Turbines, steam impulse stage

TTiere are two main types of expansion turbines axial flow and radial flow. Axial flow expansion turbines are like conventional steam turbines. They may be single-stage or multistage with impulse or reaction blading, or some combination of the two. Turbines of this type are used as power recovery turbines. They are used where flow rates, inlet temperatures, or total energy drops are very high. 

Figure 14-16G. Impulse type single stage steam turbine with shaft type governor. (Used by permission Westinghouse Electric Corp., Steam Div.)...

Liquid turbines are large, slow-moving devices, and gas and steam turbines are small, fast-moving devices. This is easiest to see for an impulse turbine, for which we previously showed that the optimum velocity of the blade is one-half that o f the jet. So the speed of a single-stage impulse turbine rotor is set by the available jet speed. At Hoover Dam the fluid drops about 700 ft. Applying Bernou can solve for the... 

The first successful steam turbine, developed by de Laval [4], was a simple one-stage impulse turbine, as described above, and it turned at about 20,000 rpm. 

Steam turbine stage designs are generally either of an impulse or reaction type. 

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