Labyrinth seal fitted on the back surface of a compressor wheel of a turbocharger:

A labyrinth arrangement is  fitted to the back of the compressor impeller to restrict the leakage of air to the gas side. It also prevents the oil being drawn into the compressor. Labyrinth seals use high rotational speed of the shaft to its advantage.

Labyrinth seals or glands are fitted to the shaft and casing to prevent the leakage of exhaust gas into the turbine end bearing, or to prevent oil being drawn into the compressor. To assist in the sealing effect, air from the compressor volute casing is led into a space within the gland. A vent to atmosphere at the end of the labyrinth gives a guide to the efficiency of the turbine end gland. Discoloring of the oil on a rotor fitted with a roller bearing will also indicate a failure in the turbine end gland.