Turbines performance charts

Using the turbine performance chart in Figure 9.9 we can find the efficiency and speed of the turbine. If we find the intercept np from 0.75 on the jc-axis and 2.8 on the pressure ratio axis, we see that it is very close to the rotor speed factor = 5000 line, and in the r] = 0.70 efficiency region. (More or less optimum operating conditions in fact ) So we can conclude that... 

Figure 9.9 Performance chart for a typical small radial turbine.

Figure 5-7 is an analysis flow chart for examining types of turbine impeller performance requirements. 

The theoretical values for enthalpy may be read from a Mollier chart, where hj is the enthalpy of the steam at the turbine inlet, and hg is the enthalpy of the steam at the exhaust pressure and at the inlet entropy. The expansion of steam through the turbine is theoretically at constant entropy. These theoretical rates must be corrected for performance inefficiencies of the particular turbine. The calculations presented here are good for the average design, but exact values for a particular make and model turbine must be quoted by... 

Comments The calculation can be performed graphically on the Mollier chart, as shown in Figure 6-q. The procedure is very similar to that for turbines and the calculation is left as an exercise. 

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