School of Physics Lecture Demonstration Manual

Fc-8 Smoke Ring Generator

Published: Monday 13 March 2006 - Updated: Tuesday 29 March 2011


To demonstrate vortex flow via the formation of large stable smoke rings.



Click on pictures to enlarge.

Smoke Ring Gen Diagram 2

Smoke ring Gen Diagram


 INTRODUCTION: The apparatus described below and illustrated on the accompanying diagram produces smoke rings af approximately 30 cm. in diameter. The rings travel for distances in excess of 10 metres before decay. With the correct lighting the rings are clearly visible to large audiences and it has been used with great effect as a Corridor Demonstration. The large size and long life allow many of the interesting properties of smoke rings to be studied. During experimentation with the device oscillating ellipsoidal smoke rings were produced by altering the shape of the exit hole.

Our smoke ring housing consists of a 30 cm. length of industrial cardboard piping set upon a chipboard stand (figure 1). The pipe is of the type used for the construction of concrete pillars and we obtained suitable offcuts for a few dollars. A large hose clamp secures the rubber sheet diaphragm which is of 1.5 mm thickness. This size has proved to be adequate in strength and suitable in flexibility. A second aluminium plate is glued to the centre of the diaphragm to ensure maximum displacement of air on compression. An aluminium disc with a 30cm. aperture fitted with a sliding door completes the enclosure.

The dimensions given are not critical for the operation of the generator

The smoke source consists of a commercial fog generator of the type used in theatres and is introduced into the apparatus via a small side opening. Please note. The smoke generator is hired if this demonstration is required so suitable advance notice must be given.

Safety notes

Electrical Safety 


top of page