Vortex ring toys
Encyclopedia
A vortex ring toy generates vortex ring
s – rolling donut-shapes of fluid – that move through the fluid (most often air, and sometimes water). A smoke ring
is a common example of a vortex ring. Because of the way they rotate, a vortex ring can hold itself together and travel for quite a distance.
A vortex cannon generates vortex rings, typically using acetylene-air or hydrogen–oxygen explosions.
Single vortex rings are remarkably stable in diameter and speed, and can travel in quiescent air over long distances before their kinetic energy is dissipated by fluid friction. Outside its core, energy is transferred from one fluid parcel to the next, while the parcels just outside the core have nearly the same velocity as the parcels just inside, so are also without much friction (since friction originates from difference in fluid velocity between adjacent fluid parcels).
Upon striking an object, the ring proceeds to pummel the target with a short, brief burst of swirling wind as the vortex dissipates. An interesting demonstration of the airflow pattern of a vortex ring toy can be made by having a smoker blow a smoke cloud into the toy prior to it being fired. The smoke will travel in the vortex, making a very large smoke ring. Some toys are built with a smoke generator in the toy, with the purpose being to blow smoke rings.
Vortex ring
A vortex ring, also called a toroidal vortex, is a region of rotating fluid moving through the same or different fluid where the flow pattern takes on a toroidal shape. The movement of the fluid is about the poloidal or circular axis of the doughnut, in a twisting vortex motion...
s – rolling donut-shapes of fluid – that move through the fluid (most often air, and sometimes water). A smoke ring
Smoke ring
A smoke ring is a visible vortex ring formed by sudden release of smoke. It can be created by blowing smoke from the mouth, quickly lighting a cigarette lighter and putting it out or holding a burning incense stick or a cigarette vertically, pushing it with the burning side up and suddenly pulling...
is a common example of a vortex ring. Because of the way they rotate, a vortex ring can hold itself together and travel for quite a distance.
A vortex cannon generates vortex rings, typically using acetylene-air or hydrogen–oxygen explosions.
Vortex ring toys
The most common vortex toy works by not expelling a quantity of air from the toy in such a way as to create a vortex ring. The energy from this vortex is transferred between air particles, in effect moving the vortex downrange. The core region of the vortex ring always consists of the same fluid, as it travels through the fluid, while outside this core the fluid will be set in motion by the approaching vortex ring, move for some time and return to rest after the passage of the ring. That is the way for instance a smoke ring stays visible after quite long distances of travel, while most of the smoke from outside the vortex ring core is left behind in the region near its source.Single vortex rings are remarkably stable in diameter and speed, and can travel in quiescent air over long distances before their kinetic energy is dissipated by fluid friction. Outside its core, energy is transferred from one fluid parcel to the next, while the parcels just outside the core have nearly the same velocity as the parcels just inside, so are also without much friction (since friction originates from difference in fluid velocity between adjacent fluid parcels).
Upon striking an object, the ring proceeds to pummel the target with a short, brief burst of swirling wind as the vortex dissipates. An interesting demonstration of the airflow pattern of a vortex ring toy can be made by having a smoker blow a smoke cloud into the toy prior to it being fired. The smoke will travel in the vortex, making a very large smoke ring. Some toys are built with a smoke generator in the toy, with the purpose being to blow smoke rings.
External links
- Fluid dynamics lecture covering vortices
- An animation of a vortex ring
- Giant vortex ring generator
- Toy Box Physics: Vortices, Air Cannons, and Mushroom Clouds
- Professor T.T. Lim's personal site at University of Singapore. Includes rings collisions and a number still images, amongst other things.