A method and apparatus for monitoring the condition of the thermal barrier coating
on turbine blades and vanes is provided. The coating is monitored with ultraviolet
sensors which can detect ultraviolet radiation emitted from electrical discharges
and glow coronas at the surface of the blades and vanes. Such electrical glow discharges
and coronas are the result of friction electricity found at the surface of blades
and vanes, and are also due to the high pressure, temperature and velocity conditions
within the turbine. As the thermal barrier coating deteriorates, the electrical
discharges and glow coronas and associated UV emissions decrease in magnitude or
have other characteristic changes, thus permitting monitoring of the corona to
detect changes in the coating over time.
