Trajectory of a rotor with processional or whirl motion

Rotation with processional or whirl motion ↓

<img>Rotor trajectory

This image is the raw data that recorded during a rotordynamic experiment. Two eddy-current displacement sensors are installed on the test rig. These two sensors lie perpendicular to each other in the cross sectional plane with respect to the rotor axis. Each sensor measures one displacement component of the rotor surface. The displacement components are later combined to form a time history of the rotor trajectory. It is shown in the image.

The rotor was rotating with respect to its axis under 40 Hz and whirling under 6 Hz. The two senors were simultaneously sampled at 2.56 kHz frequency and recorded about 10 s data. The trajectory image is produced by MATLAB with the actual raw data.