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Heron (Hero) of Alexandria 1st c. BC.
As with his name there are various Greek names given to the device, air ball
or air sphere which have given rise to the idea the device looked something
like this.
However this is an expensive and wasteful design particularly in making
metal spheres. As he was wealthy this may have been the ultimate embodiment
of the version he showed off. However it raises many questions as to what he
used to lubricate the rotating connections with the sphere. Not only would
the sphere be expensive but it is totally unnecessary and causes the
spinning to be accelerate more slowly and its top speed to be slower due to
steam cooling by the sphere.
If the sphere was considered "necessary" then condensed steam would be spun
to the jets and expelled as liquid. Thus this is no quite a purely steam
turbine rather steam being used to expel denser water.
Consider the following alternate construction. Think home kitchen pressure
cooker.
This is a pot with a lid. (Don't mind the gap in the image.) Note the lid
need not seal rather only be heavy enough to stay in place. The heavier the
less steam escapes and the more goes to the spinner.
From the top we see the spinning part in place.
Removing the spinner we see a hole in the lid with a simple smooth, raised
surface surrounding it. The bottom of the spinner would have a matching
depression. The spinner itself would be hollow and the hollow tubes
attached. This does not require bearings or lubrication as they are
constanting keep apart either be escaping steam or by a layer of condensed
water.
And finally the finished device in action.
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