My PBL Project Smoke Ring Cannon

Action Video

1) Introduction

DRIVING QUESTION: How to form smoke rings?

A smoke ring is a visible vortex ring formed by smoke in a clear atmosphere.

Smokers may blow smoke rings from the mouth, intentionally or accidentally. Smoke rings may also be formed by sudden bursts of fire (such as lighting and immediately putting out a cigarette lighter), by shaking a smoke source (such as an incense stick) up and down, by firing certain types of artillery, or by the use of special devices, such as vortex ring toys. The head of a mushroom cloud is a large smoke ring.

A smoke ring is commonly formed when a puff of smoke is suddenly injected into clear air, especially through a narrow opening. The outer parts of the puff are slowed down by the still air (or by edges of the opening) relative to the central part, imparting it the characteristic poloidal flow pattern.

The smoke makes the ring visible, but does not significantly affect the flow. The same phenomenon occurs with any fluid, creating vortex rings which are invisible but otherwise entirely similar to smoke rings.

When blown in still air, a smoke ring usually travels roughly straight from the opening over a surprisingly large distance, maintaining its shape, until dispersed by turbulence or other interference

2) Materials

• • Liquid Fog

• Smoke Ring Cannon

• • Fog Machine

3) Procedure

1. It's easy to make your own air blaster using materials that you can find at the hardware store. Start with a 5 gallon plastic bucket (about $3 in any hardware store). Carefully cut a 2 to 3 inch hole in the bottom center of the bucket.

2. Stretch a membrane across the top of the bucket. Believe it or not, a piece of clear plastic shower curtain works great. Just stretch a piece of the shower curtain over the top of the bucket and secure it in place using a bungee-type cord.

3. Lightly hit the shower curtain with your hand or the end of a stick. An invisible blast of air shoots out of the hole. Just aim the air cannon at someone or something across the room and send a blast of air their way with a whack of the membrane.

http://www.stevespanglerscience.com/lab/experiments/air-cannon-smoke-ring-vortex-launcher#sthash.sFj0wccI.dpuf

4) Scientific Principle

A smoke ring is a visible vortex ring formed by smoke in a clear atmosphere.

Smokers may blow smoke rings from the mouth, intentionally or accidentally. Smoke rings may also be formed by sudden bursts of fire (such as lighting and immediately putting out a cigarette lighter), by shaking a smoke source (such as an incense stick) up and down, by firing certain types of artillery, or by the use of special devices, such as vortex ring toys. The head of a mushroom cloud is a large smoke ring.

A smoke ring is commonly formed when a puff of smoke is suddenly injected into clear air, especially through a narrow opening. The outer parts of the puff are slowed down by the still air (or by edges of the opening) relative to the central part, imparting it the characteristic poloidal flow pattern.

The smoke makes the ring visible, but does not significantly affect the flow. The same phenomenon occurs with any fluid, creating vortex rings which are invisible but otherwise entirely similar to smoke rings.

When blown in still air, a smoke ring usually travels roughly straight from the opening over a surprisingly large distance, maintaining its shape, until dispersed by turbulence or other interference