Turbines, steam reaction 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. 

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

The dominating principle in turbine design involves expression of the efficiency of the energy conversion in nozzles and buckets or in reaction blades, usually referred to as stage efficiency, as a functon of the ratio u/C. The blade speed u, feet per second, is calculated fi em the pitch diameter of the nozzle and thus determines the size of the wheel at a given number of revolutions per minute and C, also in feet per second, is the theoretical velocity of the steam corresponding to the isentropic enthalpy drop in the stage, expressed by the formula... 

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