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Given is a shaft powered by a steam turbine that rotates unloaded (i.e without generator) at $ \omega $ rad/s and a torque of $T$ Nm. How would one match a generator to extract power requiring a certain torque/rpm such that the shaft does not slow down or better operate at maximum efficiency?

I imagine that when choosing a generator that matches rpm and torque exactly the shaft will not rotate at all.

Assume all relevant parameters are known.

jessegerritsen
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  • Why will the shaft become stationary? Or did you mean stationary relative to the generator shaft? – Solar Mike Oct 12 '22 at 09:17
  • @SolarMike I would assume that under a certain generator load the shaft will settle at a certain rpm. The shaft without a generator will rotate at an rpm such that driving force (by the steam) matches the friction force in the bearings. – jessegerritsen Oct 12 '22 at 09:22
  • The Torque $T$ when appied to the generator will rotate the generator at at $ \omega $ rad/s. The shaft turns. Very unclear at what you are asking. – StainlessSteelRat Oct 12 '22 at 17:16

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The efficiency of a steam turbine is driven by steam inle tenergy and outlet temp/pressure. I have never heard of a steam turbine that will run unloaded without overspeeding without speed control. Clearly, taking power out of the system via a generator will slow the turbine down. Generally, this is covered by a governor which introduces more steam when it does.

Your "given" condition isn't realistic unless you found a turbine running out in the wild, which seems unlikely. Generators are matched to turbines based on the turbine nameplate data and the steam available to it.

Tiger Guy
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