What is the purpose of seals in a gas turbine and name a common seal type?

• A. To prevent oil and air leakage and maintain pressure; labyrinth seal.
• B. To cool the turbine and reduce emissions.
• C. To control fuel metering.
• D. To provide mechanical support.

Answer: (A)

Seals in a gas turbine are there to stop oil and air from leaking out of the lubrication and bearing areas and to keep the proper pressure in those zones, while also helping keep hot gas paths from intruding into the lubricated sections and keeping contaminants out. This containment is crucial for reliable lubrication, shaft stability, and overall efficiency.

A common seal type used for this purpose is the labyrinth seal. It uses a series of tight clearances and staggered, labyrinth-like paths between the rotating and stationary parts. The complex path greatly reduces leakage without relying on contact, which makes it durable at high speeds and temperatures typical of gas turbines.

Other options don’t fit because cooling the turbine, reducing emissions, controlling fuel metering, and providing mechanical support are handled by other systems (cooling and emission controls, fuel system components, and bearings/structures, respectively).