Gas Turbine Handbook : Principles and Practices

190 Gas Turbine Handbook: Principles and Practices
Figure 12-2. Dual spool gas turbine estimated parameter changes
with high pressure-turbine nozzle area change.
through the turbine nozzles and turbine blades, and along the rims
of the turbine discs to cool the metal temperatures exposed to the hot
gases. These cooling paths are small “sieve-like” passages that are
vulnerable to plugging by contamination in the gas turbine inlet air
stream. Even a partially plugged cooling passage will result in ‘local’
temperature increases that can be significant. The resulting damage
is often seen as localized burning or melting of the airfoil.