Strawberry Lance Blower

The Proust effect is the name psychologists have given to our reaction when a smell triggers a particularly vivid memory. Well today I invented a new one for the psychology community to grapple with, ‘geometria adductus suavis recordatioor’ or ‘The Booth Effect’ for short. This is when a geometrical shape reminds you of a childhood sweet (candy for the Americans). To be honest I don’t imagine this will catch on super widely so first I will take you back to the beginning - positive displacement lobe pumps.

The Roots Blower

One such pump invented by Francis and Philander Roots (there really are not enough people are called Philander these days). The brothers Root were trying to invent a better way of extracting power from the head of water available at their water mill when a bench prototype of their device was spun up and allegedly ‘blew the hat off’ one of the brothers. The fellows were canny enough to recognise a good hat remover when they saw one and so in 1860 they patented the ‘Roots blower’. The blower was originally deployed to inject air into blast furnaces – but many variants of the original design have evolved into a multitude of applications – many to compress air on the intake side of internal combustion engines.

The original design of Roots blower has alternate Hypocycloid and Epicycloid curve segments - those curves formed by a smaller circle rolling around the interior and exterior of a base circle. If the radius of the smaller rolling circle is an integer divisor of the larger circle radius – you get these cool periodic shapes:

Now if you place a like profile one pitch circle away and have it contra rotate – you have the basic Roots blower (external timing gears are used to stop the surfaces contacting)

As you can probably tell by inspection the ‘lobed’ design leads to a ‘pulsed’ flow delivery - to reduce this effect you can increase the number of lobes and introduce a twist on the impellers. All of which I thought might make a visually pleasing demonstration of what Turtlestack Automation can do with custom features.

Custom Feature Example

The path to a Roots blower profile gear did not run true and included a few accidental abstracts along the way …

Demo

Despite the teething problems - it is now working stably …

Half way through developing this custom feature I found I had a sudden and near-overwhelming desire for Strawberry Lances – The Booth Effect in action - disappointingly these never tasted as good as they looked!

If you are interested in playing with this demo or have a problem which would lend itself to a NX CustomFeature solution in your company please get in touch. Turtlestack Automation turn difficult design problems into a simple everyday part of your modelling process all wrapped behind an intuitive interface we will design together.