Certain Type Turbofan Engine Whole Vibration Model with Support Looseness Fault and Casing Response Characteristics

Figure 17

The time domain waveform and frequency spectrum before and after the noise reduction when rotating speed is 21000 rpm.

(a) The waveform before the noise reduction

(b) The waveform after the noise reduction

(c) The spectrum before the noise reduction

(d) The spectrum after the noise reduction