What does "clearance" refer to in gas turbine design?

In gas turbine design, "clearance" is primarily defined as the distance between rotating and static components within the engine. This spacing is crucial because it ensures that there is no contact between these components during operation, which could lead to catastrophic failure due to wear or damage. Proper clearance allows for thermal expansion, helps maintain operational efficiency, and minimizes the risk of rubbing, which can create unwanted friction and heat.

The design must account for variations in temperature and pressure that can affect the dimensions and tolerances of both the rotating parts, like turbine blades, and the static parts, like the casing. Managing this clearance effectively is essential to the overall reliability and longevity of the gas turbine system.