Monday, 3rd of October 2011 - Methods of mounting the fan above the flame

With the group decision made to use a spinning fan as the added visual stimulus - a method had to be used to suspend the fan above the flames to allow the heat to pass through and in turn spin it variably depending on the amount of flames that are active. Several methods were discovered with some brainstorming:

Sketch: Brainstorming for fan suspension system

Through the exploration we can across a few ideas. They were split into two sections: hanging and supported. Hanging referred to the fan being suspending by a flexible material or something that was not physically holding it in place. Supported referred to methods that would suspend the fan in place and use a bearing system of some kind to allow the fan to spin freely. All methods proved to be somewhat viable although there seemed to be some common problems:

Hanging
The problems with most of the hanging concepts is that in using a flexible material to suspend the fan while the hot air spins it will cause problems once the material has wound itself up to a point where the fan must attempt to spin the other way. Eventually any kind of material that suspends the fan in this way will be subjected to this. It will cause the fan to spin back and forth in an irregular formation and eventually come to an ultimatum where the fan will stop spinning all together when the force from the heat and the force from the tensioned material will equal out.

Supported
The problems with having a supported fan are much the same. You will lose out on the visual affects by have an almost static spinning fan (as opposed to a dynamically moving spinning fan with hanging applications) and there will be much the same problems with the use of bearings in the creation of too much friction. With very little force being produced by the flames, the bearings friction co-efficient will easily overcome the force of the heat. This will also add a less fee flowing fan movement which will move away from the positive visual stimulus that is required.

However a solution was found when looking at a magnetic levitation globe (available from national geographic):

Image: Levitation globe

Through the use of a mix of permanent magnets as well as electromagnets - the globe is able to levitate steadily as well as spin completely frictionlessly. This seemed to be the perfect solution to creating a frictionless bearing system to suspend the fan above the flames, while allowing it to spin freely and easily.

How does it work...?

It seems this type of magnetic levitation has already been achieved using an Arduino circuit board. Basically, the concept uses an electromagnet as the hanging support with a permanent magnet as the levitating device. Because the electromagnet is able to be variably controlled, the magnetic strength between the two can be adjusted to make whatever is levitation to sit at the desired position. The output to the variable electromagnet however, is controlled by a hall effect sensor - these output an analogue reading of what the magnetic field is in the immediate vicinity. So, when the permanent magnet gets close enough, the hall sensor will read that there is a change in the magnetic field and will adjust the variable electromagnet accordingly to allow the object with the permanent magnet to levitate and spin freely. The following video demonstrated magnetic levitation via an Arduino circuit board.

Using magnetic levitation to suspend the fan will allow it to "hang" freely without the need for any kind of mechanical support as well as spin with very minimal friction. This means the heat from the flames below will be able to control the speed at which the fan moves easily and more noticeably to allow for the positive visual stimulus to take full affect.