Fountain Nozzles

[Bju90]

I have been toying with the idea of using an expanding nozzle in a 1" fountain. The purpose being to have a wider spread in the fountain spray.

My idea was testing a simple cone shape nozzle with some angles like 15, 30, 45 degrees. Nozzles would be made from clay, formed with some 3d printed tooling. Other thought was casting a high temp resin but for a simple geometry the clay should suffice and is safer. 

Anyone tried similar?

[Zumber]

Generally nozzle diameter is larger inside the fountain tube and getting smaller towards its end like an english letter 'A' shape, this is usually to reduce pressure generated inside fountain and prevent fountain from being bursted. You are exactly doing opposite to this just like an english letter 'V' shape?? Just to have wider spread?

While doing this you have to keep in mind that nozzle diameter inside of tube should be sufficient enough to withstand pressure generated inside fountain. Also it may also affect on height of fountain.

In first case pressure at nozzle opening inside of tube is less as it's diameter is large and it is a bit more at opposite end as it's diameter is getting reduced so in this case height of fountain is higher.

It is exactly opposite in second case.

[Bju90]

Would still retain this 'A' shape you refer to on the inner side that help funnel micro stars and gasses through the nozzle and reduce back pressure. Then past the throat would use a diverging or 'V' shape to assist expansion of the gasses which should result in a lower height but potentially wider spread and potentially reduce the intensity of the heat/flame colour so the micro stars would be visible sooner

 

[SKC]

Generally the idea is to keep a nozzle 1/3rd of the id of the tube.

But experienced pyros do understand when and why to increase the diameter considering granule sizes, composition pressure and the spread & height they want. So there is no big fat rule book. 

Everything depends upon practical experiences.

[Carbon796]

" commercially " available fountain tooling. Is generally made to form, some amount of a convergent/divergent nozzle profile.