Thermal Performance of a Ceramic Coated Turbine Vane under Transient Gas Conditions

The thermal performance of an air-cooled turbine vane, uncoated and coated with the NASA thermal barrier coating system (yttria stabilized zirconia plus NiCrAlY bond), was experimentally studied at both transient and steady state gas conditions in a four-vane cascade. The steady state full-throttle and idle gas conditions investigated were 1550 K, 8.3 atm and 940 K, 7.1 atm, respectively. The ceramic coating reduced the temperature gradient within the airfoil and increased the time constant of the airfoil metal wall by 20 to 50 percent compared to the uncoated vane. The metal temperature of the ceramic coated airfoil also lagged changes in the gas temperature by about 0.4 seconds. In addition, the ceramic coating increased the full-throttle airfoil cooling performance which resulted in a decreased metal temperature of 200 kelvins.