Page 231 - Steam Turbines Design, Applications, and Rerating
P. 231
210 Chapter Eleven
where L = ⋅ n ± M
= 0, 1, 2, 3,...
n = number of packets
and
0 ≤ L ≤ N/2 [or (N − 1)/2 for N being odd]*
and
N = number of blades
A graphical depiction of this equation is given by Ewins and Imre-
gun. The horizontal designation is harmonic content and the vertical
designation is the nodal diameter. For a system having N blades and n
* Explanation: Where L is greater than or equal to zero, and where L is less than or
equal to N/2 or N-1/2 (for N being odd).
Figure 11.24 Continuously shrouded or
unshrouded bladed disk (40 blades).
(Dresser-Rand Company, Wellsville, N.Y.)
Figure 11.25 Eight packets, five blades in a
packet, total forty blades. (Dresser-Rand
Company, Wellsville, N.Y.)
