Engine Order Reference
Key relationships for engine order excitation in turbomachinery — frequency, resonance speed and excitation sources.
Engine order frequency
f_EO = n * N / 60 f_EO [Hz], n = engine order [-], N [rev/min]
Resonance speed
N_res = f_n * 60 / n N_res [rev/min], f_n = natural frequency [Hz], n = engine order [-]
Common excitation sources
- Upstream stator vanes: EO = number of vanes
- Upstream struts: EO = number of struts
- Combustion hot streaks: EO = number of burners
- Inlet distortion: EO = number of distortion lobes