rotating inverting triangle balloon
It flies like a water-weenie toy: smoke-ring propulsion. Ring vortices can sometimes move without turbulence, since they are themselves a stable form of turbulence (vortex shedding.)
Speculating on shockwave-suppressed smoke-ring propulsion back in
1999, I still wonder whether any shape of ring-vortex can go transonic wo/shocks...High-speed Vortex Blimp
Question: inside a large sphere of fluid hanging in free-fall, if we launch a travelling vortex-ring inside, will it be disrupted when it hits the (inner) surface of the sphere? Or will its constrained region of momentum pass through the interface and carry a blob of fluid into the surrounding space? If the latter, then the large sphere could be propelled by ejecting small spheres ...but wouldn't it only experience a reaction force and a change in momentum at the moment the small sphere left the main mass, and not earlier when the vortex-launcher was originally fired?
Yet a ring-vortex is composed of closed-loop flows, so how can it transport any linear momentum in the first place? Yet apparently it does, since a vortex-launcher experiences a non-negligible "kick" when flinging out a vortex-ring. (And any fluid jet can be modeled as stacked ring-vortices.) Owners of "Wham-O" air blasters could knock over cardboard gorillas. I'm musing on pulsed-detonation "smoke ring" engines where the exhaust orifice is the intake as well: an AC version of the Feyman Sprinkler problem. Also, crowds of jellyfish living in a spherical pond in free fall. Do jellyfish end up ejecting themselves from one side of the sphere, while their vortex-rings are ejected from the opposite pole, and the pond itself doesn't interact much with either? Needs me a ten-gallon ball of salt water floating in a hundred-gallon tank of density-matched freon! Or see what happens when playing "scare the goldfish" while flying parabolas on the Vomit Comet.
((((((((((((((((((((((( ( ( (o) ) ) ))))))))))))))))))))))) William J. Beaty Research Engineer beaty, chem washington edu UW Chem Dept, Bagley Hall RM74 billb, eskimocom Box 351700, Seattle, WA 98195-1700 ph 206-762-3818