What is the operation principle of labyrinth seals?

• A. They Rely On Contact Between Mating Surfaces
• B. They Rely On Lubricant Film To Seal
• C. They Use Stepped, Tortuous Paths To Impede Gas Flow Without Contact
• D. They Rely On Magnetic Fields

Answer: (C)

Labyrinth seals work on a non-contact, throttling principle. They use a series of stepped, winding passages around the shaft so gas must pass through a long, narrow path. Each turn and tight clearance creates a pressure drop, effectively impeding leakage without any metal-to-metal contact. This non-contact design means the seal can handle high speeds and temperatures with minimal wear, which is exactly why the geometry, rather than a film or contact, governs its sealing effectiveness.

Relying on a contact between mating surfaces would cause wear and require different wear-friendly materials and maintenance. Seals that depend on a lubricant film trap oil or grease as the primary barrier, which is a different sealing approach. Magnetic-field-based seals aren’t the typical method used in turbomachinery labyrinth seals.