Oil whirl is a condition peculiar to journal bearings. It manifests itself as a vibration of less than one-half rotational speed. It is caused by a lightly loaded bearing riding up on its high-pressure wedge and going “up over the top and around.” There are some temporary measures that can be taken to alleviate oil whirl. The temporary measures are to change the oil viscosity, by adjusting the oil temperature or a different oil. Another temporary measure is to run the machine in a more loaded condition. Oil whirl is aggravated by excessive bearing clearance. The cure is to increase the load on the bearing. This usually requires a redesign of the bearing and is best handled by the bearing or machine supplier. When oil whirl becomes severe, there is a potential for the shaft to rub the inside of the journal. This causes friction and subsequent localized heating. Oil whirl produces high vibration levels at 0.45X rotational speed. Oil whirl produces high vibration levels at 0.45X rotational speed.
This experiment helps the understand the effect of oil whirl on machinery vibration. The equipment at different shaft speeds can be conducted for studying the effect of speed on the vibration level in oil whirl.