CNCCookbook Software and Information for Machinists

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Model Steam TurbinesThis page has my notes on model steam turbines. I haven't built one yet, but plan to someday.

W arning: Be careful with steam and especially steam turbine engines. Engines operate off energy and can generate significant forces. Steam explosions, bearing failures, and othermaladies can be extremely hazardous!

A full on gas turbine is on my list as well, but model steam turbines are much simpler to build. I believe Bogstandard was to first to make me aware they even existed through his postson the HMEM board, so I dedicate this page as a tribute to him and his wonderful "blingy" projects.

Steam Turbine Ref erence Material

The first modern steam turbine was invented in 1884 by Englishman Charles A. Parsons:

Parson's First Turbine...

There are two kinds of turbine, the impulse and reaction varieties:

Two kinds of Steam Turbine. Most models will be "impulse" turbines...

Most models will be of the impulse variety due to the difficulties of producing the complex curves for a reaction turbine. Most commercial turbines are reaction. With an impulseturbine, steam velocity is everything, but there are tradeoffs. An air powered engine will generate the most velocity with a converging nozzle such as is described on the three rotorturbine below. However, steam is heated and can expand. In that case, providing more volume just before injection to the rotor blades converts as much heat as possible to velocity. So,a diverging nozzle (such as the "trumpet" nozzle on de Laval's turbine below) works better there.

Another issue is operating efficiency versus RPM. One of Parson's essential insights was to use successive stages that each expanded the steam a bit more to extract maximumenergy from the steam expansion as well as designing a turbine that could run at a little slower rpm's than his predecessor's turbine Dr de Laval:

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