Centrifugal Pumps Design and Application 2nd ed - Val S. Lobanoff, Robert R. Ross (Butterworth-Heinemann, 1992)

Pipeline, Waterflood and CO 2 Pumps 155
Figure 10-20. Blade passing frequency.
ing one or more of the sympathetic frequencies, or changing the pump
generating frequency by a change of speed or blade number. With a
bolted-on crossover a simpler solution is to add calculated pipe length
between pump case and cross-over, which will change the wave length
and relocate the acoustic frequency away from the generating frequency
(Figure 10-21),
Figure 10-21. Acoustic frequency.