to suggest this might be happening? Well, we do observe that in successive solar cycles, more/less sunspot activity takes place in the southern/northern hemispheres. We also observe an ~11 year reversal of magnetic polarity between leading and trailing sunspots. If as Nicola Scafetta suggests, the Sun has a natural frequency of oscillation around 10.8 years, and as with our solar-planetary theory, the gas giants and terrestrial planets have interaction periods at 10.38 and 11.86 years, then we have a potential explanation for the beat period at around 11.07 years which characterises the average length of the solar cycle. We should also recall Ray Tomes’ Z axis theory here, which postulates that the gas giants are gravitationally pulling the core of the Sun up and down by a couple of km relative to its envelope as they move above and below the tilted Solar equatorial plane.
Clearly there are many factors which will affect the characteristic oscillation period of a ‘thermoacoustic engine’, as the youtube video says. The same is true of the Sun; the mass of the core, the viscosity of the surrounding fluid, the rate of heat flow from core to surface, and possibly coupled with the harmonic interaction of the planetary gravitational effect too. Simple it ain’t.