What is the primary function of gland steam in a steam turbine?

The primary function of gland steam in a steam turbine is to seal the turbine rotor carbon rings. Gland steam is introduced at the seals of the turbine to prevent the escape of steam, which not only maintains efficiency by reducing losses but also protects the turbine's internal components from potential external contaminants.

By effectively sealing the rotor, gland steam minimizes the amount of steam that can leak out of the turbine, ensuring the system operates at optimal pressure levels and efficiency. This sealing capability helps in maintaining the performance and longevity of the turbine, as it reduces wear on the carbon rings and enhances overall reliability.

The other functions listed, such as lubrication, cooling, and increasing steam pressure, while important in other contexts and systems related to turbines, do not accurately describe the primary role of gland steam. These aspects are typically managed by other systems within the engine architecture.