Overall Thermal Performances of Double-Wall Effusion Cooling Covered by Simulated Thermal Barrier Coatings

A coupling configuration of double-wall cooling and exterior surface thermal barrier coating (TBC) is one of the most promising thermal protection methods of hot components of modern gas turbine. The combined influences of coating thickness, impingement layout, and cooling air flowrate on the overall thermal performances of such configuration were discussed deeply, to provide the valuable guidance of design. Overall effectiveness measurements were implemented under engine-matched Biot numbers and mainstream-to-coolant temperature ratio. Conjugate heat transfer simulations provided the additional information difficult to be acquired by the measurements. The results indicated that the contribution of TBC is much larger than that of increasing the cooling air amount. The thicker TBC can produce the stronger insulation, while the higher risk of thermal damage of itself. The larger coolant flowrate enlarges the benefit of TBC, while the trend is suppressed by the thick TBC. The constant coating thickness cannot bring to the uniform metal temperature, which can be solved through properly adjusting the backside impingement. The trends in overall effectiveness with TBC's thickness are independent on the change of internal impingement.