How are the inner and outer liners of the combustor protected?

The inner and outer liners of the combustor are protected primarily through circumferential film cooling. This technique involves the strategic introduction of cooling air along the surface of the liners. The purpose of this cooling is to create a thin, protective film of cooler air that insulates the liner surfaces from the intense heat produced during the combustion process.

This film acts as a barrier, preventing direct contact of the liner materials with the extremely high-temperature gases. As a result, this method not only maintains the structural integrity of the liners by reducing the temperature they experience but also prolongs their lifespan. Effective film cooling is essential in managing thermal stresses and ensuring the overall efficiency and reliability of the gas turbine's combustion section.

While thermal insulation and heat-resistant alloys do play roles in overall engine design and material selection, they do not provide the same immediate protective measure within the combustor environment as circumferential film cooling does. Periodic maintenance, on the other hand, supports the ongoing performance of the system but does not provide direct protection during operation.