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Campbell, Goodman, and SAFE Diagrams for Steam Turbine Blades 215

Figure 11.30 Resonant-vibration stress.
Mode 1 first tangential
2–6 tangential fixed supported mode
7 second tangential
Stimulus I—1x nozzle passing
II—2x nozzle passing
(Dresser-Rand Company, Wellsville, N.Y.)

By using an energy method, Weaver and Prohl calculated the
response of a packet of blades due to nozzle-passing excitation. The tur-
bine disk in their paper contained 6 blades per packet with a total of
192 blades. The number of nozzles was 92. Their response calculations
showed that the response of the blades was highest when the nozzle
passing frequency coincided with the tangential fixed supported
modes. The first tangential mode response was very low compared to
the tangential fixed supported mode response. A Campbell diagram is
drawn using their data (Fig. 11.28). A SAFE diagram using their fre-
quency numbers (assuming that the disk is very stiff in tangential
direction) has been constructed. Assuming that the excitation comes